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People that use an A/B setup

Discussion in 'Amps and Cabs' started by Baba, Aug 18, 2005.

  1. Baba

    Baba Supporting Member

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    If you A/B/Y to two different amps, would a simple A/B/Y switch work, or is there any ground loops or noises I should be concerned about?
     
  2. teefus

    teefus Silver Supporting Member

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    i have used a whirlwind selector for this with two different amp set ups and never had a problem with gorund loops or noise.
     
  3. Chiba

    Chiba Gold Supporting Member

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    As long as you don't have any ground loops, a simple ABY will do the job. The only problem is you can't tell if you'll have a ground loop until you hook up an ABY.

    Without dissing anybody's products, I'll just tell you that I've used a metric half-ton of different ABY boxes, and the only ones that work worth a crap are powered in some way. In my experience, passive ABY boxes aren't good for amp switching - they've all given me trouble in one area or another (tone suck, pops, ground loops, failure, etc.).

    I've been using a Tonebone Switchbone for the last year or so and it works fine. Turns out my amps DO create a ground loop when hooked up together, but the SB has a ground lift, so problem solved.

    The SB is certainly not the only good ABY out there - Lehle, Framptone, and several others make excellent powered ABY boxes.

    --chiba
     
  4. Baba

    Baba Supporting Member

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    Hmmm, two completely different responses, interesting!

    I was hoping I COULD get away with the Morley/Whirlwind type, but maybe not???
     
  5. teefus

    teefus Silver Supporting Member

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    the whirlwind selector is an optical switcher, 9v dc powered. i have never had a ground loop when using 2 pv c30's, a rivera bm60 and a valvetech hayseed custom. to the credit of the switchbone, i think it has a built in boost switch too.
     
  6. bluesmostly

    bluesmostly Member

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    I got the Switchbone on Doug Roccaforte's advice "it is the best amp switcher, period" I think he said.

    It really is awesome. No tone suck, noise or pops, and it takes care of hum and hiss and ground loops.

    As a bonus it has a nice boost and a separate output for the tuner that takes it out of the signal path - I really love that feature.

    Good luck
     
  7. Killa-B

    Killa-B Member

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    The switchbone is pretty nice, but I like the Kendrick ABC box much more. It's AC powered, 3 discreet transformers drive the signal so there is zero tone suck and it's one better than the A/B/Y setup. You can often find them for about $125-150.

    There are simple ways to lift a ground loop if you run into that. One is using one of those adapter plugs with tab and reversing the plug of one of the amps. Everything is still grounded through the chasis of the grounded amp or your switchbox.
     
  8. MuseCafeChris

    MuseCafeChris Senior Member

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    In my experience you really hear the tone suck with these in Y mode, running both amps at the same time. One on/one off, I'm sure there's some compromise there but if so barely discernible.
     
  9. Baba

    Baba Supporting Member

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    I've got either a switchbone or headbone on the mind, just trying to see if I could get away with it on the cheap.

    I was also able to find a lot of info with a search here. Thanks for the input guys.

    P.S. - You guys suck, never would I have thought about running two amps and switching if it weren't for this place!
     
  10. GAT

    GAT Gold Supporting Member

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    I use a Lehle 3/1 or Dual for two or three amps live. Works perfect. Joe Bonammasa uses the Lehle 3/1 also. Had bad luck with the Switchbone.
     
  11. riffmeister

    riffmeister Gold Supporting Member

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    If the A/B/Y unit is not transformer isolated between the two channels, you will have ground loop hum issues. It's the physics of the matter, no getting around it, period.

    With a passive ABY such as a Morley or a Whirlwind, GLH can be minimized by plugging both amps into the same power strip, and it can be avoided entirely by lifting the ground on one of the two amps. As long as one of the two amps is grounded, you are safe.
     
  12. Steve Dallas

    Steve Dallas Supporting Member

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    I use a Lehle switcher to A/B/Y my amps. It includes an isolation transformer (or 2) and is switched with high quality relays. You can sometimes get away with a passive box if you modify one of the guitar cords going to one of the amps. You have to clip its ground so the amp gets its positive signal through the cord and the negative through the ground in the power cord.

    Whatever you do, don't defeat the ground on one of the amps! One venue with bad power and you are a dead fiddler!
     
  13. Baba

    Baba Supporting Member

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    So, riffmeister says to lift the ground on one of the amps, and s2amps says do not.

    Does it matter that I always run wireless? :D
     
  14. riffmeister

    riffmeister Gold Supporting Member

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    If you are using a passive ABY, lifting one of the grounds is safe. Of course, if the grounded amp develops a problem while you are using it, well, then all bets are off.....;)
     
  15. riffmeister

    riffmeister Gold Supporting Member

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    P.S. Before I got the Framptone ABY, I was using a passive Morley ABY. I solved the GLH problem with the Morley by lifting the ground on one of the two amps. And I live to tell about it! :p
     
  16. Steve Dallas

    Steve Dallas Supporting Member

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    Technically, you are not safe because you are now relying on a guitar cable to carry the ground from one amp to the other. That's OK for the signal ground, but not the power ground in case of a nasty short or spike. A guitar cable won't handle it, and you will become the new ground conduit.

    Best to lift the ground on the guitar cord and not the amp.

    I'm not sure how wireless plays into this. I think it might protect you...
     
  17. Chiba

    Chiba Gold Supporting Member

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    You can defeat the ground on your amp at the wall if you want to, but I'd like to refer you to LSchefman's recent post about his friend's sister that got electrocuted and died. Defeat the ground on your amp at the wall and that could be you.

    --chiba
     
  18. Supertgtr

    Supertgtr Member

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    Fulltone has an A/B switcher schematic on his web site that I'm currently in the midst of building. If you're good with a soldering iron, it's an easy cheap project.
    I'll let you know how mine turns out. I should be done with it this weekend.
     
  19. riffmeister

    riffmeister Gold Supporting Member

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    makes sense. thanks for the explanation. another reason I'm glad to have the Framptone ABY.

    :)
     
  20. Den

    Den Member

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    I'm also using the Radial Switchbone and thinks it's perfect. With my Rambler and Tomcat I'd be screwed without the groundlift feature. I also think the boost built into the SB is awesome. You can boost mids, or not and adjust the overall amount of boost ... very cool.
     

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