Bottlehead Forum

Bottlehead Kits => Eros Phono => Topic started by: galyons on February 10, 2015, 08:19:02 AM

Title: EF86 Cathode bypass 100uF
Post by: galyons on February 10, 2015, 08:19:02 AM

Quote from: Paul Joppa on December 23, 2010, 08:01:19 AM

Haha! Sorry, it was unclear and has been a confusion before. Yes, from a stability standpoint the 100uF could be a lower capacitance and the 2200uF could be a larger capacitance. Below about 50uF, the 6922 cathode bypass will have an audible effect on bass extension and I do not recommend it.

I think 160v is close to an optimum rating for the 100uF if it is electrolytic, and the 2200uF should have a low voltage rating, like 4 or 6.3 volts. Higher voltage ratings should work; they will eventually lose their ability to withstand the full rated voltage but should continue to perform well at lower voltages as long as it's enough to maintain the chemistry. Sorry I don't understand that low-voltage chemistry very well yet.

Looking at replacing the cathode bypass 100uF with a film cap, (MPP).  Would 68uF be enough above 50uF to avoid issues?  Any concerns over 250v versus 400v.  (IME in the brands I'm considering the 400v is a better quality cap.)

Cheers,
Geary

Title: Re: EF80 Cathode bypass 100uF
Post by: Grainger49 on February 10, 2015, 10:22:06 AM

Geary,

The stock cap is a 100uF@160V.  Anything at or above that voltage works.

Title: Re: EF86 Cathode bypass 100uF
Post by: galyons on February 10, 2015, 10:25:45 AM

Thanks Grainger!

Title: Re: EF86 Cathode bypass 100uF
Post by: galyons on March 22, 2015, 04:35:32 PM

Pinging the common genius again on lowering the capacitance of the cathode bypass cap.   Would 62uF be enough above 50uF to avoid stability issues and/or loss of bass extension?

Cheers,
Geary

Title: Re: EF86 Cathode bypass 100uF
Post by: Paul Joppa on March 22, 2015, 05:42:36 PM

Quote from: galyons on March 22, 2015, 04:35:32 PM

Pinging the common genius again on lowering the capacitance of the cathode bypass cap.   Would 62uF be enough above 50uF to avoid stability issues and/or loss of bass extension?

Cheers,
Geary

Not entirely - there will be changes in stability and extension. I gave my best guess above about when they would become audible, but not having tried it myself I can't say anything more. Try it and find out!

Title: Re: EF86 Cathode bypass 100uF
Post by: galyons on March 25, 2015, 02:58:50 PM

Thanks Paul. I will give them a try. (But likely after I listen to the stock 'lytics for burn in!!)

Cheers,
Geary