Bottlehead Forum
Bottlehead Kits => Kaiju Stereo 300B amp => Topic started by: drewh1 on March 03, 2016, 11:25:23 AM
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Just arrived, big heavy box. Can't wait to start. I already made a cherry base for it, hope the plate fits :D Still need to order the EML Tubes and V-Cap caps. I am doing a couple of mods right from the start, having built three kits already and modified them, I feel pretty comfortable with the design mods I'll be making.
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Dang, this thing is heavy, if that is any indication of how it is going to sound, then it is going to sound great! Just ordered caps and tubes, so hopefully everything will be here by the time the wiring is done.
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Really curious about the use of a 0 ohm resistor as opposed to a single wire for ground on pin 4 of the driver tube? Noise filter?
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It does just function as a more convenient jumper.
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Looks like I am having a similar problem to Ed's (ebag4). I am trying to complete the HV tests but keep blowing the 1.5 fuses. No smoke or smells of any kind so I don't think I fried anything.
I double checked all the wiring and everything looks correct, had glowing tubes and proper voltages prior to this test so I'll try a larger fuse to get through the test.
Let me know if you think I should look at anything else prior to trying a larger fuse.
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Try a 1.5A or 2A slo-blo.
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Thanks Doc. Radio Shack was out of 2A's so I got 3As to test with.
Could I run with a 2A slow blow on a permanent basis? or just to test it?
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Drew, I just tried the 2 fast blow, they did just that. Then I tried the 2amp slow blow,, it powered up and held.
2 amp held on mine until I had it all put together with the 300bs in, but had to go with the slow blow.
Best,
Ed
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Just completed all my HV checks. Used a 3A fuse.
10U - 268
14U - 554
15U - 271
53U - 75.3
65U - 76
Moving forward!
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Music! Tomorrow I'll take some final voltage readings to see where I stand for the EML tubes. Too late tonight, but I just had to get it done.
I assume I should take some voltage readings before installing the DC Filament regulator?
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Congrats Drew!
Best,
Ed
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Thanks Ed!
Paul J - After letting things settle in a bit and setting hum pots etc, I measured final voltages.
both filament voltages are 5.25
63u - 72.1
33u - 72.8
c2 - 429
B2 - 428
If I measured correctly, I come up with 30.8 watts? I am guessing the voltage on pin 2 is not the way to measure plate voltage?
Looks like the filament voltage is perfect if I need an additional 5%. Will the DC Regulator take it down to 5 V, thus leaving me with low filament voltage?
I have attached some photos of my input wiring with Goldpoint and servo motor volume control.
drew.
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Having the same issue with blowing the 1.5 fast on HV tests after putting in the 300Bs. Thanks to you guys, had some slow-blo replacements on hand that I'll try tonight. Appreciate you blazing the trail for us (not literally of course)! :-)
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2 amp slow blow fuse worked. Got 73.4V and 72.7V on 53U and 65U respectively, with no other changes made since blowing out the 1.5V fast fuse.
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Great. Ed just got a clarification on the fuse issue. Check the other threads.
So after about 10 hours I thought I would post a quick review. All this is in comparison to a modded stereomour FYI.
So, wow. I am impressed. Bass is deep and well defined. Instrument separation and clarity are excellent. Has just the extra punch and volume I need with my 92 dB speakers. Vocals are amazing, right where they should be and slighly forward. Most 3d presentation of any amp i have owned. It improved on pretty much everything. And I really enjoyed the stereomour. The only thing I am missing a bit are the super crisp cymbals but things are not even settled in yet. Can't wait to hear it with the Eml's. Should have them later this week. I am glad I waited for this amp. Just what I wanted. Gonna set the stereomour up in the bedroom with a small pair of hemp speakers.
Paul j. BTW I posted voltage readings a couple of posts back.
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Since I don't have any post in this thread, I must have asked for voltages in another thread. I don't recall why I asked for that - too many posts under the bridge, plus a weekend spent throwing acres of driftwood logs back over the bulkhead.
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Ah. Makes sense. My apologies. You were helping me set up the Eml's meshplates in the thread titled use of bias probe. I thought it would make sense to continue it here. I want to set up correct voltage for the meshplates
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Thanks Ed!
Paul J - After letting things settle in a bit and setting hum pots etc, I measured final voltages.
both filament voltages are 5.25
63u - 72.1
33u - 72.8
c2 - 429
B2 - 428
If I measured correctly, I come up with 30.8 watts? I am guessing the voltage on pin 2 is not the way to measure plate voltage?
Looks like the filament voltage is perfect if I need an additional 5%. Will the DC Regulator take it down to 5 V, thus leaving me with low filament voltage?
The voltage the plate sees is the plate voltage minus the DC voltage at the top of the 1K resistor. For one side, this is 429V-72.1V, so 356.9V. Current through that tube is 72.1mA, so plate dissipation is about 26 Watts.
Your filament voltage is within 5%, which is great. The regulator will regulate to 5V (at a tighter tolerance than 5%). I'm not sure what you're asking when you mention low filament voltage. Low filament voltage for a 300B is going to be more like 4.5V.
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Paul - thanks for that explanation. I knew I was missing something.
So - EML Mesh draws 1.4 amps so, 5.25 volts on 1.2 amps (sovtek tube) would be more like 5 volts on the EML. Does the DC regulator (not yet installed) provide 5V independent of current? if so I that is perfect for the EML. Spec is 5v +/- 4%
26 amps is the maximum plate current for the EML. It would be better to have it at 24, recommended is 22. But it all looks workable with no modification. However, if I wanted to bring it down, what would be the best option?
That leads me to a follow up question - I might be moving in with my GF :o. House voltage there is 119, mine is 125. How much does a difference in AC voltage affect the output voltage of the transformer? Might be just right if it reduces the voltage a bit.
BTW - I appreciate all the time you are taking to respond!
drew.
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I'm sorry - 28 is the maximum current. 26 is within operating range.
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It would be very impressive to see 26 Amps of plate current through an EML tube. I think you probably mean 26 watts.
For what it's worth, after all of this discussion I put my EMLs in my Kaiju and ended up going back to EHs. Thought the EMLs were not as open sounding in my system. YMMV, TANSTAAFL, WYSIWYG.
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So - EML Mesh draws 1.4 amps so, 5.25 volts on 1.2 amps (sovtek tube) would be more like 5 volts on the EML. Does the DC regulator (not yet installed) provide 5V independent of current? if so I that is perfect for the EML. Spec is 5v +/- 4%
You might see something like 5.2V on the EML's, PJ would probably have a more educated guess, but in any case, you can just plug them in. I could have sworn a few months ago that the EML spec was +/- 4%, this is getting pretty tedious to keep up with.
It would be better to have it at 24, recommended is 22. But it all looks workable with no modification. However, if I wanted to bring it down, what would be the best option?
Western Electric specs 36 watts as the maximum plate dissipation for the 300B, with some suggestions in application notes that you can go as high as 40. The ultimate question here is why a manufacturer would call a tube a 300B when it can only dissipate 22 Watts. There are many amps commercially available that have been manufactured over the last 20 years that run at over 30 Watts of dissipation, so this seems pretty unusual.
Are you running the 300B mesh? The operating point that you measured and posted is one that is recommended on the EML website for the 300B mesh, so I wouldn't adjust it at all.
That leads me to a follow up question - I might be moving in with my GF :o. House voltage there is 119, mine is 125. How much does a difference in AC voltage affect the output voltage of the transformer? Might be just right if it reduces the voltage a bit.
You'll still be on the correct transformer tap. You might see something like 4.95V instead of 5.25V, and there would also be a slight reduction in plate dissipation.
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Great! Thanks Paul - I don't have the Mesh Plates yet, should have them by the end of the week. I am measuring everything with Sovtek's. Gonna plug them in and listen when I get them.
I am learning a lot from this project and really appreciate the detailed answers. Also, really loving the Kaiju - you guys do a great job in design and support.
drew.
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Just installed the DC regulator. Dead quiet, can't hear anything with ears right upmto speakers. Now have 4,91v on the filaments.
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It looks like I will be out of spec on the filament voltage with the .51 resistors and the DC regulator.
So based on the specs of the EML drawing 1.4 amps, I calculate I need .45 ohm resisters to bring the voltage up to 5V spec.
6.3 - 5 = 1.3 1.3/1.4 = .92 .92/2 = .46
correct?
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Just installed the DC regulator. Dead quiet, can't hear anything with ears right upmto speakers. Now have 4,91v on the filaments.
Hey Drew, anxious to learn if you perceive any difference in the music vs AC other than the lower noise floor. Please post a pic as well, I would like to see what it involves.
Thanks,
Ed
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I got the DC heater even though I have terribly inefficient (92db) speakers :P. Paul suggested it because EML recommends using it on their tubes. For my budget, these tubes are expensive, so I am being very careful about getting things right. I did a lot of research on the debate about sound. Like many things in audio there is little agreement.
Here is a quote from the Emissions Lab site on providing power to EML tubes "Use DC filament heating. AC heating will not sound better, because these will hum, and there is nothing better sounding about that."
I did some critical listening late last night and could not hear any differences. The hum was noticeable even on my speakers so I think it is a good call.
Bottom line, it is an easy build: very simple circuit board and a couple of wires, and it is not very expensive for what you get. I would recommend it. Sorry I don't have a picture. If you send me your email by PM, i'll send you a copy of the manual.
drew.
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Could you quantify "noticable"? I.e. do you mean if you put your ear up to the speaker, you can hear a little hum in a quiet room, or do you mean that it is audible from the listening position. Also, what were you seeing on the hum balance measurement?
Please do not offer distribute manuals (or any portion) without permission. A large portion of kit cost is the time and effort of writing these manuals; they are the property of Bottlehead, and we do not take that lightly.
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Hi Josh. Apologies about offering the manual. I wouldn't have except that Ed is already a kaiju customer . at any rate it did not happen
The hum was apparent with ear to speaker and barely audible in a dead quiet room. I listen nearfield at 9ft away. Hum pots were at 4 to 8
mv if I remember correctly. Speakers are dead quiet now.
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It looks like I will be out of spec on the filament voltage with the .51 resistors and the DC regulator.
So based on the specs of the EML drawing 1.4 amps, I calculate I need .45 ohm resisters to bring the voltage up to 5V spec.
6.3 - 5 = 1.3 1.3/1.4 = .92 .92/2 = .46
correct?
More precisely, you should include the 0.1A through the hum pot. Assuming the EI tube is drawing exactly 1.2 amps (it's probably close but not exact), that's 1.3 amps total. Adding the resistor drop to the measured 4.91 volts, I get 6.236 volts from the filament supply as seen at the tube - the 0.064v difference from the target 6.30v is probably lost in the wires. Using 1.5 amps for the EML plus hum pot, I get a target of 0.412 ohms each. This can be done by paralleling the 0.51 ohm resistors with 2.14 ohms each. 2.2 ohms is close enough and readily available. A half watt rating is adequate, though I'd spring for 1-watt resistors. Might as well get some 2.0 ohm and some 2.4 ohm resistors at the same time in case you want to adjust further.
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I hate to always be the pragmatist here, but we are dealing with such low resistances that the resistance of the solder joints can influence the readings. Because of that I think picking an exact value may always be a matter of cut and try.
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Thanks Paul and Doc I'll get an assortment of values per Paul's suggestion. And Paul, I really appreciate the details you provide as I am learning a lot with this project and your information is always a bit help.
Problem is I don't want to stop listening 😁
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finally complete with tubes and all modifications in place, well except I have some Mudorf Silver/Oil 10uf's on the way. But that is the LAST thing I am doing, really.
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Looks great Drew! Anxious to read your thought on the EMLs.
Best,
Ed
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Thanks Ed - Don't know if you saw my other post, but I went through the ringer to get these tubes so I hope they work out. They look awesome and are very well made apparently, feel very solid anyway.
I'll will give them a week or so to break in and provide some feedback on them. So far they sound pretty darn sweet though.
drew.
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Thanks Ed - Don't know if you saw my other post, but I went through the ringer to get these tubes so I hope they work out. They look awesome and are very well made apparently, feel very solid anyway.
I'll will give them a week or so to break in and provide some feedback on them. So far they sound pretty darn sweet though.
drew.
Wow Drew, just read the thread, that sucks. I didn't read if you were able to get it rectified or if you had to fork out more $$, hopefully not the later.
Hope they are worth the effort.
Best,
Ed
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I put up posters in the hood advertising a reward. Sure enough someone contacted me, so I did fork out a bit more money, but at least not to TubesUSA!
I am thinking of adding these transformer covers over the chokes. I think I like the clean look and the driver tubes stand out more against them. They need to be modified slightly to fit just right.
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I like them, I was looking at some aluminum covers on eBay. I'm still undecided at this point.
Best,
Ed
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Mundorf's are in! As soon as I get a new driver tube, I can start listening again.
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Back up and running again. New driver
tubes and caps, ouch. I bit painful at first but after ten hours I am starting to hear some promising sounds! I think I'll run it continuously for the next couple of days and get this break in thing done.
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I've used Mundorf caps in the past. In my experience they definitely benefit from an extended run time. But in the end it's worth a it.
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Thanks for the encouragement. I almost pulled them out yesterday these are the older 1200 volt I read they take even longer. I let them run all day yesterday and today. Listening to pendercky violin concerto. Starting to sound like music again. Mids are smoothing out, bass is returning and the soundstage is deepening. I didnt notice this much change with the vcaps but they were only .1 so maybe not so much to break in. Or maybe I have more joy to look forward too.
What a great hobby!
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The problem with building your own amp is it is like painting your own house. I look for and find every small issue I can find and can't just sit back and enjoy it. I have been obsessing about every detail, spent the other night evaluating 6 different variations on speaker cables, actually made a spread sheet and evaluated a variety of qualities.
All of this is very interesting, but I think I just want to get over it and enjoy the music. Gonna try to do that tonight, wish me luck!
drew.
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Good Luck! ;D
Best,
Ed
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Fwiw, I am finally done. After weeks of moving things, swapping Cables, measuring, breaking in caps, swearing and self doubt, I have a sound that I am ecstatic about. Finally have bass, midrange, and crystal clear treble, imaging, depth, pinpoint instrument placement and musicality. I can't drag myself away and keep going through my music collection hearing details and experiencing things I have not before.
I congratulate Paul on his design but also did major modifications from the start. What I have learned is that every little detail makes a difference. But you will have to figure that out for yourself. If you do build a kaiju and want suggestions let me know.
I do highly recommend the Eml's tubes without reservation. They seem to keep delivering more and more as I make other small improvements. Great amp, fun project, this is it for awhile really . . .
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Congratulations Drew, I'm not quite where you are in the process. It may take trying the EMLs to get there. The Sophia RPs are good and still only have about 15 hrs in my amp, since they were used previously I don't know what to expect regarding break in.
Best,
Ed
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Give them some time - I used to be such a skeptic about stuff breaking in. I think as my system has gotten better, I hear more differences.
Be cool if we lived closed enough to swap tubes, I am in San Francisco Bay area. would love to hear the differences.
Oh, I also installed some NOS (60's) 5670's. Not expensive and maybe a bit smoother than the JAN's that BH provided. If I remember, you already swapped out your driver tubes.
BTW, you got me interested in open baffle speaker designs, maybe my next project, along with converting my Stereoumour to 45's.
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Give them some time - I used to be such a skeptic about stuff breaking in. I think as my system has gotten better, I hear more differences.
Be cool if we lived closed enough to swap tubes, I am in San Francisco Bay area. would love to hear the differences.
Oh, I also installed some NOS (60's) 5670's. Not expensive and maybe a bit smoother than the JAN's that BH provided. If I remember, you already swapped out your driver tubes.
BTW, you got me interested in open baffle speaker designs, maybe my next project, along with converting my Stereoumour to 45's.
I'll give them more time, I believe in break in, I just didn't know what to expect since they were used previously.
I'm just outside of Louisville KY. In another life I was in the San Francisco area fairly often, the company I worked for had a branch in Hayward.
You are correct, I did pick up some NOS GE 5 star 5670s, they sound nice but I still find myself listening for something my Stereomour does, a certain presence on a couple of tracks. I am beginning to suspect a difference in caps, but I dont recall hearing it until I put the JJs and the psvane in the Stereomour, maybe not until the JJ had broken in. I may try the Mundorf silver oils in the coupling cap position like my Stereomour has, unfortunately I won't be able to get Ampohms in 10uF, even if I could they wouldn't fit! Don't get me wrong, the Kaiju does some things that the Stereomour doesn't, and it does so without strain, I am really enjoying the sound, however, if I can get the sound tweaked just a tad more I will be completely happy. Of course I need to be more patient, the Stereomour didn't sound the way it does overnight.
Regarding open baffle speakers, for me they were addicting. I have been listening to OBs since the early 2000s. The set I am running currently are the best I have had, they use the same bass section as my previous pair which used a coaxial driver from 200Hz up, the current set are more refined. The only roadblock for OBs is you have to pull them out from the front wall a minimum of 36", more is better.
Best,
Ed
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Sorry to spam your thread Drew, but since I mentioned it in my post above, I thought I would post what I have found to be the issue. I noted above that I was looking for a "presence" on a couple of tracks that I enjoyed with my Stereomour that seemed to be lacking in the Kaiju. Well Im happy to say that presence is back! It seems my Auralic Aries auto updated the same day I received my Sophia RP tubes. I did not realize it had updated, nor did I realize that my DSD tracks were playing as PCM. The two tracks I was specifically having an issue with happened to be DSD files, once I found that the update had defaulted to the DOP setting off, I turned it on and Viola! There was the presence I was missing.
Sorry for the rambling.
Best,
Ed
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No worries Ed, I am glad to know someone else is obsessing as much as I am. Quick story for you: at one point I seemed to lose all of my soundstage and everything sounded flat and 2d. I swapped Cables and moved things around. After a week of frustration, I discovered I had at some point plugged the amp into the digital component side of my my power conditioner. I moved it to the high current side and everything sounded great again.
Glad you enjoying the sophias. Try sitting back with a beverage and listening for a while. It's fun!