Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: Loquah on April 06, 2014, 01:58:54 PM
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I'm just about to embark on some hot-rodding of my S.E.X. and it got me to thinking I should consider the Mainline next. Looking at it though, there aren't a lot of caps to play with as far as I can tell so I wanted to check if anyone can suggest any specific caps worth changing?
My first thought was the Dayton 10uF caps on the output tubes. Are these operating as output caps?
The only other caps I saw were the tiny yellow ones that bridge a couple of the pins on each output cap (I can't easily see them enough to provide a better description at the moment). Would these benefit from replacement with some nice Russian teflons?
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The 10uF caps are the coupling caps. They can be 10-20uF, and probably should carry at least a 200V rating. (160V might work, but would really be pushing it)
The tiny yellow caps on the sockets are out of the signal path and implemented for silent operation. There's a good chance that if you swapped them for something else, that alternate cap would not perform as well, and you would likely end up with a dysfunctional Mainline.
The 0.1uF 400V capacitors on the center PC board can be swapped out as well. They won't have nearly the influence that the 10uF caps have, and the available space on the PC board is somewhat limited. You can help yourself out by using a 250V capacitor here, which will see more than 250V at start-up, but will operate at 225V otherwise, which I would consider acceptable.
-PB
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Paul, i don't know the exact Mainline circuit but I know it's a spud so maybe instead of coupling you're referring to parafeed caps?
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Yeah, he means the parafeed coupling caps, that is, the caps that couple the plates to the output transformers.
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Cm'on, you're usually not that diplomatic!
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You caught me on a good day. So how's that projector?
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The 10uF caps are the coupling caps. They can be 10-20uF, and probably should carry at least a 200V rating. (160V might work, but would really be pushing it)
The tiny yellow caps on the sockets are out of the signal path and implemented for silent operation. There's a good chance that if you swapped them for something else, that alternate cap would not perform as well, and you would likely end up with a dysfunctional Mainline.
The 0.1uF 400V capacitors on the center PC board can be swapped out as well. They won't have nearly the influence that the 10uF caps have, and the available space on the PC board is somewhat limited. You can help yourself out by using a 250V capacitor here, which will see more than 250V at start-up, but will operate at 225V otherwise, which I would consider acceptable.
-PB
Thanks PB. The S.E.X. will be my test dummy before I move to the Mainline. I'll be sure to post impressions.
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Slight issue with the ps board. Interesting enough the tubes have filaments that are heated by a voltage of, yes, you guessed right 6.3 volts! Mine has an issue and the voltage starts decreasing over time so the image starts fading. We diagnosed this over the weekend and Curt will send a new board. Not very different from debugging an issue with a tube amp :)
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Wow. Any ideas on the cause?
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Apparently a faulty trimpot.
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Lachlan -
You're following that Dan and Xavier have thread-jacked this to be about CRT projectors and not Mainlines, right?
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Lachlan -
You're following that Dan and Xavier have thread-jacked this to be about CRT projectors and not Mainlines, right?
Haha - no, I thought they were referring to the power supply board in the Mainline. Thanks for preventing further embarrassment on my part!! :o
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How many 10uF caps would I be looking at replacing if I wanted to upgrade? I'm still waiting on my Mainline (and the manual), but I'd like to order the caps in before the Mainline kit gets here so I can put them in during the initial build.
For these 10uF caps, should I go with a lower voltage (e.g. 250V) or with a higher voltage (e.g. 400V or more)? How would that affect the function of the cap? the sound?
Think there would be any benefit to replacing the Daytons with 10uF 400V Mundorf M-CAP MKP Series ??
In your opinion, what are the best brand and/or type of cap? Metallized Polypropylene Capacitors? Paper In Oil Capacitors? Paper In Wax Capacitors? Polyester Film Capacitors?
Thanks!
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How many 10uF caps would I be looking at replacing if I wanted to upgrade? I'm still waiting on my Mainline (and the manual), but I'd like to order the caps in before the Mainline kit gets here so I can put them in during the initial build.
For these 10uF caps, should I go with a lower voltage (e.g. 250V) or with a higher voltage (e.g. 400V or more)? How would that affect the function of the cap? the sound?
Think there would be any benefit to replacing the Daytons with 10uF 400V Mundorf M-CAP MKP Series ??
In your opinion, what are the best brand and/or type of cap? Metallized Polypropylene Capacitors? Paper In Oil Capacitors? Paper In Wax Capacitors? Polyester Film Capacitors?
Thanks!
Possibly a good idea to hold fire for a little bit longer as a couple of Mainline users have recently installed some rti 10uf 310VDC Teflons (still some available) initially made for use by Audio Research in their reference tube pre-amp. I am hoping we will get some feedback soon they have the potential/reputation to be a bit special. They should be a good way into the 500hr burn in that the Teflons require now.
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Think there would be any benefit to replacing the Daytons with 10uF 400V Mundorf M-CAP MKP Series ??
Don't know much about the Daytons but the Mainline deserves much better than regular MKP series, i would want supremes at a minimum.
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Looked up some cap ratings online, and the Mundorf Supremes seem to get really high ratings consistently:
http://www.laventure.net/tourist/caps.htm
https://www.head-fi.org/t/284863/orgy-of-capacitors-the-cap-thread
http://www.humblehomemadehifi.com/Cap.html
How many do I need to order? Would there be any benefit from going for 12uF or 18uF instead of 10uF ??
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Looked up some cap ratings online, and the Mundorf Supremes seem to get really high ratings consistently:
http://www.laventure.net/tourist/caps.htm
https://www.head-fi.org/t/284863/orgy-of-capacitors-the-cap-thread
http://www.humblehomemadehifi.com/Cap.html
How many do I need to order? Would there be any benefit from going for 12uF or 18uF instead of 10uF ??
You need 2 caps. I'll let others confirm the benefits or different capacities to be certain, but my understanding is that larger capacitance doesn't really help so long as you start at the right level (i.e. too little is bad, but more than enough isn't better).
Can you get some for me while you're at it?? :P
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Bottlehead designs for a flat response at or below 20 Hz, but PJ always states a range for Parafeed caps. Increasing the value of their capacitor will extend the low end. Whether or not it will be audible depends on a list of factors.
For instance the 18uF will go almost an octave, 8 notes, lower than the 10uF. PJ urges everyone to experiment and report the findings.
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Bottlehead designs for a flat response at or below 20 Hz, but PJ always states a range for Parafeed caps. Increasing the value of their capacitor will extend the low end. Whether or not it will be audible depends on a list of factors.
For instance the 18uF will go almost an octave, 8 notes, lower than the 10uF. PJ urges everyone to experiment and report the findings.
My wallet thanks you for the extra exercise of opening and closing over and over... ;)
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If I installed a switch to change between capacitors while the Mainline was still on, does anybody see any potential problems associated with this?? I'd be looking to install several caps attached to the switch so that I can do quick A/B testing during operation.
Would a higher capacitance value affect the higher frequencies?
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If I installed a switch to change between capacitors while the Mainline was still on, does anybody see any potential problems associated with this??
Would a higher capacitance value affect the higher frequencies?
I wouldn't recommend the switch. You'd be switching high voltage DC (even if you switched the cold side of the cap, there will be a charge spike across the contacts)
The actual construction of the capacitor will influence high frequency tonal balance, but not the actual value itself.
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Alrighty, so I am about to order 15uF Mundorf Supreme caps for my Mainline, but before I do I want to make sure I've got this right:
A higher capacitance will not cause a change in the tonal balance of the amp, but could lead to greater low frequency extension ??
Main difference would be the cost difference between a 10uF and 15uF capacitor in this case ??
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We can't tell you that putting in a different cap won't affect the tonal balance. Putting in a larger cap can move the resonance of the LCR circuit, and that can change the shape of the bass response. Going bigger is usually not too much of a problem. But to be sure of what it going on the best thing to do run a frequency response curve. Beyond that different materials and construction can change the sound in different ways and you really just have to smoke it and see.
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So I ended up getting 10uF Mundorf Supreme caps, which I will burn in (200-300hrs) and do a review on to let others know how they modify the sound of the Mainline.
Question:
Would you foresee any problems if I also tried running both the Mundorf and the Dayton caps in parallel to see how it would sound?? Probably won't run that combo long term, but thought it may be worth a try ;D
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There's no harm in trying, but I wouldn't expect to be very happy with the results.
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. . . Would you foresee any problems if I also tried running both the Mundorf and the Dayton caps in parallel to see how it would sound?? . . .
I would add the Dayton with a pair of jumpers. This is easier and if you like it you can solder them in.
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Hmm, I prefer the mechanical stability that comes along with a solder joint. De-soldering is relatively easy using a de-soldering braid or pump.
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But PB/CB said it might not be a positive combination. I'm lazy and take the easier way out.
I have paralleled/bypassed several dozen caps. I always make the sonic derision with jumpers because I have to add the cap, remove it, add it, remove it till I am sure of what I'm hearing.
Of course, I break in my caps first so that isn't a factor.
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I did exactly that when adding a bypass to the power supply in my Quickie, without being able to switch in/out quickly i would never have been able to tell the difference between the cap and my imagination.
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Would something akin to the attached image (for each side) work if I wanted a permanent setup where I could switch to one, or both, of the caps on at a time. The switches would only be flipped when the amp was off. Switches would be flipped to discharge when the amp is off to bleed the caps, then switched to the desired setting for which cap I want in the circuit. Would there still be a charge spike across the contacts in this situation if switching was done with amp off?
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It's really not a great idea to switch caps like this with DC across them. (Note that for speaker crossovers, this does not present any issues)
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I still don't understand, is it a bad idea to switch them only when the amp is on, or bad idea in general even when the amp is off and unplugged?
My idea was that after I turn the amp off and unplug it, I switch both of the switches to the "discharge" position to bleed them through their respective discharge resistors, then switch both of the switches back to the "off" position, thereby taking both of the caps out of the circuit. Then by switching one or the other switch to the "cap on" position it would essentially be like having only the one cap directly soldered in, then I can plug the amp back in and turn it on??
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The capacitors retain voltage for some time after the amp is turned off. They have dangerous voltages when it is on.
If you wait 30s after the amp is turned off the voltage should be gone. But I worry more about your picking up noise due to all the additional wiring.
Bottlehead is very careful in their design of circuits. The Seduction/Reduction audio path is only about 3" long, maybe 4". But this keeps the wiring from picking up noise. You could pick up anything from hum to a radio station.
It is a situation of trying it and see if it picks up any extraneous noise.
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If you're going to work it like that, you don't need the discharge resistors.
Just put the switches inside the amplifier, and you'll be fine. (This will prevent curious fingers from switching them while the amp is running)
In the Mainline, I would expect those caps to retain charge for a maximum of 10 seconds after you shut the unit off.
-PB
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Suffice it to say, the Mundorfs are a *little* bigger than the Dayton caps...
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LOL. Which Mundorfs are you using (model and capacity)?
Has anyone tried Auricaps? I'm thinking of those as a direct replacement for the Daytons.
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I didn't want to spend too much; went with the Mundorf Supreme 10uF 600V.
I looked at ratings for the Auricaps in comparison to the Mundorf's (see my previous post with comparison websites), decided that the Supreme's were the ones for me.
For those interested, partsconnexion.com has a sale of 20% off their caps until midnight April 30th ;D
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Thanks for reminding me of the links.
I'm left wondering which of the 2 options (Mundorf Supreme vs Auricap) will provide a more faithful, transparent rendition of the recordings? I love the Mainline for its neutrality and don't want to make it overly warm. I love the Mundorf Silver / Gold / Oil Supremes in the S.E.X., but there's no doubt they're a little on the warm side so not sure if the Mundorf Supremes polys will bring the same warmth to the Mainline. Reports suggest that the Auricaps have a little warmth too, but perhaps not as much as the Mundorfs. That said, the write-ups you linked to would suggest that the Supremes offer superior transparency... I'm torn! ???
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Sorry for the double post, but this is the sort of review that has me confused. Great info, but I'm not sure if I'm sacrificing something valuable (e.g. high frequency detail) for the other benefits of the Supremes.
Coming from the Auricap, the Supreme was on the other side of the fence, highly musical, entertaining and perhaps not the most accurate sounding of capacitors. Although the tonal balance is quite neutral, the Supreme has a very polished and refined midrange with the right amount of meat throughout the frequency range. Musical notes are presented with texture and fine nuances, making the Auricap sound dry in comparison.
Easily the most pleasing of the caps tested this far, the Supreme combines the weight and treble extension of the Claritycap ESA with the speed of the Wima MKP10. Coupled to its highly resolving and musical nature and affordable price, do consider the Supreme for your next purchase. To nitpick, the only criticism against the Supreme against its competitors so far would be a slight loss of resolution in extreme high frequencies, and its artistic rather than honest approach towards music. The latter point is subjective anyway and you may personally have a preference for this.
Taken from: http://singaporehifi.blogspot.com.au/2010/09/capacitor-shoot-out.html
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Loquah, wait until you have upgraded the .1uf caps in the S.E.X. amp before forming any opinions on the Mundorfs. I'm pretty sure you are experiencing what i found but in reverse, the .1uf poly caps are what you are really listening to now, not the full range of the Supremes abilities.
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Oh, good point. I was thinking that by doing a reverse order of yours that I wasn't restricted by the other caps at all, but of course they are all connected a linked in a single system.
I'm hoping the teflons will arrive this week...
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That's the thing having two sets in a row its very hard to differentiate each other and makes the whole process that bit more complicated. Also dont forgot about the burn in time too, the Mundorfs seemed to settle in very quickly for me but the Russian Teflons took forever, as in 100's of hours. Just be prepared to wait it out as they will sound terrible for a while.
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That's the thing having two sets in a row its very hard to differentiate each other and makes the whole process that bit more complicated. Also dont forgot about the burn in time too, the Mundorfs seemed to settle in very quickly for me but the Russian Teflons took forever, as in 100's of hours. Just be prepared to wait it out as they will sound terrible for a while.
Is my memory correct that I can burn-in the teflons by rigging them inline with appropriate resistors and driving signal through them from an amplifier? I.e. from positive terminal of output to resistor, then from resistor to capacitor input lead, then from capacitor output lead back to the negative terminal on the amp? I'm thinking of using my Quattro (solid state) amp to do the hours so will rig up a 6.3mm jack to appropriate positive and negative connections similar to speaker taps.
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Thanks for reminding me of the links.
I'm left wondering which of the 2 options (Mundorf Supreme vs Auricap) will provide a more faithful, transparent rendition of the recordings? I love the Mainline for its neutrality and don't want to make it overly warm. I love the Mundorf Silver / Gold / Oil Supremes in the S.E.X., but there's no doubt they're a little on the warm side so not sure if the Mundorf Supremes polys will bring the same warmth to the Mainline. Reports suggest that the Auricaps have a little warmth too, but perhaps not as much as the Mundorfs. That said, the write-ups you linked to would suggest that the Supremes offer superior transparency... I'm torn! ???
Check out the new Auricap XO series of caps (www.audience-av.com/capacitors/axo_description.html) over the Supremes if you want neutrality; they seem to be an improved version of the previous version of Auricaps. I'm listening through a pair of HD800's with an Anedio D2 DAC - two very precise/clinical sounding pieces of audio gear - so I wanted to add slightly more musicality to my Mainline through a slightly off neutral cap; Mundorf Supremes.
Also check out the Jantzen Superior Z-Cap:
https://www.parts-express.com/jantzen-10uf-800v-z-superior-capacitor--027-497
Jantzen Audio Superior Z-Cap MKP 800VDC - 2% tolerance
Technical specifications: metallized polypropylene film, high-grade copper lead wire. The finish is a flame-retardant tape wrap, and the end of the caps is resin sealed to protect against humidity. Loss angle tan = 0.00002 to 1K; Loss angle tan = 0.00001 to 10K.
Sound: Very neutral and coherent balance, they don't seem to high-light anything and I mean that in a positive way! They are a little flatter in presentation than their more expensive brother, the Silver Z-Cap but still better than the Clarity Cap SA in depth and spatial information. In direct comparison with a Clarity Cap SA they are less up-front in the lower treble and have a better texturing of acoustic instruments like a violin for example. In the upper treble they are slightly brighter than a Mundorf Silver/Gold which probably explains the good spatial information and separation. Compared to the Jantzen Audio Silver Z-Cap I find them the more musical of the two and I will definitely add them to my favourites list.
Verdict: 10
That was taken from: http://www.humblehomemadehifi.com/Cap.html
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At least as of this morning, it looks like there's one pair of RTI's left in stock at tctubes if you want to go the teflon route. (http://tctubes.com/teflon-capacitor.aspx)
Mine are only at 100 hours or so, and I believe Jamie said he was still hearing changes at around 500 hours (which is what AR apparently recommends in terms of teflon burn in) - so I'm probably in no position to give a final verdict. But they do seem to be excellent caps!
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At least as of this morning, it looks like there's one pair of RTI's left in stock at tctubes if you want to go the teflon route. (http://tctubes.com/teflon-capacitor.aspx)
Mine are only at 100 hours or so, and I believe Jamie said he was still hearing changes at around 500 hours (which is what AR apparently recommends in terms of teflon burn in) - so I'm probably in no position to give a final verdict. But they do seem to be excellent caps!
Hi Mike. My RTI's took a shade over 500hrs to settle down they have been stable for the last week or so now. I'm looking forward to hearing some feedback from you guys on how they are working out in the Main line. I can not imagine doing without them now.
Jamie
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Thanks for the various links.
In Australia, buying high quality caps is a little tricky. So far the only local retailer I've found stocks Mundorf and Auricap (hence my suggested options for the Mainline). Shipping from companies like Parts Connexion, etc. is prohibitively expensive
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Just pulled the trigger on those last 2 RTI teflons for my Mainline. My first cap upgrade! Pretty excited :-)
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Just pulled the trigger on those last 2 RTI teflons for my Mainline. My first cap upgrade! Pretty excited :-)
Glad you were able to snag that last pair! They're a little too large in diameter to fit down against the top plate where the stock caps sat, so I ended up sticking zip tie mounts on the sides of my output transformers to hold them in place. In truth, the leads on the RTI's are so stiff that this really isn't necessary, but I understand vibrations can impact the sonics of caps so I figured it couldn't hurt.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fcdn.head-fi.org%2F1%2F12%2F12b2ab2a_20140322_232102.jpeg&hash=29c8c963de6e62949e2f57b681cf9b474f94073f)
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Hi Mike,
Thanks for the hint. Did you order your RTIs matched? Also, did you notice any improvements in sound?
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In truth, the leads on the RTI's are so stiff that this really isn't necessary, but I understand vibrations can impact the sonics of caps so I figured it couldn't hurt.
It's good that you anchored them down, the 5 lug terminal strips will thank you.
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A curious question about fitting those rti caps in the Mainline. Would there be enough room to fit them in the space they are currently position but closer to the top plate if the boards were offset a little to make the gap wider or is there something hidden that I cant see that will not allow them to drop down or perhaps increasing the height of the boards stand off so they would slide in underneath? Main line build pics are a bit thin on the ground to see.
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Mainline Jamie... it's your destiny ;D
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A curious question about fitting those rti caps in the Mainline. Would there be enough room to fit them in the space they are currently position but closer to the top plate if the boards were offset a little to make the gap wider or is there something hidden that I cant see that will not allow them to drop down or perhaps increasing the height of the boards stand off so they would slide in underneath? Main line build pics are a bit thin on the ground to see.
Jamie, I need to do a little work on my Mainline so I'll take a look when it's upside down and see if I can take a pic or 2 for you.
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Jamie, here are some pics and even a video that will hopefully help...
http://youtu.be/MVpA4FvrmrI
The link above may not be live straight away as it's still processing at the time of posting.
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Lachlan that's great actually thanks.
Edit actually its fantastic because I can clearly see the easiest option as there is plenty of space would be to move the OT transforms slightly further to the back of the Mainline. If not covering the top like I have done with carbon on the Crack I would fill the holes with weld sand flush and re-drill the top plate for the new position.
Thanks
Jamie
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Most 10uF caps that carry a 200V rating will fit without this much effort.
You may also consider using longer standoffs under the C4S boards, if you are just on the edge of being able to squeeze them in.
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... the easiest option as there is plenty of space would be to move the OT transforms slightly further to the back of the Mainline....
If you move the transformers that direction they will pick up hum from the power transformer. They are centered fore and aft on the power transformer because there's a null in the pickup pattern at that point.
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What do the caps attached directly to the 6C45 tubes do? Any point replacing them?
I've just ordered some Russian Teflons for the caps on the 12AU7 board and will probably get some Mundorfs or Auricaps to replace the 10uF Dayton. I've read as much as I can and still can't decide between M-Cap Supremes and Auricap high resolution. Any suggestions?
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What do the caps attached directly to the 6C45 tubes do? Any point replacing them?
These are RF suppression caps that are out of the signal path. Substituting them with something else would potentially make the amplifier sound a lot worse.
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What do the caps attached directly to the 6C45 tubes do? Any point replacing them?
I've just ordered some Russian Teflons for the caps on the 12AU7 board and will probably get some Mundorfs or Auricaps to replace the 10uF Dayton. I've read as much as I can and still can't decide between M-Cap Supremes and Auricap high resolution. Any suggestions?
For a slightly more dry and airy presentation, I'd say go with the Auricap XO. The Supremes that I have in now are supposed to have a little more weight in their upper mid-range, and maybe very slightly warmer and smoother sounding presentation.
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If I wanted to get picky, what way should my capacitors be facing in reference to the inner vs. outer foil? Inner foil towards the output transformers?
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What do the caps attached directly to the 6C45 tubes do? Any point replacing them?
These are RF suppression caps that are out of the signal path. Substituting them with something else would potentially make the amplifier sound a lot worse.
Lucky I checked!
Is there any point changing caps other than the 2 pairs of Daytons? I think the only others in the kit are the various power supply caps. Would upgrading to Panasonics or something similar be noticeable in any way?
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If I wanted to get picky, what way should my capacitors be facing in reference to the inner vs. outer foil? Inner foil towards the output transformers?
Yes, that's what usually works best.
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Lucky I checked!
Is there any point changing caps other than the 2 pairs of Daytons? I think the only others in the kit are the various power supply caps. Would upgrading to Panasonics or something similar be noticeable in any way?
The various power supply capacitors are Panasonics. You can look for 10,000 hour rated variants if you're looking to run different parts.
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Whoops. I was carelessly referring to the hi-end Panasonics I was recommended for my friend's Crack that I'm building. Careless because: A) I didn't confirm what was already used and B) because I didn't specify which Panasonics I was referencing as an upgrade. Sorry about that!
For the main caps, I went for some Auricaps which should arrive today. I decided that I can always spend more later for a further upgrade if I want to try Mundorfs, but also decided to keep the Mainline as neutral and accurate as I can whereas the Mundorfs are a bit warm and lush (which is great in my SEX, but I want some variety)
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Yeah, a huge strength of the Mainline is that it does not require high voltage parafeed capacitors. This allows one to look more for the 200V rated speaker crossover caps, which are not all that large and reasonably inexpensive.
Although the amplifier will have more than 200V across these caps at start-up, the voltage will drop within 5-10 seconds, which is not particularly taxing. Film and foil caps in particular seem quite tolerant to this.
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So would you suggest changing some of the power supply caps for that nth level of modification / upgrading insanity?
If so, what would an example option be to replace the PS caps with?
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I installed the Auricaps tonight and I'm really happy based on very preliminary impressions.
They're much bigger than I expected (based on the pic on the supplier's site), but just fit between the C4S boards and the output transformers. I'll provide photos of the finished install tomorrow.
Very early impressions (<10 minutes of play time) are that they are completely neutral (as reported in various reviews), but incredibly transparent with rich, deep layering.
I'm off to bed now, but looking forward to some quality time spent with the Mainline tomorrow and some more detailed impressions to share once burn-in is more complete.
On that note, can anyone tell me roughly how long I should expect poly caps to take to burn-in fully?
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I would give them roughly 100 hours before considering them fully burnt in. Recommendations on needed burn-in time will vary considerably from which source the information is taken from.
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Thanks swich! If they're going to get better still, I'm very excited! I've put about 2 hours on them now and they're sounding marvellous.
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I installed some FT-3 teflon caps in the regulator board tonight and honestly can't hear any noticeable difference, even without burn-in when these caps can be a little harsh. Is it safe to assume that changes to the regulator board caps shouldn't really affect the sound or might I be best waiting for burn-in?
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That position has some sonic influence, but it's pretty small. The 0.1uF/220 Ohm resistor presents a low impedance at high frequencies, which stabilizes the operation of the TL431.
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Thanks for clarifying :)
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Thanks everyone for all your help with capacitor upgrade options / discussions, etc. I posted all my thoughts on both the S.E.X. and Mainline upgrades over at Head-Fi, but here's what I wrote in case you don't want to have to split time across 2 forums:
S.E.X Attenuator & Capacitor Upgrade - May 2014
During May 2014 I began to modify my S.E.X. and Mainline amps beginning with the volume pot in the S.E.X. which I replaced with a stepped attenuator, assembled using high quality Dale Vishay resistors. I chose this particular attenuator because the Dale resistors are known to be very transparent and are actually the same as those used in the Mainline kit. By all accounts, you can achieve similar results with other options - the key is transparency.
Attenuator Installation
The first thing to note if you are changing your attenuator (or potentiometer) is that you might need to carve out a bit of extra space from the locking channel where the pin / tab of the attenuator sits into the chassis plate in order to prevent it spinning. Thankfully, the aluminium chassis plate is easy to work with using either a hand-file or a dremel. In my case I had to lengthen and slightly enlarged the stock groove linked to the hole for the volume pot in the chassis plate. This isn't visible from the top once the volume knob is in place so don't stress if it's not the tidiest job ever (so long as you don't overshoot the width of the volume knob, but that would take some extreme carelessness).
Once the hole is ready, mounting the new attenuator is as easy as the stock one. Remove the supplied nut and washer(s), insert the spline through the hole, align the locking tab / pin and tighten the nut from the top side of the chassis. That's it for mounting - simple! The next step is wiring and that can change depending on the model of attenuator you choose so please refer to the provided instructions for your attenuator of choice and the instructions from the S.E.X. kit. If you get stuck, the wonderful people on this forum can also usually help.
Do be aware at this point though that you may find the stock volume knob sits a little higher than it used to. It's not a major drama, but for the aesthetically inclined, you might need to modify the stock knob or track down a different one if you want the knob sitting flush against the chassis.
Attenuator Sound Improvements
You're not going to make a change like this unless there's a payoff so let's discuss what happens when you change the attenuator. The exact changes may vary depending the brand / model used, but if you go for something known for transparency (like I did) then you'll get a nice increase in the detail and clarity of your S.E.X. The signature of the amp doesn't change significantly other than perhaps a slight bit more brightness, but it's subtle enough that I'd say to expect no real change in signature and just an increase in detail retrieval and texturing of sounds.
As an upgrade, I would say it is absolutely worth it. Including the time taken to modify the hole in the chassis I would say this is a 1-2 hour project and delivers a sound upgrade second only to the C4S mod. You can complete this mod on a budget of about $50 USD, but can also spend a bit more for more exotic attenuators if you want to.
Capacitor Upgrades
Next on my list was a double-barrelled capacitor upgrade. I approached the upgrade in 2 stages at the excellent advice of either JamieMcC or mcandmar - I apologise for not remembering which one gave that specific advice, but they both deserve kudos for their input and support over the course of multiple mod discussions around capacitors and the like. The reason for the 2-stage approach was to isolate the impact of each pair of capacitors, but the problem was that the sound was still limited by other caps in the system so I am going to summarise the whole upgrade in one hit because I can't truly describe the full potential of the FT-3 teflons I installed first without having upgraded the other (output) caps which then brought their own influence to the sound. Hopefully that makes sense...
I started off installing some FT-3 0.1uF teflon capacitors (the same as the ones used in the Mainline upgrade below) and immediately noticed improvements even though they require significant burn-in. These caps replaced the pillow-shaped brown / orange capacitors that sit over the tube sockets. Early improvements I noticed were cleaner, clearer textures in the sound and better layering of instruments in the soundstage (i.e. different instruments were now more clearly defined 'in space' within the soundstage). As I said above though, the full impact of the teflon caps couldn't reveal itself because they were hidden behind the stock output caps (which are good, but able to be improved).
Stage 2 was the installation of output capacitors - the ones that connect the sound to your ears (kind of). I chose the Mundorf Supreme Silver / Gold / Oil caps for this purpose after doing a lot of reading about this particular model's excellent warmth and midrange. I decided that the Mainline should stay as neutral as possible while the S.E.X. would become my fun, organic, musical amp. Don't get me wrong though - this doesn't mean I was trying to turn the S.E.X. into some kind of thick, syrupy mid-monster. I wanted musical, enjoyable sound that was still nimble, agile, liquid and accurate. The good news is that the mods were a resounding success.
With the Mundorfs installed, the S.E.X. instantly took another small step in a very positive direction. All of the sound was warmer and fuller, but not at all heavy or thick. Music is still well-paced and lively, but with a little more note weight (not quite as good as the Mainline in this regard, but closer) and more present mids.
The staging from the S.E.X. is still excellent, but the Mundorfs added to what I was already hearing from the FT-3 teflons by helping to deliver greater fine detail and textural cues.
No doubt there are even more (subtle) changes that took place as a result of my upgrades, but the inability to truly A/B makes a direct and detailed comparison impossible. What I can tell you by way of a summary is that the S.E.X. post-upgrade does everything good that I wrote about above only now slightly better and with a dash more soul and warmth. I imagine you could get similar improvements with different cap combinations too and encourage you to give it a go. Changing these 2 caps on the S.E.X. is a relatively easy process and it's fun to hear what results.
Mainline Cap Upgrade Update
Over the past few weeks (April-May 2014) I've installed two sets of capacitors into the Mainline starting with a set of 18uF Auricap High Resolution capacitors in the position of the stock Dayton 10uF capacitors and a set of 0.1uF FT-3 teflon capacitors fresh from Romania replacing the stock 0.1uF Daytons on the Bias Regulator board.
FT-3 Teflons - 0.1uF 600V
I'm going to start this update with the teflons on the regulator board. I've literally just finished this installation and it may require some time for burn-in of the teflon caps, but I honestly can't hear any noticeable difference in the sound and would question the value given that the installation is a bit ugly and clunky due to the size of these capacitors. As you can see in the image attached I've had to run fly leads from the teflon caps which are cable tied to the Auricaps. I've also use some heat shrink tape to create an insulating buffer to keep the teflon caps sitting a little way off the Auricaps (even though there should be no issue with them touching due to the plastic coating on the Auricaps.
These FT-3s cost around $10 per pair plus postage (via eBay) so it's a small enough investment that I really don't mind if they have done absolutely nothing to the sound because they haven't taken anything away and if they provide improvements after burn-in then that's great.
I found some variation in the bias settings (adjustments to ensure identical voltages for each output tube) following the install so if you do change the regulator caps be sure to double-check the biasing if you want to maximise performance.
Auricap High Resolution Polypropylene - 18uF 400V
These have been in place for a few weeks now and are definitely a worthy upgrade. They cost me about $130 for the pair from a local supplier and are the best $130 I've spent in a while. As you can see in the picture, they just fit in the space between the C4S boards and the output transformers, but still need a tie down using an adhesive anchor on the chassis (the same as the ones supplied with the Mainline kit to tie down the Cat 6 cables).
If you've read my review of the Mainline on Head-Fi, you'll know that the treble on the Mainline in stock form is extended and detailed, but still smooth and non-fatiguing. I did say in the original review that there's no hint of fatigue when listening to the Mainline, but I have to call myself a liar now and say that there must have been the tiniest hint of harshness / graininess there. I know that because now it's gone and its absence has left all of the Mainlines magic on full display. Don't get me wrong, the stock Mainline kit is in no way flawed. In fact, as I see it, the ability to spend $130 and 15 minutes to bring the amp to another level shows just how good this circuit is.
The sound with the Auricaps is basically identical to the overall sound of the stock Mainline only smoother, more defined and just better. Treble is smoother while still fully extended and detailed. Midrange textures are sophisticated and intricate, and the bass is extended, textured and punchy. As I said above, the best thing about the Auricaps in the Mainline is that they don't change a great thing. They keep the Mainline's signature and neutrality completely intact and just let it do what it does better. It's hard to say exactly how much influence the Auricaps have had on this next part, but I would swear that the Mainline now has a clearer, stronger image than before. This is most likely due to the slightly smoother treble allowing all the other auditory cues to arrive cleanly and accurately, but the staging and imaging now with the Beyer T1s is really magical. It was good before - outstanding even, but it definitely seems even better to these ears now. I am having "wow" moments multiple times each day.
One other note as to why I chose the 18uF rather than a direct replacement of the 10uF stock caps. From the reading I did, a larger capacitance can provide better bass response which I was keen to explore to see if there was any room for improvement in the case of the Mainline. The results are that if there's an improvement there I can't tell. The hardest challenge here is that you can't quickly A/B a capacitor change like this so it's all based on auditory memory and the difference in bass extension (if there is one) is small enough to be insignificant, unlike the change in sophistication and smoothness in the mids and treble.
Capacitor Wrap
The only other caps in the circuit that could potentially benefit from upgrading are the electrolytics used on the power supply board, but they fit so neatly on the board and are already good quality Panasonic capacitors so the potential benefits here seem questionable (although I'm always open to being convinced otherwise).
If I were asked today what to upgrade in the Mainline, I would strongly urge building the stock kit first and then considering the Auricaps if you like the stock sound. If you yearn for something warmer or lusher - more tubey perhaps - then the Mundorf Supremes might be a better choice (write up of Mundorf Supreme Silver / Gold / Oil coming to the S.E.X. review soon), but I definitely think there's huge value in hearing the stock kit first so you know which way to tweak (or not tweak) the sound if you choose to upgrade the output (technically parafeed coupling) caps. Unless something changes in the coming days / weeks in which case I'll be back to edit this post, I wouldn't really recommend changing the regulator caps. Keep the build neat and simple.
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Nice job and a enjoyable read thanks for sharing your experience with the mods. Its going to be a handy reference.
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I've been running the RTI 10uf 310VDC Teflons for around 200 hours. Sonic shifts were continual till about ~100hrs it seems. Its settled down quite a bit now, and I very much like the sound I'm getting. Great texture, solid punchy base, shimmering highs with no obvious roll-off; Very glad I picked them up. Let's see what the next ~300hrs. bring.
Possibly a good idea to hold fire for a little bit longer as a couple of Mainline users have recently installed some rti 10uf 310VDC Teflons (still some available) initially made for use by Audio Research in their reference tube pre-amp. I am hoping we will get some feedback soon they have the potential/reputation to be a bit special. They should be a good way into the 500hr burn in that the Teflons require now.
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Was TCTubes the only supplier of the RTI 10uF Teflon caps? They don't seem to be floating around anywhere else. I'm finally getting along to my own build after getting some other projects out of the way. I have a set of Jupiter 10uF 300V Flat Stack caps I'll be using, along with a pair of 0.1uF 600V that aren't much larger than the stock caps. Pretty excited as I've enjoyed using the Jupiters in other builds.
The 0.1uF caps are a little off in their rating as they were some odd stock from the manufacturer. 0.116uF. Assuming that's acceptable as many caps are +/- 20%.
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The 0.1uF caps are a little off in their rating as they were some odd stock from the manufacturer. 0.116uF. Assuming that's acceptable as many caps are +/- 20%
That won't be a problem, might even be a slight plus...John
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Loquah, thanks for the great build reports and reviews!
I have already ordered the 10uF/400VDC XO Series Auricaps and the Mainline hasn't even been shipped yet:)
I read the XOs are something to look forward to.
Can't wait to get building
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When replacing the 10uF caps, do the inner foil leads connect to 15 and 25?
From studying the schematics, I am sure they do.
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When replacing the 10uF caps, do the inner foil leads connect to 15 and 25?
From studying the schematics, I am sure they do.
Sorry for the slow response! I've hardly been on this forum (or any lately). Did you get it all wired up yet?
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No worries.
I am building very slowly.
Just about to finish input wiring.
Will post some work in progress images
if I get around to it.
Edit : Just did:)
http://bottlehead.com/smf/index.php?topic=7463.0
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Nice one!
By the way, I checked my build (and discovered I got one of the Auricaps the wrong way around), and you're spot on about the red leads connecting to 15 and 25 - the same terminals where the red leads from the output transformers are connected
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Thanks Loquah, means a lot!
Was happy to see the transformer working to specs, and the attenuators are finally in there.
Today I received a black XLR connector so all parts are "in house".
I like the way the manual is chaptered so I can really think through the process before actually building. I believe it makes a good looking build. Will post as I progress.
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The 10uF caps are the coupling caps. They can be 10-20uF, and probably should carry at least a 200V rating. (160V might work, but would really be pushing it)
The tiny yellow caps on the sockets are out of the signal path and implemented for silent operation. There's a good chance that if you swapped them for something else, that alternate cap would not perform as well, and you would likely end up with a dysfunctional Mainline.
The 0.1uF 400V capacitors on the center PC board can be swapped out as well. They won't have nearly the influence that the 10uF caps have, and the available space on the PC board is somewhat limited. You can help yourself out by using a 250V capacitor here, which will see more than 250V at start-up, but will operate at 225V otherwise, which I would consider acceptable.
-PB
Speaking of which, I'm seeing that initial startup voltage hit ~320-325V on the 10uF Caps for around 5 seconds or so. Its a little disconcerting to watch. However I'm getting the impression that the rating for poly caps in general have a high margin. For example Auricap posts their stress and life tests here: http://www.audience-av.com/capacitors/PDF/Auricap_Specifications.pdf
Would it suffice to say that poly caps in general reflect this sort of rating/life margin? I'm sure you haven't seen or plan to see any of these Dayton caps explode ;D
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It is not unusual for the full B+ to appear on the output caps at startup. After all, the tube is not conducting and it has nowhere to go.
Caps have AC ratings, DC ratings and surge ratings. You are seeing the surge at startup. Sadly most film manufacturers don't give surge ratings.
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Speaking of which, I'm seeing that initial startup voltage hit ~320-325V on the 10uF Caps for around 5 seconds or so.
Capacitors are able to tolerate a voltage surge for some time at startup, which can be significantly above their rated operating voltage. In the case of the Mainline, the 12AU7 will pull the B+ rail to +225V and the 6C45PI plate will pull down to ~150V. Each tube will do this without the other in the socket.
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I was about to drop on the April sale at pCX and grab a pair of 10uF flat packed Jupiter caps... I still may - this is a sickness after all. I've read great things about them. Plus, they look so cool.
Then while I'm mulling this over... suddenly my Mundorf Mcap EVO - Silver / Gold & Oil decided to open up and let their presence be known. After a year of installation no less! I've never thought a cap could take this long to come into its own, but there it is. Or I could just be nuts. :o
http://www.partsconnexion.com/prod_pdf/evo.pdf
Well not generally revered as a top flight cap, the idea behind Mundorfs EVO winding tech intrigued me. Their not hideously expensive either. (Actually, Mundorf must have recently fixed that by releasing an EVO 'supreme' version - ha ha ha). So while not totally impressed with these EVO SGO and gearing up to do something about it - a year of listening goes by and a couple days ago I realize they must have just 'clicked' in to place. They'd been holding back the full picture this whole time (IMHO).
Goose-pimples showed up. Angels wept. Etc. ;D
Maybe I'm nuts. Maybe the little bastards picked up on the threat of replacement...
But at this point I can't help but recommend them if you have to patience to break them in. A year! OY!
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Has anyone compared 10uf caps to something larger? I think I read you can go up to 20uf. I'm just talking value, not physical size or brand.
I'd like a bit more bass and if I go larger than 10uf in the quality of cap I'd like to use we're talking an investment.
I'm not opposed to tacking on an 8uf or so but real estate under that hood is premium so I'm asking before I do something not so smart... :o
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I went thru a number of comparisons from 10 to 30 and settled on 15uF Jupiters. I found these to be the best bass without losing any sparkle for my setup (HD800's - Mainline -fed by BiFrost MB). It took about 2 weeks of back and forth to settle on these or Mundorf Supremes. But my experience is limited to Mundorf, Jupiter and Obligatto oilers, there may be better caps for bass and more affordable ones out there.
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I would caution folks that sometimes the perception of more bass is more about the overall tonal balance that the cap delivers than the effect of more capacitance. That is to say, with two different 10uF caps you might perceive different bass presentation just because one of them sounds softer in the highs.
If you really want to know what's going on with the bass, you need to run response curves of the amp with each type of cap installed into a load that best represents the headphones you will be using. The idea is that the cap is part of a resonant system. As the cap value changes the resonance frequency shifts - bigger uF = lower frequency. The ideal cap value positions the resonance just below the amp's "normal" rolloff, mostly determined by the plate load inductance. This gives the bass a little more extension by creating a sharper knee to the LF rolloff. If you go too big with the cap you might get a dip at the rolloff frequency and a resonance bump somewhere below the dip. Too small and you will probably hear the classic small box speaker type of midbass hump as the resonance dominates at some frequencies above the normal LF rolloff.
I know that objective measurement seems like too much work to a lot of people. It's worth learning how these parts work if you're going to mess with them in a useful manner.
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Thanks Doc!
I think you've a point. I shouldn't say the bass is lacking and the balance is excellent. I'm probably just a bass junky and am looking for my fix. ::)
What I probably should do is expand my listening experience with headphones to see if I really need "more bass" or if the headphones I'm using are lacking a bit. That, over chopping up my Mainline anyday...
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So my Mundorf Supremes in the coupling position have settled in delightfully. Now I'm wonder what to mess with next. Am thinking of replacing the Daytons on the c4s board or possibly doing a bypass on the coupling caps. Anybody done this? Thoughts on effectiveness or values for doing a bypass?
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I haven't ever heard a coupling capacitor bypass that I thought did anything positive.
The Mainline isn't one of those kits where there are really any parts to upgrade other than the coupling caps.
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Thanks . Wasn't sure there would be anything meaningful from other mods. What I hear now is so astounding. But then, I didn't think there could be anything meaningful before I put the "better" caps in in so I thought it would be worth checking. On to the Crack-a-twoa :)
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Not been any posts here for a while
Been trying out a new secret sauce recipe in the Mainline 10uf RTI Teflons topped off with a dash of of Duelund Cast Copper the results have been pretty yummy...
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I'm installing some auricap and would appreciate a check on the installation. The short lead is the black lead and goes to 20u and 30U ? The leads are beautiful but very long. Should I trim them or just let them be? Another question: is it possible to remove one spring and ball bearing from the Attenuator after it has been built?
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The black lead is the outer foil, and generally goes toward the source side, not the load. The source side is the side that connects to the 9 pin socket, which is 20 and 30. It's a very good idea to provide extra mounting support for heavy caps. Even using something like blu-tack to stick each cap to the chassis plate will be really helpful.
Yes, you can pull out a spring and ball from each switch after they are built.
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Thanks Paul.
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Any thoughts on these rike caps for the mainline?
https://www.partsconnexion.com/RIKES-84093.html
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Any thoughts on these rike caps for the mainline?
https://www.partsconnexion.com/RIKES-84093.html
They are about 3.5" in diameter and 4" long. 600V caps will be much larger than 250V ones, and I don't think you're going to get these to fit without some custom fabrication.
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Thanks for the thoughts on size. Very good point.
Any recommendations on specific Mundorf's or teflon or copper? There's just so many out there to choose from.
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A 10uF teflon cap will be about as big as your head, and you'll need 2 of them.
These should fit nicely:
https://www.partsconnexion.com/MUNDORF-71341.html (https://www.partsconnexion.com/MUNDORF-71341.html)
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A 10uF teflon cap will be about as big as your head, and you'll need 2 of them.
These should fit nicely:
https://www.partsconnexion.com/MUNDORF-71341.html (https://www.partsconnexion.com/MUNDORF-71341.html)
LOL! It wouldn't be the first time someone has put the caps external to a Bottlehead amp! :-)
Thanks for the pointer to the "Mundorf Capacitor 15.0uF 250Vdc MCap® Classic (MKP)"
I gotta ask, though, if this cap is significantly better, why not include it in the base build? It's only $10.82/ea. I assume they would be a little cheap in bulk or wholesale.
Is it "better" or just different than the included caps?
mcandmar mentioned on page one that a high quality mundorf cap ("supremes at a minimum") would be warranted.
The "Mundorf Capacitor 15.0uF 600Vdc MCap® Supreme" is 41mmW x 106mm L - would that fit?
The "Mundorf Capacitor 10.0uF 600Vdc MCap® Supreme" is 36mmW x 106mm L - better fit?
The 10uF are $57.40/ea at MadiSound. (+$6 to $9 shipping)
https://www.madisoundspeakerstore.com/supreme-caps/mundorf-10.0-mfd-supreme-caps/
What's the sonic difference between using the 10uF vs the 15uF?
Also, just re-read Loquah's post (#74). Thanks
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Thanks for the pointer to the "Mundorf Capacitor 15.0uF 250Vdc MCap® Classic (MKP)"
I gotta ask, though, if this cap is significantly better, why not include it in the base build? It's only $10.82/ea. I assume they would be a little cheap in bulk or wholesale.
While there may be bulk pricing, I bet if we ordered 50 of them it would take 6+ months for them to arrive. The caps that we get come right from the manufacturer and are nearly always in stock. They are also metalized polypropylene, just like the Mundorf caps.
Is it "better" or just different than the included caps?
I have no idea, you'll have to smoke it and see. These are the Mundorf caps that best fit the phyiscal space.
mcandmar mentioned on page one that a high quality mundorf cap ("supremes at a minimum") would be warranted.
The "Mundorf Capacitor 15.0uF 600Vdc MCap® Supreme" is 41mmW x 106mm L - would that fit?
The "Mundorf Capacitor 10.0uF 600Vdc MCap® Supreme" is 36mmW x 106mm L - better fit?
The 10uF are $57.40/ea at MadiSound. (+$6 to $9 shipping)
https://www.madisoundspeakerstore.com/supreme-caps/mundorf-10.0-mfd-supreme-caps/
With your Mailine assembled in front of you (you will hopefully build the amp with the stock parts first), you can cut out a piece of paper that's the footprint of the cap in question and make that judgement call for yourself.
What's the sonic difference between using the 10uF vs the 15uF?
There will be slight differences in the bass response, either will work nicely.
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Excellent ideas Paul. Thanks for the explanations.
What sort of celebration will you have on your 10,000th post? :-)
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In my Mainline i went for Mundorf Supreme 10uf SGO's (because i thought they would just fit when i measured on pictures). These just did not fit, by 1mm or so. You can secure them a bit higher up in the amp with some zipties.
They were a bit too expensive not to try. They sound good.
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In my Mainline i went for Mundorf Supreme 10uf SGO's (because i thought they would just fit when i measured on pictures). These just did not fit, by 1mm or so. You can secure them a bit higher up in the amp with some zipties.
They were a bit too expensive not to try. They sound good.
Interesting. Thanks.
These?
https://www.partsconnexion.com/MUNDORF-71366.html
a little too pricey for me, but good to know if these are 1mm too big, then 44mm should fit.
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What sort of celebration will you have on your 10,000th post? :-)
I hadn't noticed!
It's good to know the SGO caps don't fit.
Mundorf isn't the only company making capacitors BTW, there are other choices.
https://www.partsconnexion.com/DYNACAP-64040.html (https://www.partsconnexion.com/DYNACAP-64040.html)
https://www.partsconnexion.com/JENSEN-78830.html (https://www.partsconnexion.com/JENSEN-78830.html)
https://www.parts-express.com/jantzen-audio-10uf-400v-z-standard-capacitor--027-282 (https://www.parts-express.com/jantzen-audio-10uf-400v-z-standard-capacitor--027-282)
https://www.parts-express.com/audyn-cap-q4-10uf-400v-mkp-metalized-polypropylene-foil-crossover-capacitor--027-118 (https://www.parts-express.com/audyn-cap-q4-10uf-400v-mkp-metalized-polypropylene-foil-crossover-capacitor--027-118)
https://www.parts-express.com/audyn-cap-plus-10uf-800v-double-layer-mkp-metalized-polypropylene-foil-crossover-capacitor--027-141 (https://www.parts-express.com/audyn-cap-plus-10uf-800v-double-layer-mkp-metalized-polypropylene-foil-crossover-capacitor--027-141)
Still, I could post 100 different high end caps that would fit, and a bunch of people will buy Mundorfs that don't fit and eventually do damage to their amplifiers.
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Uhh, not just the Mundorf's that don't fit. I went the beeswax route....
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Insetting. Thanks.
These?
https://www.partsconnexion.com/MUNDORF-71366.html
a little too pricey for me, but good to know if these are 1mm too big, then 44mm should fit.
Can't say for sure 44mm will fit. Depends a bit on how you mount the output transformers.
You can move them around a bit on their rubber rings.
I see no reason to go for 15uf vs 10uf?
Edit: when on a budget.. K75-10 250v 10uf is a bit on the large side of things. But is a possible upgrade from standard caps/mundorf supremes.
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The 10uf Audyn interlink Plus capacitors are a nice fit in the Mainline ;-)
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The 10uf Audyn interlink Plus capacitors are a nice fit in the Mainline ;-)
Do you mean this one?
https://www.parts-express.com/audyn-cap-plus-10uf-800v-double-layer-mkp-metalized-polypropylene-foil-crossover-capacitor--027-141
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Do you mean this one?
https://www.parts-express.com/audyn-cap-plus-10uf-800v-double-layer-mkp-metalized-polypropylene-foil-crossover-capacitor--027-141
Yes those ones in your link, I picked a used pair up off of ebay to try out in my Mainline for £15 the pair! Worth keeping an eye on used listings lots of interesting options turn up in the 8uf-15uf area for a fraction of the cost new.
Will see if I can get to the amp to take a pick for you later.
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Ok found a pic, I have not cut the leads to size to permentently fit the Audyn caps as they have only been fitted temporarily otherwise I would have trimmed the leads shorter so the capacitors sat closer to the underside of the top plate with a bit of Velcro added for further support. They do fit in the space nicely and their leads are pretty sturdy which helps when it comes to keeping the caps in place.
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Ok found a pic, I have not cut the leads to size to permentently fit the Audyn caps as they have only been fitted temporarily otherwise I would have trimmed the leads shorter so the capacitors sat closer to the underside of the top plate with a bit of Velcro added for further support. They do fit in the space nicely and their leads are pretty sturdy which helps when it comes to keeping the caps in place.
thanks for the picture. Very nice.
I may have missed it, but what effect do those caps have on the sound?
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I'd vote for the Audyn caps as well. I've used them a bunch lately.
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@PB: What is that in your second pic? A monoblock tubeless amp?
With 2 power transformers?
Edit: mistook what I now assume is an OT for a PT. Assuming 1PT, 1 OT and 1 Choke, what's the other transformer?
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Power transformer, output transformer, plate choke, and power supply choke (not necessary at all, but the holes were already there).
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In my Mainline i went for Mundorf Supreme 10uf SGO's (because i thought they would just fit when i measured on pictures). These just did not fit, by 1mm or so. You can secure them a bit higher up in the amp with some zipties.
They were a bit too expensive not to try. They sound good.
So, I'm about to install the same capacitors in my mainline because I got a good deal on them and had a little bit of a question regarding securing it-
Is it okay if the capacitors touch other components? Or do they need to be completely free-standing? I'm not really sure how hot those two top blocks on the side get or if it's bad if the capacitor touches the PCB so I just thought I'd check.
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So for some reason the Mumforf 10uf SSGO juuuust got inside my mainline. Tom-a pretty much hits it on the head with his review. They sound good. Mine had 10 hours of use when I put them in but the more I listen the more I notice has improved. As of now I don’t think the upgrade was super worth the money, but I reserve the right to change my mind lol
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I'm very glad how it worked out for you. I think in my Mainline they just didn't fit. It's a matter of mm's. Don't have any pictures of the undersides unfortunately.
Let us know what you've come to think of the Mainline after some months of use! Do post in the headphones with Mainline thread! For me it's a magical pairing with HD800's. It's absolutely stellar. Never heard an amp like it (and have been to a massive amount of headphones shows over the last few years).
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I'm very glad how it worked out for you. I think in my Mainline they just didn't fit. It's a matter of mm's. Don't have any pictures of the undersides unfortunately.
Let us know what you've come to think of the Mainline after some months of use! Do post in the headphones with Mainline thread! For me it's a magical pairing with HD800's. It's absolutely stellar. Never heard an amp like it (and have been to a massive amount of headphones shows over the last few years).
So it's been a few months and I swear to god that the SGO's really opened up! I haven't gone back to the old Daytons because desoldering is a PITA for me/I'm not inclined to, but the texture of notes, dynamics, base response and detail retrieval really opened up! Imo they've made the amp rather less polite than it used to be and far more lively! It definitely sounds a little "tubier" than it used to, but it's still very tight and detailed. I also use my mainline out of it's balancedconnection with the HD650, ZMF Atticus, Verite and Auteur. They all sound fantastic out of the mainline but I have to say the Auteurs and Verite really pair beautifully with this amp when upgraded.
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If anyone needs a pair of Mundorf Supreme Filter Caps, 10uf. I have a new pair that I just received for my Mainline and then changed my mind and ordered a pair of 15uf Caps. I order from Europe, so not worth the cost of returning the set of 10uf caps.
I'm in the United States, Florida to be exact and will ship them for free anywhere in CONUS. Price is $90 for the pair.
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Hey everyone, I got the urge for another cap upgrade recently when I found a well priced pair of 800V 15uF Jantzen Superior Z-Caps on eBay. Installed them tonight and I'm noticing some really nice improvements over the Auricaps I had in there before (regular Auricaps, not XO as far as I know). The Jantzens, even without burn-in time, have a really nice attack to them that is a bit faster than the Auricaps which were really nice, but the Jantzens sound more transparent so far and I expect they'll only improve over time.
I'll provide another update after some further listening, but I can recommend these as a very affordable significant upgrade (just over $100 USD for the pair) for the Mainline coupling caps.
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Has anyone tried changing the transformers to toroidal ones?
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Has anyone tried changing the transformers to toroidal ones?
If you changed the power transformer to a toroidal one, I would expect enormous noise issues (despite what the marketing literature claims for them).
I haven't seen line level toroidal output transformers but I would speculate that high frequency response would suffer a bit.
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For advice: do you think it would be more beneficial to replace the stock 10uf caps with something higher end like an auricap xo, or to instead keep the stock caps and do a bypass with a higher end .1 uf cap?
Or go crazy and do both :)?
Just found myself in the upgrade stage of both my mainline and my crack! Appreciate any opinions!
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I would recommend performing that experiment on your own. The results that I have observed don't tend to agree with the mainstream philosophies.
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So for some reason the Mumforf 10uf SSGO juuuust got inside my mainline. Tom-a pretty much hits it on the head with his review. They sound good. Mine had 10 hours of use when I put them in but the more I listen the more I notice has improved. As of now I don’t think the upgrade was super worth the money, but I reserve the right to change my mind lol
I put these cpas in my Mainline and liked them right from the start.
I have about 30 hours on them and they are a real improvement (for my tastes).
I have these caps in the para-feed position on all my amps (vice the Crack) - I guess I like what they do to each component.
The result of Cap changes are indeed subjective so be careful spending this much money on the changes ....
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Auricap XO 10uf 400vdc arrived and have been installed in the mainline. Re-biased, and currently putting some time on them!
They fit very comfortably, no issues.
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Hey everyone, I got the urge for another cap upgrade recently when I found a well priced pair of 800V 15uF Jantzen Superior Z-Caps on eBay. Installed them tonight and I'm noticing some really nice improvements over the Auricaps I had in there before (regular Auricaps, not XO as far as I know). The Jantzens, even without burn-in time, have a really nice attack to them that is a bit faster than the Auricaps which were really nice, but the Jantzens sound more transparent so far and I expect they'll only improve over time.
I'll provide another update after some further listening, but I can recommend these as a very affordable significant upgrade (just over $100 USD for the pair) for the Mainline coupling caps.
Hi Loquah,
If you have any updates, I am interested to hear from you on your impressions of the Jantzen Superior Z-Caps. Thank you. :)
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In the following statement (taken from the capacitors web page) the outer lead would be connected to 20 and 30?
"The outer lead out, closest to the edge of the capacitor, is connected to the outer foil and as such should be connected to the lowest impedance path to ground, generally the signal output."
Thank you!
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Greetings,
I want to install a set of .1uf vcaps as bypass caps in my mainline. They have a red and black lead. What side does the red league go to?
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From the instructions from the manufacturer:
"If using as a bypass cap to ground, connect green lead to ground."
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I am going down the cap rabbithole 😜 first the red and gold Audio Research, they are really rich and big sounding but the base seems to be a little loose. I burned them in around 200 hrs, not enough to reach their full potential but enough to get a feel for them. then based on what Jamie has been doing with Duelund bypass caps I added some V-cap .1uf to bypass those. Didn’t really know what to expect but I have to say the highs are substantially better, I was rather shocked. Doc told me to watch out for smearing when I bypass those 10uf caps but I haven’t heard any smearing or ringing so far.
Next I have some Audyn tri-reference 15uf caps to try. These are monsters but if I move the boards forward I can fit them in. I’ve also ordered some Jantzen silver Z caps 15 UF. That I will try in a few weeks.
I’m also going to order a pair of the Duelund silver bypass caps that Jamie is using and try those in combination with his capacitors. I’ll report back my findings.
I tried to post photos but the bottlehead forum won’t let me do that. I posted them over on headfi
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Hey everyone, I got the urge for another cap upgrade recently when I found a well priced pair of 800V 15uF Jantzen Superior Z-Caps on eBay. Installed them tonight and I'm noticing some really nice improvements over the Auricaps I had in there before (regular Auricaps, not XO as far as I know). The Jantzens, even without burn-in time, have a really nice attack to them that is a bit faster than the Auricaps which were really nice, but the Jantzens sound more transparent so far and I expect they'll only improve over time.
I'll provide another update after some further listening, but I can recommend these as a very affordable significant upgrade (just over $100 USD for the pair) for the Mainline coupling caps.
Hi Lachlan
I purchased a pair of the Jantzen Superior 15 uf capacitors based on your recommendation. Any tips for how you installed and secured them, as they're much larger than the previous capacitors there!
Thanks
- Alex
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Well, I'm thinking of getting new caps. So many to choose from. The first thing I want to try is 10uf vs 15uf (maybe 20, to really emphasize the difference). I was thinking of just getting the daytons, then I will be comparing as similar caps as possible, so the only difference would be the rating of the caps. Then, if I can hear a difference I like, move "up" to a "better" cap. Does that make sense?
I found myself contemplating getting and Eddie Current Aficianado for a really good price, but a cap upgrade for the Mainline might be a better way to fulfill my urge to do something.
My Mainline has Dayton MPT 10uF 250V 5% Audio Grade caps.
Seems like the options are DMPC and PMPC. Any idea which one was shipped with the Mainline?
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The first thing I want to try is 10uf vs 15uf (maybe 20, to really emphasize the difference). I was thinking of just getting the daytons, then I will be comparing as similar caps as possible, so the only difference would be the rating of the caps. Then, if I can hear a difference I like, move "up" to a "better" cap. Does that make sense?
Yes, this is a very good idea.
Seems like the options are DMPC and PMPC. Any idea which one was shipped with the Mainline?
It's quite likely that the factory takes a big lot of DMPC and measures them all and the ones that are very close to the nominal value get the PMPC wrapper. I wouldn't spend the money on the 1% caps for this application.
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Hi Lachlan
I purchased a pair of the Jantzen Superior 15 uf capacitors based on your recommendation. Any tips for how you installed and secured them, as they're much larger than the previous capacitors there!
Thanks
- Alex
Hi Alex,
Sorry about my slow response - I'm not here (or on other forums) as often these days. The Jantzens are a bit tricky to install. I ended up using cable tie anchors (the adhesive squares with the flat holes to take cables ties through them) and then attached the caps using a couple of cable ties joined together for length. The caps themselves then sit snugly between the 6c45pi boards and the transformers, but are not held in by the boards which is why the cable ties are necessary.
I've attached and artsy photo to show where they sit (but not how they are held in place)
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Hi Alex,
Sorry about my slow response - I'm not here (or on other forums) as often these days. The Jantzens are a bit tricky to install. I ended up using cable tie anchors (the adhesive squares with the flat holes to take cables ties through them) and then attached the caps using a couple of cable ties joined together for length. The caps themselves then sit snugly between the 6c45pi boards and the transformers, but are not held in by the boards which is why the cable ties are necessary.
I've attached and artsy photo to show where they sit (but not how they are held in place)
Thanks Lachlan - sounds like I did similar as I also used some cable ties and anchors to get them in there. The Jantzen's sound pretty good so thanks for the recommendation. Keep up the good work on your Youtube channel!
Thanks
- Alex
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I got around to playing with caps on the Mainline and wanted to share my impressions along with some below average pictures, and pose a question to the community. I have some cable tie anchors on the way, but I have a surplus of 3M Dual Lock (think non-gendered Velcro but on steroids) which actually works pretty well.
Obbligato Ultra Premiums:
I used the .1uf/1000V and the 10uf/1000V and I changed them out at the same time. @ 100 hours, I can't say that my impressions changed over that time.
- Much bigger difference that I anticipated caps would make
- Smooth and gooey, made the Mainline sound like a Crack (not really, just in that direction)
- With well-mastered modern recordings (non-acoustic instruments/vocals) goose bumps are common and my jaw hit the floor many times.
- With acoustic instruments/natural environment recordings, I am missing the fronts of the notes. I am missing clarity. Classical music just sounds mushy.
- Like above the bass and dynamics in general are really lacking for acoustic instruments. The more musicians on stage the more diffuse this all sounds.
- My goodness, the 3 dimensionality is on another level when listening to pop and hip-hop (Sam Smith, Kendrick Lamar, Taylor Swift (listening for the mastering not the content :-[))
- It is so odd that the 3D quality is gone with classical music. Sounds like just another diffuse tube amp
My vision for the Mainline is to highlight it's neutrality. While the Obbligato's were a nice journey (for very little $$$), this sound is not what I want for my Mainline.
ClarityCap CSA:
One of my goals in this initial fourrée was to try and determine the effect of using 15uf vs 10uf coupling caps. I left the .1uf/1000V Obbligatos in place as I only purchased the 15uf/250V ClarityCaps.
- Again not a big change after the first 25 hours, which is why I feel OK posting some pre-mature impressions
- Bass is more extended. I dislike that term. I mean that I can hear the bass region louder with slightly more detail than on the Obbligatos.
- The clarity in articulation is much better. It is still a little more diffuse that I remember the stock caps sounding, but this could very well be the .1 uf Obbligatos that are still there. In fact, I believe that I am hearing the Obbligatos based on that specific characteristics I am hearing.
- While it might seem that I have arrived at a nice combination, the total result is much less that the sum of its parts. On the HD800 (stock) this combo sounds very similar to the Garage1217 Ember. I can usually pick out the Mainline due to the size of the room vs. the space between the instruments. Either the Ember is really good with 800 (it was my first time pairing them), or this cap combo is robbing the Mainline of some of it's best traits. I can pick out the Mainline now mostly due to that slightly diffuse articulation.
- Weight. While I have most of the articulation back, the weight of each attack is now subdued. Perhaps another reason why this sounds so similar to the Ember?
I'm most likely going to pull the trigger on the .1 uf CuTF V-Cap, but I am still wanting some opinions on 10uf vs 15uf for the coupling caps. I have access to a Mainline with these V-Caps (he has the 10uf V-CAP ODAM) and I like what I hear. Based on my experiences, I may go with the 15uf V-CAP ODAM but I wanted to see if anyone had any objective feedback. Does moving to 15uf change the frequency response? If so, in what areas? Or maybe the differences between 10uf vs 15uf on the Mainline is purely subjective. I'm curious as to other's experiences in this area.
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It's not a huge difference between 10uF and 15uF. After reading 2/3 of your post, my initial reaction was to recommend the ODAM, so I think you're on the right track.
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I was emailing about caps with a frind of mine (crack owner), and here's what he thinks. Any of this make sense?
Are these the capacitors in series just before the output? If so, the capacitors form a high-pass filter with the load of the headphones. See picture. The cutoff frequency (where the power is attenuated by 1/2 or 3 dB) is 1/2piRC. So if the headphones are 150 ohms and the coupling cap is 10uF, the cutoff frequency is about 100 Hz. A 20uF cap drops the cutoff to 53 Hz so you'd hear more of the very low end.
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There's an output transformer, so that diagram does not really apply in that way.
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Thanks for the response PB! I wanted to put down some listening notes while it was still fresh in my head, sorry for the long post. In re-reading what I wrote, I may have come across a bit negative. Quite the contrary! This is still very much sounding like the Mainline in all cases just with a slight tilt a various directions. The V-Caps arrive today. My friend has a Mainline with 10uf ODAMs. I’m getting the 15uf.
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Oh not to worry! The 10uF caps included with the Mainline aren't particularly expensive and it's certainly worthwhile to experiment with other parts, though I agree that there are a lot of "audiophile" caps out there that aren't really to my liking.
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I finally got around to changing the caps from the dayton 10uF to the same quality dayton 20uF. To my old ears, the 20uF caps sounds slight darker. I did give them 10-20 hour burn in (FWIW). I wouldn't say better; only different. I think I prefer the 10uF, but the difference was very subtle to me, and might just be poor audio-memory. I just don't understand how people can listen to something, make a change that takes minutes, then listen, then hear very subtle differences. I can barely hear suite differences with A/B testing.
Well, back to listening to music and neurotically curating my music collection.
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Hi everyone,
I've just ordered some capacitors to try a little capacitor rolling of the stock 10uF Dayton output caps in my Mainline and I was thinking about how to do A/B comparisons between different capacitors.
Reading back through this topic, I see than in the past people have proposed switching the capacitors in situ, with strong feedback advising against.
I was wondering what people actually ended up doing? Any advice?
Call me crazy, but this was my thought:
- Take a mono source and connect it to both L & R inputs.
Externally to the Mainline, connect the stereo headphone output and wire it to the A and B side of a toggle switch, take the common out to both the L & R sides of a headphone socket.
Now using the external A/B switch, one could listen to either the Left side or the Right side of the Mainline.
Compare L & R with the stock Daytons - satisfy oneself that they sound more or less the same.
Swap out a capacitor on one side only..... then one has an instant A/B comparison between the two caps, with no nasty DC volts being switched.
Granted, it would only allow a Mono comparison, but I'm thinking that it would provide instant comparison of tonality / bass extension / any audible effect of changing the capacitor value.
Thoughts anyone?
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It sounds very reasonable. My only caveat is that there will always be some differences between channels. They will usually be very subtle, but then so are the differences between good capacitors. For example, very small differences in level affect preferences even when they are not audible as level differences per se.
A good test might be to see what differences you hear with identical caps. Do you prefer the sound of one channel over that of the other? At the least, try swapping tubes to see if that channel preference changes. When comparing two different caps, you may need to swap caps and repeat the test so they get tested in each channel.
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If I understand you correctly that seems like a reasonable solution. You could build an adaptor that plugs into the output jack, a short cable to the switch and a short cable to an external headphone jack. That way you don't have to make connections inside the amp other than change one cap. Pretty cheap to make, 1 stereo plug, 1 stereo jack, 1 spdt switch and and a box to mount them in.
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That is certainly an idea worth trying!
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Hi Paul,
> there will always be some differences between channels. They will usually be very subtle,
Yes - this was what I had in mind in step 4 : "Compare L & R with the stock Daytons - satisfy oneself that they sound more or less the same."
Of course there is an assumption being tested there :) If they don't sound "more or less" the same, then that is another rabbit hole for exploration!
> very small differences in level ....
Yeah I was thinking about that after I posted. I might measure that. If they were significantly off then perhaps one would need to take steps to trim the levels (maybe at the source).
Hi Lee,
Yes, that's exactly the sort of thing I had in mind.
I did also think that one could sum the two outputs, but with one phase reversed, and directly monitor the difference signal. Of course, as Paul J points out there are other contributing differences in the channels and one would be listening to all of these differences, not just the differences between the caps.
I think that it might be a useful discovery technique though - for example, I would have thought that if there is any extra bottom end change when changing the cap value, then it would be readily discerned in the difference signal.
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As far as summing and phase reversal on one channel is concerned I think you may be disappointed as you will get a null or cancelation of frequencies especially in the lower frequency range. I think your initial thought has merit and would be a good place to start. But having said that, empirical data is always needed to prove or disapprove theoretical solutions. Meaning as James Brown would say " It's your thing, do what you wanna do "
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Hi Lee,
Yes the cancellation is exactly the point.
If the two channels were perfectly identical, then the phase reverse & sum would result in a perfect null - i.e. silence at all frequencies.
Then, if a change in one channel is supposed to (say) extend the bass response, then one would expect to hear just that blob of extra bass in the difference signal.
Not something nice to listen to, but a diagnostic tool.
Of course in the real world things are far from perfect, but if that (say) extended bass response was significant, I would expect to be able to hear it in the difference signal.
It is a technique that I have used in the past when eq-ing or otherwise treating a mix - for example, applying a de-noise algorithm. It can be all too easy to focus on the one parameter one is adjusting, to go too far and totally miss the havoc that one is wreaking somewhere else in the mix.
The phase reverse trick can be very revealing of what else is going on, unwanted artifacts and suchlike. Once you can isolate the artifacts and learn what they sound like, they are easier to spot in a dodgy mix.
But I digress! I was just thinking aloud that it might be worth a go here too - was just an idle thought. Easy enough to try.
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You could just run a response curve of each channel and compare. It's going to be very subtle.
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Hi Doc,
Yep I'll probably do that as well.