MM preamp resonant peak cap/res value for passive MM setup application?

[ObeyDaRiffness]

Hello. So, I'm planning to build a passive stingray, with a G&L style "OMG" mode switch and a Tonestyler, to get the clearest and liveliest tones out of it without active circuitry. I remember I've read that most of the signature "color" the preamp gives comes from a specific resistor Leo inserted in the circuit that shifted the resonant peak of the pickup, and that this resistor can be wired passively achieving more less the same effect. Which is the value and where do you put this in, gentlemen?

 

[RobbieK]

I remember I've read that most of the signature "color" the preamp gives comes from a specific resistor Leo inserted in the circuit that shifted the resonant peak of the pickup

FWIW, Leo didn't have much to do with this preamp. It was designed in the late 80's at Ernie Ball. And the part is a cap, not a resistor. It's a 2n2 across the pickup at the front end of the 3-band pre. But yep, that's what it does. Shift the resonant peak of the pickup. There's a bit more to it of course, but yeah, I've modded a couple of passive stingray pickup basses to get closer to the 3-band vibe. You'll have to account for the capacitance of your guitar cable, and also realise that with the z load of passive pots you won't get nearly as much of a resonance. But if your amp has a graphic eq with a control in that 3-4khz range, a little boost here will get you surprisingly close to the treble tone of an active 3-band stingray.

If you skip to 15:15 you'll see me demonstrate what that 2n2 cap does...



For years I've been fascinated by that 3-band EB pre. Its front end is really quite strange. Not just that cap, but also the sallen-key hpf. Personally I've never really liked the inherent bass cut of this pre. I've often wondered if it was a design lifted from a phono pre or something. Or perhaps that 2n2 was some kind of misprint from the days of handwritten schematics... If anyone is reading this who worked at EB in the 80's, pm me!

 

[sikamikanico]

If you're using a Tonestyler, you probably don't need that extra cap - it might have that cap in one of the settings. That's what ToneStyler does, switches between different caps to switch around the resonant peak.