I just finished an Organ Donor build and am noticing the volume drop as well. Love the effect! I was thinking of adding a 10K trimpot between pins #1 & #2 of IC 4.1 (the final output stage of the second opamp) to find the sweet-spot and increase the output a bit. Thoughts?I can bump up the effected volume in the algorithm if the dry signal is loud enough, boosting the overall output would raise the noise level.
Any luck w this? Just boxed mine up and have the same issue.I just finished an Organ Donor build and am noticing the volume drop as well. Love the effect! I was thinking of adding a 10K trimpot between pins #1 & #2 of IC 4.1 (the final output stage of the second opamp) to find the sweet-spot and increase the output a bit. Thoughts?
I've not gotten there yet. It's currently in my decals queue while I finish up a couple other projects. I intend to post back when I do get there.Any luck w this? Just boxed mine up and have the same issue.
Any luck w this? Just boxed mine up and have the same issue.
I just tried the modification I mentioned. I lifted (cut) pin #2 and soldered a 20K trimmer across pins #1 & #2 of opamp #4. It made no audible difference to my ears. I futzed with the trimmer value all way off (counter-clockwise) to all the way up (clockwise) and could not hear a difference. I checked the trimmer variance with a DMM before I applied the modded opamp to the circuit and the trimmer does indeed vary from 0 Ω to 20k Ω.@Cybercow Tried this, actually went up to 15k. Helps the volume drop a bit (not completely). Introduces a bit of noice into the wet signal. I’m keeping it there.
Is this what you mean or lift Op Amp Pin 2 from PCB?You will need a resistor from Pin 2 to ground in order to get any gain out of IC4, or if you try, on IC1. As far as the capacitor in series with the pin 2 to ground resistor, realize this will form a high pass filter which will attenuate frequencies below the cutoff freq. This may not work to well with the octave down of this pedal.
Yes, Pin 2 has to stay lifted.So Op Amp Pin 2 is still lifted as Pin 1 & 2 are linked on PCB?
Thanks! I get that - as I suggested in my last post where I mentioned that I did a little remedial education on opamps. I just hadn't gone there yet. Will post later with a photo of the additional resistor. I'll try a 5K Ω first. (It's been decades since I did the math.)You will need a resistor from Pin 2 to ground in order to get any gain out of IC4, or if you try, on IC1. As far as the capacitor in series with the pin 2 to ground resistor, realize this will form a high pass filter which will attenuate frequencies below the cutoff freq. This may not work to well with the octave down of this pedal.