Boss pedal switch lag?

[jonathansuhr]

Modded a DS1 (probably the seventh or eighth one I've done). Everything works perfectly except when I switch the pedal on while sustaining a note, I notice a very momentary drop in volume then the effect engages. The drop is only a few milliseconds, but it is noticeable when sustaining notes. I've tried setting the DS1 volume to unity, below, and louder than my clean signal, but I still notice the drop no matter where I set the volume.

I'm thinking it could be that the LEDs I'm using as clipping diodes need to be fed an initial voltage for a split second, but I'm not completely sure. Any ideas?

[edvard]

Are you using FET switching?
What schematic did you use?
Does this happen with all your builds?
From all I've read, it could be a capacitor at the head of the circuit that's charging when you first kick it on.
Check that first, make sure it's not larger than it needs to be for the frequency range you're operating in.

[jonathansuhr]

Yes it is a regular DS1 with Boss switching with a few part changes. I've modded a handful of DS1 in the past, and none have had this problem.

C2, C8, C9, and C14 have 1uF caps now, C3 has 0.047uf, C11 has 0.01uf, and C1, C5 have 0.1uf.

Do any of those look suspect?

[edvard]

I've looked at the DS-1 schematic and I can't fault any inputs, so I don't think input caps are doing it.

You may have a laggy FET in the switching that isn't opening up as fast as it should.
There are two of them switching the active circuit, so check both.
Also make sure the 1Meg resistors feeding the gates isn't out of spec.
I've been experimenting recently with FET switch simulation in LTSpice, and I've seen too high a resistance to the gate slow down it's release time.
This somehow causes the other side a 'turn-on' volume ramp on the order of milliseconds.
Human senses can detect time delays of ~16 ms, so this is definitely within range of what you're hearing.

If you think the diodes are the culprit, make sure they're not burnt out, and check the 470nf capacitor feeding that section.
If you somehow got a 'bogey' cap that's way too big, your original suspicion may be correct.

Beyond those, I'm stumped.