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I was looking at the back panel of this Fender Pro Reverb,
and it has both Effects Send/Return AND PreAmp Out/In jacks.
I was wondering what circumstances the Effects Send/Return
would be used instead of the PreAmp Out/In.
Or if there is a situation where both would be used?

I also noticed the Effects Send/Return has a button that gives you a choice between Series or Parallel.

Which is preferred under what conditions?

I hope this isn't too stupid of a question, but my Peavey amps only have what they call EFX Send/Return jacks,
and my Fender Hot Rod Deville only has what they call a PreAmp Out/In jacks.
Neither have both EFX and PreAmp jacks, yet but both seem to have the same sound and tone when I insert an effect in the jacks.
Is the signal for an EFX loop tapped from a different place in the circuit than for the PreAmp In/Out?


moonbaby Thu, 08/09/2007 - 10:14

Yes, yes, and ...yes! That Pro sure offers a lot of flexibility, eh?
SERIES:This is where the entire signal is routed from the preamp, to the Send jack, which you would then route to the effects'unit(s) input. The Return jack will then route the effects'output to the remaining preamp circuitry. This is especially useful for processors like compressors and equalizers, as well as effects that have onboard mixing. Also good for effects like chorusing or flanging, where the blend of processing is done by the factory to get the desired results. This acts like an insert loop of a mixing board channel.
PARALLEL: This is where the signal is internally 'split'. This routes a portion of the signal to the effects' Send, while the signal ALSO still goes through the entire amp circuitry, simultaneously. The Return jack is then mixed back into the "preamp>power amp" signal chain. This works best with delays and reverb type effects. This acts more like an 'Aux Send' and Return on a mixer. The effect and 'dry' signal run in parallel...
The Preamp Out/Power Amp In are almost always Series. And the tap of the Preamp out is directly before the power amp. This, too, can be a useful place to route an EQ or compressor, especially "line level" rack-type gear, as opposed to "stompbox" type effects. So, basically, stompboxes should be patched at the effects Send/Return, set either to Series or Parallel, while rack gear would go thru Pre Out/Power Amp In.
Have I confused you enough? To make matters more confusing, there really is no industry standard over "where" the signal is actually tapped, or how they are named. Some Peaveys are Preamp Out-to-Power Amp In, some are 1st Preamp section Out to 2nd Preamp section. Who knows? The factory, but you can experiment and see what works best with your individual playing and effects.