# Duo-Phase vs Bi-Phase



## bengarland (Apr 28, 2019)

I'm new to building pedals, so apologies if this is an obvious question...

I ordered the Duo-Phase PCB and it seems that it is missing a couple features of the Bi-Phase (I could be wrong...)


Sine/Square wave selector for LFOs
Pedal inputs (and accompanying toggle switches)

Is there any way to hack it to add these features?

I'm assuming with no Sine/Square switch that it's hardwired for Sine wave?

Anything else I should know about this particular board / build compared to an original Bi-Phase?

Please be generous with your answers, since I'm new to this and still trying to wrap my head around all of the jargon...

Ben


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## bengarland (Apr 28, 2019)

It also seems like there's no knob to select the source for Phasor B Input. Is this able to be done manually based on how the cables are connected on the rear? e.g. how would I patch it so that Phasor A is the Input for Phasor B? Is it as simple as literally running a short 1/4" cable from the Output of A to the Input of B?


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## Robert (Apr 28, 2019)

The Duo-Phase doesn't do square wave LFO or have an expression pedal input.   
Technically you _could_ add an isolated switched 1/4" jack to substitute the Rate pot when a pedal was plugged in, but I haven't tried this.

Both of the wiring diagrams in the build doc would give you series operation. (Phaser A > Phaser B)

The diagram on Page 5 is hard wired, so it would always behave this way.

The diagram on Page 6 allows you to use each side independently if you wanted, but when only using the outside pair of In/Out jacks the two phasers would be internally connected (via the switched 1/4" jacks).


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## Cucurbitam0schata (Jun 9, 2020)

Like @PedalPCB mentioned above: Has anyone tried to add an expression jack at the Rate Pot?


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## cooder (Jun 9, 2020)

Cucurbitam0schata said:


> Like @PedalPCB mentioned above: Has anyone tried to add an expression jack at the Rate Pot?


Yes I have and it works great for me. I do happen to have a suitable expression pedal with I think a 10K pot when I measured it, and that works fine for me. So I guess you gotta check or modify an expression pedal to have a ballpark close pot value to the B25K. I have the expression jack mounted on a switched jack, so when expression pedal is not connected it just works as normal with dashboard pots.


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## soothsayer86 (Jun 30, 2020)

cooder said:


> Yes I have and it works great for me. I do happen to have a suitable expression pedal with I think a 10K pot when I measured it, and that works fine for me. So I guess you gotta check or modify an expression pedal to have a ballpark close pot value to the B25K. I have the expression jack mounted on a switched jack, so when expression pedal is not connected it just works as normal with dashboard pots.


Could you post some pictures of your completed build with the expression mod? I am thinking about doing this myself.


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