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Old 21st May 2010, 06:50 PM   #1
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Default Cap choices coupling

Hi
New to the forum
I'm in the process of trying to change caps in my pp amplifiers
The amps are very solid state sounding and i'm trying to empart a bit of musicality and body to the sound the stock caps are Sonicap gen 1 although balanced sounding they lack musicality I eventually switched these to the Russian k40's although musical I lost all of the transparency and dynamics the music seems rolled off

The next set of caps I want to try out is a mix hybrid sort of
I was thinking of going with Dynamicaps in the input positon and Jupiter in the Finals (the amps only have 3 coupling caps no cap goes to the output tube)

I want to somehow try to keep the transparency and good dynamics of the Gen 1 and add some midrange and frequency extension with the Jupiters

Any thoughts on this combo

I currently have vcap teflons in my pre amp and before I went with the Russian k40 the system was a bit too analytical and revealing
The k40 smoothed things out but at the expense of everthing else

Any input appreciated
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Old 21st May 2010, 06:58 PM   #2
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No offense meant, but...

You are wasting your time. You have succumbed to the metaphysics of this stuff. Most if not all of the difference you hear is in your head.
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Old 21st May 2010, 07:06 PM   #3
SY is offline SY  United States
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Far more likely that any problems you might be hearing can be most effectively dealt with by optimizing topology and operating points rather than throwing money blindly at brand names. Could you post a schematic?
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Old 21st May 2010, 07:11 PM   #4
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Sorry Guys I don't have a schematic ..these are Dodd Audio 120 monoblocks
Tubes are kt 77/el34 and 5687 input solid state rectification
Not sure if this helps
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Old 21st May 2010, 07:29 PM   #5
SY is offline SY  United States
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Quote:
Originally Posted by bluemike View Post
Sorry Guys I don't have a schematic ..these are Dodd Audio 120 monoblocks
Tubes are kt 77/el34 and 5687 input solid state rectification
Not sure if this helps
It shouldn't be too hard to trace out if you can't find a schematic. Good practice, too. Most commercial tube amps can be greatly improved with a few extra parts or a tweaking of the values of parts already there.
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Old 21st May 2010, 08:39 PM   #6
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I have no clue when it comes schematics or how to trace out - sorry
I thought this was a straight forward question
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Old 21st May 2010, 10:26 PM   #7
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If it was me I'd stick with polypropylene caps from any reputable source.
The tubes operating points and any electrolytic caps would be next to look at for me, as would reducing loop feedback and adding local feedback as practical.
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Old 22nd May 2010, 01:38 AM   #8
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Quote:
Originally Posted by bluemike View Post
The amps are very solid state sounding and i'm trying to empart a bit of musicality and body to the sound the stock caps are Sonicap gen ...
That solid state sound is more likely being caused by too much gNFB. Reducing the gNFB, assuming that the reason for excessive gNFB in the first place was not an attempt to cover up a horrible open loop design (there is all too much of that going around) will do more for sonic improvement than supposedly magical audiophool capacitors (or any other gimmick).
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Old 22nd May 2010, 02:12 AM   #9
ervinl is offline ervinl  Indonesia
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I just know if too much gNFB will reduce sonic. I instead use as much gNFB but with "tube character" resistor like Allen Bradley in this position (feedback R and bypass R/divider), in order to get the tube sound through this gNFB. Am I doing wrong? I use 33k/10k (3.3 gain), while normal circuit implement 10 to 20 of gain.
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Old 22nd May 2010, 03:48 AM   #10
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I thought it wasn't a good idea to use the same type of caps for all coupling postions
I agree that a good polyprop in the input stage is good but a teflon cap in this position may be better no ?
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