Amp Phasing Question

[Deshiakeb]

Hey all - I have a question about overall phasing of an amp. I have a Mesa Lonestar, a Fuchs ODS50 and a Marshall 1959slp. I would like to pair the Fuchs and Marshall with the Mesa like Joe, with the Mesa being the amp always on. So I was researching all this out and I came across this in my Mesa manual.


NOTE: Engaging the EFFECTS LOOP circuitry adds a substantial amount of circuitry and two tubes and this additional circuit reverses the phase of the entire amp. This is no cause for alarm and if we hadn’t told you of this, you probably would never have known. Sonically there is no difference other than the incredibly subtle difference in the sound the circuit itself adds. The only time you will ever need to consider this reversal of overall phase is if you ever run the LONE STAR in Stereo with another amp (not another LONE STAR as it would be in phase with its Loop activated). In this case you would probably want to separate the two amplifiers by at least a few feet if not on the other side of the stage.


I would like to keep the amps relatively close, but according to this it says I should keep them a part. Is there a solution to changing the overall phase of the amp (is doesn't have a polarity switch) and what would happen if I kept them close together. Is this even an issue or am I totally overthinking this? As for a switcher I haven't picked one out, but I'm leaning towards the Voodoo Lab amp switcher if that matters.

Any advice and help would be much appreciated.

Thanks,
Jack

 

[ecc83]

Hi Jack and welcome. AKAIK there is no concensus in the industry as to whether guitar amps are "inverting" or "non inverting" from input jack to speaker* or indeed, what happens to that polarity if an FX loop is used. (pedals are similarly always unspecified)

In the case of a combo you can always decide which amp is "right" and flip the speaker connections on the other. Heads are different because one side of the speaker jack is earth and making that the "hot" pin could be a danger to solid state amps.

If you need a phase (more correctly "polarity) switch box do not pay silly money for one. Any amp tech worth his salt should be able to make you one for $30 or so.

*Will check this in another place FULL of amp'sperts!

Dave.

 

[Gtoboy]

Or if, as it appears, you are splitting one signal to two amps simply wire a female TS connector to a male using speaker wire with the tip on one wired to the sleeve on the other. Short enough wire wont need shielding and this can be used on either the input or the speaker output. Plus if you use it as a "check" , all you have to do is try it with and without and if there are polarity issues the bass should be better in one configuration.