Coincident Frankenstein 300B SET

Seamaster

Seamaster

Active Member
A new 300B SET in the house, I ordered from Coincident in Canada. The amp sounds wonderful from hour zero considering the parts they put in there (see pictures), big applause to Mr. Blume as an amp designer. Those no name MKP 0.47uf coupling caps are really an eye sour though. What do you guys think?

The sound signature of the amp right now is (tube) neutral and lean a little bit to the warm side (less than 10%), no normal 300B sluggish sound here, the bass is pretty solid with Zu with outstanding speed and extension for a tube amp especially for a 300B SET. Attack, yes this amp can attack, I am not sure with other speakers (because I just sold my Tannoy Turnberry SE that I have owned for 12 years right before this) with lower efficiency rating but with Zu (101dB, 12 Ohm), this 300B attacks harder than my 845 mono block, it is hard to believe. The top end is open but with little bit of grainess, I hope it will smooth out after 200 hours. The imaging is very sharp compare to my Melody M845 SET. The vocal is a standard 300B deal， charming, same as my 300B (2.5V 300B in place of 2A3) driven 845.

What can I do to improve the amp and maintain most of its current sound signature? A little more density is welcome here. Currently I have a pair of 0.47uf 600VDC Jupiter copper in paper and 4 Jantzen Superior Z 1.0uf 800VDC on hand, why? it is a long story...... I was told the Super Z are the bypass filters for electrolytic caps in the power supply section but they are too big to fit, by looking at the amp, which of 4 electrolytic caps did he refer to?

Here some YouTube video samples:

Vocal

Speed

Bass

Thanks.
 

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I don't have the schematic of the stereo Frankenstein 300B but here is what's going on in the mono block version:

Screen Shot 2022-08-27 at 01.20.46.png Screen Shot 2022-08-27 at 01.20.27.png
 
Nice amp! Swapping coupling caps will take you to a special level of audio hell. ;-) But if you want a denser sound try the Cornell-Dubilier 942C series--the higher the voltage rating the better they sound. This is my go-to cap for building amps precisely because they have a dense, palpable sound without sacrificing speed or air. I find them very close to V-Caps in signature at a fraction of the cost. I've tried a LOT of coupling caps and I always come back to these. I would maintain the same value out of respect for the designer's intentions.
 
Copper V-Caps (CuTF) should be ideal. Expensive but well worth it in my opinion. All of my gear now has them as couplers.
 
Salectric said:
Copper V-Caps (CuTF) should be ideal. Expensive but well worth it in my opinion. All of my gear now has them as couplers.
Click to expand...

Is Copper V-Caps (CuTF) is going to change the tonal balance toward to cooler side? Thanks. I have Mundorf SGO in my preamp, I found them have a hair of too much HF energy.
 
zackthedog said:
Nice amp! Swapping coupling caps will take you to a special level of audio hell. ;-) But if you want a denser sound try the Cornell-Dubilier 942C series--the higher the voltage rating the better they sound. This is my go-to cap for building amps precisely because they have a dense, palpable sound without sacrificing speed or air. I find them very close to V-Caps in signature at a fraction of the cost. I've tried a LOT of coupling caps and I always come back to these. I would maintain the same value out of respect for the designer's intentions.
Click to expand...

Thank you.

Does Cornell-Dubilier 942C have natural timbre like copper caps?

https://www.mouser.com/c/passive-co...lm-capacitors/?m=Cornell Dubilier&series=942C
looks like the 942c do not have higher than 460VDC
 
Seamaster said:
Thank you.

Does Cornell-Dubilier 942C have natural timbre like copper caps?

https://www.mouser.com/c/passive-components/capacitors/film-capacitors/?m=Cornell Dubilier&series=942C
looks like the 942c do not have higher than 460VDC
Click to expand...

That's 460VAC, 1600VDC:

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/942C16P47K-F?qs=oi6qnwyrdkyt7ryZSYQ1Nw==

I've only tried 2 copper caps. Miflex KPCU, and the 942C are superior IMO, more depth and solidity. Also V-Cap CuTF--I find these very similar in timbre for a fraction of the cost, as I mentioned.

John Broskie of TubeCad turned the DIY community on to these and they are excellent caps. Every fellow DIYer I've recommended them to agrees. I do not like thin, airy sound, or "smooth" gluey oil-cap sound. These are clean and rich. They will sound a little dark until they break in.

They're $11. You're probably going to try many many caps but before you spend a lot of money you should try these. I can't guarantee you'll like them but they are very, very good, better than anything else I've tried except V-Caps.

Also, V-Cap TFTF's are discontinued and now on sale, .47/600VDC for $117 each. If you want a really superb cap get those. The newer CuTF are a little crisper on top, but the TFTF are amazing. What I'm using in my Aikido preamp right now. Have no desire to change them.
 
Also, I have Janzen Superior-Z. Too bright for my ears. The C-D's just hit it straight down the middle, as they say in golf. ;-)
 
zackthedog said:
That's 460VAC, 1600VDC:

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/942C16P47K-F?qs=oi6qnwyrdkyt7ryZSYQ1Nw==

I've only tried 2 copper caps. Miflex KPCU, and the 942C are superior IMO, more depth and solidity. Also V-Cap CuTF--I find these very similar in timbre for a fraction of the cost, as I mentioned.

John Broskie of TubeCad turned the DIY community on to these and they are excellent caps. Every fellow DIYer I've recommended them to agrees. I do not like thin, airy sound, or "smooth" gluey oil-cap sound. These are clean and rich. They will sound a little dark until they break in.

They're $11. You're probably going to try many many caps but before you spend a lot of money you should try these. I can't guarantee you'll like them but they are very, very good, better than anything else I've tried except V-Caps.

Also, V-Cap TFTF's are discontinued and now on sale, .47/600VDC for $117 each. If you want a really superb cap get those. The newer CuTF are a little crisper on top, but the TFTF are amazing. What I'm using in my Aikido preamp right now. Have no desire to change them.
Click to expand...
Thanks for finding that, I was looking and looking..... I will defiantly investing 942C, sounds really promising, BTW, can you identify the two .47uf caps in my amp? Thanks.
 
Seamaster said:
Is Copper V-Caps (CuTF) is going to change the tonal balance toward to cooler side? Thanks. I have Mundorf SGO in my preamp, I found them have a hair of too much HF energy.
Click to expand...

I agree that SGO caps have a HF emphasis. The CuTF caps in the values I use (.01, .1, .22 and .47uf) do not emphasize the highs. The older TFTF caps were also good and I used them before the coppers came out. However, some people thought they sounded cool. The CuTF caps are significantly better than the TFTF—more even tonal balance and more subtle detail. For what it’s worth. the SGO caps fall well below the two V-Cap models. All in my opinion of course.
 
Digi-Key also stocks 0.47uf Cornell-Dubilier 942Cs in a few voltages.

https://www.digikey.com/en/products...sXXgMggN2mHoN9lRRNbaldOTRAtFGh9KACgmypwLnVUoA

They also have a free shipping option, which is particularly helpful on small orders. Details here: http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562

I picked up some of the 942Cs a while back based on @zackthedog 's recommendation but I haven't used them in anything yet. It may be a while since my currently breadboarded project is directly coupled.
 
Salectric said:
I agree that SGO caps have a HF emphasis. The CuTF caps in the values I use (.01, .1, .22 and .47uf) do not emphasize the highs. The older TFTF caps were also good and I used them before the coppers came out. However, some people thought they sounded cool. The CuTF caps are significantly better than the TFTF—more even tonal balance and more subtle detail. For what it’s worth. the SGO caps fall well below the two V-Cap models. All in my opinion of course.
Click to expand...

I completely agree with all this. I had CuTF in my preamps but one failed (!!). Good thing my Williamson builds are tough... I had older TFTF's on hand so that's what's there now. For the close-out price, the .47/600VDC are a very good buy, IMO. CuTF's are twice that, so I was thinking cost for the OP. ;-)
 
Seamaster said:
Is Copper V-Caps (CuTF) is going to change the tonal balance toward to cooler side? Thanks. I have Mundorf SGO in my preamp, I found them have a hair of too much HF energy.
Click to expand...

No. CuTF's are NOT bright, they are extremely well-balanced and coherent. Everything is in it's proper place. The reviews that say "as close to no cap as possible" are correct, IMO.
 
Seamaster said:
Thanks for finding that, I was looking and looking..... I will defiantly investing 942C, sounds really promising, BTW, can you identify the two .47uf caps in my amp? Thanks.
Click to expand...

You took a close-up pic of them. The white MKP .47/630V caps.
 
FlaCharlie said:
Digi-Key also stocks 0.47uf Cornell-Dubilier 942Cs in a few voltages.

https://www.digikey.com/en/products...sXXgMggN2mHoN9lRRNbaldOTRAtFGh9KACgmypwLnVUoA

They also have a free shipping option, which is particularly helpful on small orders. Details here: http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562

I picked up some of the 942Cs a while back based on @zackthedog 's recommendation but I haven't used them in anything yet. It may be a while since my currently breadboarded project is directly coupled.
Click to expand...

Broskie says the higher the voltage rating, the better they sound. He explained this somewhere on his blog but I can't find the reference.
 
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