2. amps-preamps
  3. 139915-2206

Bypass capacitor position?

Hi all. I've had a pair of Coincident Frankensteins for a number of years and just opened them up to put in new capacitors.  In doing so, I discovered that the previous owner had installed bypass caps on the power supply capacitor bank.  Those bypass caps are, however, in different positions on the two monoblocks.  Obviously they're both within the same capacitor bank, just linking different parts of the chain, so perhaps that isn't an issue.

Sometimes I think I can hear a small difference in the two amps, but if it's there it's really subtle and I may be creating a self-fulfilling prophecy.

Can anyone provide input on if this fact will change their operation/sound?  I'm trying to figure out whether to cut one of them out and move it, and if so, which is the appropriate position...

Monoblock 1:  https://photos.app.goo.gl/NMGYvU1sdHbGLqb37
Monoblock 2:  https://photos.app.goo.gl/ogDkNio1DyqvM1rs6

Thanks...
128x128cal3713
12 responses Add your response
salectric
747 posts
 
I can’t see the wiring details on my phone.  However, it appears the two channels are mirror images of each other so the bypass capacitor positions would logically be reversed as well.

i notice each amp has what appears to be a Jupiter copper foil capacitor.  That is probably the coupling cap between the input and driver sections.  (I can’t tell for sure because I can’t make out the wiring connections.)  If that is correct, it is a major upgrade over the stock cap.  
grannyring's avatar
grannyring
6,438 posts
 
I agree. All looks fine to me.  Nice to see an all film cap power supply.  Not often done, but really is a nice improvement in SQ. 
cal3713's avatar
cal3713 OP
1,421 posts
 
Everything is mirrored, but you’ll notice that the yellow REL-caps are in the same position (i.e., both next to the leftmost power supply capacitor)... sorry, I should have been clearer about what capacitor I was talking about.

I put in the Duelund CAST caps... previously were some little Solens.


grannyring's avatar
grannyring
6,438 posts
 
Nice decision on the Duelund caps! Bypass them with the Duelund .01uf pure silver bypass cap for another nice jump in realism.

Those power supply caps all appear to be in parallel from the pics? Not entirely sure, but it looks so. Can’t see real clearly. If so, all is fine as the actual position of the bypass makes no difference.
erik_squires
15,791 posts
 
I had a pair of the Duelund pure silver caps, eye watering expensive and... meh.

Didn't really do a thing in my set up.

If anything, I'd suggest sticking to copper and just using a very small version of the same.
georgehifi's avatar
georgehifi
10,312 posts
 
cal3713
 Everything is mirrored,
but you’ll notice that the yellow REL-caps are in the same position
Doesn’t matter, in both pics it seems that it goes from ground to the B+

Cheers George
grannyring's avatar
grannyring
6,438 posts
 
Erik, 

I also use them extensively, not just once, and they work marvelously with both Jupiter copper foil and Duelund caps in electronics.    Not sure if you actually tried them with these two caps and in electronics...not crossovers? 
erik_squires
15,791 posts
 
@grannyring

Nope, just in crossovers. :)

Best,
E
johnsonwu
467 posts
 
small difference in the 2 amps....  the Frankenstein uses a "Hail Mary" type of biasing on the 300B as far as I can tell.  The sound is very dependent on the plate voltage of the 6EM7.  Good luck getting the 2 to sound the same.

cal3713's avatar
cal3713 OP
1,421 posts
 
Thanks for the input everyone. I went with the tinned copper cast option. Figured I might as well match the speaker cables... And just a step more expensive than the straight coopers. Not eye watering like the silvers.

@grannyring I read on one review (either that huge capacitor comparison site or jeffspace) that they didn't like the silver bypass on those tinned-copper caps. Might still give it a shot though... Thanks for the suggestion. (And the power cords sound great. I tried to go back to stock and it was a huge step back)
grannyring's avatar
grannyring
6,438 posts
 
I did not use the silver bypass caps  on the tinned copper Duelund caps. I only used them with the CAST. It may not sound good with the tinned copper caps, I  just don’t know. I thought you used the original CAST line.
atmasphere's avatar
atmasphere
11,615 posts
 
I agree. All looks fine to me.  Nice to see an all film cap power supply.  Not often done, but really is a nice improvement in SQ.
@grannyring

FWIW there are electrolytic capacitors used in this amp. There are 4 of them visible near the top of the photos.

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