Can I just jumper a gain pot if I don't want it?

[MBFX]

See title. Let's take the LPB-1, or a similarly simple FET booster like the AMZ as an example. If I want to use one of those as a gain stage without a knob, can I simply omit the knob? Jumper goes from output cap to input of the next circuit? What if I want to reduce the gain - test how loud I want it with a pot, measure resistance, use appropriate resistor in series with output going to input of the next circuit?

 

[manfesto]

On the LPB-1 (and lots of pedals) the volume pot is a voltage divider so if you wanted to lock it to a specific setting, you’d need two resistors, one for each side of the wiper. Like, if you wanted to replace a 100K pot and have it set to 50%, it’d be a 50K resistor from the cap to output, then a 50K from output to ground.

 

[MBFX]

Thank you! The resistors connect where 1 and 3 would go, and 2 is the junction of the resistors, is that correct?

Also, are those resistances (generally, in this case, knowing there will be exceptions) directly proportional? A 100K pot could be set at 75% fixed resistance by using 75K and 25K, etc?

 

[hamerfan]

Thank you! The resistors connect where 1 and 3 would go, and 2 is the junction of the resistors, is that correct?

Also, are those resistances (generally, in this case, knowing there will be exceptions) directly proportional? A 100K pot could be set at 75% fixed resistance by using 75K and 25K, etc?

If its a linear pot, yes.

 

[jwin615]

If two legs of the pot are tied together on the pcb/in the circuit, as often done, no need for a second resistor.
Alternatively, use a trim pot/trimmer and one of the trim it boards so you still have some adjustment available if needed.
You can even use a trimmer in series with a resistor or two so you get a "sweet spot only" type of adjustment, making the trimmer less sensitive.
I've done this with CLRs several times so I stead of adjusting from 0-100, it adjusts from 60-90, per day.
If careful, one can take a box style multi turn trimmer and bend kegs 2 to leg 3 and use it that way as well. IDK why multiturn trimmers aren't used more often in this hobby. A few cents more and finer adjustment...

 

[HamishR]

If two legs of the pot are tied together on the pcb/in the circuit, as often done, no need for a second resistor.
Alternatively, use a trim pot/trimmer and one of the trim it boards so you still have some adjustment available if needed.
You can even use a trimmer in series with a resistor or two so you get a "sweet spot only" type of adjustment, making the trimmer less sensitive.
I've done this with CLRs several times so I stead of adjusting from 0-100, it adjusts from 60-90, per day.
If careful, one can take a box style multi turn trimmer and bend kegs 2 to leg 3 and use it that way as well. IDK why multiturn trimmers aren't used more often in this hobby. A few cents more and finer adjustment...

Because I never know where they begin and end. I always feel like I've broken something!

 

[HamishR]

BTW, to the OP I have done this before. Sometimes I have wanted to leave a pot at fully on for example so have simply bridged between pins 2 and three on the PCB. At other times I have found a setting I liked so measured the resistance between pins 1&2 then 2&3 when the pots was set at my desired setting. Removed the pot and used resistors at the closest values to those readings instead. A pot is just a variable resistor after all.