A simple varitone circuit for your bass -

Dark Horse · #1 11-04-2009, 01:31 PM

This is a simple varitone circuit that you can use on your bass. It uses a 2 pole, 6 position rotary switch that is available at your local Radio Shack for about $3, and a few capacitors. Basically, for about $5-$6 and a little time, you can add a bunch of flexibility to your bass. I used this circuit on a SX P Bass - you can listen to the sound sample below.

SIMPLE VARITONE - PRECISION BASS

The way this is wired, you will have one "open" position (no tone control), and five different additional tone variations. In the MP3, I started in the "open" position, scrolled through the other five positions, and then went back to the open position again. I played the same simple riff in all positions so that you can evaluate the sounds properly.

You will need a soldering iron, solder, some wire, wire cutters//stripper, a multi-meter, a sharpie, some capacitors, the aforementioned switch, and a few minutes of your time. You should also know how to solder and be "practiced" at it, as well as familiar with the use of a multi-meter. I won't go into that stuff - there are a zillion places on the internet to get that info.

When you get the switch, turn the switch either right or left till it doesn't turn any more. Sometimes it is easier to attach a knob to the shaft to make it easier to turn. You'll want to set your multi-meter to the "beep" position. You can tell when you're in the right setting because your multi-meter will "beep" when you touch the red lead and black lead together. Now, with the meter in the "beep" position, look at the bottom of the rotary switch. Hold the end of the BLACK lead on one of the two "center" poles on the switch, and then touch the red lead to the outside poles until you hear a a beep. Make a mark next to this pole with your sharpie. That is the first position. Now, turn the switch one click, and repeat the previous process. That is the second position. Repeat this until you have all 6 "active" outside poles marked. Also be sure to mark the center pole that you used. Now, it is as simple as following the diagram that I drew up and attached below. All "grounds" can connect to the back of the volume pot. Make sure that the "switch" end of the capacitor leads do not touch each other. On the "ground" end, touching is fine as they all end up connecting to the same place anyway. Your jack will hook up as it normally does - same for your pickup(s). All this does is replace your tone pot.

Enjoy !

PS - you can also use this circuit and put it in a separate enclosure, so you have a "pedal" or "table top" varitone control !

Jo6Pak · #2 11-04-2009, 01:56 PM

EXCELLENT - THANKS!

TheBasicBassist · #3 11-04-2009, 02:11 PM

that's awesome
i've always been curious about the varitone.
it's sounds great, thanks for posting man.

THand · #4 11-04-2009, 02:16 PM

Cool. Thanks!

Dark Horse · #5 11-04-2009, 02:39 PM

No problem. I hope you guys find it useful. I tried to keep things as simple as possible. Remember, in some positions you'll have a bit of volume drop, simply because the varitone bleeds more frequencies to ground.

Stealth · #6 11-04-2009, 02:42 PM

Thanks for the schematic - very nicely explained and laid out.

G00D+~VIBES · #7 11-04-2009, 03:22 PM

I need direction towards a resource where I might come to understand the implications of this when applied to a Jazz bass set up. Really, I'm trying to conceptualize a system where one could select different cap values immediately prior to the "tone" pot, and still retain the flexibility of an independent "tone" pot.

Maybe one of these "selector" pots then into either a liner/audio/taper (i don't directly recall the language) pot. Which ever would be most apropo obviously.

greenboy · #8 11-04-2009, 05:22 PM

G00D+~VIBES,

This provides the same circuit function as what you are after on one or another of the switch positions, depending on what your bass currently has in it for a cap.

BigOldHarry · #9 11-04-2009, 05:27 PM

How many variations of the cap values did you play with? Just curious...

BTW - I like the sound possibilities - much more fun than standard tone control...

Dark Horse · #10 11-04-2009, 05:53 PM

Quote:

Originally Posted by BigOldHarry

How many variations of the cap values did you play with? Just curious...

BTW - I like the sound possibilities - much more fun than standard tone control...

I've been doing these for so long that I just threw them in there, no playing around because I knew how I wanted this bass to sound. But when I started, I tried out a bunch of cap values and materials.

For a big "thump/dub" bass tone, you may want to use a .1uf on the end - something like these values

.001uf
.0047uf
.01uf
.033uf
.1uf

That makes for a versatile, really cool setup.

rodgersk24 · #11 11-04-2009, 07:12 PM

Dark Horse,

This is wonderful, thanks for posting this!

Does this eliminate the tone knob, so you don't have the option to vary the tone once the cap has been selected?

Thanks!

EDIT: Yep, I see in your initial post that it does! Apologies for that...

Is there a way of using this with a tone knob, or does this eliminate the possibility of using one altogether? Apologies, I see that G00D+~VIBES and greenboy were talking about the tone pot, but I didn't quite understand greenboy's response...

greenboy · #12 11-04-2009, 07:19 PM

Sorry, I just skimmed and didn't even notice the schematic didn't have a tone pot. Typical varitone wiring does use a tone pot, with the varitone circuitry taking the place of the two leads of a normal cap wiring, if I recall.

Mojo-Man · #13 11-04-2009, 07:20 PM

This is cool.
But if you don't want to mod your bass.
Get a Birdsong B-Box.
It's a passive 6 way varitone pedal.
That is totally passive. (no batteries)
Just line in, line out. into amp.
Sounds, and works great.
Works for any instrument.
I've had one on my pedal board for over a year.

Dark Horse · #14 11-04-2009, 07:20 PM

Quote:

Originally Posted by rodgersk24

Dark Horse,

This is wonderful, thanks for posting this!

Does this eliminate the tone knob, so you don't have the option to vary the tone once the cap has been selected?

Thanks!

EDIT: Yep, I see in your initial post that it does! Apologies for that...

Is there a way of using this with a tone knob, or does this eliminate the possibility of using one altogether? Apologies, I see that G00D+~VIBES and greenboy were talking about the tone pot, but I didn't quite understand greenboy's response...

Sure -

If you want top vary the amount that bleeds to ground, use another pot - run the leads on the "ground" side of the capacitors to lug-3 of the "tone" pot. Connect lug 2 and 1 of the "tone" pot to each other/ground. That will vary how much goes through to ground, and the varitone switch will determine what frequencies go to ground.

I can draw a picture if needed and post it tomorrow. Let me know.

Dark Horse · #15 11-04-2009, 07:22 PM

Quote:

Originally Posted by Mojo-Man

This is cool.
But if you don't want to mod your bass.
Get a Birdsong B-Box.
It's a passive 6 way varitone pedal.
That is totally passive. (no batteries)
Just line in, line out. into amp.
Sounds, and works great.
Works for any instrument.
I've had one on my pedal board for over a year.

Or build this one into a box for about $10-$15

I'm sure the Birdsong is similar, though it may use a inductor on the varitone as well. Varitones are great, aren't they ?

Dark Horse · #16 11-04-2009, 07:23 PM

Quote:

Originally Posted by greenboy

Sorry, I just skimmed and didn't even notice the schematic didn't have a tone pot. Typical varitone wiring does use a tone pot, with the varitone circuitry taking the place of the two leads of a normal cap wiring, if I recall.

This is a simple "frequency selected bleed to ground". Many Varitones work this way. Some use a inductor to retain a bit more highs though.

greenboy · #17 11-04-2009, 07:39 PM

I pretty much found coils on a bass varitone to be a waste though, just as I don't find two pickups out of phase on a bass to be particularly useful... Actually after about three cap values (or two, and a combining of them as a third value) I'm pretty much satisfied for live varitone-with-a-tone-knob use.

lbwdog · #18 11-04-2009, 07:44 PM

Quote:

Originally Posted by Dark Horse

This is a simple "frequency selected bleed to ground". Many Varitones work this way. Some use a inductor to retain a bit more highs though.

Frame this in my mind please...
For use in a typical Jazz bass, using a Volume, Blend, and Varitone, how should it be wired?
Will it fit in a Jazz control cavity?

Dark Horse · #19 11-04-2009, 07:49 PM

Quote:

Originally Posted by greenboy

I pretty much found coils on a bass varitone to be a waste though, just as I don't find two pickups out of phase on a bass to be particularly useful... Actually after about three cap values (or two, and a combining of them as a third value) I'm pretty much satisfied for live varitone-with-a-tone-knob use.

Yeah, I don't see the need for the inductor with bass either - that's just my preference though.

The "bleed level/tone" setup is nice to maximize versatility.

Dark Horse · #20 11-04-2009, 07:52 PM

Quote:

Originally Posted by lbwdog

Frame this in my mind please...
For use in a typical Jazz bass, using a Volume, Blend, and Varitone, how should it be wired?
Will it fit in a Jazz control cavity?

Even on the blend circuit, the volume pots "lug 2" is the output to the jack, if I remember right - basically you'd take that wire, just like in the volume pot in the diagram, and hook it up as shown. You won't need to touch the "blend" part of the circuit.