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-   -   Bypassing filter caps with Smaller caps (http://www.diyaudio.com/forums/tubes-valves/210251-bypassing-filter-caps-smaller-caps.html)

mbeards 6th April 2012 06:45 PM

Bypassing filter caps with Smaller caps
 
Hi everyone,

I am wondering what results people have with bypassing large filter and other large bypass caps with a small bypass capacitor to provide a better path to ground for high frequencies.

I have heard of this a few times but I am wondering if it is a good thing to conceder? I usually see somewhere around .1 uf recommended.

Thanks

vinylkid58 6th April 2012 06:58 PM

Bypassing PS filter caps is quite common, and beneficial.

jeff

Shoog 6th April 2012 11:48 PM

You only need it on the final cap, and my experience is that it definately improves high frequency performance to a surprising degree. It also works on cathode bypass caps.

Shoog

AJT 6th April 2012 11:54 PM

never used any.....

speakerfritz 7th April 2012 01:02 AM

you need faster caps.....if your power supply are electrolytic's, you can use poly film, meta lfilm, etc. if your power supply caps are ply film, then you need metal film, etc

AJT 7th April 2012 04:19 AM

never felt any need for it in my tube amps....i used some on my ss amps though...

Shoog 7th April 2012 09:07 AM

Quote:

Originally Posted by speakerfritz (Post 2975613)
you need faster caps.....if your power supply are electrolytic's, you can use poly film, meta lfilm, etc. if your power supply caps are ply film, then you need metal film, etc

I was surprised at how much difference it made to electro power supply caps.

Shoog

AJT 7th April 2012 01:14 PM

what i do is build my transformers with as low dc resistance in the windings as i can....that makes my ecaps charge faster than otherwise with conventional transformers.....that is why i do not need those added caps....

Troncones 7th April 2012 03:02 PM

I have asked before and didn't get an answer so here we go again. I believe with the proper test you should be able to see what you hear. Where will you see the difference with the PS cap bypassed? Output at HF? Sine Wave shape? Square Wave shape? Or??

Shoog 7th April 2012 03:13 PM

Quote:

Originally Posted by Troncones (Post 2976101)
I have asked before and didn't get an answer so here we go again. I believe with the proper test you should be able to see what you hear. Where will you see the difference with the PS cap bypassed? Output at HF? Sine Wave shape? Square Wave shape? Or??

You can be an objectivist and attempt to find an appropriate measure to show what you are looking for, or you can insert a high quality film cap onto the last stage of your power supply.

One is easy and you are the judge of any change, the other requires sophisticated high resolution test equipment and a rigorous protocol to judge your results by.

There are a few people on these boards who claim that if they cant measure differences in THD then there will be no differences in the final sound - experience has told me they are wrong. I know which approach I go for in these circumstance.

I am a trained scientist and know full well the limits of measurement techniques in deciding these questions. On this particular point about caps - I was extremely skeptical until I tried it. I was also extremely skeptical about using transformers for input phase splitting and interstage duties (knowing absolutely for a fact that they degrade THD figures) but now I have not built a valve amp without them for about five years.

You takes your choices and builds your own crosses.

Shoog


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