Amp Capacitors, their differences and tonal affects?

[imsilly]

Lately I have been finding a lot of contradictorary opinion on capcacitors in vintage amps.

So I want to clear up a few queries:

Which particular caps need to be replaced and how often?

Which caps have the largest tonal effect on an amp?

Which modern caps give the most authentic tweed and blackface tones?

[muchxs]

Originally Posted by imsilly

Lately I have been finding a lot of contradictorary opinion on capcacitors in vintage amps.

So I want to clear up a few queries:

Which particular caps need to be replaced and how often?

Electrolytics in the power supply. How often do you replace them? It depends. It depends on age, brand and whether or not the amp has been used. Electrolytics "form" when voltage is applied to them. I can watch them "form" on my tester. An old cap will start below value and gradually rise hopefully to full rated value. Electrolytics tend to hold up better in amps that are used at least once a week. Stick it in a closet for ten years, the electrolytics "forget" that they're capacitors.

If you want your amp to perform consistently you may want to consider a cap job every ten years whether it needs it or not. The degradation in tone is so gradual you probably wouldn't notice it until it became really bad.

Originally Posted by imsilly

Which caps have the largest tonal effect on an amp??

ALL of them?!!

Seriously, if the electrolytics in the power supply are past their prime the amp will have no balls at all.

If the electrolytics used as cathode bypass caps are past their prime the voicing of the amp will drift from what the manufacturer intended. It may drift in a direction you prefer, it may not.

Leaky coupling caps dump DC into the next tube stage. DC on the grids makes all sorts of funky noises.

Drifted tone caps change the center frequencies of your tone controls.

Originally Posted by imsilly

Which modern caps give the most authentic tweed and blackface tones?

I shouldn't touch this with a ten foot pole!

It depends on what you mean by "authentic tweed tone". By "authentic tweed tone" some people mean how the amp sounds with dead electrolytics, drifted or leaky coupling caps, drifted resistors, maybe tubes well past their prime and a funky dried out old speaker. The amp isn't the way Leo intended it. If I serviced that amp you might complain bitterly because it sounds very different compared to before I worked on it.

Which one is the "authentic tweed tone"?!

[imsilly]

When I say "authentic" I should really say expected or cliched tone. Like you expect Fenders to sound cleaner and brighter as they go from Tweed, to Brown, to blonde, to blackface and finally silverface.

My issue is you oftern see people appauled that someone has popped some Orange Drops into a tweed. Or some other such combination. The idea is the amp goes in sounding like a blackface or a tweed and comes out sounding like one. Or even better sounding more like that cliche of an amp you recognise from recordings or that one time a friend of your's let you play on his amp or some other such occassion.

I also realised that certain manufactures of caps claim to sound like this or that old cap that is no longer manufactured. I mean everyone has seen at least a picture of an old tweed filled with Astrons and wondered if there was someone who manufactured a similar cap now. Or those blue molded Mallory caps in blackfaces.

On a final note, it would also help me altered the tone subtley to my own specs if I knew replacing this cap with that cap would have this effect.

[markw51]

Like muchxs sez, the electrolytic caps are the ones that don't last for many years. However, the non-electrolytics do - maybe they never need to be replaced, and unless they need to be replaced cuz they are shorted or open, I wouldn't. That's my take.

[muchxs]

Originally Posted by imsilly

When I say "authentic" I should really say expected or cliched tone. Like you expect Fenders to sound cleaner and brighter as they go from Tweed, to Brown, to blonde, to blackface and finally silverface.

I'll simply say there's a lot of misinformation on thios topic. Guys read something on one website, believe it to be true and mouth it on another website.

Common misconceptions are:

There are "right" or "wrong" speakers

There are "right" or "wrong" tubes

There are "right" or "wrong" capacitors.

Sure there's "right" or "wrong", say you stick a 6BQ5 in a 12AX7 socket or replace a .1uf@400v with a 1uf@40v. Swapping the same value for the same value, though? Some people think it's magic, stick EL34s in your Twin and it's a Marshall. No, it isn't.

The final answer is that your tone is your tone. If your tone comes from a cheap guitar with rusty strings played through an IC amp powered by a battery made out of a potato... that's your tone. Who am I to argue?!

Originally Posted by imsilly

My issue is you oftern see people appalled that someone has popped some Orange Drops into a tweed. Or some other such combination. The idea is the amp goes in sounding like a blackface or a tweed and comes out sounding like one. Or even better sounding more like that cliche of an amp you recognise from recordings or that one time a friend of your's let you play on his amp or some other such occassion.

Many claims of "tone" originate in commercial interest. There's rarely any science involved. My favorite bogus claim...

A certain transformer manufacturer claims their expensive transformers transform a certain cheap amp. It wouldn't have anything to do with the three essential resistor changes, would it?

Originally Posted by imsilly

I also realised that certain manufactures of caps claim to sound like this or that old cap that is no longer manufactured. I mean everyone has seen at least a picture of an old tweed filled with Astrons and wondered if there was someone who manufactured a similar cap now.

I certainly hope not.

Those old Astron electrolytics are very poorly made compared to modern electrolytics. It's not that they weren't the best technology available at the time, it's just that there's been 50 years of technological progress since then.

Joke: John 5 should play through old tweeds with original Astron electrolytics. Because they're Zombie caps! If they're not dead yet they're living on borrowed time.

Originally Posted by imsilly

Or those blue molded Mallory caps in blackfaces.

You're really splitting hairs when it comes to differences between one replacement coupling cap and another. The usual situation is to replace a drifted component with one that's in spec and say, "Wow! Those caps sure made a difference!" Or make other changes while you're in there.

Originally Posted by imsilly

On a final note, it would also help me altered the tone subtley to my own specs if I knew replacing this cap with that cap would have this effect.

You'd be altering the tone very subtly. Having said that:

I wish I could get old yellow Astron coupling caps at a decent price. It sidesteps an argument if nothing else. Replace Astrons with Astrons in pre-63 Fenders. That's signal caps only. 50 year old electrolytics are for display only.

Lacking Astrons I reach for Cornell-Dubilier "greenies" or Sprague 6PS "Black Beauties". All tested and spec'ed, of course.

I have absolutely no problem using 715P or 716P "orange drops". As far as I'm concerned they're a perfectly acceptable replacement for "blue caps".

Original "mustard" caps are still available for old Marshalls if you're willing to pay the price.

[tonebro]

I'm about to build my second amp, a 5E3... and am considering using Sozos. I also have some SBE 6PS Orange Drops, too. Any comments on either or?

[muchxs]

Originally Posted by tonebro

I'm about to build my second amp, a 5E3... and am considering using Sozos. I also have some SBE 6PS Orange Drops, too. Any comments on either or?

I've used 6PSs in 5E3s. No complaints. You can easily build a great sounding Deluxe with those. If you have a nagging feeling that maybe you're missing something you could build another Deluxe with Sozos...