LM13700 Janglebox Bug?

[thewool]

Hi.

Built this and it works. But the middle and dark switch positions sound the same.

Can somebody who has also built it check if its a bug or not. Thanks.

http://tagboardeffects.blogspot.com/2016/05/lm13700-janglebox.html

[bowanderror]

It's been a while since I played with the switch on mine, but I remember thinking the bass setting didn't sound that different. Try adding another 22nF cap in parallel with the one at the top of the layout, from the top row to the third row. That should let a bit more bass through.

There is some chat in the comments over at Sabrotone about his vero layout that has some other suggestions. You may also want to read through & ask for help on plesur's original Janglebox thread over at FSB. The switch wiring should be the same whether you're using the original CA3080/NTE996 or the more modern LM13700 for the OTA.

[thewool]

Thanks. I tried adding another cap in parallel as you suggest and no matter what I put there, it makes no difference.

So maybe there is something wrong with the layout.

Ultimately i'd want the middle position to have less bass.

[alltrax74]

I built it from Mark's layout (CA3080) and the difference between the 3 switch positions is quite important
https://tagboardeffects.blogspot.com/2014/06/janglebox.html

[induction]

Do you have a DMM? Can you tell us the DC voltage on lug 2 of the switch?

[thewool]

Getting zero voltage at all the 3 switch lugs in all positions.

[alltrax74]

You should get 0v only on lug 2

[induction]

Without the schematic, it's hard for me to offer too much help, but...

This schematic uses the 3080 equivalent, and it should have 0V on all 3 switch lugs in all positions.

Looking at the linked vero, the switch on the 13700 version appears to operate in the same way, but I haven't fully reversed the vero into a schematic, so I might be missing something.