different type caps sound different?

[hasserl]

...I did NOT purposely try different caps....i tore the amp apart to clean it up and when i put it back together, one of the components that i had removed to get to some solder joints i wanted to clean up was that cap. When i put it back together i used a DIFFERENT cap. same value, different brand. Heres the key....I DUID NOT EVEN THINK ABOUT IT ! I simply put the same value in w/o the slightest thought about tonal differences. When the amp was fired up the tone was so bad it sounded like i frucked something up in reassembly. It took a day or so of trying to see what had changed and change anything back to the way it was when it hit me that the only difference between this horrid tone and how it was before was that cap. I had no hopes of that making this kind of difference, but i put it back anyways because i wanted to use process of elimination to figure it out. When i replaced the cap the tone changed back.

I've had plenty of times when I've fired up an amp in the evening to do some playing, and the tone was horrible, just awful, where you can't dial in a decent tone no matter what you do. So I shut it down and go in the house and watch tv or get on the computer. The next day I go out and fire it up again, and guess what? Damn if it doesn't sound great again. What's up with that?

I've had this happen after working on an amp for maybe a few hours, changing parts values or tweaking a circuit, only to just get disgusted with the whole thing and shut it down for the night, only to fire it up again a day or two later and it sounds great.

I realize that it's just me. It's my ears, it's something that happens to me in the way I perceive the sound; it's not the amp.

I've had similar experiences when working on recording projects; sometimes in the recording process, sometimes when mixing. Sometimes it just sounds awful and I shut the project down for the night and go away and do something else. Coming back to it the next day, all is good again. I know the recording didn't change overnight. I know it's me. Let's just be honest here and admit that we are all subject to all kinds of stimuli that effects how we perceive things, and as RG has pointed out, you can't stop it even if/when you know it's happening, let alone when you are unaware.

I realize how confident you are that the difference you heard is real and not perceived. But forgive me for not being so convinced. I wasn't there, I didn't experience it myself. And even if I did I would still question it, because of how I (make that we) perceive things. What makes your story difficult to accept is that I've never experienced a change in cap type or brand (while maintaining the capacitance value) result in such a drastic change as you describe. It simply doesn't happen, unless as Steve has pointed out there is something wrong with the cap.

We know the circuit is loosely based on a modified Marshall topology, so we kind of know the circuit (you've posted schem's a few times). I don't think many of us are so unfamiliar with it that we wouldn't know what to expect from a change in a treble cap. Maybe you are being perfectly reasonable, but surely you can see how it looks to the rest of us, can't you?

Don't take it so personal when someone challenges you on something you post here, particularly when you are not just relating a personal experience, but when you stake out a position on a topic as you did early on in this thread. When you stake out a position it is perfectly normal and reasonable to be challenged. the normal and reasonable response is to provide backup, without being personally insulted. We're just talking objects here, not making personal attacks.

[octal]

I just want to say this again because it seems many people never read this in one of my posts because i keep hearing ya'll talking about placebo type scenarios and audiophiles and how they critique every little thing. ]

Daz- To be fair, I did say in so many words that I didn't think it was worth worrying about the difference between properly functioning capacitors when there are so many other things which have drastic, scientifically provable tonal effects (speaker type, eq, biasing, NFB, circuit topology.) I'm not at all denying you heard what you heard when you changed caps, but I think perhaps you got a rogue batch of capacitors.

Nathan

[guitician]

I would say that on paper they all sound the same, and that, when they are involved with moving air in your ear canal, to you, they will all sound different.

Why do most steel string acoustic guitars of the same size and construction sound different? They are all made of wood, glue, steel strings and finish. The subtle acoustic differences are not part of any spec, but they are there, none the less.

[daz]

hasserl....But you see, you aren't understanding HOW different it was. I've been playing since 70 and gigged for 25 years on a regular (usually weekly) basis. So i'm thoroughly versed in that ear fatigue and day to day hearing changes. I understand those well and deal with it constantly. what you need to understand is that i'm saying the difference was far more than that. It was like the difference between presence at zero and treble at 12:00 and how it would sound with treble and presence at 3:00. Nite and day would be a good description. I would say double the absolute largest difference i have ever heard due to ear fatigue or those day to day changes in your hearing of room acoustics.

It was a difference no one here would ever consider as possibly being due to any such thing, i guarantee it. thats why i put it in the terms i used. I can't get the point across if i respond with kid gloves !! No one listens if i choose my words carefully so as to not offend, tho thats not my intention in any case. I'm not trying to sound angry as some think, but I have no other option in trying to convince anyone of what i experienced. Even you just assumed it could hearing changes and i can't stress enough that i'm fully aware of that and it's just not close. Take you fav amp and lets say to your ear the treble sounds perfect at 12:00 Do you think if you turned the treble all the way up you could imagine your hearing could change from day to day and make that much difference? Thats why i said a cap can make a huge difference. my two point are that and the fact what i heard was as intense as i just described. thats all. But when many disbelieve you, trying to get the point across is too hard a task to accomplish while trying not to offend anyone. So i'll just leave it at that.

[Steve Conner]

Yeah, and what Hardtailed and I said is that you heard this huge difference because you had a batch of silver mica caps that were breaking down under signal voltage, causing a lot of harsh, nasty distortion in the treble.

I remember the thread you started saying that you rebuilt your amp and it sounded terrible with a nasty high end, and the bad capacitor kind of fits those symptoms.

So yes, you heard a real difference, I don't think anyone should doubt that, but I say that it's the difference between a bad capacitor and a good one.

[daz]

yes, but UR missing things. One, as i already said, i have tried several of the same types. Also, and i have eluded to this but it too gets lost in the translation, the ones that were making it harsh would be the ones that are fine. Those i have used in the entire amp since day one including the tone stack, and they are the same ones you get from antique, turretboards.com, and other online sources. The are fine ! It's the place in the circuit thats to blame for the harshness. It's that simple. The DEFECTIVE caps are the ones i got locally and have waaaaaaay less effect in adding high end. But again, i have several. 4 to be exact, and i have since tried the others and they all sound that way. So if it's a matter of being defective, it's a defective batch, not a single defective cap. And it's not the circuit that destroyed them because if that were the case the other type would too have been destroyed.

[Hardtailed]

A defective batch is what we've been saying all along...

What is the specific part of the circuit where you had this behavior?
Is it by any chance a DC-blocking part (most likely the cap that feeds the treble control in the tone stack)

The situation I've encountered with those no-name 470pF Silver Micas would not happen as a treble bleed cap, or a treble peaker (in parallel with a 470k resistor, classic Marshall style), but would happen in DC blocking parts (like the tone-stack).

[R.G.]

As a general observation, there can be no discussion, not even a quiet difference of opinion with a true believer. Any difference of opinion with a true believer merely causes the believer to think worse of the person holding the other opinion.

Human faith in whatever the faith is in, is by definition not logical, and immune to debate.

[guitician]

Daz, that cap on the left looks like a 680pf +/-5%? It's p/n doesn't look like 470pf. It's a blurry picture...

The other....CM05FD470JO3 is a Mil-Spec Cornell-Dublier part number......470pf +/-5% 300v -55C/+125C

[Steve Conner]

Ohhh, RG just called you a "true believer"! :P

I really think you should mail him one of each kind of cap, the one that sounds bad and the one that sounds OK, and he can see for himself.

[uvacom]

Daz, that cap on the left looks like a 680pf +/-5%? It's p/n doesn't look like 470pf. It's a blurry picture...

The other....CM05FD470JO3 is a Mil-Spec Cornell-Dublier part number......470pf +/-5% 300v -55C/+125C

I agree, the one on the left definitely is not a 470pf. I don't think they even make 470pf in that type, just 500pf. Of course, with 5% tolerance it's possible that if the left one is a 500pf cap (it does look more like 680 but it's blurry), then it could be as low as 475pf, and the 470pf could be as high as 498.5pf. Then again, there could be as much as 17.6% difference between the two.

[daz]

It's a 500pf. whats the point? i measured both with a meter and they were way too close to make a difference. in the context i used them in you could triple the size b4 you'd hear anything. Come on guys, trust me. just because a few people think i'm getting hot here doesn't mean i'm lying, stupid, or oblivious to such simple things. you guys are just a step away from questioning what size soldering tip i use and how that could be the issue.

[uvacom]

It's a 500pf. whats the point? i measured both with a meter and they were way too close to make a difference. in the context i used them in you could triple the size b4 you'd hear anything. Come on guys, trust me. just because a few people think i'm getting hot here doesn't mean i'm lying, stupid, or oblivious to such simple things. you guys are just a step away from questioning what size soldering tip i use and how that could be the issue.

Everybody trusts that for some reason you heard a difference. Nobody has called you a liar, stupid, or oblivious. What nobody will trust, because it is not something that makes sense from a scientific standpoint, is that the difference is due to anything besides a discrepancy in the physical parameters between the devices and/or one part being faulty. Why do you think there was a difference? I have to say, when you have to caps that are not labeled the same value, that sets off some red flags for me, because we are probably *not* talking about caps of the same value, and the vast majority of the time that is the real reason for any tonal difference when caps are swapped. I think the soldering tip thing is a strawman - how could there be anything *more* germane to the discussion than the capacitance value itself? That's not getting off track at all.

Where in the circuit was this cap?

[Groover]

As a general observation, there can be no discussion, not even a quiet difference of opinion with a true believer. Any difference of opinion with a true believer merely causes the believer to think worse of the person holding the other opinion.

Human faith in whatever the faith is in, is by definition not logical, and immune to debate.

Thank you R.G. I have never heard this expressed better. Are these your original words? May I use them? They could come in handy in SOOO many situations, this thread being only a minor example.

[Groover]

Is there any way to export the parts of this thread relating to daz's experience to a new independent thread? It is kind of taking on a life on it's own.