Tone cap values when there's no tone pot!?!

[bongomania]

I'm running this one pickup direct to the jack, interrupted only by an on-on-on switch. Position one is direct, position two will have a small-value tone cap to ground, and position three will have a larger tone cap. The pickup is a two-wire humbucker that reads 7.7K on the ohmmeter. I have a vast selection of caps to experiment with, and I plan to do just that, but I was hoping somebody could suggest a good starting value for this situation. Thx!

[tubby.twins]

If you are looking for a dramatic or noticeable difference in tone, you should try a .047 mfd capacitor. This should cut out most of the treble, and give you a good resonant peak in the midrange.

If you want something more subtle, try a .022 mfd capacitor. This will take out less of the treble, and the resonant peak will be a bit higher in frequency and less noticeable.

I would expect that a .033 mfd capacitor should produce a result somewhere between these two. Remember that you can connect multiple capacitors in parallel to add up the values.

I wouldn't recommend any higher capacitor values (.068, .100) without a tone pot to control how much is being rolled off, unless you're looking for a "dub" tone.

Different pickups react in different ways to tone capacitors. Don't be afraid to experiment!

[bongomania]

So... those are the values normally associated with a tone pot. You're saying minus the tone pot the values should be the same?

[tubby.twins]

Originally Posted by bongomania

So... those are the values normally associated with a tone pot. You're saying minus the tone pot the values should be the same?

Right. The wiring scheme you've proposed (cap without the tone pot, switch instead) means that the capacitor is going to be fully engaged in the circuit when switched on. There won't be a 250k or 500k pot between the signal and the capacitor, acting as a variable resistor. So you should try capacitor values that make sense in another bass (with a tone pot) when the tone pot is rolled all the way back (i.e. fully engaged).

EDIT: Since you mentioned you were using an "on/on/on" switch, make sure you use the right lugs. I am guessing the center position should be wired up as "no tone cut", and either of the up/down positions should select one or the other capacitor. Test this with a multimeter to make sure you connect your capacitors to the right lugs, so they aren't active when the switch is in the center position.

[GlennW]

I do that all the time. IME it sounds much better without the tone pot.

The potless cap value will sound a little brighter than the same cap with a pot. For example, a .1uF sans pot will sound brighter than the same cap with a pot. It's really more presence than "brighter". You'll see.

There are exceptions, depending on the sound of the particular pickup, but I usually like stuff in the .047 - .1 range, but I have no use for a clackety tone, some people like it.

Here's an example: Duncan SCPB-3 and cap switch

[BassLife77]

Originally Posted by bongomania

I'm running this one pickup direct to the jack, interrupted only by an on-on-on switch. Position one is direct, position two will have a small-value tone cap to ground, and position three will have a larger tone cap. The pickup is a two-wire humbucker that reads 7.7K on the ohmmeter. I have a vast selection of caps to experiment with, and I plan to do just that, but I was hoping somebody could suggest a good starting value for this situation. Thx!

for more variety you can do what I did and build a box with a 12 pos rotary and a bunch of different caps, like a decade switch. I also put in a no-load pot that can adjust the tone of the cap is being used. the basses have tone pot bypass switches. I am experimenting with putting different resistors and switches with the caps. the tone possibilities are endless

[bongomania]

Oh certainly, varitone switches are cool, but honestly every one that I've used has only had two or three really good tones in it. So I'm just setting this up for the two best tones plus bypass.

FWIW in my first experiment .022 was too bright, and .033 is better but still tonally equivalent to a regular tone pot rolled only maybe a third of the way off. I'll keep experimenting of course, but my guess at this point is that .047 will be my "light tone" setting and .1 will be my "heavy tone" setting.

[GlennW]

Try adding them in parallel while you're experimenting. I often like .069 (.047 + .022) and .08 (.047 + .033).

[idoru]

Bongo: can't believe you missed all the theoretical stuff in the various Varitone / Tonestyler threads, so here's the link to Helmuth Lemme's original article:

http://www.buildyourguitar.com/resou...emme/index.htm

There's a table with common pickup types vs capacitance and the resulting resonant peaks. Very useful.

For a two value switch, I'd suggest .047 uF for country/dub style tones, and maybe grab a cap that rolls off around 800 Hz - 1.4 kHz to taste. The lower value is a little more funky, the higher value is more of a grindy tone.

Or do what I did, and build an external box with a 12-way to get used to what you actually use.

c-

[bongomania]

Hmmm... no offense, but I think you may have mis-read or misunderstood some of the earlier posts.

[idoru]

How so? What you propose is a 2 value version of the Tonestyler. I just pointed out a site that tells you how to calculate the rolloff frequency of an LC circuit, which is what you have there with your pickup, caps and 3-way switch.

I gave you some suggestions for caps to use, based on that info - but my suggestion is still to wire up a quick project box with an even spread of cap values so you can get a feel of what the different cutoff values sound like with their particular resonant peaks. It's the resonant peak that adds the character - if you don't want that, wire in a 22k resistor to reduce it (incidentally, that's part of Fender's "Greasebucket" circuit).

[EDIT] Don't mean to sound snippy here, I was just surprised given your superb compressor reviews that you were thrown by a few little capacitors

c-

[bassbenj]

Originally Posted by bongomania

Oh certainly, varitone switches are cool, but honestly every one that I've used has only had two or three really good tones in it. So I'm just setting this up for the two best tones plus bypass.

FWIW in my first experiment .022 was too bright, and .033 is better but still tonally equivalent to a regular tone pot rolled only maybe a third of the way off. I'll keep experimenting of course, but my guess at this point is that .047 will be my "light tone" setting and .1 will be my "heavy tone" setting.

I've put a tone cap position on my Fender Jazz switch and it's sort of OK (I forget what value I finally ended up with). But using just a cap isn't really quite what you want. That is because the tone, the roll off and the peak in the spectrum for a given tone depends on the cap value, the tone pot value, and the Inductance of the pickups. Hence since the pickups are fixed (unless you buy new ones) that means you don't adjust L but C (capacitor) and R (pot resistance) are up for grabs.

So if it were me (and it IS me because I want to go back to my Jazz and reselect that "tone" position with both an R and C instead of just a C) I'd wire a box with some caps of various sizes (around the values you already found) plus a tone pot. Then you wire it in temporarily and search for tone you like. When you find it, you note the value of the capacitor in use and then use an ohmmeter to measure the value of the resistance of the tone pot. Then in the final bass circuit you wire in the cap and a fixed resistor of that value in series and you got it!

[lowfreqgeek]

I'm not gonna really add anything other than to say that an LC and and RLC circuit are different things. The purpose of the resistance in the circuit is to dampen the resonant peak created by the L-C. You can't replicate a tone pot rolled off with just a simple cap bypassing the coil because it's not an equivalent circuit, nor is it functionally equivalent to an RLC.

If you're simply trying to replicate 2 positions with a regular tone pot, you have to add a resistor to the circuit to dampen the peak. If you're looking to boost a certain frequency before rolling off, then don't use the resistor.

[ehque]

Originally Posted by lowfreqgeek

I'm not gonna really add anything other than to say that an LC and and RLC circuit are different things. The purpose of the resistance in the circuit is to dampen the resonant peak created by the L-C. You can't replicate a tone pot rolled off with just a simple cap bypassing the coil because it's not an equivalent circuit, nor is it functionally equivalent to an RLC.

This is what i thought when i read the OP.

[bongomania]

Originally Posted by idoru

Don't mean to sound snippy here, I was just surprised given your superb compressor reviews that you were thrown by a few little capacitors

I guess the reason I responded the way I did was because it seemed to me (confirmed by your comment there) that you were assuming I had no idea how any of this works. Far from it. All I asked for was a suggestion of a good value to start with, considering the absence of the R part provided by a pot. Minus the pot, .047 is nowhere near country/dub, not with this pickup anyway. GlennW understood exactly what I was talking about.

Speaking more generally to the thread, I didn't say anything about emulating a tone pot.

For the record, I have tried about ten different values in there now, and the range between .068 and .133 is most appealing with this specific pickup. I keep going back to .9 as my favorite overall tone, so I may just set it up with one tone cap (and bypass) instead of two cap choices.

Question answered, "problem" solved, all done here. Cheers!

[idoru]

Respect, mate. No worries then - how's about some sound clips? Never really got an idea of what particular sound you were going for in your OP, so I'd love to hear what you ended up with (with a honking great cap value to boot!). And just what kind of pickup is it?

c-