SOLVED Octarock issues

[DGWVI]

Posting this primarily to hopefully get a schematic from @Robert

Built two of these, both exhibit the same issues. I've gone over all parts to verify values, and have touched up every joint at least twice. I've tried different power supplies, and I've swapped the CD4013s from some surplus stock to Mouser supplied chips, and the issue persists

The other two voices work perfectly, but the -1 octave doesn't wanna behave. It'll work for a few moments immediately after applying power, and then it dies out. Sometimes it comes back in. I'm almost wondering if it might be my use of MLCCs and/or Tants .


Video to illustrate -

I also have a Pearl OC07 clone with the same issue. But, neither of the Ocelots I've recently built have this problem

 

[Cybercow]

In my experience, a pedal performing like that would have me looking carefully at ALL the electrolytic caps in the circuit. It sounds like one of the ≥1µF caps may be loosing its 'muchness' after it warms up and somehow fails to consistently retain its charge/discharge capability.

 

[DGWVI]

In my experience, a pedal performing like that would have me looking carefully at ALL the electrolytic caps in the circuit. It sounds like one of the ≥1µF caps may be loosing its 'muchness' after it warms up and somehow fails to consistently retain its charge/discharge capability.

There are only three electrolytics in the octave down portion, all 1u. I'll take a look at those. There's another after the Emitter follower, but the other two voices come though as they should.

 

[DGWVI]

Solved!

The Tayda 2N5457s were the culprits

 

[Cybercow]

Solved!

The Tayda 2N5457s were the culprits

Glad you sorted it.

 

[Betty Wont]

Has Tayda even carried 2N5457 since 2014?

 

[Guardians of the analog]

Has Tayda even carried 2N5457 since 2014?

The SMD mmbf201 and 5457 I've bought from them, as well as the j202

 

[Betty Wont]

The SMD mmbf201 and 5457 I've bought from them, as well as the j202

I used to get those there too, but they've been out of stock for a long time. The j202 are still a great value.

 

[DGWVI]

Has Tayda even carried 2N5457 since 2014?

I bought them years ago, but recently enough that they're in the pink bag, which I can't recall when they switched over to that.

The 2N5485s I replaced them with are working perfectly, and also Tayda sourced.

The 2N5457 in the input buffer of all three circuits also works fine . I'm guessing being biased with the 100k and getting slapped with the thump just doesn't work for that particular batch

The SMD mmbf201 and 5457 I've bought from them, as well as the j202

This is the first issue I've had with any of the JFets I've gotten from them, but those were all bough a long time ago, and I generally only ever use em in common drain buffers, where they work fine

 

[Cvoxdog]

Thanks DGWVI for having and solving that problem! This was my exact experience too. I built this last night and was losing my mind since there was only a faint octave down signal. After reflowing every joint and it still didn't work I then assumed it was my jfets since they were through hole. I was hopeful the vendor I bought them from made sure they were ok but as soon as I swapped them for smd on adapters the pedal worked.

 

[DGWVI]

Thanks DGWVI for having and solving that problem! This was my exact experience too. I built this last night and was losing my mind since there was only a faint octave down signal. After reflowing every joint and it still didn't work I then assumed it was my jfets since they were through hole. I was hopeful the vendor I bought them from made sure they were ok but as soon as I swapped them for smd on adapters the pedal worked.

Awesome! Glad you got yours working, too

 

[NickC]

just the same problem! i'll try to change the 2N5457

 

[NickC]

done with some old 2n5458 and now it sounds amazing! thanks!