EHX Small Clone

taxfree

Member
I built a Small Clone clone according to the tagboardeffects model and I did the mix modification, replacing the 20K and 22K resistors with a B50K potentiometer and it works.
The only problem: there is a volume increase in the extreme dry/wet positions. Any suggestion?

Replaced resistors are shown in the attached diagram.
1642034042492.png
 

thewintersoldier

Well-known member
I know @Bio77 went thru this recently with a CS-9 chorus he was working on. Same issue as you. He ended up bumping up to or B250k C250k and all was right in the world.
 

thesmokingman

Paid Hater
remembering that those resistors are summing so if you replace with a single gang pot as a voltage divider setting the summing ratio, ideally you'd still want some series resistance for current limiting when one side or the other reaches 0 R
 

Bio77

Well-known member
I'm not sure this is a problem can be resolved with a different pot. Take a look a the blend circuit on Madbean's Porkbarrel or PedalPCB's Caesar. Those blend pots send some of the signal to ground. There is some magic there I haven't fully wrapped my head around. I'd love to get a better understanding of this, if anybody is in the know.
 

taxfree

Member
I've seen Pork Berrel's and Ceasar's schematics, but they look a little different to me as I don't know much about electronics (there's a Vref that doesn't in Small Clone).

I did the following test: I used a 20K potentiometer and a 12K resistor in series on terminal 1 and another on 3. In the central position, I should have approximately 20K and 22K for each side and turning CCW or CW I have dry or vibrato , but not 100%, probably because there is a fixed value of resistance.

I think this solution is acceptable, but I have other problems that I haven't been able to solve yet. The pedal sound has a lot of treble and brightness, and I miss mids and bass. Maybe that's why I have the impression that it sounds slightly less volume than off.
 

thesmokingman

Paid Hater
as it is a passive mixer, there is going to be some signal loss overall and some inability to reach 100% wet/dry because you're not also bleeding the other signal to ground/vref ... only adjusting the summing ratio.

for instance, the pork barrel fixes the summing ratio at 1:1 (27 and 20K resistors in series in the 2019 schematic) and uses the potentiometer to create two voltage dividers formed by pot resistance between the lug and wiper and one summing resistor(20K) to determine how much of each signal goes to vref vs passing through the summing resistor.
 
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taxfree

Member
Do you think that if I make this connection, using these values, it can work? Should I connect terminal 2 of the potentiometer to point 5 of the IC? 1642793828542.png
 

thesmokingman

Paid Hater
I would make R34 12K and R35/R36/R37 10K and the blend pot needs to be bigger, probably 50K like the 2019 version of the pork barrel and yes you can ground to pin 5 of the op amp or any other virtual ground point. so when the mix pot is 50/50 you have the exact same thing you had before you started in terms of summing ratio and the resistance to vref is sufficiently large
 
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