Effects of Capacitor Values

glynnw · 6702

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Offline glynnw

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on: November 17, 2015, 07:34:50 AM
I want to replace the 3.3 uF Solens - in an earlier thread someone said that values of 2.2 to 6.8 would work.  A one time I seem to remember it being said here in the Paramount section that the larger values might render better bass.  Considering the much higher cost of the larger caps, what is to be gained, if anything , by using a 6 uF as opposed to a 3 uF cap?

PC, J River software, opticaRendu, Schitt Ygg DAC,Tortuga Pre, Torta Radu tube buffer, Linear Tube Audio ZOTL10, Spatial Audio X5w/pair of GR Research dual 12" open baffle servo subwoofers tamed by DSpeaker Dual-Core DSP , Audience AU24 SE  spkr cable, handmade silver interconnects,

Offline Paul Birkeland

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Reply #1 on: November 17, 2015, 03:33:33 PM
The easy answer to this question is to buy the 6.8uF Solen cap that matches the stock cap, listen to them both, then come back and let us know what you find!

The knowledge earned by the time and rather small investment in the second pair of caps will give you more confidence in purchasing the appropriate parallel feed capacitor value.  (Do note that this value will also depend slightly on the speakers you use)

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline glynnw

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Reply #2 on: November 18, 2015, 06:24:34 AM
What?  Me do research? 

Actually yours is a good idea.  Thanks

PC, J River software, opticaRendu, Schitt Ygg DAC,Tortuga Pre, Torta Radu tube buffer, Linear Tube Audio ZOTL10, Spatial Audio X5w/pair of GR Research dual 12" open baffle servo subwoofers tamed by DSpeaker Dual-Core DSP , Audience AU24 SE  spkr cable, handmade silver interconnects,

Offline Trajan

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Reply #3 on: December 17, 2015, 03:17:58 PM
I replaced the output coupling cap with a nice 4.7 microfarad Mundorf.  It was bigger, but fit.  Bass was very good.  I just blew a EL84 cathode bypass cap on one channel (I have been messing with alternate driver tubes so no worries on the stock design).  I replaced it with a 47 microfarad Solen film cap in each channel (as big as my fist  but it was what i had on hand).   :)   The  amp works fine and had no loss of bass in my system (I can still hear 20 Hz.)  It looks like the corner frequency is very low on the output tube (under 1 Hz I believe).  So there is some opportunity for lowering the microfarad values a bit on that cap potentially.  Bass is luscious and the amp appears to have a bit cleaner highs with no oscillation or pops.  Just my results.  Be careful subbing values and be prepared to accept the blame if it goes bad, but it sure is fun.
« Last Edit: December 17, 2015, 03:21:04 PM by Trajan »


Offline Paul Birkeland

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Reply #4 on: December 17, 2015, 06:19:16 PM
The feedback in this design makes it incredibly sensitive to capacitor changes.  What exactly happened to the cathode bypass cap?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Trajan

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Reply #5 on: January 27, 2016, 08:56:28 AM
I've been away for a while, so sorry for the delay.  The output tube cathode bypass cap not coupling cap blew its guts (sorry for my haste in typing).  I think having the legs of it spread 180 caused some issues.  The giant Solen Film cap mentioned before fit (barely with some tweaking) with no loss of bass that I could tell.   


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