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CDXL reissue (DOD440) trimpots to full size pots?

Dali

Well-known member
Hello, I was wondering...

I finished my CDXL reissue (DOD440) and before boxing it I was wondering if it's a good idea or not to change those 2 10K trimpots to "real" ones accessible on the top of the box like normal ones.

I'm asking because I felt my different guitars really needs different settings there and being hidden inside the box could be frustrating in the long run.

I saw someone just drilling holes on the back of his enclosure to gain access to such trimpots but still looks inconvenient with my observation (each guitar needs a different value).

If I ever do such modification do I only have to replace the trimpots R20 and R23 with B10K, put some wires to reach the connection and that's it?

Thanks for helping me with a first "mod"!
;)
 

Dali

Well-known member
I would say the "emphasis" for lack of a better word. The documentation has even the schematic if it helps anyone find better words. English is a second language for me...

As for the trim-to-pot, which one is the correct pinout? Red or Green? Or another variation(1B,2A,3C)?
1582652859397.png
 

Chuck D. Bones

Well-known member
I'm a fan of moving trimpots to the front panel. Not appropriate for all trimpots, but for these I would do it. One caveat: don't expect the full range of rotation to be useful.
 

Dali

Well-known member
I'm a fan of moving trimpots to the front panel. Not appropriate for all trimpots, but for these I would do it. One caveat: don't expect the full range of rotation to be useful.
Do you mean that if the trimpot had 10 "values/positions" only 3-to7 would produced different sound for example?

And if so would a different value instead of 10K for the pot would be more interesting? A lower value?
 

Chuck D. Bones

Well-known member
Quite possibly. At the ends they might sound the same, or not good, or no sound at all. Depends on the circuit. In the CDXL reissue, R23 sets the tuning range for one setting of the DIRECTION switch. I'll be damned if I know what R20 is supposed to do. Maybe put a hard limit on the sweep. I think they would be set once and forget. Try 'em and see.
 
Just finished my CDXL Reissue Envelope Filter - so, so fun. I'll toss out a build report soon. I'm already thinking about my second build, because messing around with right trimpot produces wild results (especially when turned way up and the toggle switch is in the "down" mode). Would be fun to have that on the front.

@Chuck D. Bones - any chance you got your trimpots swapped when you were talking abour R23/R20? I'm hoping you did, otherwise, something's extra goofy with my pedal! For me, R20 on the right is really fun to mess with... R23 has me scratching my head.

So, questions for the hive mind:
- What exactly does R23 do?
- What exactly does R20 do?

1583932615859.png
 

Chuck D. Bones

Well-known member
IC2.2 is the peak detector that converts the envelope, the instantaneous loudness, of the guitar signal to a voltage that is then used to sweep the filter. R20 sets the bias of the peak detector amplifier. R20, along with the LEVEL control, sets whether, and how much, that amplifier is driven into saturation. When that amplifier saturates, it could load IC1.1 in such a way as to cause distortion, just a guess. I would think that mainly, it would cause the filter sweep to go just so far and stop there when you strike a note, then tail off. In other words, instead of a smooth filter sweep, the sweep would be more abrupt. Maybe you could upload a sound sample.

IC2.1 inverts the envelope signal, or not, depending on the position of the DIRECTION switch. R23 sets the bias for IC1.2 when the switch is in one position, and does nothing when the switch is in the other position. It kind of acts like another RANGE control, but only for one position of the DIRECTION switch.
 
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