Amp Switchers (Page 1 of 2)

Phase issues can be had with different amplifier models as well as brands.  Some Fender amps are wired to be out of phase from the factory (the speaker actually pulls in when a note is hit instead of pushes out).  This is fine with just one amp or two of the same model.  If you run another amp whose phase is positive, then you run into sound waves canceling.  This occurs mostly in the lower frequencies and only happens when both amps are running simultaneous.  This is why their is a phase switch.  I read once Joe had this issue with his Dumble style amps and simply made a reverse speaker cable to fix it.

I got a Champion PURE AB-Y from championpedals.com for $109 shipped last month.   Jeremy is a one-man-show just starting out, but I couldn't be more pleased with it.  He made it a crazy lime green color for me, so it 'sticks out' on my already colorful pedal board!  Crazy leds, too.  Made an Orange one for the Orange T.T. (A side)and a dark, almost black/blue one for my Blackheart(B side).   "Y" of course is both at once!   It has transistors so there's no troubles with it.  I have an Aphex ab-y that works with most amps, but I suppose it could be trouble with certain ones.  It was only $45 new.  I've used the Voodoo labs thing when I had three amps, and it's excellent, but pricey.

I just found a Radial Big Shot A/B/Y.  True Bypass, 180 degreee phase inverter and a switchable transformer to eliminate hum for $77 on eBay.  It's passive so there's no power supply needed.  Anyone use this or heard anything about it?

Amps will be a Fuchs ODS and a Marshall 25/50.  Or any combination of Mesa Boogie MKIIB, DC5, Fuchs and Marshall.

I've used one. They are great, but because they are passive there is no light to tell you A, B, or both. It's a small thing, but is a small negative in my opinion.

A couple weeks ago I saw a Lehle 1@3 used in perfect condition. I bought it for 100 bucks. Sounds great, no noise or anything. I found out that it's one of the 200 original like JB has. Really proud of it. I don't like the look of the new ones. I prefer my original .

I use the 'A.r.t. Coolswitch' ABY switch... I usually leave em both on at the same time so I get the blend of the two Marshall's I use  but hey, when I use one or the other now and again, the switching works fine, no power supply needed, and less than £40 here: www.absolutemusic.co.uk
Rus

Keeley Framptone 3-banger has been awesome.  Not cheap unless you find one used which I did 3 weeks after I bought a new one, used it was at $180 usd.  Spent around 300 on mine but it's a fair piece of kit.

At the risk of being redundant, the phase switch can be used in a multi-amp setup to quickly match the phases so that the speakers of both amps are pushing air in the same direction at the same time.  If the signals are out of phase, the result is that one amp's speakers are driven forward at the same time as the other amp's are driven backwards.  The tone suffers because the sound waves partially cancel each other, or it causes a phaser effect. 

A quick way to test for phase alignment is to play with both amps facing the same direction and listen to the sound.  Then, turn one amp around and listen again.  If it sounds better with one amp turned around, the amps are out of phase.  This is where you could use the phase switch to correct the problem by switching the phase of one signal path on the switcher.  Without a phase switch, you would have to reverse the polarity of one amp by swapping the positive and negative wires on the speaker cable.

As was mentioned earlier, it is important to do this with everything hooked up; otherwise, pedals can introduce phase issues.

Keep in mind that ground loops and hum can be caused when the power (amp OR pedal) is not shared by both rigs.  To minimize noise, you need to make sure that the amps are powered by a common outlet and the signal path to each amp is completely isolated.  Sharing pedals by both amps may cause hum unless the effects loop/switcher has a ground lift feature.

Always, ALWAYS test outlets for a proper grounding and DO NOT use ground lifters on power plugs.  Improper grounding in multi-amp rigs can kill you.  I feed all my amps through a single inline ground fault power cord and I test the outlet I plug it into with an outlet tester (Home Depot - $10).  Joe said in one of his posts that he's been zapped more times than he can remember - perhaps that is one of the reasons why he uses a wireless setup. 

Hope this helps.

EDIT:  Here's a link with a good illustration of the grounding concepts mentioned above http://www.pedalsnake.com/page.php?id=1113