Tone Switching

[dugg]

Years ago when a good friend of mine was working for N. Steinberger in Bklyn, we hooked up a circuit to do a listening test on various kinds of caps of the same value. I'm a piano tuner by trade and am well known to be able to hear minute variations in sound that other musicians don't. Well, I couldn't hear poop. No difference at all between caps. I hate to burst bubbles, but I'd suggest that if I don't hear it, neither do you.

[psw]

I think I mentioned this before in relation to this project...

If you think about capacitors as a mechanical device or something...say flight of stairs...no matter the colour, made of wood or concrete...they do a job (filtering highs)...regradless of the construction, the sairs take you up or down...

hmmm...maybe not a good analogy...

anyway..."Tone Capacitors" don't add tone....they are there to subtract it in proportion to the resistor in the pot. The mojo of cap type and construction is largely that related to the historical use of them in guitar lore. You only hear them when they are dialed in to remove highs...which they do in relation to the value or the cap and the amount of resistance dialed in with the pot. The taper of the pot has more of a significance to the tone control operation than the cap anyway...and all they do is to subtract highs...

The addition of a coil...like the "inbetween" sounds of a strat can be interesting as it can create a selective mid-scoop type of thing...still a subtraction, but an interesting effect over a straight diminishing of the highs that a tone cap does...

...

In reality, few people ever use a their tone controls...EC's "woman tone" is an exception I guess (though more of an "effect") and on a super bright guitar like a telecaster to tame it down (or do those wha like swells)...JB gets some interesting sounds on a strat by using the tone controls to roll off the highs of one pickup in combination with another...but again, theses are rare exceptions...

...

It is interesting that a simple long lasting battery preamp could have active tone controls that both add and subtract...yet any attempt to offer these on guitars (other than to bass players and on acoustic preamps) have been a resounding failure!

...

In short...you don't need to be a "piano tuner" to hear the difference, there is none till you turn the control...and when you do, it is subtracting highs according to the values of the components (not their colour or construction)...

[bluesy]

In short...you don't need to be a "piano tuner" to hear the difference, there is none till you turn the control...and when you do, it is subtracting highs according to the values of the components (not their colour or construction)...

I agree, especially when speaking about guitars, but I feel I should mention that special breed of audiophiles that claim to hear the sound of different capacitors (even when they are the same value) in their hifi equipment. This seems to spill over to guitars as well.

The thing is, if there is any effect at all, of swapping one cap for another of different type, but same value, it is very slight. Your time is certainly better spent tweaking other areas.

[ansil]

i tell everyone this. remove the stock tone control ie or just cut the connecting wire to the vol. check out what your guitar sounds like for real. then utilize and eq pedal or rack mount to determine the freq you would like to shape.

for instance the old m3's had an inductor in them so they sucked out 1khz according to the paperwork i never tested this after all. personally i used duncans's tone stack calculator and found a nice eq setting i liked and added that in my guitar. although i did this with a single mosfet driving it. a simple turn of the knob goes from mid boost similar to a wah but not as harsh down to a basic bass heavy mid and high's nominal sound.

but that is me. another option is to http://www.muzique.com/schem/filter.htm and take the math out of it and plug in your numbers to get the freq response you want. i am not saying you won't lose a little bit of output but its an interesting option ot do. keep in mind one thing though in the case of a lowpass filter is that the series resistance will need to be reallysmall to keep down on loss's. and on a highpassfilter the resistance will need to be high to match the internal resistance needed for the pickups to function properly. another option is to apply this individually to the pickups themselves and switch it on and off via the tone switch then have the volume pot. this will allow you to not be hampered by the volume pot's imp.

and alas there is my standard trick of putting in a resistor and a cap in series and paralleling that with another smaller cap and using the tone pot as a blend pot for tone with no connection to ground. in doing so you now have reduced the load and you are utilizing the capacitor inline with the guitar which will have more effect on which capacitor (not enough really to worry.) you use. keep in mind also the human ear can not really distinguish much more than a factor of 10X to perceive a 2X increse or decrease in freq and gain response.

thus if you are going to implement my idea you would need to take say a 1uf cap and a .01uf cap (i realize this is more than ten fold but this is taken from an actual working instrument) keep in mind you will lose some bass energy with the smaller cap so i add a smalll trim pot or resistor to the larger capacitor much in fact like an old layout for say a marshal or fender tone stack. where the treble pot as it is called is actually a blend it is blending via the 250k pot a say 470pf and a .022uf cap. and the rest of the circuit has a different effect but if you look at the 68 - 100k slope resistor you see this inhibits bass frequencies. do not fear though the amount of tone and volume you saved by cutting out the original cap and pot to ground makes up for any losses you will incur with my mods.

the nice thing about this is you can make your pickups custom to your axe. you got a bass heavy neck pickup lets fix it. too much treble in the lead pickup roll some off. the really nice trick is when you do this you get an interesting effect when you combine them together then you get more of a notch filter which i have been hard pressed to find someone who didnt like it.

AS WITH ALL MY MODS AND ADVICE, DO SO AT YOUR OWN RISK. I AM INSANE AND HAVE SPENT WAY TOO MANY HOURS DISECTING TONE IN THE STUDIO AT HOME AND SUCH. as LK used to tell me i am sort of a weird genius at making stuff that shouldn't work happen.

ps if you need some schematics let me know i can draw up most of this stuff in a heartbeat but i dont' get online but about twice aweek so drop me an email. not a pm

[rockitmarty]

I can't even wire in new pic-ups without something going wrong. i think the gun was too hot for the pots and damaged them, can that be diagnosed without visual confirmation

[ottovola]

REANTAL & posters-

Lots of great ideas here, I'd like to add mine:

In case anyone is into trying out a cap/coil switching tone control, here's the info. I'll describe the process, and then provide a parts list. First off, I have to say that I went a little overboard with my switch, I think I mostly use 4-5 settings out of the 12, and you could most likely do well with only one coil. Also, a disclaimer- I am not technically adept, just a tinkerer- I can't explain the science here nor guarantee my accuracy. This thing is pretty fun- I get bored pretty quickly, especially when practicing- a change in tone is awesome.

Couldn't figure out how to post pictures, so if you'd like to see it, try here: Tone Circuit Pics

1) Looking at the coil (inductor), it has 6 wire leads. You only need 2. One side of the coil has a 'P' imprinted on it- I believe this is for primary. Turn the coil so the 'P' side is facing you. Snip off the other 3 leads from the other side. Then snip off the middle lead, leaving one to the left of the 'P', and one to the right of the 'P'. It took me forever to figure this out with trial and error!

2) Solder your caps to the left coil wire lead. The other coil lead should go to ground. Experiment a little (different coils/cap values) to find your favorite tones- there are a multitude of possibilities. (the other end of the caps should be your hot wire)

3) If using a rotary switch,(these can differ) connect the hot to the center terminal. Connect the caps in desired order to the outer terminals. Connect the coil right wire lead to one of the terminals. Connect the ground to this terminal, as well as one end of any caps you don't use with a coil. (now one position is an off switch- very fun for playing tricks on your friends). Leave one outer terminal unconnected (or break it off) to be your bypass setting.

My 5 favorite settings : Off (ground), .22 cap to TL-021R coil, .22 cap to TL218-R (this is the dogmeat setting I mentioned in another post- It actually is pretty cool it sounds fat like an old fender amp sound), .047 cap to TL012-R coil, & .0033 cap to ground (best straight cap-cool midrange sound)

Parts list from Mouser.com:

1 x switch # 105-SR2511F-12S

1 x coil # 42TL012-R

1 x coil # 42TL021-R

1 x coil # 42TL21-RC

3 x cap # C320C224M5V5TA (.22mf)

2 x cap # 140-100Z9-473Z-RC (.047mf)

2 x cap # 140-50S9-102J-RC (.001mf)

1 x cap# 140-100Z5-223Z-C (.022mf)

1 x cap I bought from Radio Shack- .01uf 100ICG

A note on parts: I don't think you have to be too particular about the caps (any cap with these values should work- get these anywhere. Also you may like other values- try it out! ), but the coils- I tried 10-15 different ones, these three were the only usable options I found. The only exception is the .22 mf cap- I really got better results with this particular cap (printed K5M on part). The switch was a 12 selector switch, You could choose any value you want (6 position, etc), just get one with a long shaft to fit in a guitar!

Test these out- have fun.

Edited November 1, 2008 by ottovola

[reantel]

Thanks so much for posting this. I'm going to order some parts this week and try it out.

Thanks again

[ottovola]

A couple more combos to try:

.001 Cap (102J) to TL218R Coil

.01 Cap (100ICG) to TL218R Coil

I just reassembled the Ibanez I installed one of these 12 position switches in I mentioned earlier- & these are the 2 settings I'm using the most for rhythm sounds. Try it with the guitar volume rolled down, suddenly the harmonics just pop out- very sweet. This only works for the lower strings, top 3 will sound dead- so good for metal rhythm sounds. Of course, this is my experience with a 7 string using lots of distortion! So really could be different on a 6 string.

Cheers.

[guitar101]

I was just thinking today about all the different tone capacitors out there and I had an idea for hooking different ones up to a switching system…2, 3 or 5 way switch, switching between different capacitor tones.

Does anyone know if this has been done? Better yet, is this even possible, logical, or legal?

Has anyone tried it? How would you wire this?

Yes it is possible. I am a little bit of a Bill Lawrence nut. He is designing a new line of pickups called micro coils. From what I read browsing the Wilde-Gate forum at the Fender Info-Base board he is proposing the same idea. Using the new low impedance micro coils and providing capacitors to alter the tone instead of tone pots. So I guess it is possible.

[guitar101]

I was just thinking today about all the different tone capacitors out there and I had an idea for hooking different ones up to a switching system…2, 3 or 5 way switch, switching between different capacitor tones.

Does anyone know if this has been done? Better yet, is this even possible, logical, or legal?

Has anyone tried it? How would you wire this?

Yes it is possible. I am a little bit of a Bill Lawrence nut. He is designing a new line of pickups called micro coils. From what I read browsing the Wilde-Gate forum at the Fender Info-Base board he is proposing the same idea. Using the new low impedance micro coils and providing capacitors to alter the tone instead of tone pots. Whether it will work better I don't know but it's a bit unconventional so it

probably won't become mainstream.

[AndrewCE]

OK, speaking only about values here, there's not a lot of point in having different cap values. The formula for what a tone control (which is really a low pass filter) does is

F = 1/(2*pi*R*C)

If you double the cap size, that's EXACTLY the same as halving the resistance. So just use one cap, and multiple resistors (or trimpots at different settings) and you'll hear exactly the same thing (and save the cost of all the other caps). If you are using a trimpot as well as a normal tone control, the R in that equation is the total resistance.

what does "F" mean? frequency? frequency of what?

i'm pretty sure that halving the resistance and doubling the capacitance don't give you the same frequency response curve. maybe at one specific frequency it's the same, but not the whole curve.

[bluesy]

OK, speaking only about values here, there's not a lot of point in having different cap values. The formula for what a tone control (which is really a low pass filter) does is

F = 1/(2*pi*R*C)

If you double the cap size, that's EXACTLY the same as halving the resistance. So just use one cap, and multiple resistors (or trimpots at different settings) and you'll hear exactly the same thing (and save the cost of all the other caps). If you are using a trimpot as well as a normal tone control, the R in that equation is the total resistance.

what does "F" mean? frequency? frequency of what?

i'm pretty sure that halving the resistance and doubling the capacitance don't give you the same frequency response curve. maybe at one specific frequency it's the same, but not the whole curve.

We are talking about the various frequencies found in what you call a guitar's sound. F in the formula is the frequency at which the filter starts to work. It is defined as the point where the signal is attenuated 3 dB, or 70.7%(the "half power point indicated below). Higher frequencies are attenuated at 6db per octave, lower ones are left mostly alone.

The slope is fixed because it is only a single pole filter, so if the frequency that you calculate is the same, the response must be the same.

Note that the formula given in the graph is the same as the one I gave, because w = 2*pi*F

[AndrewCE]

Oh so it's the cutoff frequency.

Thanks, bluesy!

But that only tells you that the cutoff frequency will be the same in the two cases (halving resistance vs doubling capacitance). Is there a way to know that the entire frequency curve will be the same? Or at least approximately the same? I don't think there is.

Also, how do you know that there will be a 6 dB drop per octave?

[bluesy]

Oh so it's the cutoff frequency.

Thanks, bluesy!

But that only tells you that the cutoff frequency will be the same in the two cases (halving resistance vs doubling capacitance). Is there a way to know that the entire frequency curve will be the same? Or at least approximately the same? I don't think there is.

Also, how do you know that there will be a 6 dB drop per octave?

The 6db figure can be calculated, but check any text or online reference for any single pole filter. Sometimes it is expressed in decades (I think it's 20db per decade).

How about an analogy? The capacitor is a bucket, and the resistor is a faucet restricting the flow of water (electricity). For a given size bucket, and faucet setting it will take X seconds to fill the bucket. Now get a bucket (capacitor) twice as big, and halve the restriction (resistor) - meaning the flowrate will be doubled. The bucket still takes the same X seconds to fill.

[AndrewCE]

Oh so it's the cutoff frequency.

Thanks, bluesy!

But that only tells you that the cutoff frequency will be the same in the two cases (halving resistance vs doubling capacitance). Is there a way to know that the entire frequency curve will be the same? Or at least approximately the same? I don't think there is.

Also, how do you know that there will be a 6 dB drop per octave?

The 6db figure can be calculated, but check any text or online reference for any single pole filter. Sometimes it is expressed in decades (I think it's 20db per decade).

How about an analogy? The capacitor is a bucket, and the resistor is a faucet restricting the flow of water (electricity). For a given size bucket, and faucet setting it will take X seconds to fill the bucket. Now get a bucket (capacitor) twice as big, and halve the restriction (resistor) - meaning the flowrate will be doubled. The bucket still takes the same X seconds to fill.

But the response curve is only the same in single pole filters?

Here the last set of graphs shows that cascading filters provides a different response, even if it still has the same cutoff freq:

http://www.dspguide.com/ch19/2.htm

so maybe the stellartone knob has multiple pole filters...

btw, i'm dont think your analogy applies well to AC cicuits and signals

[bluesy]

But the response curve is only the same in single pole filters?

Here the last set of graphs shows that cascading filters provides a different response, even if it still has the same cutoff freq:

http://www.dspguide.com/ch19/2.htm

so maybe the stellartone knob has multiple pole filters...

btw, i'm dont think your analogy applies well to AC cicuits and signals

That page is about DSP filters and is looking at recursive filters. Also cascading 2 single pole filters gives you a 2 pole filter, so the slope is doubled to 12db per octave.

I was only saying that there was no need to have multiple caps for a tone switching circuit to allow you to achieve all the desired cutoff frequencies (with single pole low pass filters), just vary the resistance.

The analogy demonstrates the time constant of the RC circuit, and that is exactly what determines the cutoff frequency, so yes, it does apply to AC.

[AndrewCE]

But the response curve is only the same in single pole filters?

Here the last set of graphs shows that cascading filters provides a different response, even if it still has the same cutoff freq:

http://www.dspguide.com/ch19/2.htm

so maybe the stellartone knob has multiple pole filters...

btw, i'm dont think your analogy applies well to AC cicuits and signals

That page is about DSP filters and is looking at recursive filters. Also cascading 2 single pole filters gives you a 2 pole filter, so the slope is doubled to 12db per octave.

I was only saying that there was no need to have multiple caps for a tone switching circuit to allow you to achieve all the desired cutoff frequencies (with single pole low pass filters), just vary the resistance.

The analogy demonstrates the time constant of the RC circuit, and that is exactly what determines the cutoff frequency, so yes, it does apply to AC.

well it's like you just said, all single pole filters can react the same by just varying the resistance; so the only useful mod would be to make multiple pole filters and cascade them at different switching positions; and that requires multiple caps

oh you mean like, filling up the bucket over and over, like 500 times a second...

[bluesy]

oh you mean like, filling up the bucket over and over, like 500 times a second...

Only if you don't trust the mathematics. A time constant is just that, constant, doesn't matter how frequently you try to fill or empty it.

Another way to look at it is that as frequency goes up, the impedance of the capacitor (ac resistance if you like) goes down. So as frequency get's really high, the capacitor starts to look like a short circuit, and since it's shunts the ac to ground, the high frequencies don't get through. Hence it's a low pass filter.

[AndrewCE]

oh you mean like, filling up the bucket over and over, like 500 times a second...

Only if you don't trust the mathematics. A time constant is just that, constant, doesn't matter how frequently you try to fill or empty it.

Another way to look at it is that as frequency goes up, the impedance of the capacitor (ac resistance if you like) goes down. So as frequency get's really high, the capacitor starts to look like a short circuit, and since it's shunts the ac to ground, the high frequencies don't get through. Hence it's a low pass filter.

only what if you dont trust the math?

i know how all that works, i just dont think a bucket is the best analogy for a capacitor