Pulled Coupling Caps

[dumbassbob]

My 64 Bandmaster came back with all the BlueCD Caps pulled,How much do they make for the vintage sound..and if "good"caps are used as replacments will it be close to as before I just got it back and was pretty bummed to see 5 caps in a bag

[Chuck H]

5 coupling caps in a bag?!? I guess they were all leaking?!? Sounds like a shotgun attempt to me. But as far as tone goes, don't sweat it. I know GW uses caps of the same construction and materials. Any difference, if present, would be so tiny that if any one thinks they can hear it they're blowing smoke up their own a$$.

[soundguruman]

Well, they do go bad with age and they do get noisy and microphonic. They are really not designed to last more that 20-30 years.
But I have seen much older ones last 50 years or longer, not cause they were designed to, just because they were used lightly.

There is really a "window" of age where they leak just a tiny bit of voltage, and that's when they sound "vintage."
But after that age, they leak too much.
So, it could be a legitimate concern.
There is one cap that should be removed: "the death cap." Fender used those blue caps for the death cap. And that "should" be removed.

[Gibsonman63]

Electrolytic capacitors have a finite life and should be replaced as needed. The Blue Mallory caps seldom go bad. I had the orange drops for coupling caps in my Super Reverb for a while and it was brittle, ice-picky and impossible to dial in a balanced tone. Cleaning up the lead dress and running Sozo's balanced things out tremendously in that particular amp.

[Chuck H]

I believe GW uses Mallory 150's. Same dielectric as the old blue ones and similar construction (rolled into a cylinder). I've never known them to make an amp harsh. The OD caps have that rep, though it hasn't been my experience. I do think that polyester and polypropylene sound notably different. But this is based on only two specific cap brand/makes. The OD 715p's and the 150's. Not better or worse, just a little different. For a vintage "Fender" tone I would go with the 150's. Which I'll bet is what GW used to replace those blue "tootsie roll" type caps.

I've never known a film cap to become microphonic in any way that could be significant to a guitar amp. Leakage in film caps is rare at any age. And even a little is a bad thing. When you consider that there could be 300VDC on one end of a coupling cap and the following stage biases at 1.5VDC, even a little leakage can significantly boff the amps function.

[pdf64]

GW?

[52 Bill]

GW?

Gerald Weber

OD=Orange Drop

[JoeM]

GW?

Gerald Weber

[dumbassbob]

Thanks guys...I was alittle heart broken when I saw that bag CD Blues,a 120pf,a 290pf domino cap,and a grid (R) He said my 64 had a different curcuit added since it was a transition model... Fender would add "things" to try out on a few amps It had paracitic Oscilation and took another 16 hrs to find...So a Amp I bought for $125. GW got $1200.and it only took 2 yrs,It still an't the same,but I am giving alittle time to break in..the bass sounds ok, but I do not like the highs...he told me to send it back for #7 trip

[J M Fahey]

I would *love* to get the same kind of customers GW gets.
I can't believe every time he shows his crass incompetence, instead of shunning them away (which would be the proper reaction to his goofs) they instead come back begging for more .... and paying for it, of course.

***16 hours*** bench time to find a parasitic oscillation in a *simple* Bandmaster?
Oh my God !!!!!!

[soundguruman]

Thanks guys...I was alittle heart broken when I saw that bag CD Blues,a 120pf,a 290pf domino cap,and a grid (R) He said my 64 had a different curcuit added since it was a transition model... Fender would add "things" to try out on a few amps It had paracitic Oscilation and took another 16 hrs to find...So a Amp I bought for $125. GW got $1200.and it only took 2 yrs,It still an't the same,but I am giving alittle time to break in..the bass sounds ok, but I do not like the highs...he told me to send it back for #7 trip

I sincerely doubt that I would have charged more than $300 to completely service it, including caps and tubes.
I mean the whole bloody thing.
AND of course, the warrantee would have covered anything for 6 months.
I never charge for fixing stuff that I miss, that's my fault.

[Chuck H]

I never charge for fixing stuff that I miss, that's my fault.

Nope. But I'll bet if you ask GW, it was a new problem each time it came back. Which it may have been. Maybe the parasitic happened as a result of his work!?! Who knows. But I would be embarrassed if I were him. Putting the amp back stock should have been a simple, affordable service. And it should have been easy to fix any other issues in the process. The notion that many successive failures actually occured isn't flying with me. I've had amps come back because after I put them in proper working order some weak part failed. That's a bummer. And unrelated to the original repair. But I usually feel obliged enough to do the repair for free at that point. A bag full of capacitors on the third time in isn't something that should have been missed the first time... Or the second! And I'll wager there's nothing wrong with those caps either.

Bob, look up how to test capacitors for leakage and don't throw those caps out until you've tested them yourself! And don't return the amp to GW for adjustment to the top end. Do the work yourself and ask questions here as needed.

[Chuck H]

JM, maybe you should write a niche book like GW. Instant cred. You need to include lots of lore and myth. Oh, and tell people they can improve the low end response on their Super Reverb by increasing the size of the first triodes cathode bypass cap (already 25uf and fully bypassed for guitar use). Or that they can improve fidelity my removing the 68k resistor from the input jack (this resistor, in this circuit has a -3db around 15k). Make sure to include some ambiguity that leaves readers more confused while thinking they understand at the same time. And it wouldn't hurt to lie about inventing a particular type of speaker either. The customers will line up at your door.

[soundguruman]

JM, maybe you should write a niche book like GW. Instant cred. You need to include lots of lore and myth. Oh, and tell people they can improve the low end response on their Super Reverb by increasing the size of the first triodes cathode bypass cap (already 25uf). Or that they can improve fidelity my removing the 68k resistor from the input jack. Make sure to include some ambiguity that leaves readers more confused while thinking they understand at the same time. And it wouldn't hurt to lie about inventing a particular type of speaker either. The customers will line up at your door.

You know what?
I don't think there was anything wrong with the caps either.
I think this jerk is screwing you with random guessing and parts replacements.
Get another tech. The one you have, apparently, does not know jack about tube amps.

You want more bass response? Increase the value of the bias filter capacitor "slightly" not too much.
I'll bet you never heard that. It works.

[Chuck H]

You want more bass response? Increase the value of the bias filter capacitor "slightly" not too much.
I'll bet you never heard that. It works.

You should stop saying that. Someone will want you to explain how and why.