CDXL Response

[benny_profane]

My CDXL build (corrected board) is having a number of issues.

1. With ‘Level’ maxed out, I get my clean signal with a fizz mixed in, but no autowah.
2. The response is sometimes extremely slow, and only kicks it on the decay of the note. This happens at various points of the sweeps.
3. The wah doesn’t fall smoothly. It peters out in a very wobbly (think super fast phaser) way.
4. Overall, it’s very weak (when it’s catching the input signal). Not at all as extreme as a wah sweep should be.

I used the Xvive VTL5C4/2 from SBE. I’ve tried various values at R9 (i.e., 2k2, 4k7, and 6k8). 4k7 seemed to get the closest. I’ve also tried various dual op amps (i.e., TL07, TL062, and TL022). The TL072 has the worst response.

I’ve tested the circuit both with and without a buffer before it.

I’m wondering if others have had good luck with the Xvive reissues or not. I know there’s one successful build report, but that’s it. In any case, any ideas?

 

[Chuck D. Bones]

Haven't breadboarded it yet (got a PlimSoul mod going on the breadboard), but I did run some simulations. Are you absolutely sure that C6 & C7 are the right values? You can read them both?

Try this: temporarily install (tack solder) a resistor in parallel with R5. Anything around 470K will work. See if that makes any difference. This test will at least prove or disprove that the filter Q is too high in your build. I remain skeptical that there is anything wrong with the Xvive part. Still possible, just no convincing evidence.

 

[benny_profane]

I've only got 4 of them, so I will not be selling any. Sorry.

No worries (worth a shot!). Thanks for the response. Still looking forward to your findings.

 

[RajahMoore]

Sorry to be resurrecting an old thread, but I really wanted to build a CDXL classic. After waiting a couple months and never getting notified for the pcb, I figured I'll make myself a PCB based on PedalPCB schematic and layout as a way to get familiar with EAGLE. At the time I didn't know people were having issues with this thing, so I went and got myself the xvive reissue vactrol from SBE. Had this same exact problem but after messing around, I actually ended up lowering the R9 to 870ohm, and swapped the C5 to 10uF. Not sure how well it performs compared to the original but it seems to be working for me.

 

[daeg]

Has anyone tried building this with dual LDR's and an LED?