breaking in capacitors for amp?

[ulysses]

hey guys

i recently bought some sozo caps for my amp and it is suggested that they need to be broken in. see:
http://www.sozoamplification.com/break_in.html

now i dont want to have to break them in - they sound muddy. so i took them out and now i want to create a circuit that will break them in for me.

i have 5x .022uf caps and 4x .1uf caps

i was thinking of simply running them all in parallel with 9 volts running across them for 100 hours.

does anyone have any experience with "breaking in" caps? is there any way to know when a cap is "broken in" without listening to it?

cheers
ulysses

[jonathan perez]

why would a cap need to be broken in? please correct me if im wrong, but that sounds like mojo garbage.

[aron]

It's been so long since I _really_ worked on amps. Apparently you can do this to (usually) large electrolytic caps. The idea is that you slowly increase the voltage over time and it will "form" the capacitors. Now I have never done this, but there's lots of posts that suggest that this does improve the tone of the amp.

In any case, I'm trying to figure out how to ID a bad silver mica cap that I KNOW is bad, but how can I test it to be bad? I even have the sencore capacitor tester, but I haven't been able to see anything suspect about the cap in question.

[MartyMart]

It's been so long since I _really_ worked on amps. Apparently you can do this to (usually) large electrolytic caps. The idea is that you slowly increase the voltage over time and it will "form" the capacitors. Now I have never done this, but there's lots of posts that suggest that this does improve the tone of the amp.

In any case, I'm trying to figure out how to ID a bad silver mica cap that I KNOW is bad, but how can I test it to be bad? I even have the sencore capacitor tester, but I haven't been able to see anything suspect about the cap in question.

..... Just swop it out anyway  !! 
( though I understand that they can be expensive .... dollar a piece or so .... )

[soulsonic]

The concept of "Forming" electrolytics is something that some people recommend for new caps and other people only recommend for old caps that haven't been used in awhile. From my personal experience, I'm leaning towards the theory of needing to be done only on old caps because I've noticed no difference when I've done it on new ones vs. "just turning the amp on". To "Form" an electrolytic, the idea is to slowly turn the voltage up with a Variac on the mains. The first time I tried this, I did it over a period of 10 hours, starting with the Variac at 60 volts or so and slowly bringing the amp up to it's correct voltage.
This was a stupid waste of time and didn't do anything good at all.
So now I just turn the amp on and it's fine.
If I'm confronted with a very old amplifier, I guess it's kinda a judgment call whether to do anything like that or not. Usually, if the caps in an old amp are icky, I just replace 'em and don't worry about it.

Now with the coupling caps...... it's hard to say - I do believe that NEW amplifiers "break in", but I can't say that it's just the coupling caps that are breaking in... it seems more like it's everything, but I wouldn't be suprised if the caps were part of that process. I think the description on Sozo's site is misleading and mojo-filled, but I will agree that the sound of an amp changes within the first few hours of it's life. But I wouldn't say it takes as much as 100 hours.... I'd say more like 10 hours of playing loud is usually enough to do it. I'm guessing 10 hours because it seems to be about a week of playing through it about an hour or two a day.

But whoa... you said they sound muddy? Well, they shouldn't, even if they're not broken in. To me, the "non-broken-in" sound isn't something that obvious - it's more of a "just doesn't sound as good" weird thing that can sort of be described as "smeary" on the top end. A non-broken-in sound is more of a slightly ugly bright sound (in my experience), that's more of a subtle "hardness" on the highs than anything you could really describe in a concrete way such as "muddy". Muddy may just be what those caps sound like.

I'm not sure hooking a 9v up to those caps would really do anything to help break them in. Personally, I would leave them in the amp and run a tone from a noise generator into it and have it plugged into a dummy load so I wouldn't have to listen to it. I'd leave it running all night and by the morning it should be well on its way. To me, running a constant signal through it at the voltages it's going to encounter in the circuit is the best (and possibly only) way to break the caps in.

You never know - they may just be muddy sounding caps.....

[aron]

>..... Just swop it out anyway

Right, but I'd really like to be able to identify _why_ it is bad. ESR, leakage, something should show up on the tests.

[aron]

Maybe the caps are in the wrong way? Now where's that article....

ahhh found it:

http://www.harpamps.com/micKdiy/Cap-Orientation-Test%20.html

[aron]

Here's the man's site:

http://aikenamps.com/OutsideFoil.htm

[soulsonic]

Usually, you can lift one end of the cap while it's in the circuit and measure to see if any DC voltage is appearing on it. If it's good, there shouldn't be any DC. The thing is, you MUST lift one end for this to be accurate. You check for DC on the end that's been lifted.

[MetalGod]

I would just turn the amp on and let the caps form over a week or so.  I remember putting some Russian Military 'fast' caps in a plexi clone build, they sounded dark and wooly from the get go but I presevered (too lazy I guess, heh).  Anyway, after a couple of weeks the amp's sound changed and became much more focused in the bass end and very percussive and aggressive.

Those Sozo caps have a great reputation, I'd give 'em a couple of weeks to break in. 

[R.G.]

Breaking in non-electro caps? Oh, please!

My friend Tim Taylor hailed from Oz, and apparently in his part of the place, all of the indigenous birds with hooked beaks that resembled parakeets and %^&*atiels were referred to as "%^&*ies". It was part of his local vernacular to, when presented with something which did not pass the smell test, say "Walohcs!" We were baffled by this, and he explained that it was an acronym. It stood for "What a load of hot %^&*ie sh_t!"

There have been many times when "Walohcs!" was the right thing to say over the years.

[Gus]

I have not heard dry mylar(PET)film caps change with break in.  I have not tried oil caps

  Al electros yes after forming if they were not used for some time.

I would measure the DA and the leakage at working voltage before using them and after "break in".   I would also test other mylar caps of the same voltage and value.

A more interesting test might be the inductance of the cap.

[soulsonic]

I will swear, hand on heart, that I've heard new amplifiers break in, but I won't swear 100% that it's the coupling caps.... I think it's other stuff. I use PET caps all the time in pedals and other things, and I haven't really noticed their sound change, so I'm definitely tempted to agree wholeheartedly with Gus and R.G.

I've used the original "mustard" caps that the Sozos are supposed to be a copy of and I don't see what the big deal is. I didn't detect any fancy mojo in the tone - I just used 'em cuz that's what I had on hand. I think Mallory 150 is just fine if you're looking for a PET cap.

Anyone else here prefer the sound of PET caps to Polypropylene (Orange Drop) caps? I've done several amps with both kinds to compare, and I definitely notice a more "soul-ful" tone with the PET caps. If there's anything special about the Sozo caps, it probably has more to do with the fact that they are PET caps than anything else.

[vanessa]

I had a tube amp that I loved. It died one day needing a cap job in the power section. I had the tech replace all the caps with 'orange drops' and all the electros replaced while he was in there. I've not liked the tone since. It went from being a very warm sounding amp to being kind of sterile. Funny thing was it originally had what looked like Mullard tropical fish caps for all the poly's. I thought the orange drops would be the modern equivalents. So I'm thinking over time the originals might have degraded to a point that the tone (for me) was optimal? Maybe you could call it broken in?

[R.G.]

I had a tube amp that I loved. It died one day needing a cap job in the power section. I had the tech replace all the caps with 'orange drops' and all the electros replaced while he was in there. I've not liked the tone since.

That's too bad. Caps other than electrolytics never need changed unless they're broken. Orange drops are no tone panacea.

It went from being a very warm sounding amp to being kind of sterile.

In engineer-speak "treble loss" is what a guitarist would call "warm". When a guitarist says "sterile" he usually means "I now hear crossover distortion".

Did you get it rebiased at the same time? You might look into a rebias to relieve the sterility.

Funny thing was it originally had what looked like Mullard tropical fish caps for all the poly's. I thought the orange drops would be the modern equivalents. So I'm thinking over time the originals might have degraded to a point that the tone (for me) was optimal? Maybe you could call it broken in?

It's sure that it had degraded over time. But there are many possibilities other than the pseudo-mojo of the caps being involved.
- did the tech get every single cap value right? No soldering errors?
- did the tech match the cap values he took out of the amp by measuring them, or did he put in what a schematic from somewhere else told him was right?
- did you also replace tubes? Any other changes?

It's possible to "dirty up" a new electro cap to match an old one. But changing out all caps, even the non-electros, is practically asking for problems. 

Look at a rebias first.

[vanessa]

Re-biasing is a great tip. I would bet that to be the issue. I would also guess that over the years the bias might have drifted, maybe to be a little warmer due to the caps slowly failing. I forgot all about that. I'm pretty sure they re-biased it when they put in the new power filter caps. They might have biased it a little 'cold' just going off a bias chart. I'll have to get under the hood and see where it's at. Thanks R.G.!