Switch troubleshooting

[Stilts]

Hi all,

For my first foray into stombox design, I've just done myself up a looper, stutter and clean blend switch in one box and all is working nicely except for the clean blend section of it. Wiring all seems to be done as per schematic - I was wondering if you guys may be able to double check if the schematic itself is done up wrong. After the effects loop I put in a DPDT with the intention of it adding a clean signal back in after the effected signal, but currently it's functioning as a kill switch. Any clues? Sorry if it's a bit of a newbie mistake, I'm just having a little trouble pinpointing what's gone wrong with it.

[Mick Bailey]

When the 'add clean' is activated it's shorting between the send and return jacks. Most pedals won't like that and will go into feedback or some other unpredictable behavior. If you plug a patch lead directly from the send to return does it still act as a kill switch?

To get an effective clean blend you need something more complex to buffer and mix the effected/clean signals.

[Stilts]

When the 'add clean' is activated it's shorting between the send and return jacks. Most pedals won't like that and will go into feedback or some other unpredictable behavior. If you plug a patch lead directly from the send to return does it still act as a kill switch?

To get an effective clean blend you need something more complex to buffer and mix the effected/clean signals.

Ah, thanks for that. I tested it with an octaver to start with and it fed back pretty badly, but an overdrive box went alright with it so I assumed power supply may have been at fault with that. If I took the clean signal straight from the input jack rather than after the switch would it make any difference?

[Mick Bailey]

Taking the signal of the input jack rather than after the switch still amounts to the same thing. The reason your overdrive box was ok is possibly down to that box changing the phase of the signal.