The truth about caps

[cminor9]

There's no such thing as "somewhat scientific", an experiment is either scientific or it's not.

I would be only replacing filter caps. I wouldn't be in the amp replacing anything else. That's a fairly controlled experiment, isolating the thing being tested. The somewhat comes in because there would be no way to know for sure that the caps were exactly within tolerance, since I lack a cap tester. And the act of soldering could reflow some solder around a resistor that was never soldered in good to begin with. Or opening the chassis could let the gremlins and aethers out. Hence the phrase somewhat scientific. It's somewhat scientific in the same sense that many scientific experiments are "somewhat" scientific. It's not hard to imagine that even some laboratory experiments have variables that are unmeasurable, or maybe has variables that people don't even know they need to measure. Did you know that all of the tachyons and neutrinos streaming through the atmosphere make lab rats develop cancer? Neither did I! Maybe I shouldn't have used "somewhat" as a qualifier. I should have said it's as controlled of an experiment as is within my current capabilities. Perhaps you could do better since you probably have better equipment.

Having six caps across two amps sort of minimizes the possibility of a bad cap. One cap, sure. But one bad cap in each amp? A lot less likely. Not impossible, just less likely.

I totally agree with your 3db rule. Thing is, I am about ready to tear down my most troublesome and therefore most time consuming build cause it sounds like CRAP because of a very specific tonal quality. I don't care how many decibels of difference it makes, the amp either sucks or it doesn't. If it still sounds like crap I'll never pay more than $2 for a filter cap and tear that MF apart. If $15 worth of new caps removes the specific and identifiable quality (to me; but I'd bet you can hear it. Taking a few days off, I might record it and share) then it's money well spent, cause my time will have been saved. Either way, I'll learn something, and that's worth the money to me.

I don't need to do a double blind test. I am not an audiophile who wants to believe; if anything I am pretty skeptical. Part of me wants to try this and be able to laugh off people who buy into premium cap snake oil. The other part just wants the stinking 6G3 to be worth all the time and money I put into it, so I can justify spending a few bucks before giving up on it as a lost cause. Like I said, if I still hear the bad sound I am tearing the thing apart and never buying anything but cheap filter caps. It's just that stokes mentioned something very specific, and he has generally in the past been very helpful and knowledgeable. I won't dismiss his opinion as quickly as I might dismiss that of some n00b.

And were it not for the fact that I can hear the same problem, only much less so, in an amp that has two of its four filter caps from the batch of xicons I bought, I know it's not just that I messed something up in the build. More xicons == more crappy butt-tone.

you might as well take Frank Zappa's advice: "Shut up and play yer guitar"

And yes, I can't wait to get this done so I can go back to spending my time practicing. Got some more jazz trio gigs coming up, and I *really* need to focus on those.

[Chuck H]

Dai, if you go to The Amg Garage "Trainwreck Discussion" and search "sozo" you'll find some stuff. Most of it is Geetarpicker (Glen Kuykendal, is that how it's spelled?) pioneering the mods and discussions following. I didn't find the exact thread I remember, but I found enough similar info to fill in. It is definitely eluded to that the higher ESR is thought to sound better in the Express clones.

I also searched the archives for your old thread but came up dry. I did find a thread where you put R.G.'s 47ohm series resistor to the test. You reported a definite difference there. Both better and worse depending on what a player might want. I also found a lot of stuff where you and I are discussing ESR, series vs. parallel caps, etc. It seems we've been down this road before. Too bad my memory can't reach all the back to the last epoch when it all happened.

Steve, It's interesting that in your photo the smaller cap is a 2200uf and the huge can they stuck it in says 6800uf. Not only does this seem like shinanagins but it looks as if it may have been ill chosen or factory second parts used to do it. And who can measure 6800uf anyhow to know if it's off? I can't do it with my DMM.

Chuck

[Phostenix]

I thought the truth about caps is that they are 2 conductors separated by a dialectric.

Sorry, carry on.

[R.G.]

I thought the truth about caps is that they are 2 conductors separated by a dialectric.

Almost. They are two conductors and a dielectric designed to separate the buyer from his money in many circles. In those arenas, knowing what a capcitor is and does is a positive detriment to selling the magic goods.

Magic capacitors - and resistors, and wires, and insulation, and, and, and - may look ordinary outside, but the insides are filled with pure unobtainium.

[Phostenix]

... but the insides are filled with pure unobtainium.

Hey, the nut on my PRS is made of that, too! Audiophile Grade Guitars. I like the sound of that.

Ha! Sound of that....

I'm a little punchy tonight.

[dai h.]

Dai, if you go to The Amg Garage "Trainwreck Discussion" and search "sozo" you'll find some stuff. Most of it is Geetarpicker (Glen Kuykendal, is that how it's spelled?) pioneering the mods and discussions following. I didn't find the exact thread I remember, but I found enough similar info to fill in. It is definitely eluded to that the higher ESR is thought to sound better in the Express clones.

thx Chuck. Maybe I misunderstood, but did you mean (mods to) the Trainwreck amp to get "the old sound" or the alu electros themselves? Also, I thought I saw some thread there (amp garage) where it was mentioned that low ESR (maybe just for some of the positions?) was the key rather than the opposite (perhaps high is better for some while low is better for other positions?).

I also searched the archives for your old thread but came up dry.

had it saved, and here is the part where R.G. mentions the specific value range to simulate higher ESR:

From: R.G.
Date: 6/24/2005 11:57 PM
Subject: Re: Filter caps in series Q?

Yep - sometimes a direct spec of ESR is hard to find. Makers really don't want to be testing that, so they're goosy about specifying it.

ESR is one of those things that is usually not needed in today's low voltage high current supplies. The frequency is too low. I suspect that if you look at capacitors specified for high frequency switching power supply outputs they may spec ESR.

Here's what to do about ESR: Go get an ESR meter kit. There's an outfit in Australia (Oz to you that live there 8-) )that sells the kit, about US$80. It reads ESR directly. Dick Smith, as I remember.

You can repair a lot of equipment by reading the ESR on the caps and replacing the suspicious ones.

As to how much resistance is enough, the only good way to do that is to measure the ESR of the old, bad cap, then stick in a resistor of that value.

They're usually in the low ohms range, under 100 for certain. OK, I found the manual.

Yep, the ESR for a good cap is always under 20 ohms, and that's for a 1uF cap at 250V rating. There's a table of ESR values for good caps of various sizes and voltages.

The manual says that ESR typically needs to get to 10-30 times the "good" value to cause trouble. Obviously, it can go as high as infinitely more than the normal (in an open cap) but somewhere in the 10-50 range is going to cause problems. So an old, bummer 22uF/250V cap that's about to die might have an ESR of 90 ohms. I'd measure the ESR, you could experiment with 5-50 ohms.

I also searched the archives for your old thread but came up dry. I did find a thread where you put R.G.'s 47ohm series resistor to the test. You reported a definite difference there. Both better and worse depending on what a player might want.

hmmm... guess my brain is headed down the early senility chute...

[Chuck H]

hmmm... guess my brain is headed down the early senility chute...

Chuck said: "I also found a lot of stuff where you and I are discussing ESR, series vs. parallel caps, etc. It seems we've been down this road before. Too bad my memory can't reach all the way back to the last epoch when it all happened."

Your not alone brother.

Chuck

[guitician]

I wonder if the audio industry will ever develop something akin to the mass spectrograph? Something that analyzes every possible thing occurring in a stream of waveforms. Like a Cat scanner for the instantaneous position of the electrons/air molecules as they change in every 1/3 octave. I guess hype is just a cheaper way to go...lol

[stokes]

Just to clarify,I am not speaking of coupling caps,tone caps or bypass caps.I am not an audiophile and dont buy into any of the hype about Sozo's or Auracaps or the like.Those are for the Hi-Fi guys.There are some differences in the type of caps used as coupling caps in guitar amps,the most noticeable being a Mallory 150 type compared to the orange drops,but even that gets too much attention for my concerns.I am not an engineer or pretend to be,have no interest in debating ESR or any specs.I only speak from what I know from my own experiences in the amps I have worked on and the symptoms and cures I have found.cminor9,I am confident that if you take those xicons out and replace them with the aforementioned Sprague or F&T's your 6G3 will sound better.Will it make it absolutely 100% sound like an original 6G3?Absolutely not,but better,yes.Oh,and I did cut open a Sprague 30uf/500v that I had in my "to be discarded"pile of crap that came out of an early '80's Boogie amp and compard it to one I purchased in the last batch I ordered and found them to be the same,no sneaky smaller cap in a larger can.I still cant imagine why they would put a smaller cap in a larger can.

[Chuck H]

Oh,and I did cut open a Sprague 30uf/500v that I had in my "to be discarded"pile of crap that came out of an early '80's Boogie amp and compard it to one I purchased in the last batch I ordered and found them to be the same,no sneaky smaller cap in a larger can.

Hmmm... The one I cut open was also a 30uf/500v, keeping accuracy and all (I accidentally tortured it in such a way that I didn't plan to reuse it ). It was from about two years ago, purchased from Mouser. And I did find a smaller cap inside a larger can just as the earlier photo shows. I wonder why some would be like that and others not!?! And I wonder if there is any difference in performance between the two. But I can assure you that it's true.

Chuck

[rudutch]

will this sound better than brand "X" capacitors?

submitted for your entertainment

Aaudio Imports: Product

[defaced]

Why, do tell, would someone cut open one of those caps in the first place?

Simple: it was dented. I'm not putting 250-300v across a dented cap.

[cminor9]

submitted for your entertainment

Aaudio Imports: Product

from the page, "each and every fuse has also been accurately measured and checked in order to bring your equipment to the highest standard."

LOL! Measured? How!?

[rudutch]

from the page, "each and every fuse has also been accurately measured and checked in order to bring your equipment to the highest standard."

LOL! Measured? How!?

I asked that very question to a Bussman fuse rep.... It blows when you test it and then they are hard to sell, right?

his answer was "ohms law and a micro ohm meter."

Yup, he war right and I learned something

[guitician]

What, even fuses are being hyped......