Tweakers' Asylum

Please help with selection of output caps

76.99.179.191

hukkfinn

Hi,
I need help with a preamp cap upgrade!
Preamp: modified Conrad Johnson PV12
Power amp: Odyssey stratos extreme monoblocks
Speakers: Vienna Acoustics Beethoven
The CJ preamp is very detailed BUT the bass, the punch, the WEIGHT of my music are lacking (pop and rock, e.g. the Beatles). Mids and highs are pretty and accurate but can be slightly bleached out.
The CJ (original) output caps are 2.0uF, 250VDC polystyrene.
----------------------------------------------------------
ISSUE: Which output caps? Vcaps? Sonicaps? Auricaps?
----------------------------------------------------------
I WANT: seriously correct timing (i.e., my music MUST GROOVE), bass authority, bass and midbass WEIGHT, punch, in-the-room presence of drum whacks, overall naturalness, human-sounding vocals, soundstage depth.
I DON'T WANT: airy, transparent, detail-detail-detail, enhanced treble, hi-fi sounding.
Suggestions?

Edits: 05/31/09 05/31/09

Follow Ups:

CORRECTION: stock caps in the CJ are polypropelyne - hukkfinn 07:44:00 06/06/09 (0)
...not polystyene.

Any others with a view about the best popular cap for my desired warm, bass-punchy sound?

Thanks,
Hukk
RE: Please help with selection of output caps - garymuffley@fuse.net 16:36:11 06/03/09 (4)
What is the input impedance of your power amp?
- Reason for this question? - hukkfinn 07:41:46 06/06/09 (2)
  You got me curious!
  Hukk
  - The input impedance of the poweramp... - jeffreybehr 09:19:25 06/06/09 (1)
    ...is parallel with the (output) load resistor of the preamp, and that paralleled impedance determines the filterpoint of the output cap. The lower that resistance, the HIGHER the filter point. That's one reason others are suggesting you increase the size of your preamp's output caps. The higher value the output cap, the lower the filter point.
    -------------------------------------------------------
    Tin-eared audiofool and parttime landscape fotografer.
    http://community.webshots.com/user/jeffreybehr
    - Wow - hukkfinn 09:23:03 06/06/09 (0)
      Thank you -
      OK what is a filter point, and why is it good to make it lower?
      Hukk
- Input impedance of my power amp = 10,000 - hukkfinn 16:46:33 06/03/09 (0)
  .... which I am told, is unusually low, with many modern SS power amps having 50,000 or 100,000 these days.
  
  I have Odyssey Stratos Extreme monoblock power amps.
  
  Thanks for any help,
  Hukk
RE: Please help with selection of output caps - DaveT 14:38:23 06/02/09 (0)
I have done extensive testing of various input caps for a T-Amp. There should be a one-to-one correlation for the output caps for a preamp to that of input caps to a T-Amp. Imbedded in the Capacitor test are other capacitor tests. My tests are economical capacitors (including electrolytics), while some of the other referenced tests include expensive boutique capacitors.

First, polypropylene will yield a much better presentation than a polyester cap. There are any number of more costly capacitor topologies, but polypropylene is a good middle of the road audiophile quality capacitor.

I suggest you try 1.0 MFD film caps from Radio Shack (RS) for starters. You can start with (2) 1.0 MFD caps wired in parallel. This will replicate the 2.0 caps you currently have. If you desire more bass add another 1.0 MFD capacitor in parallel. Once you get what you want in the way of bass weight (i.e. the total capacitance) then you may choose to try other caps. The RS caps are readily available for a great number of readers.

I strongly suggest Auricaps, which is my personal favorite, but I find the Radio Shack caps very close in presentation at little cost.

If you have specific questions regarding caps I tested you may message me directly. I hope this helps.
DaveT
- Capacitor Test (Open in New Window)
RE: Please help with selection of output caps - Ugly 23:13:35 06/01/09 (0)
You may be getting a bit rolled off in the low frequencies. More C could be what you seek but....

If it were me, in order to avoid making more than one change at a time, I'd want to try a larger capacitance of the same technology, manufacturer, voltage and tolerance rating. If you have then determined you have solved the frequency response issues with a capacitance value change then go on to try and roll different manufacturers and technologies. But that may just be me.
Any other help? Should I be considering Nichicon? - hukkfinn 19:30:35 06/01/09 (1)
Thanks very much for any opinions.
Hukk
- As far as I know, Nichicon ... - andyr 03:48:09 06/03/09 (0)
  only make electrolytics. You certainly shouldn't use electrolytics for coupling duties.
  
  Now, other posters have suggested increasing the value of the coupling caps (input and output) as this will make the intrinsic roll off lower. This is certainly something you can try ... but maybe the make of amp you have is simply ... bass-shy compared to others?
  
  Regards,
  
  Andy
RE: Please help with selection of output caps - fmak 10:40:07 05/31/09 (3)
Have you considered a valve change?
- Need a more fundamental change - hukkfinn 11:24:44 05/31/09 (2)
  I've tried at least 2 dozen various valves
  Thanks
  - RE: Need a more fundamental change - Face 16:07:17 05/31/09 (1)
    Natural=Duelund
    
    Weight+Depth+Bass Authority=Claritycap MR
    - RE: Need a more fundamental change - hukkfinn 19:32:12 06/01/09 (0)
      Thanks.

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