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Post by pablogilberto on Jun 11, 2020 7:46:43 GMT -5
Hello!
I have observed that most guitar wiring uses a resistor and capacitor network for tone control functions.
I'm just wondering why inductors are not generally used?
I have seen inductors being used in active onboard preamp designs.
I want to understand why do we prefer capacitors over inductors?
And if capacitors have some advantage, why do some on-board preamp builders use inductors?
Thank you!
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Post by sumgai on Jun 11, 2020 14:16:39 GMT -5
pablo, Hello! I have observed that most guitar wiring uses a resistor and capacitor network for tone control functions. I'm just wondering why inductors are not generally used? I have seen inductors being used in active onboard preamp designs. I want to understand why do we prefer capacitors over inductors? And if capacitors have some advantage, why do some on-board preamp builders use inductors? Thank you! Short answer: Cost. Long answer: Because the main idea of a guitar (and a tone control) is to be able to obtain broad-frequency response, or to be able to trim down the higher frequencies. The former is good for most things rock, country, or much of blues (Albert King, anybody? Howzabout Roy Buchanan?). The latter works nicely for a great amount of jazz, some blues, and lots of contemporary "new wave" type stuff. Capacitors do this in comfort, inductors can't do it without a fair amount of circuitry shenanigans. Inductors are best suited to trimming away much lower frequencies, or when used in combination with caps, such a pair can either reinforce or scoop out a mid-frequency portion of the audio spectrum. A fair number of guitarists like this latter possibility, but it does add cost, and it does add potential points of failure. Any questions? HTH sumgai |
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Post by thetragichero on Jun 11, 2020 16:48:55 GMT -5
only inductor i like in my guitars is a pickup
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Post by ashcatlt on Jun 11, 2020 18:34:05 GMT -5
Yeah I mean we’ve already got an inductor, and frankly most of the action of the tone control is the RL lowpass. In a lot of ways, the capacitor actually keeps the T pot from sweeping that RL cutoff too low. It sets a lower limit to the cutoff so that it doesn’t go to total silence when you turn it down. Course imaginary numbers and vector math add up to resonance when you combine Ls with Cs and that is also important, but most of the real action of the T pot is pickup inductance.
But that gives us a big hint as to why we don’t see other inductors in our passive guitars. With the sort of impedances we’ve got, an inductor needs to be pretty big - basically on the order of our pickups which can be up to 4H or more for some HBs - and to get that much inductance, the component itself ends up being physically pretty large. That’s not really practical just for space reasons and can also get kind of pricey. You can get the about the same filter out of an RC network in a much smaller space and a lot cheaper.
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Post by pablogilberto on Jun 11, 2020 19:33:33 GMT -5
pablo, Hello! I have observed that most guitar wiring uses a resistor and capacitor network for tone control functions. I'm just wondering why inductors are not generally used? I have seen inductors being used in active onboard preamp designs. I want to understand why do we prefer capacitors over inductors? And if capacitors have some advantage, why do some on-board preamp builders use inductors? Thank you! Short answer: Cost. Long answer: Because the main idea of a guitar (and a tone control) is to be able to obtain broad-frequency response, or to be able to trim down the higher frequencies. The former is good for most things rock, country, or much of blues (Albert King, anybody? Howzabout Roy Buchanan?). The latter works nicely for a great amount of jazz, some blues, and lots of contemporary "new wave" type stuff. Capacitors do this in comfort, inductors can't do it without a fair amount of circuitry shenanigans. Inductors are best suited to trimming away much lower frequencies, or when used in combination with caps, such a pair can either reinforce or scoop out a mid-frequency portion of the audio spectrum. A fair number of guitarists like this latter possibility, but it does add cost, and it does add potential points of failure. Any questions? HTH sumgai "to be able to obtain broad-frequency response" By this, you mean a High Pass filter? Are you saying that we use capacitors because it functions as a Low Pass filter and we do not usually use Inductors because they will act as High Pass? Thanks! |
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Post by ashcatlt on Jun 11, 2020 20:00:04 GMT -5
Whether it's an HPF or an LPF depends on whether it is in series with the source or in parallel. That is, whether it functions as the "top resistor" or the bottom in the voltage divider. This is true of a capacitor too, and for similar reasons, but in opposite directions.
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Post by antigua on Jun 15, 2020 15:14:47 GMT -5
Hello! I have observed that most guitar wiring uses a resistor and capacitor network for tone control functions. I'm just wondering why inductors are not generally used? I have seen inductors being used in active onboard preamp designs. I want to understand why do we prefer capacitors over inductors? And if capacitors have some advantage, why do some on-board preamp builders use inductors? Thank you! The Bill Lawrence Q filter, and maybe the Gibson Veritone are the only two uses of an inductor that I know of that is genuinely beneficial. They allow for band stops (mid scoops). Cost wise, the Q filter is about 100 turns or so in a ferrite enclosure. They're not prohibitively expensive, but even treble tone controls (high pass) are rare in the guitar market, and there's an overall dearth of anything new and useful these days. You're lucky if the guitar has built in humbucker splitting. If not for BB King we might not remember the Veritone having existed at all. G&L probably pushes the PTB in order to differentiate from Fender, you don't see many (any?) other guitar makers offering it. What it comes down to IMO is that so little music has been made with non-stock guitar wiring that the sounds you get from non stock wiring is not in the musical vocabulary of most guitarists. When people talk about what is "useful" they really mean what is familiar. |
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Post by blademaster2 on Jun 15, 2020 16:19:36 GMT -5
pablo, Hello! I have observed that most guitar wiring uses a resistor and capacitor network for tone control functions. I'm just wondering why inductors are not generally used? I have seen inductors being used in active onboard preamp designs. I want to understand why do we prefer capacitors over inductors? And if capacitors have some advantage, why do some on-board preamp builders use inductors? Thank you! Short answer: Cost. Long answer: Because the main idea of a guitar (and a tone control) is to be able to obtain broad-frequency response, or to be able to trim down the higher frequencies. The former is good for most things rock, country, or much of blues (Albert King, anybody? Howzabout Roy Buchanan?). The latter works nicely for a great amount of jazz, some blues, and lots of contemporary "new wave" type stuff. Capacitors do this in comfort, inductors can't do it without a fair amount of circuitry shenanigans. Inductors are best suited to trimming away much lower frequencies, or when used in combination with caps, such a pair can either reinforce or scoop out a mid-frequency portion of the audio spectrum. A fair number of guitarists like this latter possibility, but it does add cost, and it does add potential points of failure. Any questions? HTH sumgai Agreed - it is probably cost driven but they do exist. My Framus Nashville Delux has an 800mH inductor in the tone circuit. It acts as a notch filter rather than a low pass. I also used inductors (1000mH) in all of my own home-built guitars. I call it 'fatness control'. To me it is very nice sounding because it preserves clarity. |
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Post by frets on Jun 15, 2020 16:48:36 GMT -5
I just wanted to add that for about a 1/4th the cost, you can use a Mouser 42TL018 7K Ohms 2.6 Henry and it sounds exactly like a Lawrence Q-Filter. The Q-Filter’s inductor weighs in at about 2.2H. But it has been my experience that the 2.6H sounds exactly like a Q-Filter. John did an analyses of Q-filtering as well as inductor effects within GuitarFreak. Here’s a configuration I like. You just substitute the Q-Filter for a 42TL018  As expected, it’s basically a heavy handed mid scooper. |
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