capacitor voltage ratings and sound differences

[nosaj]

I had a friend try and convince me today that this wah he is building with tropical fish caps, He is using 250v versions, so I asked him what the difference was an he said higher voltage ones sound better.

Is this analogous to sending water through a garden hose versus a fire hose and getting different pressures? Or has he fallen to someone elses I can hear something you can't?

Once he finishes I'm going to ask him to prove it by using a lower voltage cap.


Just wondering.

jason

[J M Fahey]

he said higher voltage ones sound better.

No. He has *absolutely* no clue about what a capacitor does.
Besides, that pedal will be powered with a 9V battery.
Whether the same value cap stands 10V or 1000000V is exactly the same.

Is this analogous to sending water through a garden hose versus a fire hose and getting different pressures?

真真真真真?????????????
Does the schematic specify some kind of hose?
真真????

[Enzo]

I could sit here and try to think up reasons it might make a diffrence, but it would be exactly that - me making things up.



Is it conceivable? Sure. Higher voltage caps tend to be larger, so MAYBE ther is some tiny difference in inductance in the cap. Or maybe ther is a little different ESR. MAybe larger caps means other parts have to be farther apart in the circuit, and maybe that causes some small difference. Or if the circuit is hte same size, then the parts are closer together. Seems far fetched to me, but who knows? It could also be that the higher voltage caps he likes are different caps than the lower voltage ones. Different materials, different response to temperature and voltage. In that case it wouldn;t really be the voltage so much as it was the different type of cap, that just happens to have higher voltage ratings.

Whether any of that makes any difference at all, I have no idea.

[bob p]

buy an LCR meter.

[Chuck H]

As mentioned... Inductance, spacing for parts changes layout or, if layout is the same, proximity. The real world differences will be so small that you would need very sophisticated equipment to detect it. Not very likely your ears could. The greatest difference will be in actual cap values as they relate to tolerances. As far as a 9V powered pedal is concerned, the difference in garden hose capacity theory would be like postulating how fast a tennis ball rolls down a twelve inch board vs. a twenty four inch board when both are at the same incline!?! The point of diminishing returns has long been reached!!! BUT... The difference in user confidence can be significant and shouldn't be ignored. For that reason the specific cap type may be important. I'm a painting contractor. I drive a white Ford van. As a painting contractor I'd feel pretty lame driving a blue Ford van! Even though the color makes no difference whatever in the vehicles ability to carry my tools and keep them dry.

[km6xz]

There might be a difference in dielectric absorption since the spacing is wider for higher voltage caps but overall, any claims about the "sound" characteristics about isolated parts should be met with laughter and a reminder why to never pay any attention to what that person says in the future.
An analogy would be like claiming that a "A" note sounds better than an a "C" without context of a melody, octave or harmonic content.
Or claiming "the" is better than "and".
Ask him to explain how he determined that higher voltage caps "sound" better, and suddenly all the confidence evaporates. Or better, does his playing sound better than that of anyone else who is using lower voltage caps? I would pick the player who creates more interesting music, not the one with higher or lower voltage caps. A billion volt caps will not make a bad player worth listening to, or diminish a good player's appeal.

[Mick Bailey]

Most commercial equipment is built to fairly close voltage ratings on components in order to reduce costs. More often than not a component is selected not on the basis of any tonal Mojo, but simply what's cheapest, or what will work in a given circuit. When you look inside most pedals the components are what you'd find in a transistor radio, washing machine controller or electronic toy.

The most revered pedals - the 'classics', were/are built down to a price. Higher voltage components generally mean higher cost and a redundant overhead on specification. Sometimes a higher voltage component is in there simply because they don't come any lower (disk ceramics, greenies etc.).

Tropical fish caps in their day were commonplace and cheaply made. They came in 100v, 250v, 400v, 600v and found their way into all sorts of equipment. Some old wahs contain quite a few - my early Vox has them, but the sound is the sum of everything - the contour of the pot has quite a bearing on the feel and sweep. The inductance and DC resistance of the inductor has more effect on the sound than cap voltage.

I bet tropical fish caps were used because;

1. They were cheap
2. They offered relatively high capacitance values for small physical size (at that time)
3. Radial leads mean compact layouts and smaller PCBs
4. Low inductance (at least for audio purposes)
5. They were available in a wide range of values

I saw some component analyser traces from different cap constructions - all caps the same nominal value. There were clear differences at much higher frequencies than audio, but very subtle within the audio range. A perfect capacitor exhibits only capacitance, but a real capacitor has a range of primary and secondary characteristics that affect its behavior. It's conceivable that in a given circuit the sum of these characteristics may add up to something discernible, but I would suggest that any differences are a result of differing capacitor construction types and dielectric materials rather than voltage rating per se.

[Steve Conner]

The biggest question in "capacitor sound" for me is, whether dielectric absorption is audible. This is the tendency for the capacitor to recharge itself slightly after you have charged it up and then shorted it out. It's also known as "soakage" and is pretty much the only measurable difference between different kinds of plastic film capacitors at audio frequencies.

Dielectric absorption is commonly modelled by a load of series RC networks across the ideal capacitor. That implies that it is a linear process, and as such, all it can do is alter the frequency response slightly. A filter made with the capacitor would roll off ever so slightly less than 6dB per octave, and I doubt that is audible.

If it were non-linear, then it could generate distortion harmonics, and those might well be audible. However, Cyril Bateman's measurements on plastic film caps showed extremely low levels of distortion. I personally built an oscillator using random "orange drop" style caps lifted from the junk box, and got distortion less than 0.002%. Maybe I got lucky and all the caps I picked were polypropylene, which has very low soakage. Or maybe soakage Is a linear process that doesn't cause distortion.

[Chuck H]

any claims about the "sound" characteristics about isolated parts should be met with laughter and a reminder why to never pay any attention to what that person says in the future.

Laughed heartily at that one. Just the notion that one ill informed statement could wipe out any and all credibility about anything!

[nosaj]

Well that is pretty much the line of thinking I was going with horse puckey. But rather than rely on my own opinion I wanted to ask the experts. I appreciate your comments, but I think to convince him otherwise is a loosing battle since he is a self proclaimed tone snob(whatever that means).


Thanks,
Jason

[Chuck H]

You never want to get into that discussion with someone your friendly with. It's the difference between faith and fact. If the subject of the faith is ever realized it becomes fact. Therefore, faith cannot coexist with fact on the same matter.

[nosaj]

Then how would you stop the spread of misinformation, or helping that person realize they sound like an idiot if they start talking to someone who knows whats what? I guess this is just an example of audiophoolery?

Thanks,
Jason

[Chuck H]

Keep in mind that faith has been a powerful force in human history. It's clearly a natural proclivity. Some people peak at a given point and die old without ever realizing the futility of faith. Others discover the benefits of reality somewhere along the way. Also worth noting is that there will always be someone ready to take advantage of others who have faith for their own personal gain. Which is easy because they only need to advocate without the pesky requirement of proving anything. This is also historically proven. Opposing it is about like trying to stop the wind from blowing. Indeed, some people with faith as their only motivation on an issue often make fools of themselves... Or they just try to force everyone to believe as they do. Sometimes even killing others that won't conform.

[km6xz]

After lots of experiments back in the day when audio was more important to me, the only caps that had consistently audible differences in almost ideal listening situations were disc ceramic but those suffer from Piezoelectric effects and are sensitive to magnetic fields, beside physical size due to a changing voltage across them.
When getting down to 0.002%, about the limit of analog generators, tunable notch filter distortion analyzers, the harmonic content is being competed with by noise. I could do better with my HP wave analyzer but measurements took a lot longer and only accounted for one harmonic at a time.
We are talking about intentionally highly distorted signal chains when discussing stomp boxes and guitar amps, with orders of magnitude larger influences to contend with, like the non-linear transfer functions of a vacuum tube and speaker, than any theoretical influences of capacitors or other passive devices.
A lesson or two would result in more audible difference.
I am the moderator for a large Nikon community and frequently get questions about what esoteric piece of gear to get or comparing two top lenses. I not infrequently tell them that the best single improvement in getting photos which people find compelling is not to get the latest $2000 lens but to take a hands on workshop where doing trumps talking about it any day as a way to improve the output. Same with music.

[bob p]

which nikon forum?