300B Buzz Noise

[freon2]

If an underrated 250V rated capacitor on a 420V supply rail starts to fail, can this cause buzz in the audio? This is a 300B circuit.

 

[euro21]

Yes.
On 420V supply MUST to use 500V...630V capacitors.

 

[grataku]

This a serious question or you're doing it for clicks?
I don't believe DIYaudio does monetization.

 

[freon2]

Yes.
On 420V supply MUST to use 500V...630V capacitors.

Dear euro21,
Thank you for the advice, I sort of suspected that this was the problem.

The existing cap is WIMA MKP 10 0.1 250V
Thinking of changing to >>> WIMA MKP 10 0.1 1000V

Do you think I should use a better brand cap? Audionote?

Thank You once again.

 

[euro21]

Without schematic any other advice would be unreasonable.

 

[freon2]

Dear Euro21,

Sorry, I don't know what I'm doing yet. That is why I turn to you guys, the experts.
The design is a copy of the Sun Valley 300B.

 

[grovergardner]

It's very hard to make any recommendation without knowing where the cap is located or what it's purpose is. If you don't have a schematic, it might help to post pictures of the underside of the amp and closeups of the cap itself.

 

[Michael C]

If you dont know what you are doing and are building a copy of 300b amp be carefull.there are many pitfalls to the unexperienced builder.tripple check everything before proceeding.

 

[6sX7]

any properly rated cap is better than what you got. WIMA is a good brand. unless it is horribly expensive, try it and find out. Can always try a fancy one later. Without a baseline, you won't know if fancy ones are worth the cost.

 

[euro21]

If the question was directed to "in this place -coupling capacitor between stages- is there a better product", the answer -IMO- yes.

WIMA making good capacitors, I used its everywhere (PSU, filter etc.) ... but not as coupling device.
As coupling capacitor -due to our structure- even the PP series is "mediocre", many better (mainly folie, even more so copper folie) "coupling capacitor" available.

The amplifier "quality" determines the price level of improvement.

One "average" product doesn't get much better if you puts full with pricey boutique things.

 

[freon2]

Buss noise is solved! The original coupling cap was 250V. Replaced with a fine set of Audio Note caps.
The noise is gone and the amps sound great.
I am using them to power 4 - ESS AMT's.

I can recommend you buy your Audio Note caps from an authorized distributor, all others are most likely counterfeit.