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DIY Stompboxes => Building your own stompbox => Topic started by: pjackso on May 16, 2005, 11:46:18 AM

Title: Channel Jumping...harmful?
Post by: pjackso on May 16, 2005, 11:46:18 AM
I know its not a pedal question but I'm curious if "Jumping" channels (plugging one channel into the other on the same amp) is harmful on '75 Twin Reverb?
Seems to sound great.  Way better than either channel alone...
Any insight would be greatly appreciated! :D
Title: Channel Jumping...harmful?
Post by: aron on May 16, 2005, 01:43:20 PM
I don't think there's any problem. People have been doing this for decades.
Title: Channel Jumping...harmful?
Post by: Ben N on May 16, 2005, 01:52:16 PM
Do you mean running a jumper from one channel input to the other?  No, not harmful.  If you like it, enjoy.  However, you will probably find that it results in lower volume (maybe not a bad thing on a Twin), cancellation oif certain frequencies (a matter of taste), and less effective controls.  This is because the channels of a TR, or any other Fender black or silver face era amp with reverb, are 180 degrees out of phase, because the "Vibrato" channel has three common-cathode (phase inverting) stages, and the "Normal" channel has two.  

Probably most people would prefer doing this with the channels in phase.  There a couple of ways to do this: modifying the amp to have reverb on both channels is a fairly popular, common, and not-too-difiicult thing for any amp tech and most DIY-ers.  Or you could reverse the phase of the signal going to the input of one of the channels.  Any single-transistor booster will do this; or check out the Adjusticator article at Geofex or the Mosfet Boost article at AMZ for more tailored DIY solutions.  Barber also makes a pedal pretty much intended for this, but I don't recall the name of it.

Ben