Manual for Peavey Mark 111 stereo mixing console 1979

https://assets.peavey.com/literature/manuals/80361051.pdf

dirty insert jacks on the stereo two mix,

This depends on what you are trying to do. If you want a mono output from the amp switch it to mono mode and go into one input on the amp, this will mean the amp only works mono.

If your source is stereo you will need to use two inputs on the mixer and pan them both to the side you will be sending to the amp. This will cost you two mono inputs on the mixer though.

If you have anything stereo this is the route you will need to take but I don't see why you would want to do this as surely you'd be better running everything stereo (two channel) and panning any mono signals where you want them and leaving stereo as stereo.

are you running 2 speakers in stereo?????

Hi. The mixer puts out a full range mix, the solution is in your speaker setup.

Many subs have a built in crossover that splits the signal for the tops. Check your sub specs or manual. If your subs have this, run your output signal to them first and then link them to the tops from the special daisychain socket.

If they don't have one, you can install a passive crossover to your subs or buy an external crossover unit.

The last (and not very good) option is to fake a crossover with the desk's stereo EQ. Connect the subs to the left or right channel and the tops to the other and use the EQ to remove the bass from the tops and vice versa, pan everything dead center. Obviously this sacrifices your stereo sound and isn't brilliant.

That's easily done. Simply connect the left(or right) output of your mixer to one of the channels on the peavey. Use any line input. Since the peavey is a mono system, there's no need sending a stereo mix to it.

I would recommend using a separate active crossover such as the Peavey 23XO and a separate amp for your subs.

You have to insert a track into Reaper "arm" it. If you can't figure it out, I'd suggest posting in the Peavey forums.

check for cold solder joints from the input jacks and the fader. If any look suspicious (dull or grainy) re-solder.