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Rebuilding my Eico AF-4, the cap directly after the rectifier is 20mF 450V.I want to use a film cap in that position.
A 22mF 630v Solen is 40mm or 1.57 inch dia. I have only have 1.125 under the chassis. Any suggestions? What other quality cap could you guys suggest that is about one inch in diameter? Or am I splitting hairs here?
The network is 20, 40, 40. Figure using an F&T 50mF dual can from Jim McShane to replace the two 40mF caps.
Thanks Dan
Follow Ups:
Ideally use motor runs or film caps for the whole PSU. But if there's only room for one put it as the last cap to get the most benefit.
Andy
That depends on the type of power supply setup you are using.When no choke is being used and you are using a rectifier tube where you have to limit the size of the cap,a film works best right off that rectifier tube for s charging cap.
Honest amplification is better than excessive 2nd order distortion anytime.
Is there a reason to use one over the other?
I think so.
A motor run is a film cap bathed in oil.
I believe the oil physically damps the cap.
Motor runs are just metalized polyprop tho.
I wonder how good a Teflon and foil cap bathed in oil would sound? :-)
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
This is a 25uf at 600v Wima..The 30uf is no larger physically.
Honest amplification is better than excessive 2nd order distortion anytime.
SE amps (AF-4) need better regulation and have less hum cancellation vs a PP amp. Stay with the 22uF. I would even go further with a CRC filter circuit.
"SE amps (AF-4) need better regulation and have less hum cancellation vs a PP amp."
Why does a single ended amp need better regulation? Many push-pull amps are class AB...
Single-ended amps do not have 120Hz hum cancelling unlike PP amps. The SE power supply should have the best B+ filtering possible and excellent voltage regulation with fast recovery.
You don't have to go with 22uf.
Consider going smaller. 10uf -15uf.
0.02
What effect would a smaller cap have in this location?
(Not a smart-ass question!!)
.
Freak out...Far out...In out....
What effect would a smaller cap have in this location?
A smaller C1 will always present less loading to the rectifier - tube or SS.
Also, faster recovery time which translates into a faster sonic signature.
Depending upon other factors, you may or may not hear the difference but the rectifier will notice it.
Cheers,
W
...but probably by an insignificant amount (for example, 15 µF in place of 20 µF might only reduce the output voltage by a couple of volts.) Also, film caps "punch above their weight" due to the smaller equivalent series resistance, so the final B+ voltage might not change at all
Whether you use a reduced capacitance or not, a film cap will sound faster than an electrolytic (in a good way, that is clearer, not harsher.)
Do you have room for a 3/4" thick box? Size 41mm x 44mm x 20mm. These box Panasonic film caps are available from Mouser. Good price too.Pete
Edits: 09/14/14
I use a lot of those panasonics
Look at these as well.
Honest amplification is better than excessive 2nd order distortion anytime.
The WIMA 600V film caps are even slightly smaller than the Panasonics, though somewhat more expensive. I have used the WIMAs in this role with great success, thanks to suggestions by Mike Samra in particular. I have not tried the Panasonics but have no doubt they sound great too.
I would suggest replacing ALL the electrolytic PS caps with these boxy film caps.
PERFECT! Thank you sir.
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