How to share an FX loop chain between 2 amps ?

Discussion in 'Amp Central Station' started by Ziggy587, Aug 4, 2021.

  1. Ziggy587

    Ziggy587 Tele-Meister

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    I wasn't sure if I should have posted this in the amps or the pedals forum.

    So I have a pretty straight forward setup right now: A chain of pedals going into the input of a half stack, and a chain of pedals at the effects loop. But like most guitarists, I can't leave well enough alone, so I'm adding a second amp head to my set up. I'm not planing on ever using this for a live setup, just studio. The second amp head is just so I can get different tones.

    Sharing both heads with the speaker cab seems simple enough. My speaker cab has stereo inputs, so I'll just utilize that. The effects chain for the input seems simple as well. I could either use a pedal that has a stereo output, or buy or build an A/B/Y box.

    But what are my options for sharing my effects loop pedals between the two amps? Being that this is only for a studio environment, I could just unplug the send/return cables from one amp and plug them into the other. But it would be a lot easier if I had a footswitch option for this instead. I'm really only interested in A/B'ing the amps, if I could Y the effects loop pedals to both heads that would be a nice bonus to experiment with, but I'm really only interested in A/B switching.

    I just looked through a bunch of switching pedals and didn't really see any specifically for this purpose. I found a few that have a guitar input/output and then two switchable loops. Would it be possible to use this type of pedal? They were kind of pricey though.

    Does anyone know of anything I could build? I could probably figure something simple out, but I'm always interested to see what other solutions people have cooked up.
     
  2. Zoso420

    Zoso420 Tele-Meister

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    If you have a stereo delay in the loop send one side to the return of one amp and and the other side to the return in the other amp
     
  3. Bluego1

    Bluego1 Tele-Afflicted

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    You could get a couple cheap Donner aby pedals and use them however you need them. Two send cables input to a and b then an out cable from the y to the input of your first loop pedal. The other side would be out of your last pedal into the y and then a and b going to your return jacks.
    I have no idea if that would work. It seems like it could just be nasty. A bad nasty.
     
    Last edited: Aug 4, 2021
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  4. Ziggy587

    Ziggy587 Tele-Meister

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    So here's my thoughts for a simple A/B pedal. Sorry for the crude drawing.

    [​IMG]

    Then the middle pole could be used for two LEDs. But doing it like this, that would mean I would have to tie all of the grounds together. Would that give me an issue?



    But wouldn't that bypass the preamp of one of the amps?
     
  5. glenlivet

    glenlivet Tele-Afflicted

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    "that would mean I would have to tie all of the grounds together. Would that give me an issue?"

    I would think it would be fine. So long as everything uses the same ground/grounding point ground loop issues *shouldn't* happen. Maybe make sure both amps are plugged into the same power strip, or make sure they are running off the same circuit. But...if you're only using one amp at a time....it might not matter, in that the 3PDT switch would isolate the other amp.
     
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  6. Ziggy587

    Ziggy587 Tele-Meister

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    Thanks!

    So I just had some thoughts... If I wire the switch like the above diagram, one amp will always be "dead." By that I mean, if I A/B the input of both amps, if I switch to another amp without also switching the effects loop I'll get no sound. The way to overcome this would be to simply switch both A/B boxes at the same time, which is fine in a studio setting but not so much in a live setting. Even though I'm not planning on using a setup like this for playing live, I had two ideas to overcome this.

    One, I could build the effects A/B switcher as well as the input A/B switcher into the same enclosure. I mount each 3PDT switch close to each other. Then I tool a piece of wood or metal to fit over the top of each switch, I could even tap for a small set screw for each switch so it never comes off accidentally. Then stepping on the bar should actuate both switches (in a perfect world). Of course, I know some of these 3PDT switches are fairly hard to actuate, and this approach may lead to one switch engaging but not the other.

    Or two, I make it so that the effects loop switcher doesn't leave one amp in a dead state. I could use a 4PDT switch. Again, sorry for the crude diagram...

    [​IMG]

    So jumping each send/return to the extra two poles will connect them together while the other side goes through the effect pedals. There's a few drawbacks to this approach, however. One, since one side is not running through any pedals, it's now running through two long cables without any buffers. Two, this leaves no extra pole for LEDs. And three, 4PDT switches aren't as easy to come by and are kind of expensive when compared to 3PDT switches.

    I also had the idea that if grounding is an issue, I could use a 4PDT switch where the two extra poles are for the grounds. But I think I'll go with my first diagram first and see what happens.
     
  7. mexicanyella

    mexicanyella Friend of Leo's

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    This sounds like an impressive and flexible setup idea, but if you already have all the effects and both amps available to experiment with...are you sure you want all the effects available equally through both amps simultaneously?

    If you haven’t already, I’d recommend also trying both amps in a few different wet/dry combinations, or with different effects to each; sort of capitalize on the differences and then blend them. That might yield a tone you liked more, and would require different routing solutions but maybe simpler switching.

    Not trying to discourage your idea, just wondering if you’ve tried those combinations before setting up your routing.
     
  8. City Sirens

    City Sirens Tele-Meister

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    The German company Lehle has pedals to deal with this exact situation.
     
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  9. Big Twang Theory

    Big Twang Theory Tele-Meister Silver Supporter

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    +1 for trying a wet/ dry setup. If the same effects in both amps is a must, I'm sure there's a way. But I know after I tried wet/ dry I haven't gone back. It just makes your rig sound HUGE. I'll even do it now on gigs where I bring a small amp. Last weekend I played a bar gig that volume wise, I just needed a Princeton reverb, but I brought a tweed champ to run as a dry amp. The difference is night and day.
     
  10. Lef T

    Lef T Tele-Holic

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    Mesa Head Track.

     
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  11. Ziggy587

    Ziggy587 Tele-Meister

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    Thanks, everyone, for the input!

    Running both amps at the same time is definitely something I would like to experiment with. To be honest, I've always been curious to do just that. But to elaborate a little on why I'm doing this, it's basically just to have a variety of tonal options at my finger tips. I have all of my effect pedals hooked up at once, which includes multiples of the same few effects. 2 flangers, 3 or 4 chorus, 2 phasers, 2 delays, 2 wahs, ect. I would never gig with this kind of set up. The idea is that I want access to this stuff when I'm writing, while the creative juices are flowing. If I'm coming up with a riff, if I stop to swap out chorus pedals then that might ruin the mojo I got going for the riff. Same goes for the new amp head.

    My "main" amp has been a JCM DSL, but I've been running an Orange Crush in the bedroom for a few years and it really grew on me. So I found a really nice and clean used Orange Crush head and decided to nab it. My goal is to be able to play any effect pedal I have on either amp at the drop of a hat. Thus, sharing one chain of effects in the FX loop of two amps.

    That said, at some point I'll definitely have to play out of both heads at the same time and see what that sounds like. Although that would require me to either have a stereo pedal that runs to the input, which currently I do not have (the only stereo pedals I have are in the loop) or get an ABY box. I'm most likely going to build a simple A/B box for now, mostly because I just dropped the money on the head so I don't want to spend more right now. But I'll keep an eye out for a good cheap ABY solution.

    They seem expensive. I poked around their website quickly and noticed that there were no prices listed LOL. Do any USA dealers carry this brand?

    That looks pretty much perfect for what I'm doing, although it costs more than the head I just bought LOL. It'd be nice if they made a version without the cab switching, since I have a stereo cab I don't really need that.




    Which reminds me... I got my JCM 4x12 cab on the cheap because it's a straight cab and the previous owner rewired it for a mono 16 ohm input. It still has the factory jacks and mono/stereo switch, but I wasn't too sure how to wire it so I always just used it as is. But now I'll need the stereo 8 ohm inputs, which if worst comes to worst I could just hardwire each pair of speakers as 8 ohm to a jack. But it would be nice to have that switch be functional if I can figure out how to hook it back up. If not, you guys may see a thread about that LOL.
     
  12. mexicanyella

    mexicanyella Friend of Leo's

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    I think I get where you’re coming from; if I’m understanding it you’re after maximum flexibility and inspiration possibilities for songwriting where you can select either or both amp “pathways” for any or all of the effects. What I wrote before was maybe me misunderstanding your intent, and was not intended to dismiss your idea or motivation in favor of mine.

    I’m thinking loop switchers are going to come into play, and you’re going to have fun going bananas setting it up, trying stuff. Looking forward to updates on what you go with.


    Speaking of two amps on a stereo-switched 4 x 12 cab...I used to know this metal guy who ran a Lee Jackson tube head into one half of a 4 x 12 and a solid-state Ampeg hi-gain head of some kind into the other. He had some rack multi-FX—Quadraverb or something—splitting the signal to both heads. It actually stacked up pretty neatly and he got some cool textured out of it. Always wanted to hear what he could do on drier, harder, more rhythmic riffing...I imagine an A/B setup might have been fun since the heads sounded pretty different from each other. But it seemed, after hearing what he was doing, like setting up a cab, two stacked heads and a small shallow FX rack was justified. He had a unique sound.

    If it would help, the guitarist I play bass with has Marshall 1960A and 1960B cabs and I think they are both 4/8/16-ohm mono-stereo switchable. He might let me unscrew the jackplate and take some wiring switching pics, if it would help you to see that.
     
    Last edited: Aug 5, 2021
  13. Big Twang Theory

    Big Twang Theory Tele-Meister Silver Supporter

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    If you do end up getting an AB/Y, I would recommend the Orange Amp Denonater. They're not too pricey on Reverb. They have isolated and buffered outputs (to avoid ground loop noise) and they have phase reversal to make sure your amps are in phase.



     
  14. Ziggy587

    Ziggy587 Tele-Meister

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    Yep, that's exactly what I'm going for.

    I think to start with, I'm going to just build some simple switch boxes. Mostly because I'm finding that existing products are too much money for me. And I already have all or most of the parts I would need to build them. It's mostly just 3PDT switches and TS jacks. At the worst, I can break them down and reuse the parts, and end up with an enclosure that I can't reuse.

    I think for the FX loop switcher, I'm going to build that first diagram I posted. I already have 3PDT switches on hand, so I might as well start with that. If I get any ground loop issues, then I might try a 4PDT switch instead.

    If it comes to using the 4PDT switch, I had an idea for that. I'll use one pole for the first amp and another pole for the second amp, a third pole for the LEDs, then the fourth pole to isolate the grounds. The grounds from the send/return of the first amp can be tied together and go to one side of the fourth pole. Then the ground from the send/return of the second amp could be tied together and go to the other side of the fourth pole. Then the grounds from the effects send/return can be tied together and go to the common for the fourth pole. Since you only need to make sure the grounds from each amp aren't connected to eachother, this should work. I'll just either have to use a plastic enclosure or make sure the TS jacks are isolated. But hopefully I wont have to go this route because those 4PDT switches are kind of pricey.

    Just thinking out loud... I guess another option would be to stick with the 3PDT switch and then try a "ground lift" switch using an addition SPST toggle switch. I'm not sure if this would work or not, I'm no EE expert. But if I take the ground from the send/return from one of the amps and route them through a SPST switch, then I could either have them connected or disconnected from the rest of the grounds. If I understand it correctly, the pedals would still have a ground signal from the amp that isn't ground lifted no matter which loop is selected, so there should be no issue.

    One thing I have to decide is if I want to keep the switcher with my pedals or at the amp. The usability pro and con are obvious. But then I have to also consider that if the switcher is on my pedal board, I would need FOUR long instrument cables running to the pedal board. If the switcher is up at my amp, then I only need the normal two long instrument cables going out to my board.

    If you would be willing and able to take a look at the wiring of that cab, that would be fantastic! To be honest, I could probably just figure it out myself using a multimeter. I'm just for some reason nervous about it, so confirmation would help with that.
     
  15. mexicanyella

    mexicanyella Friend of Leo's

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    I’ll see if I can catch up with him over the weekend and get a look at that cab...stay tuned
     
  16. Ziggy587

    Ziggy587 Tele-Meister

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    No rush, and no worries at all if he's uncomfortable with that!
     
  17. City Sirens

    City Sirens Tele-Meister

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    Yes.
     
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