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started on my Scott 299A and ordered up a bunch of signal caps to replace the pyramids in my set, although this question is for all amps that I will be doing (I have around 6 older tube amps to restore...) It was obvious from my mouser order that the film caps I chose (Xicon 1431 series) are metallized polypro, although I was lead to believe otherwise. I think I should be OK with the Wima FKP1 caps, but the Xicons don't look to be the film/foil I was hoping for. So at this point, what to do. Mouser has Sprague 715P, which I think are film/foil, the others I am aware of are the Sonicaps but much more expensive. Any suggestions? thanks!
Follow Ups:
Michael indicated to replace the first cap with a film/foil cap and the following caps can be electrolytics as originally installed. The original cans are dual 30/20 @ 475, I can get a film can-style cap in the first opening and place the section pole with either a 20 ufd electrolytic or a ASC 10 ufd film cap, rated at 330 vac. Which would be the recommended arrangement, the 'lytic @ 20 ufd or the film @ 20 ufd? Also, should I look to bypass the power supply caps with film caps? thanks!
should I use them instead of the 716P? thanks
As the WIMA FKP 1 caps. are metalized film, not film and foil, I would not use them in the coupling role, unless they are bypassed by an appropriate film and foil part.
A WIMA metalized polypropylene part, with sufficient capacitance, would be fine in a PSU.
Eli D.
I always had good results with those caps
charles
apparently they are mixed film/foil and metallized film...
Sometimes your better off just leaving well enough alone. If your 299A works and sounds good to you, maybe you should just replace the four original .1 couplers, the caps that could cause the most problems if they go leaky or bad.The Russian K40 pio's sound good in my 299A and MC225 and Gudeman .1 pio replacing the .068's in my Sherwood S5000 sound good so they are now a known safe choice for me as couplers.
Other than the high and low voltage supply caps and the LV rectifier, changing to many other caps may or may not be to your liking.
Years ago I replaced most of the small caps in my 299A and found myself replacing them with NOS 1960's caps until it sounded good to me again because I couldn't find a combo of new caps that sounded good to me.
But that's me.Those brown package radial lead metalized Xicons have lots of snap and zing but they can be bright or harsh. I had them in my 299A for a while but the K40's proved to be as open and lively without the edge.
Check out Mikeys recent S5000 post. There are now two pics of a Sherwood S5000 rebuild reflecting two ways to go in a rebuild.
Edits: 11/13/14 11/13/14 11/13/14
thanks, Dave, solid advice! I did replace the couplers with K42y's I had on hand, as I brought it up I was getting a lot of noise from the 6BL8's, turns out it was the pyramids leaking as replacing them totally cleared up the noise issue (sounded like fat frying in a hot pan), so I am somewhat thinking that the other pyramids may also be going bad, I believe someone here mentioned them as not very good caps. Also, I have heard conflicting info on the ceracaps, some say replace, others say not....
I had the intermittent frying sound too and it went away after I replaced the .02's on the preamp 12AX7's so I thought I was done with that issue.
Then it came back and it turned out to be a 12AX7 tube socket connection.
Moving the tube around in the socket stopped it but I never got to the bottom of it because my Sherwood arrived and I'm focusing on that right now.
I know what you mean about the varied opinions of old caps.
My new tactic is to replace the supply caps,rectifier and coupling caps then if I think there's still something that might be better, I change a pair of caps at a time, the same one in each channel to see what sonic change that makes.
Yes, the 715Ps are film and foil, BUT the leads are steel. :> (
The best value in film and foil caps. are 716P series "Orange Drops", which have OFC leads. AA sponsor Antique Electronic Supply is a source for the 716Ps.
A little more money than 716Ps, but still not stratospherically priced, are Solen tin foil and polypropylene film parts.
Soviet surplus K40 paper in oil (PIO) parts are another "reasonably" priced option. "Flea Pay" is where K40s can be found.
Eli D.
Thanks, Eli & Steve, damn, I just placed an order with AES, looks like I need to place another with them, and I am guessing I should do that thru AA so they get the sponsor, right?
HI
Jim McShane has most any cap you will need and only sells really good ones. You will know what you are getting, you won't have to guess, and his prices are competitive with anyone else's.... He often has a parts list for rebuilds of many common amps as well.
cheers,
Don
...they have tinned copperclad steel leads which are non-audiophile approved. The orange drops you might want to try are the 716 series with their tinned copper leads and pressed bodies for improved board stuffing density.
Personally, I don't have a problem with 715s in tube circuits because there's already a considerable amount of steel already present in the tubes themselves. The added steel in the 715 leads is not significant in comparison.
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