Whooshing noise on Sprit Box

[coachseeley]

Greetings,
I've made probably 12 Spirit Box pedals for a buddy of mine, and he asked if I could trouble shoot a couple of his attempts at the circuit (that are having various issues). I re-flowed all the joints, swapped in a 20k at R4, and even tried swapping ICs. Both of the circuits are weaker than unity in signal and have a whooshing/swishing tail on the repeats. I'm a paint by number builder, and unless it's a cut trace or cold solder joint/connection, I'm not all that great at troubleshooting.
Has anyone ever had that whooshing noise from a Sprit Box? Thanks.

 

[Robert]

It may or may not be related to the problem, but I don't believe those TL072's are genuine.

There have been a few troubleshooting threads recently with random issues related to bad / fake TL072's.

 

[Erik S]

I don’t have any good troubleshooting advice, but I’d love to see a pic of your buddy’s 12 spirit box pedalboard!

 

[coachseeley]

It may or may not be related to the problem, but I don't believe those TL072's are genuine.

There have been a few troubleshooting threads recently with random issues related to bad / fake TL072's.

They look different than the ones I normally use, so I wondered that. But, I tried swapping in a 4558 (not the same, but it's all I had) with not audible change in tone or noise.

 

[coachseeley]

I don’t have any good troubleshooting advice, but I’d love to see a pic of your buddy’s 12 spirit box pedalboard!

Haha! I made one for him, then he asked for a few more to gift to some friends... then it was 5 more to sell for fundraising stuff, etc... This guy has some primo stuff, some talented friends, and they love the circuit. Said he may want 25 more to sell and raise money for music grants.

 

[Erik S]

Haha! I made one for him, then he asked for a few more to gift to some friends... then it was 5 more to sell for fundraising stuff, etc... This guy has some primo stuff, some talented friends, and they love the circuit. Said he may want 25 more to sell and raise money for music grants.

Nice! It’s a cool pedal for sure. There was a thread here recently about advantages of a pre-delay control on reverb that got me wanting to dig out my spirit box.

As far as your whooshing problem, would you describe it as white noise? Does it get worse at long delay times? I think that’s a pt2399 trait, and maybe worse on some than others. You could try swapping the pt2399 chip, but I think the belton brick is just a box full of 2399s too.

Searching the forum for “spirit box noise” yields some results that look relevant.

If you can get a good sound sample, that might help get you some feedback on whether what you’ve got is normal or something weird.

 

[GAStan]

Have you tried different power supplies? Guitars? Amps? Cables? Just to rule out odd interactions...

 

[coachseeley]

Have you tried different power supplies? Guitars? Amps? Cables? Just to rule out odd interactions...

I haven't tried anything different, but this is the same power supply/guitars/cable that I use to build/test probably 40 other pedals. I built 5 other Spirit Box pedals for him a couple weeks ago and tested them on this same rig. Trying to think if anything could be different with my setup...

 

[coachseeley]

Nice! It’s a cool pedal for sure. There was a thread here recently about advantages of a pre-delay control on reverb that got me wanting to dig out my spirit box.

As far as your whooshing problem, would you describe it as white noise? Does it get worse at long delay times? I think that’s a pt2399 trait, and maybe worse on some than others. You could try swapping the pt2399 chip, but I think the belton brick is just a box full of 2399s too.

Searching the forum for “spirit box noise” yields some results that look relevant.

If you can get a good sound sample, that might help get you some feedback on whether what you’ve got is normal or something weird.

Let me see if I can record something. It's almost like that "analog-tube-spring" noise you get from a tape delay. All those are technical terms by the way.

 

[darwin999]

@coachseeley -
Did you verify all the component values?
E.g., I can't read the lettering but Is C2 really 1µF, it looks bigger than that.
Also, the colors are a bit hard to read, but is R4 really = 10k?