The difference between the reverbs and choruses in the send effects and the MFX reverbs and choruses is that the mixer Send effects can be applied to all Parts in different amounts (one Part can have a little, another a lot) but the reverbs and choruses in the MFX are only applied to the Parts assigned to them, and it’s one global wet/dry mix to everything passing through the MFX.

You will see most MFX reverbs, choruses etc. have a parameter for mix, balance, amount, whatever each one calls it. And this is where you adjust how much of that effect is applied to the dry sound.

But… Most (all?) MFX effects have a send to the global reverb and chorus Send Effects usually at the top of the edit page. This is where it gets a bit complicated… but let’s try to make it simple. On the whole, in most cases, you want a sound to go through the effect you selected (let’s use a guitar amplifier on a guitar sound as an example), and then the output of THAT to get some reverb. So you set the reverb send in the MFX edit page… BUT… you need to go to the main mixer and turn off the send to the reverb for that Part, otherwise, what you get is the sound of the uneffected guitar in the reverb send along with the distorted guitar’s reverb as well.

In other words, the mixer send to the main reverb is ‘pre’ MFX.

So you usually, if you are using MFX’s that affect the entire sound (like most of them do) have to think carefully about how you are sending to the main reverb. The truth is, most of the time, most MFX’s, you need to shut off the mixer sends to the reverb/chorus, and then adjust those sends in the edit page of the MFX.

To be honest, about the only time you’re likely to use the MFX reverb is the very rare time you want a totally different kind of reverb on a sound for a special effect. Say a gated reverb on a synth sound or a super long reverb on a piano without it being on everything else (which it would be if you set the main reverb up like that!). Most of the time, the MFX are best at things like flangers, guitar effects, enhancers, compressors (although I’m not that enthusiastic about the compressor algorithms), and other types of effects you really only want on one sound.

I hope these posts have helped, but it rather sounds like you have pretty much zero experience with mixers and effects in the first place because most of this is pretty basic. It might not hurt to go find a beginners book or website on mixing fundamentals, for studio and live stage, because, in a way, that’s really what you are doing here… An arranger is an entire studio full of everything needed for recording and live music. Mixers, effects, mic preamps, final multiband compressors and EQ…

Might as well start to understand the basics… it will pay off in the end.