Two amps and no hum

[George Moore]

 I would like to build an A/B/Y transformer isolated channel selector / hum eliminator for running two amps.
Is there a way to DIY this configuration, without buying a Lehle ABY switch / hum elimimator ?
Seems like amps with reverb iron and ot do this, a second output drives the reverb and somehow [sometimes] it is mixed back in to the signal it paralleled without major hum issues.
Would not a reverb transformer have isolated output ?
Can a reverb transformer secondary output like Fender used be made suitable for an input to another amp ?
6g15 schematic or Princeton have transformers, can the reverb input /transformer secondary signal be worked with, or perhaps a transformer with different turns ratio.

[GGBB]

BYOC makes a clone: http://buildyourownclone.com/products/amp-selector-and-stereo-fx-router.

[PRR]

Guitar pickups, and most stomp boxes, don't drive transformers well.

Reverb transformers are high voltage ratio. We don't want a different voltage, so this is awkward. They are also really "table radio" OTs, not intended to do well below 150Hz. This crimps the bottom octave of guitar. (The reverb tank doesn't like bass so this is fine for reverb.)

Unity-ratio transformers are readily available for telephone and pocket-radio applications. These are specced only to 300Hz; but R.G. used opamp grunt to overcome this over the full guitar range. Works with heftier transformers also.
http://www.geofex.com/FX_images/humfree2.gif

He also has an active ground-cancelling scheme which is effective if ground differences are small.
http://www.geofex.com/FX_images/oaspltr.gif

[wavley]

Guitar pickups, and most stomp boxes, don't drive transformers well.

Reverb transformers are high voltage ratio. We don't want a different voltage, so this is awkward. They are also really "table radio" OTs, not intended to do well below 150Hz. This crimps the bottom octave of guitar. (The reverb tank doesn't like bass so this is fine for reverb.)

Unity-ratio transformers are readily available for telephone and pocket-radio applications. These are specced only to 300Hz; but R.G. used opamp grunt to overcome this over the full guitar range. Works with heftier transformers also.
http://www.geofex.com/FX_images/humfree2.gif

He also has an active ground-cancelling scheme which is effective if ground differences are small.
http://www.geofex.com/FX_images/oaspltr.gif

What Paul said.  I've messed around A LOT with the Hum Free, it's fantastic.  If you play guitar in standard tuning, build it exactly as it is drawn.  If you down tune, play baritone guitar, or Bass VI... substitute the transformers for larger Edcor transformers with the same specs.  I have an open C guitar, a baritone, and a bass VI so I had to do the latter.

If your ground differences are small, the active ground-cancelling will work great with no loss of low end.

[stallik]

I'll also recommend the humfree. If you've not done so already, knock together a passive ABY before building an active circuit. You might not actually need anything more. I found this out after I built my humfree only to realise one of my leads had an iffy earth connection.
Also, make sure both amps are in phase or you'll defeat the object.