Help with Attenuator/Boost/Loop for line level signal

[four_corners]

Hello everyone,

I'm fairly new to building guitar pedals (about a year), but I've been having a blast making them.

I play both guitar and keyboard, but have been running into issues with a few synths/keyboards not playing nice with some of my pedals (I'm getting some nasty clipping/distortion sounds). I understand this has to do with the synth being line level, which is much hotter than a guitar signal.

I originally thought "hey, I'll just make a little attenuator pedal like the EHX Signal Pad", but then also realized I'd need to get my signal back up to line level after my effects.



So! Here is where I need some help...

I was thinking it would be cool to build a little single send/return effects loop type pedal, with the EHX Signal Pad circuit pre-send, and the MXR Micro Amp post-return to get back up to line level.

I've never built anything that didn't strictly adhere to someone else's build plans (mostly tagboardeffects), so it took me a bit to figure this out.

WARNING!!! I apologize in advance for the super messy looking illustration, hopefully it makes sense.

Does this look correct and seem like something that would work?

One last thing to add, you'll notice a little SPDT switch from the Signal Pad circuit to the "Send" output; I thought I'd add a little toggle switch so I'd be able to bypass the effects loop if I ever wanted to use this as a simple attenuator/volume pedal. I guess I could omit this though and just patch a physical cable between the send and return too, though a switch seems less cumbersome.

Thanks for all the help.

-Josh

[bluebunny]

Welcome!

It's too early (and not enough coffee yet) to follow the spaghetti, but I'm sure it's fine.     Someone will be along shortly who is sober and awake and will verify.  If it helps, Ken Stone has pretty much what you want here, albeit for modular synth levels (where the levels are higher still, but you could tweak...).

[antonis]

Dizzy enough  for nothing more than Wellcome..

[four_corners]

Welcome!

It's too early (and not enough coffee yet) to follow the spaghetti, but I'm sure it's fine.     Someone will be along shortly who is sober and awake and will verify.  If it helps, Ken Stone has pretty much what you want here, albeit for modular synth levels (where the levels are higher still, but you could tweak...).

Thanks for the welcome, and sorry for the spaghetti!

I realized I don't really need to show the ground and voltage wiring, so here is a much much simpler image without those. Might be a lot easier to follow the signal.

Thanks!

[vigilante397]

I'm sober and awake and everything looks fine, but I have to ask the question: why can't you just turn down your keyboard/synth and turn the amp up? Do you absolutely have to use the all the same pedals at the exact same levels between guitar and keys? What pedals in particular are you having problems with?

Again I would fully expect this to work and to achieve what you want it to, but I'm trying to understand why you want to take the most complicated route to solve a fairly simple problem.

[four_corners]

I'm sober and awake and everything looks fine, but I have to ask the question: why can't you just turn down your keyboard/synth and turn the amp up? Do you absolutely have to use the all the same pedals at the exact same levels between guitar and keys? What pedals in particular are you having problems with?

Again I would fully expect this to work and to achieve what you want it to, but I'm trying to understand why you want to take the most complicated route to solve a fairly simple problem.

I have some small DIY synths that don't have a volume pot, for example, the Mutable Instruments Shruthi.

Thanks for checking it out regardless, I know it seems a little bit complicated for such a small task.

[Kipper4]

Is this any help?

https://cgs.synth.net/modules/cgs60_sba.html

[ElectricDruid]

Is this any help?

https://cgs.synth.net/modules/cgs60_sba.html

+1 for the CGS stompbox adaptor. It does exactly what you're after.

Tom

[four_corners]

Is this any help?

https://cgs.synth.net/modules/cgs60_sba.html

Thanks! Unfortunately it looks like the PCBs are sold out anywhere I can find them, plus they seem to be a bit long to fit in a stompbox since it was originally intended for modular.

I think though what my built is doing is essentially same thing, so maybe I can just go with my stompbox plan. I think I can simplify it a bit more by just wiring a pot like the seymour duncan treble bleed mod instead of using the EHX Signal Pad circuit.

[Kipper4]

That pcb has 3 such modules on it. How many do you require?

The synth to stomp box converter is a simple 2x resistor voltage divider maybe you could shoehorn that in somewhere.

[bluebunny]

Ken Stone has pretty much what you want here

Is this any help?

https://cgs.synth.net/modules/cgs60_sba.html

Is there an echo in here?   

Unfortunately it looks like the PCBs are sold out

The circuit is simple enough to go on a tiny piece of vero or perf.  You don't need to go buying PCBs.

[PRR]

> I have some small DIY synths that don't have a volume pot

So DIY a volume pot. It is about the simplest thing you can DIY.

An opamp gain-stage should also be DIY-able for anybody who DIYs synths.

Switching is always like chess or crosswords. Can you actually get the pawn (or signal) from here to there, without being captured (shorted) mid-trip? These problems are solvable "by inspection" but can be tedious.

[ElectricDruid]

Ken Stone has pretty much what you want here

Is this any help?

https://cgs.synth.net/modules/cgs60_sba.html

Is there an echo in here?   

Great minds think alike,  it seems. Or fools never differ. That's the trouble with proverbs.

T.

[four_corners]

Thanks for the suggestions everyone (as well as the warm welcome to the forum!).

I'll let you know how it turns out!