Build Your Own Clone Message Board

Would it be possible to mod an amp selector in order to make the "stereo" input accept a stereo plug? I'd like to be able to use it to route the signal from a guitar with split neck and bridge pickups, without having to use a clunky stereo->2xmono adaptor. But ideally I'd also like it to work as a splitter for one mono signal, and still be able to run two mono inputs as well.

Is that possible? I was trying to think through it but got stuck because I don't understand what purpose IC1a serves in the circuit (let alone why it seems to have its power supply wired backwards).

Any help or suggestions are appreciated, as you can probably guess I've got some guitar wiring experience but have never built a pedal!

Hi - welcome to the forum!

Could you clarify a bit what you want the pedal to do? It sounds like you'd like to be able to plug a TRS plug into input A and have the pedal switch between the tip out, the ring out, and both, but also be able to function as it does stock. Is that correct?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

That's exactly it!

Anyone have any suggestions? Even some insight into IC1a's role in the circuit would be helpful...

I think this should work. It's not verified, but I don't see why it wouldn't work.



EDIT: See additional information below in this thread before implementing this mod. As of yet, this mod is unverified.

You need a DPDT on-on toggle switch, like this: http://byocelectronics.com/parts/switchtgdpdtsl1-1.html

It will likely be challenging to find a spot to mount the toggle. You may be able to get away with mounting it underneath an input jack in the way that the ground lift toggles are mounted underneath the output jacks.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

IC1b is a unity gain buffer for input A. IC1a takes the buffered signal from input A, splits it off from the A path, buffers it again, and sends it to the ring of input B. These are switching jacks, so when no plug is inserted into input B, the ring shorts to the tip and that split signal from path A is routed to the input B path.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thank you, that's super helpful. It looks like there's room for a switch by the power jack...but I was going to use that for a phase flip switch.

That won't work because the signal going into IC1a needs to go through IC1b first to be biased. You'd need to cut the trace that connects the output of IC1a to the ring of input B, and then wire a DPDT toggle as a bypass switch for the signal directly off the ring of input A.

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*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Or...

An easier solution is to use your mod, Morgan, but just add a resistor off the non-inverting input of IC1a to vRef and that will take care of it.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Thanks Keith - would that resistor need to be switched with the mod? i.e. - if you have a 10k to Vref off the non-inverting input of IC1a when the pedal is in normal mode, will it cause an issue?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

No. I haven't actually done it, but there shouldn't be an issue. You shouldn't need to "toggle" that resistor.

_________________
*patience is a virtue*

Please do not PM me. email is prefered. keith@buildyourownclone.com

Okay - thank to implement this mod correctly, all you need to do is follow the instructions above and also add a 1 meg resistor from the ring of Input A jack to ground (because when the mod is switched in, the ring connects straight to the non-inverting input of IC1a to route the signal through the input B signal path - and ground is Vref in this case because the op amps use a bipolar power supply). An easy way to implement that would be to install the 1 meg resistor right across the ring and sleeve lugs or pcb pads of Input Jack A. When the toggle is in stock position and a mono plug is inserted into the jack, that resistor will be shorted and not doing anything.

I'll update the diagram as soon as I have a chance.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thanks, I'm definitely going to try this as soon as I have some spare cash (and can find someplace stocking this kit). I really appreciate the help here!