Playing through a two-amp setup

Discussion in 'Amp Central Station' started by heshan, Jan 17, 2018.

  1. Clash Telecaster

    Clash Telecaster Tele-Meister

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    Man, you are talking way over my head there. Phase correction? All I know is that the Morley is user-friendly. It has no noise when you switch. It does not affect tone.

    Just so happens I was monkeying with my Morley today. The power of playing through two amps spread out in my music room is a cool trip.

    I was also monkeying with my BOSS footswitch. If you don't have one of these, I'd suggest one. Great investment. Can turn things on and off cleanly, silently, easily. This one is also unlatch. Can do a momentary on or off.

    [​IMG]
     
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  2. PeterUK

    PeterUK Poster Extraordinaire Silver Supporter

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    I have the Switchbone too and it’s one of my all time top three purchases.

    No affiliation either but a superb product. I normally use it with my Deluxe Reverb plugging into both channels and switching between the two or both at the same time.

    I’ve also used it for amp switching. My favourite was using my DR and an AC30 than was onstage and belonged to another band playing that night. That was tonal heaven.

    The clean boost is awesome and I use it for soloing.

    :) Peter
     

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  3. heshan

    heshan Tele-Meister

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    @Clash Telecaster I'm just going by the stuff I've been reading lol. Thanks for your suggestions!

    @PeterUK Thanks for the recommendation, I'm looking at one of the Radial switchers for sure
     
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  4. heshan

    heshan Tele-Meister

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    One more question, maybe a bit of a dumb one but here goes: Is there any difference between plugging both amps (both with 3 prong cords) into one power strip vs. plugging them into two wall sockets?
     
  5. thefruitfarmer

    thefruitfarmer Tele-Meister

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    Same socket for both amps and pedalboard is best.
     
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  6. whoanelly15

    whoanelly15 Tele-Holic

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    Stumbled across this. Dave is a boss.
     
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  7. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    You want to make sure and share a ground. Using a power strip will do that. Using the two plugs on one wall socket is fine.

    Using two completely different outlets on different walls “might” or might not share the same circuit.
     
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  8. heshan

    heshan Tele-Meister

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    Thanks guys :) So using both amps plugged into a power strip should at least fix the noise issue, if not the phase issue (if there is an issue) and its safe coz both amps are grounded. Sorry I keep going on about the safety part but I had a bad experience with electricity when I was younger! Hahah
     
  9. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    Yes. This will prevent shock hazard and ground loop noise.
     
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  10. heshan

    heshan Tele-Meister

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    Thanks a lot for all the help, everyone! Always a pleasure learning new things from you guys. I'm gonna get home Sunday and try plugging both amps into a power strip and seeing how it goes! And I definitely have my eye on the Radial Bigshot ABY
     
    Last edited: Jan 20, 2018
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  11. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    Are you on the road? Don’t text and drive!

    Be warned, it’s going to sound huge! Be sure and post an update...
     
  12. moosie

    moosie Doctor of Teleocity Ad Free Member

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    I disagree. Plugging both amps into the same socket *might* solve the ground loop hum issue. Might not.

    The issue is that with both amps connected by many of the more basic A/B/Y pedals, or probably most any stereo pedal, there's no isolation. This means that the return leg (common, running to ground) is common to both amps. So, theoretically, an electron trying to find it's quickest path back to the wall, might not always take the direct route, right out of the amp. Instead, some current will likely flow through the common leg of the instrument cable running to the A/B/Y, and then out the other side, to the other amp, and then, finally out to the wall.

    This creates noise.

    The quietest circuit will have a very controlled path for the return, or common. Best practice these days seems to be to either elevate the common above chassis ground, and then feed it to the chassis at a single point only, or if not elevated, at least funnel all returns through one location for the preamp, and another location, far away, for the power section. This keeps high current flows from stomping on sensitive preamp inputs. Part of the problem is that most older (and even not so old) amps ground everything to the chassis, at any handy point. The whole chassis becomes one big ground plane, with potentially criss-crossing current flows at different potentials.

    Even the best constructed amps (two of them) will suffer if there's one more path to ground introduced through the input instrument cable. Namely, back to the A/B/Y, then out through the other chassis.

    An active A/B/Y, with an isolation transformer and ground lift, will eliminate the problem.


    EDIT: the same situation exists when you plug an outboard reverb tank into your signal chain. You've got another "amp" (read: high voltage power supply, driving preamp tubes), which connects to the guitar amp in two ways. First, through the shared common at the wall. Or even different wall outlets, it's all ultimately 'ground'. And second, through the common leg of the instrument cable that connects them together.

    It's more difficult to correct the issue here, because there's no A/B/Y with transformer involved. The same would be true with any effect pedal, not just some big tube 'effect' like the 6G15 outboard unit, except they're all ground-isolated from each other, and the amp. Either they're battery powered, so no wall connection, or they connect through a step-down transformer, which isolates at the same time as it converts 120VAC to 9VDC.

    The preferred solution for the outboard unit, and the one which Fender uses in their reissue, is to 'elevate' the common above zero volts ground, and then connect to the ground only through a single point with a small network of resistor, cap, and safety diodes.
     
    Last edited: Jan 20, 2018
  13. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    True, it might not prevent ground loop noise, but the OP’s main concern was with the safety of it, so I didn’t go into detail.

    A good ABY with isolation, ground lift and is obviously the best solution, but it won’t hurt to try it and find out.

    No need to spend the money if it works without doing so.
     
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  14. heshan

    heshan Tele-Meister

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    @moosie thanks a lot for the explanation! I understand what you're saying (I think!). Very useful to know all this. A proper A/BY switcher is looking like a necessity now haha!

    As @JustABluesGuy said, I was primarily worried about safety so I'll give it a shot with the power strip anyway and see how it goes.
     
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  15. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    I’m glad @moosie weighed in with a much better explanation of the how's and why’s of what to expect than I am capable of.

    You probably will end up with an ABY of some kind if you are serious about a two amp rig, and I recommend it. If I had owned a stereo pedal of any kind, I would have tried that first, for grins though. It works for some people.

    I didn’t have one, and didn’t want to do stereo, but rather wet/dry and/or clean/dirt as well as either/or, so I went straight to a decent ABY out of necessity.
     
  16. moosie

    moosie Doctor of Teleocity Ad Free Member

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    You know how it is, a thread goes on for days, and you've read it all, but not just now.

    I forgot that was the intial concern, and I was just responding to @heshan's summary comment that "it should fix the noise issue".

    Sorry if it got off-topic.

    It's a hot button for me, since I just finished building a Revibe unit, which like the outboard reverb unit, is extremely susceptible to ground loop noise. I elevated the DC common, and it's quiet as a mouse. :)
     
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  17. JustABluesGuy

    JustABluesGuy Friend of Leo's

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    You didn’t go off topic at all. Far from it, as he was concerned about possible noise as well. As I was writing I figured I would get called on the noise issue, but was too lazy (and ignernt) to try and explain all that stuff you explained so well. ;)

    Your only mistake was not weighing in sooner!
     
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  18. heshan

    heshan Tele-Meister

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    @moosie I'm glad you pointed it out. Because, as you can see, I summarized that the power strip trick would solve the noise issue, and I was starting to wonder why everyone wasn't simply doing that! Haha. Now, even though I admit I don't 100% understand why, I realize that it's not a guaranteed solution. Thanks for explaining. Thanks to everyone who weighed in, actually

    I got delayed and am still away from home so I'm unable to try plugging my amps into a power strip and splitting via my stereo pedal. I'll post back here once I do. Cheers!
     
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  19. thefruitfarmer

    thefruitfarmer Tele-Meister

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    It is worth trying two amps, if you have the facility though, it does sound great.

    I ended up getting a palmer splitter box powered by battery, which does the trick. It has the phase flipper and ground lift.

    A time will come when I will want the radial, or something similar though.
     
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  20. AlbertaGriff

    AlbertaGriff Tele-Afflicted

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    Wow this was an interesting thread.

    I've played through two amps for YEARS and never had, and never thought about, phase issues or getting zapped. Granted, all my amps are grounded.

    I have never used an AB pedal, only stereo pedals (Boss DD-5/6, Fulltone Supa Trem 2, etc) and I've never had an issue, besides wanting to play for longer than I was able to, or maybe the volume getting too high.
     
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