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I think I have finally decided on the circuit I want to try for Coil tapping (with multiple resistors) and Varitone circuit with a single humbucker.
I have planned to use toggle switches for the coil tap and the varitone - so that they can be bypassed, and also so that they can be set to a specific setting.
A rotary switch for the varitone (of course), plus I will also use a rotary switch for the coil tapping circuit.
Can anyone see any issues with my plan or my diagram?
The coil tap looks right to me. It looks like with the switch off you'd have full humbucking. With the switch on you'd have 4 settings: 10k, 6.8k, 2.2k and one coil fully out.
The varitone looks like it is wired so that in the off position you have the tone-pot-no-varitone. In the on position you have varitone-no-tone-pot. It should work. I think.
Though you could leave the tone pot in the circuit, and get the same effect. If you have to tone pot wide open its out of the circuit anyway. The difference would between tone-pot-wide-open+varitone and varitone-alone would be nominal. So I think you could leave the tone pot in if you wanted too.
This is where it would good to have Weirdbits chime in ;-)
How many pole are the rotaries, 1 or more?
They are 2 pole, 6 terminal.Quote:
Originally Posted by WeirdBits
Ah ok, never mind. I was going to suggest adding a partial/half out of phase option on the unused 6th lug of the rotary for a potentially ‘more full’ single coil sound. But, it would need 3+ poles to work with your rotary set up.
You may also want to wire a trimpot (maybe 20k-50k) between the varitone caps and ground. That way you can try the different settings on the varitone and tweak how much effect they have. Or, just wire in a standard pot as a variable resistor, adjust it to the sound you want, then measure the resistance and replace it with a fixed value resistor.
Fun project. Good luck.
Thanks fender3x,
and thanks WierdBits: I will leave room to put in a resistor.
@WeirdBits
Another thought - could I use the tone pot with the Varitone circuit and the normal tone circuit? So, have the toggle switch linked to the middle lug of the tone pot, switching between the normal capacitor, or the Varitone?
It depends how much knob fiddling you want to do. The benefit of a varitone is obviously you turn the switch and you get a fixed known, hopefully usable, tone at each position. You could use a tone pot to dial in what you want each time you select a cap on the varitone, but 500K is a big range so it’s less precise for smaller values and means potentially a lot of knob twisting.
That being said, yes you can definitely use the tone pot to adjust the varitone if that’s what you want. In that case I would delete the varitone toggle switch and just connect the tone pot in and out as the link from the volume to the varitone common. Then, connect your 0.022uF tone cap on the varitone’s 1st lug and have this as you ‘normal tone pot’ setting.
And, if you’re going to that, then you may want to consider dropping the 100nF cap on the 6th lug and instead leave it empty. 100nF is going to be extremely dark and muddy (imo) and would likely rarely get used unless you have a particular need for it. If you instead leave that 6th lug unconnected then you’ll have a volume only no tone setting for an even brighter sound. That way you have normal tone at one end and no tone at the other on the varitone.
Just thoughts.
Thanks WierdBits.
Yes, I see the knob twiddling issue. Most tone controls are on a high setting (with a high resistance on the pot), and only filter a bit of the top end. The Varitone filters a lot of the top end and requires a small resistance of the pot.
So, using the same tone pot for the Varitone would mean I do not get my preset sounds.
Therefore, I will stick with my original plan, and have room for the resistor after the capacitors.
So this is my final (for now anyway) schematic for:
1 Bridge Humbucker with 1 vol and 1 tone + Varitone + Coil tap with multiple resistors (to coil split).
Just to finish this thread off:
I completed the electronics for the MBM custom with the diagram above but changed the resistor at the end of the Varitone circuit to a 10 k ohm. That seems (to my ears) to give a good selection of tones!