Better Rat Filter Pot Value/Taper?

[aziltz]

I'm about to wire up a BYOC Mouse for a friend.  I was wondering if anyone had any recommendations for value or taper changes to the Filter Pot for a smoother control?

I built a Mouse prior to this and while the Filter works quite well, it has a very abrupt sweet spot and I'm not sure how to spread it out...

thanks,

-A

[Tonemonger]

I don't know if this helps -But , one of my BMPs has a dual gang pot wired in series (it was all I had at the time).
A/B'd with another BMP the same tones are in different positions and it tapers off quite quickly -( I only use it occasionally on a trashy bass I have)- I have better sounding versions.
Now I'm guessing that if I strapped a resistor across one half of the pot , the taper would stretch yeah ?
Tricky to 'tune' But, this may work.

[Mark Hammer]

"Sweet spots" vary by user, and of course by pot.  My advice would be to take notes on what the resistance value of the pot setting is at the start and end of the sweet spot.  As well, note how much of an arc of rotation that covers.  Based on what sort of range of rotation and resistance that covers, we can make some suggestions for either adjusting the pot value, parallel taper-altering resistors, cap value, or any combination.

[80k]

I remember using a larger cap value and reducing the filter pot value by half (by adding a parallel resistor). This made a more narrow range in the tone knob, which makes it easier for me to use. I never used the filter all the way to the left nor to the right anyway.

[Mugshot]

plus 1 on the 50K filter pot. and also, i think the circuit will benefit too if a 50K pot is used for the gain control instead of the 100k original since some points of the rotation seem useless to me.

[Mark Hammer]

Since it is an RC lowpass filter, there needs to be an R in there at all times such that the C can predict a specific cutoff value. The 1k5 resistor in series with the filter pot performs that function when the pot resistance is decreased to zero, setting the maximum cutoff frequency.  In this case, with R=1k5 and C=.0033uf, that maximum cutoff is ridiculously high for guitar purposes: 32khz.  Small wonder that folks complain about how useless large arcs of the filter pot are.

If that 1k5 resistor is set to 3k9, the maximum cutoff/corner-frequency drops to 12.4khz, and with 4k7, it drops to 10.3khz.  Given how many guitar speakers roll off dramatically above 6khz, clearly one would normally have to have around 10k of series resistance (pot + fixed resistor) before starting to hear something.

With a 4k7 series resistor and a 47k/50k pot, the filter cutoff range goes from 10.3khz (min resistance of 4k7) down to 880hz (max resistance of 4k7 + 50k), which is a pleasingly usable range.

[aziltz]

BAM!

thanks mark hammer!