x2 germanium boosters in one box

Putting two effects in one box almost looks too easy, but you will save a lot of time reading the frequent questions before starting such a project...

x2 germanium boosters in one box

Postby drewberryelectronics » 26 Jan 2015, 02:32

So I've built a pedal with two slightly different Germanium boosters in it.

One is a Rangemaster style treble booster that's a bit smoother and boosts some mids too,
the other is a straight full boost that gets into slightly fuzzy territory when cranked.

Breadboarded them both up to sort out part values etc, then built up vero board versions.
When built they tested fine in my test board unit, everything worked.

As soon as I built them into the pedal with switching etc, all of a sudden I'm getting no sound.
Sound works when bypassed, but when either effect is engaged the signal goes dead.

The circuits are still working because audio probing at the input and output of each board shows that they are indeed boosting.
I've built 2in1 boxes before fine and built many pedals, I've double checked my true bypass wiring (as I assumed it was just an issue there) and everything is testing fine on the multimeter, so I'm not sure what's going on.

The pedals are in series, so I'm thinking perhaps there's some voltage issue going on?
Might try putting them in parallel to see if they're working then
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Re: x2 germanium boosters in one box

Postby Nocentelli » 26 Jan 2015, 09:03

The voltage is supplied to individual circuits in parallel, regardless of whether the audio paths are series or parallel. The only issue I can think of (apart from a wiring fault) is if both circuits are negative ground: if they are not both neg ground, you'll short the power supply. If they are bothbpositive ground, they'll work together but can't share a power supply with any other neg ground pedals in your chain.
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Re: x2 germanium boosters in one box

Postby drewberryelectronics » 26 Jan 2015, 21:42

Nocentelli wrote:The voltage is supplied to individual circuits in parallel, regardless of whether the audio paths are series or parallel. The only issue I can think of (apart from a wiring fault) is if both circuits are negative ground: if they are not both neg ground, you'll short the power supply. If they are bothbpositive ground, they'll work together but can't share a power supply with any other neg ground pedals in your chain.

Yeah I figured that would be the case.

They are both negative ground, it's basically a flipped Rangemaster circuit so that it can be daisy chained, run off normal PSUs etc. Normally I'd build it positive ground because my CAE PSU can power that fine but it's a custom build for a guy who uses daisy chains and stuff.

I've rewired the 3pdt a 3rd time and still no luck, it's absolutely bizarre. How can a board that works when plugged into a breadboard testing board stop working when wired up to a working true bypass setup? I'm thinking the input is getting grounded somewhere but multimeter is not showing any shorts anywhere.
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Re: x2 germanium boosters in one box

Postby Nocentelli » 26 Jan 2015, 22:16

Both stomp switches are good?
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