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tone capacitors?!?


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11/17/1999 6:25 AM
skott
tone capacitors?!?
does anyone know if there is any differnce (sonic, reliability, life) between basic ceramic disc caps and silver mica caps. or any other cap for that matter?  
 
thanks,  
 
skott
 
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11/17/1999 6:31 PM
Gus
In a guitar use what you like (change to taste) signal level is low. I tend to like film caps .01uf to .1uf. However in a friends 74 strat I left the .05uf large 1kv cer disk because it sounded very good with the T/S's we put in the guitar.
 
11/17/1999 8:34 PM
Mark Hammer
Somebody somewhere will disagree with me, but I don't think it makes a heap of difference what kind you use in a guitar. There are so MANY sources of signal corruption between your tone control and the speakers (or rather, your ears) that variations in cap composition are moot, even if they DO have slightly different operating characteristics. When it comes to amps and other active devices further on in the signal chain, that's a different story.  
 
Bottom line: If a ceramic disc was good enough for Leo, it's good enough for the rest of us.
 
11/19/1999 6:25 PM
Ed Rembold

 
it Does make a difference, and that difference can be huge,  
If you use the wrong Type and of course ,the wrong value.  
Use Ceramic- (here's the kicker-) class 2, tolerance +/-20%  
value .022 (darker-.047) Don't sub the class or tolerance.  
Don't care if you don't believe me, but I have done exhaustive testing, its interesting to me to note the many parts used in the Early days -because the were cheap -Are still the best to use today -even though we have so many choices. As R.G. would say -"A happy accident" There are  
exceptions, of course, But this isn't one of them.  
Ed R.
 
11/22/1999 6:13 PM
Mark Hammer

See, now here is where you and I start poking each other in the chest with our index fingers while seated at the bar. Next thing you know, somebody breaks a bottle over the counter or over a face, and your wife's writing to you in jail explaining why she hasn't visited in a while and that his name is Larry or RG or something.  
 
The recommendation (although it's more like permission not to feel guilty) for using a ceramic disc is fine by me. Other types may be more appropriate for FX or hi-fi design, but ceramic on an axe is hunky dory. I'm sure the Gerald Webers and Dan Torres's of the world might have some arcane notions about Sprague Orange drops or something, but I doubt whether other types make any difference once you've gone unbuffered through a budget 25' cable into four 12's full tilt.  
 
The *value* of that cap is something that long-time AMPAGE'rs know I have a touchy spot for. (Cripes, I'm starting to break out in a Billy Idol-cum-Elvis twitchy sneer right now!). When it comes to tone cap values, I think our "happy accident" from the 50's has turned into a blind juggernaut.  
 
You can lash me to the mast and beat me senseless (in fact, please do!...oops, wrong forum), but I think there is no such thing as one-tone-cap-fits-all. In fact, I firmly believe that front and rear pickups should have *different* tone caps.  
 
The industry's steadfast use of one value, regardless of pickup voicing or pickup use strikes me as just plain boneheaded. Because of the different harmonics emphasized by the location of each pickup, the optimal turnover frequency for its tone control is different. When it comes to rear pickups, what the user wants in a guitar-mounted tone control is something that adjusts from sharp to round. When it comes to neck pickups, the user wants something that goes from vocal to mute. If I wanted mute, I *wouldn't* be using my rear pickup. Cap values of .022 to .047 may work okay for neck pickups, but are as useless as bull mammaries for rear pickups. I would recommend something from 6800pf to .018 (ceramic disk, of course) in its place, ESPECIALLY if you are using a single coil sized pickup.  
 
If you have a regular Strat (or clone) with dual tone controls, take it apart RIGHT NOW. That's okay, I'll wait. Doo-dee-doo-dee-doo. Dum-dee-dee-dum....okay, found the screwdriver? Good, now take the pickguard off and you will see that in the interests of economy, Fender or whomever has seen fit to stick ONE capacitor in there to service both tone controls. Take your soldering iron and make that cap serve the middle tone control ONLY. Now, for the bridge tone control, solder a 6800pf-.015uf cap in there (depending on your tastes and tone pot value), and you will be much happier. End of story.  
 
When it comes to double-coil pickups, a cap of .01-.02 may be more appropriate for the bridge pickup tone control (different turnover point again). Going higher than a .02 just means that you'll never turn your tone control down past 7.
 
11/26/1999 4:05 AM
JC

Mark.  
 
I have a question for you, if you would like to give me an answer.  
 
I did the cap change to a Gibson style guitar, and although I noticed that more tone range turning the knob was usable, I believe I so noticed that "something" else has changed.  
 
And my question is: does a guitar with a .02 tone cap, for example, reproduce the same sound/tone that the same guitar with a .01 cap just turning the tone knob as needed?  
I mean: cap .02/tone knob at 3, vs cap .01/tone knob at 6 (this is just an example)  
Would they sound exactly the same?  
 
How do different cap values affect tone? bass vs highs.  
 
Please inform me if you like.  
 
jc
 
11/27/1999 12:20 AM
Mark Hammer

Happy to reply although I wish I could do it in pictorial form; it would be so much easier and more transparent. (My apologies if I underestimate your knowledge. I understand that there are many lurkers here on AMPAGE who are novices, and I try to make my replies include them wherever possible.)  
 
No, they should have some of the same effects but should not sound the same. The reason I recommend the change is that the treble cut is starting at different points.  
 
Bear in mind that tone controls normally have a *progressive* effect or "slope". Typically, the slope is 3db/octave. So, with the control turned down full (at which point the tone control is at 0 ohms, so that you effectively have a signal going straight to ground through a cap), an octave above the turnover frequency set by the cap value, the signal is down 3db, an octave above that, down 6db, and so on.  
 
Suppose I have a "turnover frequency" of 1000hz. At full "off" rotation, there is a level drop of 3db at 1000hz, relative to 500hz (because that is one octave below 1000hz), a level drop of 6db at 2000hz, 9db at 4000hz, etc.  
 
Three DB is essentially "twice as much", but twice as much of what? If the control is only turned down a smidgen, then it's twice as much of a smidgen, and twice as much again one octave further out. If I start the cut lower down in the frequency spectrum, then even a smidgen starts to snowball into something more substantial several octaves up, once we start doubling. If I start higher up, but turn the tone control *down* more, then I may have a higher turnover frequency (starting point), but "twice as much" starts to have a noticeable effect closer to the turnover frequency.  
 
For my tastes, larger tone caps tend to have a treble reducing effect across too much of the frequency spectrum for bridge pickups. Even when you turn them partly down, you've reduced the upper midrange a bit, in addition to the treble. With smaller caps, you can still reduce the treble, but the midrange tends not to be affected so much, because the turnover frequency is higher. So, you retain the personality of a bridge pickup, but can adjust the edginess of it. As you notice, more of the control's range "feels" usable because you can still keep the guts of the pickup's sound even when you turn down the tone more.  
 
If I may use a physical metaphor, consider going from the top of the Grand Canyon to the bottom. Now, you can leap from the top, OR you can take a long gently sloping path. The actual DESCENT is the same in terms of height, but the experience is VERY different. Similarly, the amount of cut at higher frequencies may be the same with different combinations of control rotation and cap value, but what happens on the way to those higher frequencies (i.e., the effect on midrange) is different.  
 
Incidentally, do not confuse the effect of a resistor and cap going to ground with the effect of a resistor in the signal path and a cap going to ground. For the first one, varying the resistance influences how much treble loss there will be at the same turnover point. In the second case, varying the pot leaves the slope intact, but CHANGES THE TURNOVER FREQUENCY. So, you would have a treble cut of 3db/octave, but it may start anywhere from 500hz or so up to 10khz, if you felt like it.  
 
If you go to any of the schematic archive sites mentioned here (RG Keen's, Aron Nelson's, Jack Orman's, etc.) you may see a posted schematic for the Proco Rat or the Bixonic Expandora distortion units. Close to the "exit" of the effect, you will see the tone control consisting of a 100k pot, in series with a resistor (which helps to set the lowest possible turnover frequency), and followed by a capacitor going to ground. This is exactly the filter I just alluded to, and the reduction of treble it provides is much greater than what you get on guitar tone controls, even though both use a pot and cap.  
 
Finally, turning one's tone control up all the way does not mean that there is *no* treble loss. There is still a path to ground through the control pot and cap, and the twice as much of a smidgen rule still applies. Some players prefer to disengage the tone control from the circuit altogether so that there is no path to ground through the tone cap, and one does tend to notice a bit more sheen and sparkle in the sound. Of course, if you have humbuckers and play through 12" speakers with the treble turned down, you may not notice the high-treble loss through the tone control. On my own guitar, I just use a 3-position toggle for tone. Middle is no tone cut (i.e., no connection through a cap to ground) and the other two positions are two different cap values yielding full 3db/octave slopes at two different turnover frequencies. I find it perfectly adequate.
 

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