Hey Guys,
I've had volume drop in a tonepad build, and guitarpcb build. Can I compensate with a resistor value? 2nd Question; Will lower gain transistors reduce distortion? Using MPS18's, thinking of 2n3907's...
Thanks
Geek
Volume drop would be easy to compensate. Check out the last inverting opamp stage: decrease the resistance before the input or increase the resistance in the feedback loop. I built one of these myself, and made it a bit more elaborate: option for vibrato (nice at faster speeds), mix control for the chorus, and volume control for the chorus and the vibrato (all trimpots). My volume control basically replaces the 10k resistor on the last opamp stage by a 20k trimpot. You could also replace the 33k or 6k8 with trimpots (larger resistance is more volume), probably with a slightly different result due to the position of the cap in the loop.
I doubt that the transistors are causing distortion, but if you socketed them you can try different ones (if you make sure they are of the right type and watch the pinout). Have you played with the 100k trimpot to minimise distortion? Does lowering you guitar volume get rid of the distortion? You could always use the same volume trick on the first opamp, in reverse: lowering the 33k will decrease input gain, and you can compensate by increasing the 33k on the output ...
This is a nice chorus, so it is IMO worthwhile to fiddle with it to get it optimised. Hope this helps.
Thanks for the info, WormBoy. Will work with it. :D
Don't play with the 33k or 6k8 resistors, they're not just setting gain, they're part of the pre/de-emphasis network so doing so will affect the frequency response of the pedal.
If you need to increase the level you should reduce the 10k resistor going in to the inverting input.
Thank you, Scruffie. Forgive, which R on the Tonepad schematic?
The one going in to IC1B pin 6.
Thank you :)