Adding volume control to Swamp Thang kit build question

[archimedes]

I have built a Swamp Thang from a kit and love the sound of it but there is a volume boost. I have added a 100k trimmer between board and output (with one leg to ground) with a treble bleed cap. Having found the resistance that gives ~ unity gain, if I replace the trimmer with a fixed resistor will I still need the ground connection or will the resistor alone in series do the job? Thanks in advance for any advice

[r080]

If I am understanding the way you have the trimmer correctly, you will need something going to ground. You need it set up as a voltage divider, which would require 2 fixed resistors.

What is a Swamp Thang? Tremolo?

[r080]

I assume it is this:

https://www.dirk-hendrik.com/swamp_thang.pdf

[archimedes]

I assume it is this:

https://www.dirk-hendrik.com/swamp_thang.pdf

It is indeed. Hoping someone wiser than me can advise on controlling the volume

[r080]

I would recommend you keep the trimmer, rather than try to replace it with fixed resistors.* However, what you could do is measure from the outer two lugs to the middle lug of the trimmer, then replace the trimmer with two resistors of the closest value. They would be in series, with the top one connected to the output cap, the bottom connected to ground, and the middle of the two would be the new output.

Here is an example of a similar trem with volume control already on it:

http://sfxguitareffects.blogspot.com/2019/03/building-runoffgroove-modified-ea.html

*I didn't look too deep into the schematic, but it is possible your perception of unity could change with different settings of intensity, hence it might be better to keep it adjustable.

[archimedes]

I would recommend you keep the trimmer, rather than try to replace it with fixed resistors.* However, what you could do is measure from the outer two lugs to the middle lug of the trimmer, then replace the trimmer with two resistors of the closest value. They would be in series, with the top one connected to the output cap, the bottom connected to ground, and the middle of the two would be the new output.

Here is an example of a similar trem with volume control already on it:

http://sfxguitareffects.blogspot.com/2019/03/building-runoffgroove-modified-ea.html

*I didn't look too deep into the schematic, but it is possible your perception of unity could change with different settings of intensity, hence it might be better to keep it adjustable.

That's brilliant, thank you very much