Dod 440 envelope filter (cdxl)

thewintersoldier

Well-known member
Great job. Is that an xvive vtl5c4/2?
Thanks, it is the xvive. I socketed some different resistors and the 2k2 resistor sets the minimum Resistance for the vactrol. I upped it to 4k7 which was used in some vintage 440s and also in the mojo hand fx 442. Made all the difference in the world. There are subtl differences in opamps as well so try some different ones.
 
Thanks, it is the xvive. I socketed some different resistors and the 2k2 resistor sets the minimum Resistance for the vactrol. I upped it to 4k7 which was used in some vintage 440s and also in the mojo hand fx 442. Made all the difference in the world. There are subtl differences in opamps as well so try some different ones.

Excellent, thanks. Some good ideas... you're making me glad I socketed the TLO72!
 

Chuck D. Bones

Well-known member
R6 is an anti-pop resistor on the output. I can't see how it would affect high-freq content unless you make it very small.
 

benny_profane

Well-known member
This seems to be the only successful build report. I and and few others can’t get an acceptable response out of the unit. Would you mind taking a look at this thread and giving some thoughts? Thanks in advance!

 

irvmuller

Member
Thanks, it is the xvive. I socketed some different resistors and the 2k2 resistor sets the minimum Resistance for the vactrol. I upped it to 4k7 which was used in some vintage 440s and also in the mojo hand fx 442. Made all the difference in the world. There are subtl differences in opamps as well so try some different ones.
I know I’m resurrecting an old forum here. I’m wondering, do you know all the changes the 442 made from the 440? I was already wanting to make this and I’m a bass player and saw the 442 was better geared for bass.
 

thewintersoldier

Well-known member
I know I’m resurrecting an old forum here. I’m wondering, do you know all the changes the 442 made from the 440? I was already wanting to make this and I’m a bass player and saw the 442 was better geared for bass.
This is a good pedal but i ended up getting my hands on a vintage vtl5c3/2. That really seems to be the key to getting the pedal to sound like it should. The reissue vactrol isn't as good sounding in this pedal. However, if you really want to build a good envelope filter I would recommend the mutron III/q-tron. Madbean had the naughty fish which is my favorite filter pedal. He replaced it with the mini-mu which is a vfe pedal and based on the same circuit. @jjjimi84 could tell you all about it but he did a video for it that does all the talkin!
 

Popnfreshbass

Well-known member
I know I’m resurrecting an old forum here. I’m wondering, do you know all the changes the 442 made from the 440? I was already wanting to make this and I’m a bass player and saw the 442 was better geared for bass.
I just built the junk trunk from madbean. And although its a bit finicky and tough to dial in, it really does sound great once you find the sweet spot.
 

JamieJ

Well-known member
Nice chris. I have the reissue version half populated at the moment. I am going through a massive Tom Misch fanboy phase at the moment and he makes a filter sound so classy.
 

daeg

Active member
I've got to give one of these a try.

I built the 440 Reissue which is actually a DOD FX25 with a direction switch. It's similar but a dual OTA implementation rather than dual Vactrol. It has a high threshold to open the filter then the filter has crazy, speaker blowing resonance. Kind of the worst of both worlds IMO.

The original 440 design seems much more user friendly.
 

Feral Feline

Well-known member
I've got the original 440 circuit covered by another PCB supplier, so thought I'd give the CDXL OTA a try.

Interesting to learn it's the FX25 (which I've already got covered as well). Maybe I'll try some more mods on my CDXL...


Wish I'd been able to snag a Naughty Fish, it was always "next time" when they were available and now they're gone. Got the VFE...
 

thewintersoldier

Well-known member
I've got the original 440 circuit covered by another PCB supplier, so thought I'd give the CDXL OTA a try.

Interesting to learn it's the FX25 (which I've already got covered as well). Maybe I'll try some more mods on my CDXL...


Wish I'd been able to snag a Naughty Fish, it was always "next time" when they were available and now they're gone. Got the VFE...
When the pandemic hit I gave my original naughty fish to a guy in my building who played bass, and someone was nice enough to send me a naughty fish board he never built. I built my second one to q-tron specs. Only a couple value changes but I think it's a little smoother sounding
 
This is a good pedal but i ended up getting my hands on a vintage vtl5c3/2. That really seems to be the key to getting the pedal to sound like it should.
Hi, I got a hold of the same vintage Vactrol but I’m still having the same issue that others seem to have had with this build. I know you said you changed the opamp and the value of R9 from the schematic, wondering if you made any other changes? Tia
 
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