mono to stereo effects loop issues

[LeoBurke]

I am putting an effects loop in an amp. IT is mono out stereo return. This all works fine. The two return signals are sent to two op transformers etc.

The problem i am facing is:
When the loop is NOT in use how do I get the signal from the preamp to two transformers?

Suggestions welcomed. Help!

Leo

[Enzo]

Wire the two return jacks together through their cutout contacts. Plugging into either one would then open the connection.

I am not sure what you mean by transformers here. I don't usually see transformers associated with effects loops.

[LeoBurke]

ah, ok.
The issue is: the amp has one preamp and two power amps (these are to support a stereo return on the effects loop).
The problem is what if we want to bypass the effects loop? Then I have a mono signal from the preamp but TWO poweramps.

Am I destined to buffer the signal from the preamp? or do I have to use more valves to create a signal of equalish level/quality to feed both poweramps with this mono signal.

L

[Enzo]

Is there not sufficient drive to simply parallel the two powr amp inputs? The cutout contacts would separate them when stereo returns were in use, otherwise, they are mono'd together.

[LeoBurke]

Thanks for your replies. Further to your suggestion to "simply parallel the two powr amp inputs": what effect would this have on the preamp?

My brain vaguely remembers gcse electronics, but it was some time ago. Please be understanding of lowtech ability, I am trying.... Would the parallel pwr amps not draw twice the power from the preamp, thus causing some change in behaviour from the preamp? Could this potentially do bad things?

Clearly looking rather uninformed now, but I hope you still have the patience to help out! Thanks,

Leo

[Enzo]

Power amps do not draw power from their input signals. They take the signal and then amplify it to provide power to speakers.

This would be exactly the same as using a Y-cord to split a signal to two destinations.

WOuld the impedances of the two power amp inputs be then in parallel? Yes. But I don't really think it will be any issue at all. The increased loading on the preamp out is not a significant amount in my view.

It won't hurt it, try it with a temporary connection.

[LeoBurke]

Ok, but do i need to buffer the signal to the effects loop? And if so, am i just as well to buffer the signal to the pwr amps in the event that i bypass the loop?

L