G-Taper Pot in Boss EQ?

[Rodgre]

I'm building a custom pedal for a friend who wants a superfuzz circuit with the semi-parametric EQ of the Boss Micro-Rack ROD-10 overdrive/distortion. The EQ has 50KG pots for the LO and HI controls and I'll be damned if I can find those online. I read in an old thread that these pots are reverse audio to midpoint, then standard audio taper after that. This is a new one for me.

If I use a standard linear or audio taper in place of this, will midpoint (no boost or cut) be not where it should be? I assume so.

What would you all recommend I try for this purpose?




Thank you!

Roger

[idy]

 small bear has 20k w...  for tubescreamer tone, but other values not so much.

https://www.diystompboxes.com/smfforum/index.php?topic=36938.0

You would try w taper, last resort linear. Midpoint will stay the same, its just that a linear will give you a sense that the change is "bunched" up. W or G will give you symmetrical cut and boost.
Taper resistors in both directions maybe not be helpful but you can experiment.

[davent]

Rod Elliot has an article on pots that mentions creating an 's' curve using a couple resistors with the pot, not sure whether that might work for what you want.



https://sound-au.com/pots.htm#chg-law

[Rob Strand]

not sure whether that might work for what you want.

That method is the opposite to G-taper.

The EQ has 50KG pots for the LO and HI controls and I'll be damned if I can find those online. I read in an old thread that these pots are reverse audio to midpoint, then standard audio taper after that.

The reason they use that is because the EQ has a high amount of boost/cut.   The problem is the amount of boost-cut rapidly increases very close to the ends of the pot.   The G pots stretch that region out making it easier to use.     You can think about the rate of boost increasing as the end of the pot gets closer to the value of the 1k resistors, for a 50k pot you are pretty darn close to the ends when you get to 1k between the wiper and the end.

The only reason I see for such a large amount of boost/cut is so you can get treble cut.   However, if you want to roll-off the highs you can remove the treble resistor to the opamp output.  You can also add a cap across the treble pot, or, across the opamp output and opamp '-' input.

The best way to play with EQ's is with a circuit simulator.

If you aren't cloning the pedal one idea is to drop the amount of boost-cut to below 15dB.  Then you can use linear pots like everyone else does.   The way you would do that is to up the 1k and 3k9 parts to get +/-15dB  bass and treble then tweak the cap values so the bass boost and treble boost curves matched the original circuit.

Another way would be to take the Bass/Treble EQ from another pedal.   The add the treble pot cap if you like.

[davent]

not sure whether that might work for what you want.

That method is the opposite to G-taper.

Thanks Rob, live and learn!
dave

[Rob Strand]

The reason they use that is because the EQ has a high amount of boost/cut.

FWIW, I have a feeling the treble side might not have that high a boost/cut.    The treble adjustment suffers because they used the same pot value as the Bass control.

Thanks Rob, live and learn!

I guess those pot tweak things have their limits (unfortunately).