Raise your wallets, I propose a test!

[Ptron]

I keep reading posts about how one type of cap sounds compared to another. I say we settle this once and for all. We need to conduct a true scientific test to see if there really is a difference. Double blind, controlled for component tolerance, all that good stuff. Here's a great article on a gizmo for ABX comparisons that somene could adapt to our needs with a mere 2-3 months work.

Now, since I'm far to lazy and unambitious to orchestrate this series of tests, I will start a prize pool for anyone who does. My opening contribution is $100. I will make my money back by betting on the outcome.

[Chuck H]

I'm not sure I could pick the best sounding 1000hz sine wave signal...There's too much chaos involved in amplifier tone for that. But it would be pretty easy to cnstruct a board with the ability to swap the coupling caps quickly. At that point we would need to remove player/user error (I exhibit plenty of player/user error) like a recording of the same set of chops to play through the input of the amp.

Just rambling on what my criteria for the test would be. In truth I think that given extremes, most people could hear the difference between, say, Mallory 150s (metalized polyester) and Vishay 715ps (polypropylene film/foil) if you swapped ALL the caps (tone stack and coupling) in an amp. At that point the differences would become clear to anyone. I say differences and not worse/better because I think both polyester and polyprop caps have their uses. I tend to use one OR the other in an amp depending on what I'm building. Though I have used them together in some amps. Some builders here commonly use both types in the same amp for their different properties. If I do use both types in an amp, it's only because I know what I want for a particular part of the circuit and I do it as a rote excercise. But I also think that anyone would be hard pressed to tell the difference if you just swapped ONE cap.

The next couple of times you rebuild, extensively mod or scratch build an amp just try to design the board so you can swap out the caps without too much trouble. Try both types and all will become clear.

Now...As for different brands of the same type/construction of cap... I guess I think life is too short to go there. But if I ever become involved in mass production, and it looks like I may, I might just build that board I described just to test different brands to find the cheapest or most space conservative, etc. cap that still delivers the goods for the amp I'm building.

JM2C on the whole cap issue.

FWIW there is a great article on the Aiken site about different cap types. Keep in mind when reading it that while what is electronically best is not subjective, what is tonally best is.

Chuck

[Alex/Tubewonder]

You'll have to eliminate all switches, relays, jacks and plugs otherwise no matter what the outcome it will be blamed on these parts affecting the sound anyway.

[Steve Conner]

All capacitors sound the same* and I can't be assed spending 2 months to prove it. I can think of other projects that would earn me a lot more than $100 for the same amount of work.

*give or take a few quibbles about the voltage coefficient of ceramic caps causing harmonic distortion

[Chuck H]

Steve, You don't really think all caps sound the same.?. Do you? Even the obvious aside (cheap ceramic vs. expensive film) there are less than subtle differences in the specific peaks and rolloffs (is that a word?) between cap types and brands. Dialectric type or construction method, I don't really care what is making the difference, but it's certainly there. I like that I can build the same amp with two different cap types and get two different amps. Or specialize a circuit with one type of cap over another. I build with Vishay 715Ps and Mallory 150s (mostly the former for their superior heat stability, the amp doesn't change tone as much when it's really hot). I promise, if you build the same amp with with all one type and then another, you will hear a difference.

Of course I would never take the challenge of picking wich type was in ONE part of a circuit (changing out one cap). But the overall effect of one type over another is obvious even to me.

Chuck

[Steve Conner]

Yes, I do. I'm an electronic engineer, and if I believed that different brands of capacitor sound different, I wouldn't be able to function in my job. I lump capacitor tone in with unidirectional speaker cable and painting the edges of your CDs green.

I could go on for hours about the strengths and weaknesses of different capacitor types and the applications they're suited for, but I don't believe that any of them affect tone of a guitar amp to a degree that you would notice in a properly controlled ABX test. Except maybe the harmonic distortion caused by cheap ceramic caps, which is a known effect, similar to the "mojo" of carbon comp plate load resistors.

That is my own personal opinion, and I'm not asking you to agree, but I felt it had to be stated.

BTW: I think a fair test of this would be to build, say, a 5E3 clone, with an arrangement of SPDT relays (hermetically sealed Hi-G's with gold contacts natch) that simultaneously A/B'd every plastic film capacitor in the amp under computer control. Maybe dipping the screen voltage to zero as it did so, to avoid making a thump (and so giving away whether the switch took place). I'll happily build such a device for anyone crazy and loaded enough to hire me to do it.

[bob p]

All capacitors sound the same* and I can't be assed spending 2 months to prove it.

Steve, I'd bet that you're one of the people who knows better than to buy into the internet lore that says that Orange Drops make a Marshall circuit sound harsh. I don't buy it, and I think that the rumor was started by somebody who was trying to sell more expensive boutique caps. Now everyone seems to believe it, even though there's no objective data to back up the claims.

BTW, nice points about unidirectional cables and CD markers. There's so much BS out there that this kind of stuff needs to be debunked.

[hasserl]

Had a guy on the Weber amp bbs call me all sorts of rude names when I challenged him on this. Of course he couldn't offer up any proof for his opinion, but EVERYONE knows it's true, just do a google search he told me. Yes, I replied, I know this is the story all over the net, that's why I called it "internet lore"; but that's all it is, lore. Didn't do any good, he still called me names.

[Ptron]

I'm hesitant to bump up my weak attempt at humor but you guys are already doing it for me.

Here's a good article on the subject from the same site. Really good stuff on that site.

[Steve Conner]

Bob P, you are damn right, I don't see any possible way in the world that a different brand of capacitor - of the same value - will make a circuit sound "harsh" or whatever. A capacitor is a capacitor.

Even if the thread was originally meant as a joke, I think it still raised points that need to be said. Designing a good sounding amp is hard enough, without cluttering your head with strange beliefs about capacitor tone.

My only real capacitor extravagance is that I try to get the heaviest duty industrial electrolytics possible, because I think they last longer, and they just plain look like they mean business, too. I'm a fan of the Rifa inverter grade types with their big beefy screw terminals, I have a set of 4 in my stereo amp still going strong after 10 years. Just don't try the old screwdriver trick to discharge them: the larger sizes will leave you with ringing ears wondering where the end of your screwdriver went

I am doing an amp build just now with those cheap Chinese electrolytics, and we'll see how they hold up...

[bob p]

and i thought i was the only guy nutty enough to use inverter grade caps...

[Steve Conner]

Well I don't usually use them in guitar amps :P
http://www.scopeboy.com/tesla/drsstc/build4/index.html

[Chuck H]

I'm sorry, but...

Remember that I'm tech impaired. Also know that it doesn't take anything away from my ability to hear. So, while I have no interest in debating the technical aspects of this discussion with formulas and simulations (which, for what it's worth, also rarely take all the needed parameters into account) I do think a double blind test would be appropriate. Not lore nor data can resolve this topic. Only a double blind test will do.

Since I DO believe I can hear a difference, I'd like to say that to me saying all capacitors sound the same (for the purposes of clarity (no pun intended) lets assume "all caps" to mean film caps with appropriate ratings for thier application) is like saying all speakers sound the same. They all function the same, right? They are simple in design and all made with basically the same materials. If you put it to serious scrutiny, you could even point out that there are only very minor measurable differences between some models that are said to sound very different. Well, I guess from a very practical and functional point of view, all speakers do indeed sound basically the same (again, for the purposes of clarity, lets keep "all speakers" to mean 12" guitar speakers). It would seem, when looking at two speakers specs and response charts that are similar, that there should be little if any audible difference. But we ALL know this is not true. But I'm also sure that if someone wanted to use math and science to discredit this, and prove that all speakers sound the same, they could.

Along the same line...If you gave two fine bakers with the same oven all the same ingredients for a chocolate cake, logic and reason tells us they would bake identical cakes. But we all know this isn't true either. That isn't to say that one couldn't duplicate the others cake. But they could each make very different cakes too. What makes a one cake different to me than another...Flavor...One of my senses. I never ate a cake with my mind. So I guess I prefere to use my ears to make my musical choices too.

Who brought the milk.

Chuck

[Steve Conner]

Well, I argue that your self-confessed "tech-impairedness" does take away from your ability to hear: it makes you hear things that aren't there. If you don't believe me, just try to find some response charts for capacitors like the ones you cited for speakers, and then show me that different capacitor brands of the same value have different response charts.

Speakers and cakes are complex objects with a lot of parameters and resonant modes that are known to have audible (or tastable) effects. Even the math skeptics agree on this, and that's why all guitar speaker manufacturers provide those charts, and grandma's cake recipe gets handed down through generations, even in scientific families.

Capacitors are lumps of metal and plastic with a reactance inversely proportional to frequency, which is the only property that affects tone (heck that's why we use them in tone stacks!) and that only depends on the capacitor value. You will not see response charts printed for capacitors, because nobody can measure any other properties that would affect the tone in such a way that a chart could be made of it.

To my mind, Rod Elliott proved in this article:
http://sound.westhost.com/articles/capacitors.htm
that capacitors can have no other effect on tone.

If we wanted to talk cookery, I say that hearing the difference between capacitor brands is about as likely as being able to taste what brand of spoon the cake mix was stirred with. But then, your grandma probably had her favourite wooden spoon that she liked to use for mixing cakes, you have your favourite brand of capacitor, and what's wrong with that after all?

I just wouldn't like anyone to think they are missing out if they can't afford some crazy $20 boutique capacitor. Science says a 75 cent part will sound the same.

[Chuck H]

"Well, I argue that your self-confessed "tech-impairedness" does take away from your ability to hear: it makes you hear things that aren't there."

Well, I don't generally (and won't in this case, really) get wound up about this sort of thing, but your argument might have been better recieved had you not implied that my lack of an electronics education predisposes me to spotting bigfoot or Elvis. That is really nothing short of pretentious snobbery. Having amicably shared posts with you in the past (I've been with Ampage about 12 years and have only just returned since the change in format), I think it's beneath you. Ham handed and clumsy even if an insult wasn't intended.

Just had to get that off my chest.

Anyhow... There are alot of characteristics that absolutely CAN change the sound of a capacitor. Capacitance vs. voltage, capacitance vs. temp., voltage vs. frequency, capacitance vs. frequency, etc. All of these and more are graphed and charted by many (but unfortunately not all) mfgs. And these parameters DO change with construction, film type and thickness, etc.

Can we hear this??? I think so. And why shouldn't I, when cap "A" changes it's capacitance with frequency and voltage differently than cap "B".

FWIW I absolutely believe there is a limit at some (very low) point. I would never buy a $20.00 capacitor and expect it to be 19 times better (or even twice as good) than the ones I am using. The boutique cap, cord, cable and silver solder sect can keep their snake oil. I don't buy it. I am a practical "show me" guy and am generally considered by my friends and peers to be skeptical.

As for why speakers get all the great comparison charts and caps don't...Well...(do I really need to go into it?) I think it's because the speakers are where the sound comes from. They appear so much more dynamic and exciting than capacitors. Any bonehead geetar player could change a speaker or plug in a different cabinet. That's why you can't go into Guitar Center and buy a capacitor. Speakers just have all the glory. And the much plainer and drier performance charts for caps are all we dull designers are ever going to get.

I did read your attachement. I think that there are excellent points made, and others ignored. This is because it is biased. Most such articles or studys are.

So I'll stick to my proposal for a double blind study.

Or we could just accept that we may both be wrong/right/whatever, and go foreward without the need to reprioritize our lives over this.

Cheers

Chuck