another capacitor question

Bill in SC

Senior Member
OK, I think I understand that the higher value of the capacitor the more low end can be expected. The lower the cap value, the more m mids and treble to be expected. Correct? That being said, I was told that different type caps even of the same value sound very different. For instance you can get the Sprague 022 "orange drop" caps for a couple of bucks for several. Yet the Sprague 022 Vitamin Q caps sell for about $30 a pair. I was told that these high priced "oil and paper" caps are the ones you want to get for optimum tone. Can some of you gurus help explain this phenomena ? Is there THAT much different for normal people to notice, or do you have to have trained specialized hearing to tell the difference?
Bill in SC
Only real difference will be ESR, most likely, here's a primer:

Personally I find about f*ck all difference in caps of same value tone-wise so I just use the 2 fer $1.49 ones from Radio Shack you could probably buy for pennies elsewhere
LOL That link might just as well been in Chinese. I would have understood it about the same!!  :)  WAY over my 'ead!!  Soooo, shrew it, I'll go with the el cheapos.  What's really weird is that we spend huge bucks on bodies, necks, pickups, and other electronics, yet when it comes to spending an extra buck to buy the supposedly "correct" audio capacitor, we try to cut corners. From what you are saying, Jack, not enough difference to spend the extra bucks?
BB in SC
I frequent a diy stompbox forum and the subject of caps comes up on an almost daily basis. The general idea is that at low voltages, there is not much difference at all in cap type, especially diffrent types of film caps, and only a very slight difference between ceramic and film. I would expect that under 100v is way more than sufficient. So, the 2/$1.49 RS types (called "greenies" by the stomper geeks) are just fine, and I defy anyone to tell the difference between those and orange drops  in any kind of a/b cap test.
In high voltage apps (tube amps, etc.), it's a different story.
Incidentally, is a great source for caps if you're buying in bulk.
Furthermore, if anyone needs .047uf films, let me know, I've got a ton of them. No charge.
IF I needed to replace the wiring on a very valuable vintage guitar, I might consider paying high dollar for vintage or vintage repro type caps. In any other circumstance, the "greenie" mylar caps do the job, never get seen and will outlast me by at least one lifetime....
Not to argue, but unless you're trying to keep everything stock, a newer cap is preferable as caps made today are of tighter tolerance. Some types of caps (electrolytic, oil) do go bad over time. Vintage repro caps are often just repainted to look like the old ones. There have been a shitload of tropical fish caps hitting the shops and ebay lately. Think those are all vintage?
caps do sound a bit different - especially in amps as tone/coupling caps

in guitars, the differences are way less - almost indiscernible

this can be argued all day - but

a.  if you take caps and a,b,c,d,e  them blindly, its likely that you cannot tell differences
b.  the very small differences will be also variable on the pickup used, due to the nature of the pickup
c.  also the cable and amp
d.  ESR has some to do with it, more for amps really, but... thats one thing that does make them different
e.  Constuction type - oil/paper/foil, poly-foil, ceramic, mylar has more to do with it - but those types have generally different ESR as well
f.  ESR is not "that" important as the caps are being used in conjunction with resistor to ground - its just not that critical.
g. If you hardly ever use the tone control - run it full treble - then it matters not a hill of beans
in most situations, especially in a guitar tone control, the value means more than the construction.

I have one pair of paper in oil caps. I used them in a tube stereo amp. A friend of mine built one, I heard it and got jealous. I built one with the same parts and got pretty much the same amp. He used paper in oil caps, and that's the extent of my rationale for dropping $32 for two .22uf caps. The amp sounds great to me. Would it sound the same with different couling caps? Don't know. I can't bring myself to fix amps that don't need fixing.

For guitar amps, I use Mallorys for coupling, spragues for power supply reservior and cathode bypass. Silver mica for my bright cap. They're cheap and don't take up gobs of chassis space. I haven't heard anything from my amps that would make me say "Damned caps. Got to find something better."
neilium said:
Would it sound the same with different couling caps?

Mallorys for coupling, spragues for power supply reservoir and cathode bypass. Silver mica for my bright cap.

Yes it would sound different with different coupling caps.  You'll find - that there is a marked difference if you use Orange drops vs Mallory vs those blue Xicon caps.  Reason being is what you hear goes through the caps, as opposed to signal being bled off with the caps.  Also there is a matter of some AC current flow (DC blocked, hopefully).  The current flow still rather small, but quite a lot larger than what you'd see on a guitar pickup.  That is, in the amp you're seeing milliamps flow as opposed to maybe one milliamp if that, in a guitar.

I've not heard much difference in the power supply, bypass, and bias supply cap.  I like the spragues because they're large, and take the heat well.  For the bypass caps... any electrolytic would do (correct value assumed), but hey, I'm buying sprague, stick with it. 

On the bias supply... there is a trick used to totally eliminate the hum from that supply.  If you look at the common bias supply, its an AC tap from the main B+, dropping resistor (large wattage for heat and to take the higher voltage), diode to give you half wave DC, a reference resistor (or combined with a pot for adjustment), and a filter cap to smooth out the half wave.  The bias still has a LOT of ripple in it at that point.  What Fender did later on - a good mod - is make a normal traditional bias supply, but then, add another resistor, about 1k, and then another cap to ground, and then bring that voltage over to the grids on the output tubes.  That second resistor and cap take out a lot of extra ripple, making it in the order of less then .1 percent residual hum. 

But I digress... in guitars, use something thats the right value and fits the space given.
-CB- said:
On the bias supply... there is a trick used to totally eliminate the hum from that supply.

I've seen the same arrangement on hifi amps. All the amps I've built, hifi and guitar, are cathode bias or battery bias.
Cathode bias or battery (grid aka C-) bias.... is there another kind?

Let me rephrase that - another kind used in amps <gg>

-CB- said:
Cathode bias or battery (grid aka C-) bias.... is there another kind?

Let me rephrase that - another kind used in amps <gg>

yup. It was an experiment. I found an interstage transformer at a flea market, still in the box, and it had a circuit diagram with it. I breadboarded the circuit for yuks. Got a 90v battery from to provide bias to the grid of a 45. It was interesting, but the parts were needed elsewhere.

Larry Lisle had a need amp in Glass Audio that was similar.
Well the bias supply was originally a "battery" supply.

You'd have the A+ (filaments) the B+ (plate) and C- (bias) batteries.

Those have been replaced with voltages that run from "the mains" (as they say in the UK).

A battery bias is no different from a grid bias,  it works and acts the same.

Cathode bias works for Class A - because the current is fairly constant on class A.  That Class A can be either single ended or push pull. 

There IS another bias setup.  A self bias scheme worked out by some of the high high end tube hi-fi crowd.  Its a twist on the self bias approach and uses a differential circuit.  Rare - complex - not for guitars or for those who dont wind their own output transformers, it doesn't really count.  There's probably other ways to get an offset voltage relationship between grid and cathode, but none are as simple as the two we're used to.