PedalPCB said:
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.
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?
Maybe between pins #6 & #7 of IC 1.2 .
You will need a Cap also to remove noise.
You will have to cut the trace for either mod.
Speak to the man, Mr PedalPCB.
Maybe between pins #6 & #7 of IC 1.2 .
You will need a Cap also to remove noise.
You will have to cut the trace for either mod.
Speak to the man, Mr PedalPCB.
Applying gain resistance between pins #6 & #7 of IC1.2 would increase the gain of JUST the dry guitar signal. I want the over-all effect, (regardless of the wet\dry Mix) to be increased to get back the approximately 3db loss. That's why I was suggesting pins #1 & #2 of IC 4.1
Applying gain resistance between pins #6 & #7 of IC1.2 would increase the gain of JUST the dry guitar signal. I want the over-all effect, (regardless of the wet\dry Mix) to be increased to get back the approximately 3db loss. That's why I was suggesting pins #1 & #2 of IC 4.1
I built mine with an ancestral apperation and order switcher it was definitely louder with the reverb first with no adverse affects so I'm assuming the reverb was louder going into the organ donor thereby increasing the volume
I'd give it a go Mark or just stick a small booster in series on the output that's what I did with my MN3207 electric mistress just added a stage 3 mini, biased the fet to just over 3v to take it just above unity as requested, lower drain voltage than advised but it worked then used a trimpot to set and forget and a mass of tape as you can see, as you know the stage 3 pcb is just over an inch square so ideal for the job
I would use a temporary off board Potentiometer with wires soldered to Pin #1 & #2 of IC 4.1 & adjust to see what happens.
If you get the 3dB boost your after but introduce noise try a 100pf cap to start with to see if that works on the offboard pot.
When & if you get it Right, Measure the pot after disconnecting from PCB & measure resistance & use an appropiate Resistor & or cap.
You will have to cut the trace between #1 & #2
If it doesn't workout for the better, just jumper again!
I 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.
After doing some remedial research on opamps, I'm thinking I may need to add a 1K Ω resistor from pin #2 to ground. Might even add a 100nF to 220nF cap in series with (after) the 1K resistor. (I'm thinking Tube Screamer gain section etymology without the clipping elements.) I'll report back after I try that.
Also, I'm guessing that the noise floor of the wet signal is an issue - based on other notes from PedalPCB on the matter.
After failing to get any acceptable gain result, I thought to do a little remedial training on opamps and though perhaps this mod needed a resistance from pin #2 to ground. So I added a 5K Ω resistor to ground and found that all signal was lost. I also tried a 1K Ω resistor, but suspected that was just more of the same - and it was was . . . . . no signal.
So, I think there is no "quick" modification that can fix this volume drop. I'm just going add a tiny "clean boost" daughterboard to the build, set the gain by ear to compensate for the Organ Donor's volume drop, and call the project done.
So, I'm about to drop this little 'dead-bug' solution into my Organ Donor to see if it can make up the circuit's volume drop.
Theoretically, this should give a good clean level increase. (I'm guessing it only calls for about a 3db to 6db boost. And the Organ Donor's final output cap should suffice for the DC decoupling between the two circuits.) It should slip in nicely between the PCB and the stompswitch. Once I find an appropriate value setting for the 100K trimpot, I'll put a dab of black nail polish on it (to set it) and leave it. I'll report back with the results.
Ultimately, neither the opamp mod nor the dead-bug buffer circuit worked for making up the volume loss on the Organ Donor circuit. I futzed with several different values of R1 & R2 (all the way up to 1M Ω) and was unable to get any volume recovery.
However, I did take a GuitarPCB "Stage 3 v.1" PCB and modified it a bit to derive a solution that does work. The PCB is quite small and easily fits vertically between the stompswitch and the enclosure. For C2, I used a 330nF instead of the original 22nF cap. And used a 100K trimpot in place of the 100K volume pot. After all, I didn't need\want to control the overall output volume with an external pot - just recover the volume loss of the original Organ Donor. And for what it's worth, the original EQD Organizer also exhibits a volume loss when engaged. This little mod nicely recovers that volume drop. After building and inserting the modded recovery circuit, I set the volume trimmer to just the right point where there is no discernible loss of volume when engaging the Organ Donor pedal.
Here is the schematic:
And here's a shot of the modded Stage-3 PCB stuffed into the enclosure. (I'll just wrap it in a bit non-conductive foam when it gets buttoned down.)
You can create a dead-bug version or use a GuitarPCB "Stage 3 v.1" PCB as I did to recover the volume loss of the Organ Donor. It works quite nicely for me.
Awesome! I'm going to try that. Is the black wire off of the center pin of the footswitch wired to ground on the stage 3? Is the red wire behind the stage 3 going to 9+? Does the other end of the red wire go to the dc jack? Thank you so much.
Awesome! I'm going to try that. Is the black wire off of the center pin of the footswitch wired to ground on the stage 3? Is the red wire behind the stage 3 going to 9+? Does the other end of the red wire go to the dc jack? Thank you so much.
Yes. Not directly. The Stage3 PCB is getting power from the DC jack thru an added 1N5817 Schottky diode. The diode was added in-line on the red wire, hidden under the main board and wrapped in shrink-wrap.
