Help Wiring Two Guitars, Two Amps, and Loop Pedal

[josh2566]

I have an acoustic guitar, an electric guitar, a loop pedal, and two amps. I like to play chords through the loop pedal, loop the chords, and then play over the top of the chords as they are playing through an amp. I don't like to use just one amp to do this because my bigger amp has effects and everything built in, so whatever amp effect I turn on also affects whatever is playing out of the loop pedal if the loop pedal is plugged into that amp. For instance, I might want to play chords with my acoustic, and then play electric guitar over it with distortion. For this reason, I use an old smaller amp to play whatever is coming out of the loop pedal and I use my larger amp to play over the loop. Right now if I want to switch a guitar from the loop pedal to the larger amp I have unplug the 1/4" cable from the loop pedal and plug it into the amp. I would rather have switches that allow me to switch where the output from each guitar goes (either through the loop pedal into the smaller amp, or straight into the larger amp). I bought four double pole double throw toggle switches (on - off - on), but then I got to thinking that I might be able to accomplish my goal with just two of these toggle switches. Here is a link to I wiring diagram I drew up showing how I think I can accomplish my goal with just two toggle switches:


Guitar Switch Possibility by Josh2566, on Flickr


My plan would be to only have one switch in an "on" position at any given time. The other switch would be "off." However, would any problems arise if I accidentally had both switches in "position 1" or both switches in "position 2" at the same time? Both of these cases would basically result in both guitars being connected together and to one of the amps. Could that hurt anything if it did happen? I was wondering if I could maybe use some diodes to keep any current from going the wrong direction to a guitar, but I'm not quite sure how it all works. Or I could just go with my original idea and use four switches, but I would like the end result to be as simple as possible (the fewer the switches I have to flip the better). Any suggestions are appreciated. Thanks.

[ashcatlt]

It's not going to damage anything, but it probably won't sound great. The electric guitar will lose a whole lot of treble connected to the low-Z output from the acoustic which I assume has a preamp in it. That preamp will probably drive the electric in parallel with the amp without tone suck, but there may be some overall attenuation. Basically, just not ideal.

With just one DPDT switch you could make sure that you never "cross the streams". One guitar would go one way while the other goes the other. Flip the switch and the swap. Course then you'd have one guitar not being played but still "live" to contribute noise and/or feedback. The guitar's volume might solve that issue.

[josh2566]

Thank you for your reply. My intention would be to only have one guitar “live” at a time. So normally I would have the other switch off altogether. So if accidentally having both switches in the same position wouldn’t hurt anything then I think I’ll be ok, since normally I will only have one switch on at a time. I just wanted to make sure accidentally having both switches in the same position wouldn’t hurt anything in case I did forget to turn one off.
Also, when you talked about doing it with just one DPDT switch, did you mean only one switch total, or one switch in addition to what I already have planned? If you meant just one switch total, I would like to be able to use both guitars for either the loop pedal or the larger amp. So I don't really want to have just one guitar only able to go to the loop pedal, and the other guitar only able to go to the larger amp. If there is a way to wire it with one switch so that either guitar can go to either the loop pedal or the larger amp please let me know. Thanks again.

[ashcatlt]

Can you please re-read my post and ask specific questions about the parts you don't understand? My reply to your most recent will be pretty much exactly the same.

[JohnH]

Welcome to GN2

A dumb question - but its still early here:

You could just plug your acoustic to the loop then to the first amp, and seperately run the electric to amp No. 2 - no switches or unplugging needed.

So what beyond being able to do that, would you want from the switched system?

cheers
John

[long813]

Dec 30, 2012 16:45:49 GMT -5 JohnH said:

Welcome to GN2

A dumb question - but its still early here:

You could just plug your acoustic to the loop then to the first amp, and seperately run the electric to amp No. 2 - no switches or unplugging needed.

So what beyond being able to do that, would you want from the switched system?

cheers
John

And you could add the circuit breaker jacks for the instrument cables to eliminate the hum.

Simple, if that's all you wanted.

[josh2566]

Dec 30, 2012 16:45:49 GMT -5 JohnH said:

Welcome to GN2

A dumb question - but its still early here:

You could just plug your acoustic to the loop then to the first amp, and seperately run the electric to amp No. 2 - no switches or unplugging needed.

So what beyond being able to do that, would you want from the switched system?

cheers
John

That only allows for one situation--looping chords with my acoustic and playing over them with my electric. I want to be able to also loop things played with the electric guitar, which means I have to be able to switch where the output of the electric guitar goes. Also, I might want to play the acoustic guitar through "Amp 2" while a loop is playing, so I also need to be able to switch where the output of the acoustic guitar goes. Lastly, I may want to play chords into the loop pedal with the acoustic guitar and then dub over those chords in the loop pedal with the electric guitar. So I need to be able to easily switch both guitars between both amps.
I can play whatever I want into the loop pedal with whatever guitar I want and then unplug the guitars and plug whichever one I want to use into the larger amp (which is what I do now), but I'm trying to avoid always unplugging and plugging in while things are on. Just a project I wanted to work on.

[josh2566]

Dec 30, 2012 15:25:54 GMT -5 ashcatlt said:

Can you please re-read my post and ask specific questions about the parts you don't understand? My reply to your most recent will be pretty much exactly the same.

How can I use one DPDT switch to "swap" which amp each guitar goes to?

[sumgai]

josh,

Hi, and to the NutzHouse!

ashcatlt is correct, no damage will result from mixing the two guitars into one amp's input, whereas the sound of that mixture will likely suck pretty big-time.

So to avoid that possibility, you described a switching arrangement that we call an A/B-X/Y box. This thing switches input A to either output X or output Y, and input B to the opposing output, such that the two inputs never go to the same output at the same time. Here's the relevant thread on that, with diagrams that I think you can follow:

guitarnuts2.proboards.com/index.cgi?board=fx&action=display&thread=3913


If you still have questions, you can ask them either here or in that other thread, you'll get an answer either way.

And whatever else you do, post samples of the results, or it didn't happen! ;D


HTH (Hope That Helps)





sumgai


EDIT:

I see that you posted the same time as I did.....

A DPDT switch will allow you to choose, with one switch, A into A and B into B or the opposite way. However, your first post did state that you sometimes wish to play into the looper, and then play again over the top of the looper's output. Now I may have misunderstood, but I took that to mean that you "want it both ways" - you can play one guitar into both amps, or both guitars into one amp, as you felt at the moment. (And as you drew up your initial diagram.) This lead me to believe that you ultimately wanted two guitars into two amps, though not necesarily both and both, at the same time.

All this comes of course from the fact that if you wanted strict isolation, you'd merely play guitar A into the looper and amp X, put that down and pickup guitar B and play it into amp Y - no switching needed! Since you asked for switches.....

HTH

[ashcatlt]

Dec 30, 2012 17:18:05 GMT -5 josh2566 said:

Dec 30, 2012 15:25:54 GMT -5 ashcatlt said:

Can you please re-read my post and ask specific questions about the parts you don't understand? My reply to your most recent will be pretty much exactly the same.

How can I use one DPDT switch to "swap" which amp each guitar goes to?

Your diagram above uses half of a DPDT switch (or an SPDT) for each input. Flip one of them over and stick them on the same switch and you're done. I would use a basic on-on, though. On-off-on will work fine, but in the center position you'll have neither guitar connected to either amp in the middle, and open cables acting like antennas feeding the amps instead.

[josh2566]

Dec 30, 2012 17:22:25 GMT -5 sumgai said:

josh,

Hi, and to the NutzHouse!

ashcatlt is correct, no damage will result from mixing the two guitars into one amp's input, whereas the sound of that mixture will likely suck pretty big-time.

So to avoid that possibility, you described a switching arrangement that we call an A/B-X/Y box. This thing switches input A to either output X or output Y, and input B to the opposing output, such that the two inputs never go to the same output at the same time. Here's the relevant thread on that, with diagrams that I think you can follow:

guitarnuts2.proboards.com/index.cgi?board=fx&action=display&thread=3913


If you still have questions, you can ask them either here or in that other thread, you'll get an answer either way.

And whatever else you do, post samples of the results, or it didn't happen! ;D


HTH (Hope That Helps)





sumgai


EDIT:

I see that you posted the same time as I did.....

A DPDT switch will allow you to choose, with one switch, A into A and B into B or the opposite way. However, your first post did state that you sometimes wish to play into the looper, and then play again over the top of the looper's output. Now I may have misunderstood, but I took that to mean that you "want it both ways" - you can play one guitar into both amps, or both guitars into one amp, as you felt at the moment. (And as you drew up your initial diagram.) This lead me to believe that you ultimately wanted two guitars into two amps, though not necesarily both and both, at the same time.

All this comes of course from the fact that if you wanted strict isolation, you'd merely play guitar A into the looper and amp X, put that down and pickup guitar B and play it into amp Y - no switching needed! Since you asked for switches.....

HTH

Thank you very much! Although I may not have explained my intentions well, you have lead me to what I believe is my solution (and possibly what others were getting at, but I didn't catch it right away). I will use one DPDT switch to chose the input, and the other DPDT switch to choose the output. This way I can choose either the acoustic or electric guitar with "Switch 1" and then choose to output that guitar to either "loop pedal/amp 1" or "amp 2" with "Switch 2." Only one guitar will be live at a time which is exactly what I want, and there will be no chance of crossing the two guitars. Not sure why I didn't think of this first, but I think it will work just fine (unless anyone sees any problems resulting--new diagram below). Thanks again to everyone.


Guitar Switch Possibility (2) by Josh2566, on Flickr


ADDITION:
I should also mention that my DPDT switches have 6 terminals. In my diagrams each colored "wire" going to a "terminal" is actually a 1/4" guitar cable going to a pair of terminals on the switch. So each colored wire in the diagram going to a switch terminal is actually using two of the 6 terminals for that switch (one for the lead of the 1/4" cable, and one for the shield of the 1/4" cable). I tried to simplify it in the diagram, sorry for any confusion.

[josh2566]

Dec 30, 2012 17:35:28 GMT -5 ashcatlt said:

Dec 30, 2012 17:18:05 GMT -5 josh2566 said:

How can I use one DPDT switch to "swap" which amp each guitar goes to?

Your diagram above uses half of a DPDT switch (or an SPDT) for each input. Flip one of them over and stick them on the same switch and you're done. I would use a basic on-on, though. On-off-on will work fine, but in the center position you'll have neither guitar connected to either amp in the middle, and open cables acting like antennas feeding the amps instead.

I think I just finally realized what you're talking about. I was thinking I had to use two terminals on a switch for each 1/4" cable (one for the lead, and one for the shield). However, can I just run the leads to the switch terminals and do something else with the shields (like splice them all together)? Then I can do what you said where in one position guitar 1 goes to the loop pedal and guitar 2 goes to amp 2, and then in the other position guitar 1 goes to amp 2 and guitar 2 goes to the loop pedal. Yes, both guitars will be live at the same time, but never both going to the same amp. Like you said, I can just use the volumes on the guitars to eliminate any noise from them while using the other guitar. If this is what you were talking about I'm just not sure what to do with the shield for each cable. Any suggestions? Thanks.

[ashcatlt]

Yep you got it! Your most recent post with the two switches is not a bad idea either.

What to do with the shields is where things might get hairy. You can just tie all of the sleeve terminals of all the jacks together (and to the metal enclosure while you're at it), but this could cause a ground loop and noise which wouldn't otherwise be there. You might be able to fix that by plugging both amps into a single power strip, or else you might need to isolate one of the output jacks. This will be true pretty much whatever switching you finally decide to use.

[josh2566]

Thank you all very much for the quick responses. I will have to decided which final direction I want to go (if I want to use two switches, or one switch and try to do something with all the shields without getting noise). I might also just make two separate switch boxes with a single switch each (basically split my second diagram in two). Then I could use the boxes individually if I ever needed to. Either way, I plan to post pictures of the finished project for anyone interested. Thanks again.

[ashcatlt]

Dec 30, 2012 18:44:16 GMT -5 josh2566 said:

Thank you all very much for the quick responses. I will have to decided which final direction I want to go (if I want to use two switches, or one switch and try to do something with all the shields without getting noise). I might also just make two separate switch boxes with a single switch each (basically split my second diagram in two). Then I could use the boxes individually if I ever needed to. Either way, I plan to post pictures of the finished project for anyone interested. Thanks again.

Great! Definitely let us know how it works out.

And now, this thread doesn't actually belong in Guitar Wiring.






EDIT: Right you are, ash.... moved to Effects Pedals it is. - sumgai

[josh2566]

I wasn’t sure if I should post this here or start a new topic. So I will start with it here since this is where all the previous info is.

Sorry for the long delay in my reply, but the switch box is complete and is working well. I bought a somewhat fancy index card box to house everything (pictures below—as well as a diagram showing the direction I went with the wiring). I had some bulk microphone cable so I used that for the wiring (I twisted both the inner lead wires of the cable together and used the shield as the ground). The two jacks on the front are the two inputs. The other two jacks, one on either side, are the two outputs. I use the switch on the left to choose which input is active, and the switch on the right to choose which output is active. There is a little bit of noise if neither guitar is being played depending on which amp I am outputting to and what effects are being applied, but the noise is not too bad. One thing I would’ve done differently would be to have used switches with no off position. There seems to be more noise when the switches are in the off position, I’m guessing due to there being no ground when the switches are off because of the way I wired it. And there really isn’t much of a reason for me to have the switches in the off position. Besides that minor issue the box works great, thanks to everyone for the help.


Switch Box by Josh2566, on Flickr


Switch Box Wiring Diagram by Josh2566, on Flickr

[ashcatlt]

Looks cool and glad its working out for you.

The noise comes from having the "hot" wire of the cable connected to the amp input and open at the other end. It acts exactly like an antenna injecting all the EM noise flying around the room directly into your amp. It would be much better to short the unused output hot to ground. The way you're switching the grounds doesn't really allow this without another pole on the amp select switch, and you'd need an on-on-on to short both in the middle position.

You don't actually have to switch the grounds, but the way you've got it now in a non-conductive box manages to avoid the whole ground loop issue.

[JFrankParnell]

Well, it's a pretty cool box, I dont think we've seen anything like it

But, i'm surprised you didnt go with stomp switches. That would have worked pretty well, as you could have got your rhythm going, and probably stomped both switches at once to change over to lead.