Parentheses works, but with volume dropping/swells

[ThickMilkyGobs]

Just finished my Parentheses build a couple days ago. Every footswitch and knob works, but I'm noticing some serious volume dropping/swells when I have the octave mode engaged with high gain on the distortion/fuzz switch turned on.

I recorded a rough audio demo here (octave mode comes in around 1:10): https://voca.ro/e0gxp3KLmZc

I believe I used 1N270's for the octave section, and the IC is a tin-can LM308 from Jamenco.




I've heard this issue can be fixed by changing the value of a capacitor, but I don't know which capacitor I need to be looking at.

Also, does anyone know how to rewire the octave switch so that it works regardless if the distortion switch is turned on or off? The boost mode works independently of the other switches, and I want the octave mode to work like that too.

 

[Nostradoomus]

Is it doing that weird volume ducking/compression when you hit a really low note?

 

[Robert]

Reverse the orientation of D1 and D2. The stripe is on the Anode on those.

 

[ThickMilkyGobs]

Tried out your suggestion with flipping D1 and D2, sadly it didn't seem to help.

I recorded another demo: https://voca.ro/mso3qlVeXtF

And yes, Nostradoomus, I get the volume swells on low notes too. I notice it when playing without the octave as well.

 

[ThickMilkyGobs]

Update: I tried various things to fix this volume dropping issue.

1. Removed the 1N270's from D1+D2 and tried BAT46's (kinda cool but got ringmod-ish sounds on higher octave settings), and 1N5817's (much more subtle and "musical"). Both still had volume dropping and swells when octave + distortion were maxed.

2. Swapped 5102 transistors with SMD 2N5457's. No noticeable change.

3. Removed C9 and socketed it with a 2.2uF instead of the stock 4.7uF. I don't notice any volume swells on low notes without the octave turned on now.

4. Replaced BS170 with a fresh one. No change.

No dice. Still trying to figure this one out.

 

[Nostradoomus]

Yeah I play in really low tunings and always drop that 4.7uf to 1uf to avoid that fartin’!

 

[ThickMilkyGobs]

Apologies for reviving a dead thread, but I figured I'd make a little update for posterity:

I ordered some AN307's from SmallBear, a supposed 1N34A work-alike. I'll make another post when I finally get them and try them out, for the octave section.

I started having an issue with the sound cutting out and making a loud "EEEEEEP" tone while playing (with the distortion and/or octave engaged), which would only go away if I (lightly) knocked the enclosure around. I soldered all the transistor's legs to their sockets instead of just one per transistor, and that seemed to do the trick. Seems like this pedal really wants you to have all the transistors directly soldered to the board, not just socketed.

Lastly, is anyone else getting really loud popping sounds when they engage any of the footswitches? The octave footswitch won't make noise if the distortion switch isn't engaged first, but it'll pop if they're both on. Do I need a pulldown resistor somewhere?

 

[blueimpala]

I'm having this issue, as well, though it doesn't seem nearly as severe as yours. I haven't tried playing super high up on the neck with it yet, but I'll give it a go next time I have a chance. I'm curious how similar our volume drop issues are.

If anyone figures this out I'd love to hear about it ?

 

[blueimpala]

I am not having the same issue as @ThickMilkyGobs. The cutout on mine is more like a "farting" (as it was referred to earlier in this thread) and it doesn't get worse as I play higher and higher notes.

Honestly, I'm not even 100% that it's an issue: It happens when I have the distortion turned past about 1 o'clock. Is it working as designed? Does turning it up just introduce so much distortion that it's clipping super hard?

Also @ThickMilkyGobs , maybe I don't know something that everybody else does, but why do you have LEDs in place for D3 and D5?

 

[ThickMilkyGobs]

Got the AN307's and put them in. The octave effect still has some volume drops when it and the distortion is cranked, but it's much less pronounced now. One step forward, one step back...

@blueimpala I opted to use LED's for D3 & D5 because I prefer LED clipping for RAT pedals. They're much louder than silicon diodes.

 

[Edenspace]

Yeah I play in really low tunings and always drop that 4.7uf to 1uf to avoid that fartin’!

What tunings do you play in? Experiencing this farting flubbiness but I’m also in drop G on a 7 string.