khoomeizhi
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Post by khoomeizhi on Jan 13, 2007 2:06:39 GMT -5
hi folks, quick hypothetical:
if was to use a different value of capacitor for the tone pot in rewiring an old p-bass, what would the effect on sound be?
schematics suggest a .05uf cap was used originally. what if i used a .1? or a .01? .001?
larger values, just more drastic tone change?
thanks- khoo
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Post by gfxbss on Jan 13, 2007 11:21:56 GMT -5
Hi khoomeizhi,
Ill start off by saying welcome to Guitar Nuts2.
now in regards to your question. it will just change the tone. ive been putting what are called varitone switches in my axes these days. its a rotary switch w/ many capacitors on it. so then i can choose between them. the best way to find out what you like is to just toy around and try different things. no one can tell you what will sound the best on you pickups.
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Post by ashcatlt on Jan 13, 2007 12:36:28 GMT -5
the capacitor passes high frequencies more easily than lower frequencies. In the case of a tone control, it passes these high frequencies to ground, basically skimming them off the output signal. The "cutoff" frequency is mostly dependent on the capacitance value. Higher value = higher cutoff frequency.
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khoomeizhi
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Post by khoomeizhi on Jan 13, 2007 13:19:11 GMT -5
thanks, folks. have i got this right, then? the capacitor on the tone pot skims off treble. the higher the value of the capacitor, the more treble skimmed off and dumped to ground...with tone turned up or down? to make it more interesting, try a multi-capped rotary switch for tone. check. true, no one can tell me what will sound the best, but perhaps they could suggest things if i give more info? i'm planning to redo all of the electronics on an old korean-made squier bullet/p-bass. will be putting in new pickups - probably S.D. 1/4pounders. i am hoping to create a bass that is best for downtuned ugly sludge. to that end, if i don't want to do something with multiple capacitors, do i want to be skimming more treble off or less? suddenly in my thinking, maybe less treble skimmed (thus more heard) could be better, with more frequencies going on, thus more ugly noise? do ya get many people around here looking to make their tone less pleasant? thanks for any tips.
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Post by sumgai on Jan 13, 2007 14:01:57 GMT -5
khoomeizhi Intentionally..... or otherwise? ;D And to the forums! sumgai
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Post by gfxbss on Jan 13, 2007 14:20:32 GMT -5
one more thing before you start putting new caps on it. even though caps are no big deal to do. try messing w/ the treb on your amp.
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khoomeizhi
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Post by khoomeizhi on Jan 13, 2007 15:17:13 GMT -5
thanks for the welcomes.
sumgai - intentionally, of course.
gfxbss - it's not just a matter of putting in new capacitors just to change the tone. this was my first real bass, of 14 years, and as, such, an old friend. when and if i get a second bass, to give time to mod the old one, and also just 'cuz, i'm planning on totally re-doing the electronics on the old buddy because quite frankly, they could be better, more shielded, etc. and because an old friend deserves new life - i will make it an impressive ugly beast. new paint, pickguard, etc., too. upon further reflection of my options for tone capacitors, though, i'm leaning more toward your idea of a varitone switch, which would give me more options in general, and would answer my questions about specific capacitors effects on tone, for future reference.
thanks.
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Post by gfxbss on Jan 13, 2007 15:26:33 GMT -5
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Post by ashcatlt on Jan 15, 2007 22:52:50 GMT -5
I think I was wrong, but you ended up getting right. I think now that higher capacitance means a lower cuttoff frequency. A tone control works exactly like the simple low-pass filter shown (and explained) here. Look under the heading Passive electronic realizationyou asked: "with tone turned up or down?" Turning the knob down decreases the resistance between your signal and the capacitor, causing more high end to be shunted to ground. The varitone as wired in the link above doesn't mention the "tone knob" at all, and will act pretty much like you've turned the tone all the way down and are using the switches to change the cutoff freq. You could just as easily connect the ends of the caps to the same wiper of the tone control that you've got a cap now and have a variable amount of cut plus a variable cuttoff frequency.
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Post by ChrisK on Jan 16, 2007 13:00:05 GMT -5
The cap determines the cutoff frequency (and of course, phase shift). The tone pot resistance in (phasor) conjunction with the capacitive reactance of the cap determines the depth of the effect. This idea is the basis for the StellarTone circuit. www.stellartone.com/files/stellartone22.pdfwww.stellartone.com/Page.asp?NavID=76It ain't new at all, having been done in the Varitone (albeit with an inductor as well), and on the Gretsch guitars way back when with the 3=pole tone switch (which selected different capacitors). And much, much, much more recently, it's also used here; guitarnuts2.proboards45.com/index.cgi?board=schem&action=display&thread=1140140143on S2 to vary the tone control cap, and on S3 to shift the bandpass peak response of a pickup lower in frequency. (When the tone pot is down to zero, the pickup(s) bandpass response is shifted way lower and peaked, which led to Fender designing their "Greasebucket" tone control [which generally works the same as just turning a "regular" tone control down to "2" {!What, a tone control is an ANALOG control?}]).
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Post by sumgai on Jan 17, 2007 4:09:26 GMT -5
Drat, I thought I'd posted a reply, not long before Chris's, just above. Seems to have been posted to the big bit bucket in the sky. Oh well..... Fast way to remember what's happening with capacitors..... If we change the value of a cap, we change the frequency at which it starts acting. ashcatlt covered that above, as did Chris, just above. If we change the resistance in a circuit that has a capacitor, we don't change the frequency of anything, but we do change the strength of any frequencies that are affected by the cap. The easy way to think of a tone control is that it's nothing more than a tailored volume control! In essence, it turns up or down the volume of a selected group of frequencies. In the case of the simple tone control on our guitar, we are affecting all those frequencies above a certain point, said point being set by the cap's value. That's really all there is to it. Well, we could get into some math, if you wish, but I think we'll just leave that for the WIKI article, it's all in there, and plenty more, if you're that masochistic! ;D sumgai
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Post by sumgai on Jan 17, 2007 4:24:15 GMT -5
khoo, Let's answer your question directly..... The value 0.05µf is generally accepted as a good starting point in one's quest for the ultimate tone. Going downwards in value (less capacitance, or 0.022µf for example) will raise the frequency at which the tone control works. The net effect will be to leave more of the treble in the output. How that strikes you is up to you, we can't tell you "this value or that value is best, period". 0.1µf will like darken your tone a lot, but then again, this is what early Fenders used, and we all know how they're rising in value, due in no small part to their tone. 0.01µf will decrease your control's effect to very little, it probably won't give you enough variety is my guess. 0.001µf is far too little for a guitar (or bass) circuit, you'll wonder if it's even working. (It is, but not in your hearing range. ;D) The varitone circuit discussed above (and elsewhere on this forum) will likely give you the widest range of options from which to find your personal ultimate tone, check it out. HTH sumgai
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khoomeizhi
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Post by khoomeizhi on Jan 19, 2007 10:44:50 GMT -5
thanks for the answers. still not sure exactly what i'll do when the time comes, but that's probably months in the future, as these things go.
the specific info is quite helpful.
k
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