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May 31, 2020, 08:14:30 PM

Author Topic: Output Capacitor Upgrading Questions  (Read 105745 times)

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Online Paul Joppa

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Re: Output Capacitor Upgrading Questions
« Reply #15 on: April 08, 2011, 11:08:07 AM »
... Is there a place online that describes how to calculate the dividing resistors?...
The trick is to have the resistors enough smaller than the leakage resistance, so that variations in the leakage don't affect the voltage division very much.

You can look up the maximum leakage current in the capacitor specifications, which depends on the voltage applied, and calculate the leakage resistance.

The amount by which the equalizing resistor should swamp out the leakage depends on the excess voltage rating available. Not that the capacitors won't have exactly the same capacitance, which will dominate the voltage split when the voltage is first applied, the resistances only come into play after that initial transient.
Paul Joppa

Offline jrihs

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Re: Output Capacitor Upgrading Questions
« Reply #16 on: April 13, 2011, 03:02:45 PM »
Here is an interesting cap review article: http://www.ecp.cc/cap-notes.html. Unfortunately ERSE caps are not compared which is unfortunate, they actually make values of interest and at least one person says they are the best they have heard...compared to what I don't know. I post this for the benefit of other beginners, but it would be interesting to hear what the more old hands think of these observations/opinions.

Cheers
John Rihs

Offline Billyk

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Re: Output Capacitor Upgrading Questions
« Reply #17 on: April 14, 2011, 02:11:08 AM »
Here is a review that includes the Erse PulseX http://www.humblehomemadehifi.com/Cap.html He calls it a good budget cap. If I recall it holds up against others in it's class.
Here is some more reading too http://www.audiocircle.com/index.php?topic=54218.0
Enjoy!
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Offline jrihs

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Re: Output Capacitor Upgrading Questions
« Reply #18 on: April 14, 2011, 05:39:30 AM »
Perfect! I was wondering where I had seen that review before! Thanks.
« Last Edit: April 14, 2011, 05:42:02 AM by jrihs »
John Rihs

Offline Laudanum

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Re: Output Capacitor Upgrading Questions
« Reply #19 on: May 16, 2011, 03:45:51 AM »
Reviving this one for some input on maybe bypassing the last PS cap.  Seems like a 2.2uf bypass cap is very common.  Im assuming because it's 1/100th?  I have a bunch of film caps from old projects but no 2.2uf.  I have some 4.7uf and 1.5uf and 1uf as well as a bunch of low value caps (.1, .47, .022, .01 etc).  Any reason why I couldnt use a 1.5uf or a 4.7 for example rather than a 2.2uf? I ask because I know there is alot of debate about this and possible resonance issues etc. etc.  But in terms of the value itself, is there any more potential issues by not sticking with the 1/100th or 1/10th that seems to be so popular?

Thanks
Desmond G.

Offline williaty

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Re: Output Capacitor Upgrading Questions
« Reply #20 on: June 21, 2011, 11:19:19 AM »
Well, I have a slightly different version of this question. I'm having a fair bit of trouble finding a place that has 100uF caps in stock. Heck, not that many different kinds of "audio" 100uF caps seem to exist at all. Here's what I've been able to find so far:

Mundorf M-Cap MKP 100uF-250V
Mundorf M-TubeCap 100uF-550V
Obligatto Film Axial 100uF-400V

Axon True Cap 91uF-250V
Solen PB-MKP-FC Metalized Polypro 100uF-400V
Solen Fastcap PPE 100uF-630V


Given that the rating is supposed to be around 200V and I've seen a couple of comments on this board about higher voltage ratings potentially sounding worse, that really leaves me with the Mundorf MCap MKP and the Axon True Cap. Are either of these any good? Given that the Axon (which at least one member has used) is only a 91uF, should I use a 10uF cap (which are MUCH more available) in parallel to it?

Offline InfernoSTi

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Re: Output Capacitor Upgrading Questions
« Reply #21 on: June 21, 2011, 06:00:39 PM »
Hmm, interesting. Is there a magic ratio between the body value and the bypass value? I was looking at a 100uF Solen and maybe some value of a Mundorf Supreme or ESA Clarity Cap between .47-2 uF.

I have heard the general rule is 1/10th for the bypass cap.  My understanding is that this can be reduced if the cap has a lower tolerance: if it is a 10% tolerance, then the 1/10th rule would apply but if it is a 2% tolerance then a much smaller bypass cap could be used, say 1/50th or some such figure.  Morgan Jones in "Valve Amplifiers" uses the figure 1/100th for modern, high quality caps.  I have also heard the ESR can be lowered by using parallel caps (two 50 uF caps in parallel would have a lower ESR than an equivalent 100 uF cap).  Morgan Jones also recommends "starring" the bypass points.

Just a thought or two about bypassing.

John
John Kessel
Hawthorne Audio AMT K2 Reference Speakers
Paramount 300B w/MQ All Nickel Iron,  Mundorf S/G 5.5 uF,  and  Vcap Teflon .1 uF
Auralic Vega DAC
CAPS V3 w/SOtM Linear Power Supply & PPA USB

Offline deltaunit

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Re: Output Capacitor Upgrading Questions
« Reply #22 on: June 21, 2011, 11:34:37 PM »
Has anyone experience of bypassing the 100uf output capacitors with a much smaller .1uf or .01uf capacitor?

I was considering going with a 1/100 1uf bypass but I don't think I have the room in the case for the type I want, a high quality AmpOhm Polyester Film. I could fit a lower quality 1uf bypass and bypass that with an even small high quality .01uf or I could just use a single high quality .1uf bypass.

Any opinions on which would be the better option? My output caps are already polyprops.

Cheers

Offline Beefy

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Re: Output Capacitor Upgrading Questions
« Reply #23 on: June 22, 2011, 11:36:59 AM »
Axon True Cap 91uF-250V

This is what I used in my build. I can't compare to any of the more exotic/expensive options, but *definitely* better than the stock electrolytic caps - and they are dirt cheap to boot.

Offline Jim R.

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Re: Output Capacitor Upgrading Questions
« Reply #24 on: June 22, 2011, 04:19:09 PM »
Any of these will be an improvement over an electrolytic IMO, with a couple of exotic exceptions.  The actual voltage is much closer to 100v than 250, but the difference in dissipation factor between  a low voltage electrolytic and a higher rated film cap is pretty much always goinng to go to the film cap.  That said, I don't know that I'd use the m-tube caps as these are really meant to be power supply caps and they may or may not sound as good as the others.

You should also be able to get the axon in 100 uF 250v from Michael percy audio, and at least one other person here used the erse caps.

That said, even the 91 uf should be just fine -- the value herre is not super critical so a bit more or a bit less won't make muc of a difference.

As for bypasses, you'd really just have to expreriment and any of the values mentioned should work fine.

Even a good film or teflon film cap may also be used in combination with the stock electrolytic and should also show some benefit.

If I were doing this, I'd try an axon, erse pulsecap, th mundoorf MKP, solen or obligato -- in no particular order and thenbypass wiith a .1 uF sonicap platinum teflon, or even maybe a .01.

I plan to use a pair of now unobtanium blackgate 150 uF 350v and may bypass them with either a sonicap platinum or a vishay ERO -- if I can hear a difference.

Again, in this application, these values (except for the minium voltage rating) are all that critical -- so 901 uF, 150 uF, no biggie.

Of course there are other cap and bypass choices, but these are what I have experience with and or prefer over some of the others.

Good luuck,

Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

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Offline Laudanum

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Re: Output Capacitor Upgrading Questions
« Reply #25 on: June 23, 2011, 02:28:00 AM »
What about bypassing the stock electrolytic output caps with a largish film cap?  Maybe 10 or 20uf or even a bit higher value. I would think that would have a larger influence on sonics than a small bypass and wouldnt cost as much, if staying within the same cap brand/range as a full out film replacement.  Im kinda skeptical that a high quality, small value (.1uf or lower) bypass cap is going to have much influence bypassing a 100uf electrolytic.  I do have some Audiocap Thetas I could try but I believe that they are .01uf .  And some larger value Dayton Film and Foils (all under 1uf, .33 may be the highest value I have).

I dont quite understand the potential resonance issues, would larger film bypass caps exacerbate them more than small value bypass caps?  What does is "sound" like?

Also, Jim ... I see that you're considering the Black Gate electrolytics, what about the Jensen Electrolytics?  In 100uf or even 220uf, they are a more compact alternative to the large value film caps and less expensive than all but the cheapest film caps.  I have used Jensen oilers (1uf) as output caps in a CDP and also to cap a "helper" tweeter in loudspeaker but that is my only Jensen cap experience, no experience with their electrolytics.    Im not that big on Solens and not so sure that the Axons are all that much different. I have used both in speaker crossovers in the past, as well as Dayton PP's so i should say that I never really liked them much for tweeter applications but I think some are still in service on drivers other than tweeters.  Also used them non-critically in car speaker crossovers. 
A Dayton film and foil bypassed with an Audiocap Theta did work out well in a phono stage I built a decade or so ago but that was all small value, under 1uf total and again, not a standard Dayton PP. 

This is more food for thought for me for a later date but I know this much, I cant put a load of money into trying different large value film caps.  If a cap "upgrade" is going to be subtle, especially with the music I listen to, it just becomes a diminishing return thing for me right off the bat.   I would probably do Speedball first regardless, since most say this is the biggest improvement. 

A lot of questions, I know.   Thoughts?
Desmond G.

Offline Grainger49

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Re: Output Capacitor Upgrading Questions
« Reply #26 on: June 23, 2011, 03:45:32 AM »
From Parts Express:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=027-616

Solen 100uF/400V $34.55, now $41 each.  Higher values are rated at 250V.
« Last Edit: March 21, 2015, 04:33:31 AM by Grainger49 »

Offline Jim R.

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Re: Output Capacitor Upgrading Questions
« Reply #27 on: June 23, 2011, 11:14:50 AM »
Laudenum,

A small, high-quality film cap bypassing a large electrolytic is fairly common practice and is not so much meant for "flavoring" the electrolytic to the sound of the film cap, but more along the lines of lowering the dissipation factor and/or shunting the self-noise of the electrolytic.  Go ahead and try the .01 -- certainly can't hurt, but if somehow it does, just take it out.  There is another cap rolling thread on the Crack, and somewhere in there I was discussiing the possiblity of bypassing the stock electrolytics with a .1 or .01 vishay mkp-1837, but as PB pointed out, the working voltage of the vishay is too low for this application.

Elsewhere in this forum others have spoken of bypassing psu electrolytics with smaller, as well as larger film caps -- the smaller, again are more for shunting out self-noise and the larger ones are more for adding capacitance and or flavoring.

I don't know anything about using the jensen electrolytics as coupling caps, and as good as they are, they are not the same kind of chemistry as a black gate, and besides, I've had a pair of closely matched 150 uF 350v BG NH caps for a while and will put them to use in this amp.

There is a "rule" that says you should not bypass a black gate, but with certain types (NH, NX, and others), and in certain situations, this can be done to god effect.

I built a millet minimax headphone mp last year for my dad and used a couple of black gate N types as output coupling caps in much the same way as they are used in the Crack, and indeed, bypassing them with a .1 uF vishay mkp-1837 was a very nice improvement -- and the caps were either 470 uF or 1000 uF if I recall correctly.

With all that said, the stock electrolytics are supposedly quite good as they are, and bypassing them with a small, quality film cap may be all one needs to do.

Unfortunately, I don't have access to the kind of instrumentation (scope) that would let me see what happens exactly when bypasses are used and/or when a resonant situation happens, so I just have to trust my ears, and I've never had a situation where bypassing a big ps electrolytic with a small film cap did not make a positive difference.  Sometimes the differences were fairly small, and in other situations, very, very good.

If you don't want to go for the sonicap platinums, then also look at the Gen IIs, as well as others with sufficient voltage ratings.  Sonicaps, IMO, just happen to be quite nice, especially for the money.  Unfortunately, most of the larger value caps, and all of the platinums are generally not suitable for BH gear as their voltage ratings are somewhat lower, but they do have the basic sonicaps up to at least 3.3 uF in 600v.

Hope this helps somewhat, but as I said, without any way of measuring or looking at what is going on, I'm basically just following the crowd and hearing what I hear.

HTH,

Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Laudanum

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Re: Output Capacitor Upgrading Questions
« Reply #28 on: June 23, 2011, 01:43:25 PM »
It does help, thanks Jim.  It cant hurt to try what I have on hand.  I can just clip them in temporarily and see how it goes.

I dont understand all the tech that made the Black Gates different but I do know that they are different internally than Jensens and other electrolytics.  I have some in use in one of the kits or rebuild I did years ago which means I have spares somewhere.  But they werent the N series and Im sure they arent the right values/voltages.  Probably the standards because I was always a budget type. 
Desmond G.

Offline Grainger49

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Re: Output Capacitor Upgrading Questions
« Reply #29 on: June 23, 2011, 11:42:38 PM »
Jumper leads and a pair of KK Teflons are what got me started on the capacitor bypassing trek.
« Last Edit: March 21, 2015, 04:34:09 AM by Grainger49 »