Thoughts on using high rated voltage caps in pedals

[DJPsychic]

I'm wondering what peoples thoughts are on using, for example, a 250VDC or 600VDC cap in a pedal?

Has anyone noticed a tonal difference between them and say a 16v? Sometimes the higher rated caps are the only option when buying from certain online suppliers. Just curious!

[ElectricDruid]

I might do it for aesthetics (looks like a tube amp!) but I've never noticed a tonal effect. Unless you count wide tolerances, maybe.

Generally I aim for 25V, 50V or so. So that there's still a margin of safety, but x2 or better is ok.

[Sonic_Fields]

Makes no tonal difference at all. Just make sure they're rated high enough and you're good to go!

Oh, also check the size when ordering higher rated components. You wouldn't be the first to discover you've ordered some huge caps... Been there, done that... 

[anotherjim]

Well, Gibson & Fender have in the past used high voltage ceramic disc tone caps in their guitars. At least 50v or 100v commonly but I believe I read somewhere that 500v ones happened and are considered to be very stable.

[davent]

Well, Gibson & Fender have in the past used high voltage ceramic disc tone caps in their guitars. At least 50v or 100v commonly but I believe I read somewhere that 500v ones happened and are considered to be very stable.

Total guess on this but i'd think their just grabbing caps from the same stock they were using in their tube amps, why have one more thing to keep in stock if you can use something you already have.

[idy]

One reason for high voltage caps is the heavier leads, makes a stiff wiring harness that a loose pot won't twist and stress the connections.

[vigilante397]

Depends on how much you feel like spending. Obviously high voltage caps are going to be more expensive, but they do look super neat. If you're willing to spend an 4-5x as much as you would on film box caps (or similar) for the aesthetics, I say go for it. "Mojo" builds are neat and customers that are curious to open the back absolutely notice the look.

But as noted above, no tonal reason to do it.

[fowl]

Total guess on this but i'd think their just grabbing caps from the same stock they were using in their tube amps

That was definitely the case at Gibson, the 400V "bumblebees" and 600V "black beauties" were exactly what they were putting in their amps at the time.  Fender typically used lower voltage tone caps, like 50-160V, in the old days at least.  There are a few 50s Strats with 400V yellow Astrons though.

[pinkjimiphoton]

two thoughts... i've read using hi voltage caps way below their rated voltage could lead to the cap not achieving its rated value...

and when i took a short period of electronics in tech school 40 some years ago, we used to charge up high  voltage caps and throw them to our friends... "here, catch!"  ZAP!  fun times at windham tech!

i would be curious, if they keep storing charge and build up a far higher voltage than the circuit they're in... i've fixed a few things that peeps have brought me cooked over the years, and the only weird thing i found in 'em was tubeamp rated caps... 400, 600v. did they store enough charge over time to lunch the circuit? beats me, but when i replaced them and the semiconductors, there never seemed to be any more problems. i DO know that high voltage filter caps can recharge from the air to close to their rated voltage over time in some cases, so to me, that makes me nervous. i would hope i'm wrong on this, but...

aesthetics are the only reason i can see to use them, personally

[vigilante397]

i DO know that high voltage filter caps can recharge from the air to close to their rated voltage over time in some cases, so to me, that makes me nervous. i would hope i'm wrong on this, but...

I have never heard that before and a quick google search didn't turn any results on it, doesn't make sense to me. Got a source on that one?

[pinkjimiphoton]

yeah, tube amp stuff 101. that's why you always discharge caps before working, even if they'd been previously discharged. they'll start recharging by themselves. you can check it with a meter, believe it or not.

combined with a flyback transformer in an older tv for instance, it can charge back up too. it was my old sound guy bob saunders who was the local electronics guru for many years that told me about that. he kept an led clock running off one, unplugged, for literally years.

i believe dan torres mentioned it in his book, too.

remember.. for all intents, capacitors are batteries. when i was a kid, we used to do terribly dangerous things with methanol powered model airplanes on long ass strings flying at each other, and they needed lamp batteries.

they'd get weak over the course of the day, if the airplanes survived long enough... some of the crashes were epic... and we were taught by my dad the science professor to just roll 'em around in the grass... they'd pick up enough electrons to regain a charge, often enough to get the glow plug things in our crappy little airplanes hot enough to work.

i did a quick google... first thing i found was this:

But yes it can but depends on how low leakage it is , or the quality factor of the plastic as the dissipation time can be pretty quick. It takes triboelectric action to create a charge imbalance and and a bipolar de-ionizer or high humidity > =50% to neutralize or balance the charge.

As I recall TEK Diff Probes with 1pF and FET's rated for 25V would blow from EOS just moving the wand and looking sideways. (I'm just kidding. The tech who repaired it so often, said she was tired of fixing it so often Although when I implemented a EOS protection plan plant-wide in the early '80's, a charge meter recorded 200V on my finger just from raising one foot off a nylon carpet after grounding myself. Q=CV so a change in body capacitance to carpet C , Q/C=V
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edited Aug 4 at 20:17
answered Aug 4 at 20:10
Tony Stewart EE75
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    What is EOS? (I'm familiar with ESD but not EOS.) –
    JYelton
    Aug 4 at 20:23
    1
    "EOS is a term used to describe the thermal damage that may occur when an IC is subjected to a current or voltage that is beyond the datasheet specification limits of the device. ... ESD is a very high-voltage (>500 V) and moderate peak current (~1 A to 10 A) event that occurs in a short time frame." ... elect.-over-stress –
    Tony Stewart EE75
    Aug 4 at 20:26

1
Ah, Electrical Overstress - interesting; thanks. –
JYelton
Aug 4 at 20:31


https://electronics.stackexchange.com/questions/580257/can-a-capacitor-recharge-from-ambient-static-electricity

BUT there's others on the same page saying it can't happen, so beats me.
i DO know bob was from the tube into transistor age, and if he told me that, it was for a reason. he said if i was working on a tube amp, even if i had discharged it, if i stepped away for a while to discharge it again, or leave it connected to ground with roach clip wires til i was done.... and not forget that


but i dunno, seems weird to me, but what the hell have i EVER known? lol

i just found this, so apparently i am wrong on this, my apologies

https://electronics.stackexchange.com/questions/13091/high-voltage-capacitor-in-a-low-voltage-system

[mozz]

ESD is basically any voltage. 5-10 volts can wipe a chip out.

[fowl]

~~~

[DJPsychic]

Interesting stuff.

I asked originally because I built a Klone, some of the film cap values I could only find in 250 or 630v.

Fortunely they were still smaller sized caps.

[PRR]

Over-rated electrolytic caps are rumored to go wrong-value over time.

Film (paper, plastic, mica, glass, ceramic) are more stable. (Some ceramics go goofy.)

An idle cap won't re-charge "from the air" but they CAN have dielectric absorption which means they do not discharge all the way. Charge hides in deep centers and leaks-back. I tend to check; more to the point, I *always* assume any "off" tube amp may be full of poison vipers, and am careful of my body parts. (In my childhood I once took 350V from leg to leg through my crotch...)

No comment on rolling glow-batteries in the grass. Gee, what do they do now? You can't buy a #6 dry cell, not since the last century.

[pinkjimiphoton]

didn't know ya couldn't buy 'em anymore, but yeah, that was definitely in the last century!

dialectric absorption sounds like what i was told about. maybe i remembered it wrong, or it was explained to me in a way hoping to keep my dumb @$$ from electrofrying myself. a little knowledge is a dangerous thing in the hands of an idiot like myself.

[anotherjim]

You've had me fondly remembering the terror of glowplug engines. The leather one-finger glove to protect when flicking the engine in to life, the erratic flights and smell of dope and balsa glue for the inevitable repairs - assuming you could retrieve the plane. The sound of those little engines whining away in the distance was the backing track of Sunday afternoons.

[pinkjimiphoton]

You've had me fondly remembering the terror of glowplug engines. The leather one-finger glove to protect when flicking the engine in to life, the erratic flights and smell of dope and balsa glue for the inevitable repairs - assuming you could retrieve the plane. The sound of those little engines whining away in the distance was the backing track of Sunday afternoons.

we used to literally chickenfight with them....lol... some of the midair collisions were truly epic!