Replacing yellow Astrons: Jupiter? Sozo?

[Rhodesplyr]

One of the last things I want to do is start a capacitor discussion, so please bear in mind that I'm trying to ask a very specific question, largely due to real, but non-technical concerns.

A customer brought me a 1958 Fender Harvard for repairs. All four signal path yellow Astron capacitors are leaky as screen doors and need to be replaced. This is not a gray-area judgment call; these are way into the complete failure category with one measuring as a dead short.

The thing is, this customer is extremely anxious about affecting the amp's vintage collector value, so he wants me to be very careful about replacing parts.

So, is there any consensus about what the most vintage-correct replacements are for '58 yellow Astron capacitors? I've used standard Sozos before, with good results, simply because I wanted an axial Mylar film & foil capacitor, but there are also the red and yellow Jupiters. Some claim the Jupiter reds are the best. Is it because they're the most expensive? I don't know. That's why I'm asking.

I don't personally drink the Kool-Aid on boutique capacitors, but I'm happy to install them for a paying customer if it's what makes him happy--and if it signifies to a future buyer that effort was made to choose the most appropriate replacement parts available at the time. Thus, this is as much about psychology as technical merit. In the end, who's really in a position to compare what a Fender amp sounded like in 1958 with new components to what one sounds like now?

So, any opinions on what the best choice is, given the parameters? My apologies in advance for asking what is partly a cork-sniffing question.

[Enzo]

My opinion:
whatever cap you install, it of course will not be the original. I don;t see how one brand of 2012 cap is somehow more vintage than some other 2012 cap. And i am sure there will be amp fans chiming in to report that so and so cap sounds more like the originals than some other brand. But that requires a real brand new 50 year old cap to compare to. As far as I know, no one makes 50 year old caps. And I'll bet my lunch money against anyone claiming to have ear memory of an amp from 50 years ago.

What matters to me is appearance though. I'd want caps in there that LOOK like they belong. Oh sure, that they perform well is a given. But those little rectangular things we see on pc boards look really out of place on an eyelet board, regardless of how they sound, for example. When I see giant film caps that look like they just escaped from some sort of speaker crossover, siting in a guitar amp, my first reaction isw "Oho, the cap snobs caught another patsy." To my eeye, those yellow axial Mallorys work just fine and look like they belong there. The new-age caps that are the size of a 12AX7 may sound terrific, but they look out of place... to me. WHen someone opens up an amp I worked on, I don't want their first reaction to be, "Oh someone has done a lot to this amp.' Like a plastic surgeon,, he doesn't want someone to remark, "Gee, what a great face lift."

[EFK]

If you are that concerned about aesthetics *and* you want to use a real mylar/foil cap, it is still fairly easy to find nos non-leaky "black cat" caps in a good variety of values, 600V or 1000V rated so they are physically big also, like the old caps. They look very good inside an old amp, and they have that 'smeared' non-harsh or over-bright tone that most people associate with old mylar caps. They certainly are duller than polypropylene caps and most new polyester caps.

[Rhodesplyr]

I've got some 1000V Black Cats on my bench right now. I removed them from a 1970 Leslie amp a few days ago because they were leaky :-)

I have heard of them failing, but I think the most reliable older Mylar caps were Cornell Dubilier's pale green Type PM. They usually test very close to original specs both in terms of capacitance and dissipation factor.

[EFK]

Yep, the "greenies" are usually right on spec, however I remember some magazine a while back did a write up on caps and went overboard in praise of those things, and now the pricing on them is often simply ridiculous, even for special restorations.

[Rhodesplyr]

Of course, selling those greenies is almost certainly illegal. I wouldn't do it. They are filled with "Dykanol," Cornell Dubilier's trade name for PCB oil. That's from Cornell Dubilier's own documentation on them:

"The PM is impregnated with DYKANOL Y to insure excellent capacitance stability with changes in temperature."

[tedmich]

sozo caps are just rebranded mallorys right? at least they were...

classic fight here
http://youtu.be/_agbTOn1fnQ

[Rick Erickson]

The generic yellow (IEC brand) Mylar/Polyester 630V axial lead caps from CE Dist. work fine. I have them in my own original 5C3 Deluxe, and have used them in every Tweed, white & brown (and some early bf) Fender rebuild I have done for many years. They are my standard replacement for any defective axial lead cap.

RE

[Bruce / Mission Amps]

The generic yellow (IEC brand) Mylar/Polyester 630V axial lead caps from CE Dist. work fine. I have them in my own original 5C3 Deluxe, and have used them in every Tweed, white & brown (and some early bf) Fender rebuild I have done for many years. They are my standard replacement for any defective axial lead cap.

RE

I do use the current batch of Mallory 150s in my 5E3 amp kits and builds, mostly because I buy a thousand at a time and that is what my customers keep asking for... BUT...I also can hear ZERO difference between them and inexpensive IEC Mylar/Poly caps... or for that matter any of those Polyester caps from the Asian rim.
Regardless, none of them are very pricey, including the Sozo caps, so IMHO, it really doesn't matter enough to have much of conversation about it.

[catstrat]

I built a Marshall Plexi clone a couple of years back for my own use and i used the Mallory 150s. One weekend i got bored and decided to have a capacitor shootout. I replaced the Mallory's with Sprague Orange drops and tested the amp. To my ear the Orange drops didn't really sound better but they sounded different. It seemed to me they sounded perhaps a little brighter,to my ear. Now next up were some of the Russian pio caps i scored off of Ebay a while back. Well sir, i fired up the amp and plugged my strat into it and it had the purist, almost shimmering like Fender Twin clean i have ever heard. Those caps are still in there today. I use pedals for overdrive and distortion and this amp handles them very well. I've got everything tuned so that any note i play on guitar, if you hold the note say 1.5 seconds or longer, that note will sustain seems like for hours. I'm convinced that the PIO caps i'm using are part of the sustain. The amp didn't respond like that before. The Russian caps are physically big. I don't know if that has anything to do with it but it seems like i remember Dan Torres in one of his articles said he felt the bigger the physical size of the cap, the better it sounds. Truth or poppycock? I don't know. Maybe someone can clear something up for me. I see on Ebay people selling old caps like the bumblebee's and the like, but i'm scared to them to try them. Are they OK to use? I know that electrolytic caps will dry out after a period of time but what about caps like Astrons or Planets. will they be ok after 40 years? Anyway, that's my two cents worth. Have a good week.

[deci belle]

Have your customer do the ebay fishing for those yellow Astrons if that's what he wants, Rhodesplyr.

If you do stumble upon caps that work noticeably different than another type for a particular application than others, like catstrat did— that's cool! Sometimes it makes a difference, sometimes it doesn't. It's just a happy accident.