I'm using an external reverb (T.C. Electronics Nova) through the effects loop and I can only get verb out of one channel (left I think) and in fact it seems that the "stereo" section (knobs etc.) have no effect whatsoever on the sound...I am not very experienced with running a P.A. and I would really appreciate some help-Thanks Do I need special cables coming from the reverb unit perhaps ?

Loaded with a custom 12" speaker, the MG50CFX delivers that iconic ... Take control of your tone with a range of digital FX and four footswitchable channels. ... also has a dual function headphone socket for silent practice or silent recording. ... Effects. Reverb, Phaser, Flanger, Delay, Chorus. Effects loop.

for more visit
https://travismoviereviews.blogspot.com/2021/04/in-earth.html

If it has a effects loop output and input on the p.a. head and a in and out on the reverb effects processor, then yes you can, just run the effects loop output signal into the input on your reverb processor, out of the output back into the input effects loop on the p.a. head, kinda like you would a effects pedal thru the effects loop of a guitar amplifier. hope this helps!

Use use an echo or reverb chamber for live recording through a desk.

A recorded vocal can be processed using a digital recording program like Audacity which is free. In it you will find a re-verb plug in which will allow you to add this effect.

Audacity Free Audio Editor and Recorder

Why are you not using the inserts? Either assign a sub channel to your effects unit or do it at a channel level. In either case using the insert.

It sounds like you're new to 'professional' mixers. You would NEVER normally use an aux for effects. Any effects will normally be inserted in the sound chain using an insert. You have a pair of group inserts if you are wanting to apply an effect to the output (these are after the mix) and would typically be used for master de-essers or possibly compressor limiters or maybe even an equaliser, it would not be sensible to use an effect like a delay/reverb here.

I would have expected you to be using the group outs for the monitor mixes and am not sure what you may be using them for otherwise. If you used these you would free up 4 of the Aux outs for a 'multi channel' reverb/echos which you could take back into other channels and back into the main mix.

What is it you are tyring to achieve?

That is the way it is supposed to work... It is a level control to control the level sent to an EXTERNAL effects unit. What external effects unit are you using? Brand and model please. If you proportion more to the effects loop, you want to make sure the EXTERNAL effects unit is on and its gain controls are up. The foot switch input should control the EXTERNAL effects unit when you plug the footswitch into the EXTERNAL unit. The footswitch input on the amp itself has NOTHING to do with the external effect loop, it only affects the amp's own DFX unit.

Did you check the polarity of the adapter? The effect box uses inner pin for negative and outer barrel is positive which is oppsite from most consumer electronics.

Depending on whether you want the external effects to be on everything or just a single mic input, you connect them to the power amp "insert" or the insert for the mic you want it on.

Looping it out on multiple mics would be tricky, but you could send the units effects into one of the monitor outputs only by selecting a "non-effects" setting in the unit and sending internal effects to one of the monitor outs, and then looping it back into another input to join the mix.

Yes you could do that. The preamp output is just a BUFFERED output of the signal sent to the power amp. And the power amp input jack is BUFFERED before driving the power amp. These impedances are neither high or low being in the 1K to 3K ohm range.

The jacks for BOTH are mono jacks so noise pickup is possible if long cables are used. The external effects unit should be well grounded and operate off the same receptacle as your Fender for system safety. Use SHORT audio cables to minimize noise.

ALL the signal will pass through the effects unit when used this way... HOWEVER the internal reverb will still be in this path. You can kill this by turning the reverb control to zero on the Fender.

Here is an article that might help:http://www.guitarplayer.com/article/reverb-troubleshooting/jun-09/97165 Here is the schematic:http://www.fender.com/support/amp_schematics/pdfs/Hot_Rod_DeVille_Schematic.pdf Check to see if someone hasn't reversed the input and output cables at the reverb tank. Then troubleshoot the reverb section .