I learned that reverb should always be used a send effect, but recently I have seen more and more composers using reverb as an insert effect per instrument group (one reverb on the string group, another on the brass group etc.)
What are your thoughts on this subject, and your preference, and why? 
Reverb: Insert FX on Groups vs Send Effects?
Technically, using them as send effects is part a performance hack (one instance vs multiple identical ones saves CPU, but gives the exact same result, as long as there are no non-linear effects involved), part a workflow thing. Itâs quicker to just send from each track that needs reverb, and you can also adjust the send level without affecting the dry level. (You can do that on some reverb plugins when used as inserts, but dry/wet control can be implemented in some different ways. Some will leave the dry signal at 0dB for the lower 50% of the dry/wet control, but thatâs not a universal standard.)
However, when going for realism, the difference between the approaches becomes less obvious, as youâll need multiple reverbs either way. A room responds differently depending on where the sound source is, and in which direction(s) it radiates sound, what other objects (other instruments, players etc) are near the sound source, and probably a bunch of other, more subtle factors. (Thatâs why some IR reverbs come with instrument specific IRs.) So, at the very least, that has to be approximated with a few different reverbs, at least for the early reflections.
Of course, if youâre using wet libraries, the position dependent early reflections, and some of the tail, is already covered, and reverb in the mix becomes mostly a matter of subtle coloring (or not so subtle, if youâre combining libraries recorded in different spaces), smoothing over any scripting issues (the downside of âbakedâ reverbâŠ), maybe adding a bit of tail and movement.
For synths, sound design, and for very up-front solo instruments, I tend to use reverb as inserts, as itâs typically part of the instrument specific sound design, and supposed to stand out from the mix - so it would be counterproductive to share the same reverb instance (or exact settings) with other instruments.
Great topic! Love it!
As you might know I have studied audio engineering and I remember that one of my educators said: âForget the Inserts or SendsâŠâ, what he meant, as an engineer you need to figure out, what works best in your situation. There are a lot of people out there, who are saying, that Delays and Reverbs should ALWAYS be Send-FX-Returns. However theyâve just learned it, âYou need to do it ONLY like thatâŠ!â, (like 2+2=4), but actually never âexploredâ other options for themselves. Itâs not bad or whatever, itâs not âengineeringâ really. Engineering is trying new crazy things, fail, go back, try again until you are happy with your result. If you are still unsatisfied, relax, think about what you want to achieve, and try to build it from scratch. (For this you need to know the basics of course). Basically what people need to do at all other âcreativeâ jobs as well. For me itâs really boring at some point, if I do the same and same stuff again, I need to feed my brain with new things, or I just stop thinking and just do what I already did. And then it becomes a bad routine in that sense. You will never grow your creative portfolio, if you take engineering as a craft you only learned once and for all. (My little excursion on engineering and creativity in generalâŠand now back to the topic )
In what situations I like to use Insert FX: For example I have a pretty dry instrument, a flute which was recorded with a closed mic, but has no room. I might put a short delay or reverb, (depends on the color and the hearing result), and insert directly on the instrument track. Because I used the reverb on the original channel I can position my signal in the room as I would like to. If my flute is mono, so my reverb will be mono as well. Make sense, because the ear identifies mono-fx much better, as they are âconcentratedâ. You can EQ and automate your channel as you like, so the original channel plays with the music and acts like a real instrument, so do all the insert fx.
If you have a signal which acts just as an FX, you donât need to send it somewhere else. Just through a reverb in the insert. As long as you donât want to âparallelâ anything, you donât need your sends.
When I use sends: Sends are copies of your original signals. With your âsend-knobâ you just adjust how much of the original channel is going to the return, where all your FX are used. That said, it makes sense to treat your Return as an individual instrument. If you send your brass-section to itâs Return, you can manipulate your reverb and EQ your reverb, compress your reverb, delay your reverb, duck your reverb, saturate your reverb, etc. but you just touch the copy, and not the original, so you can always dial in the fader, or even use crazy automation rides, and so forth. Basically you always have much more options, as you do it in parallel. With inserts itâs not possible, until you automate your dry-wet-knobs (not every plugin has it).
You can say that theoretically your send-return is your âdry-wetâ-knob.
Keep in mind, that it makes sense to use more send-returns, as first you are more flexible, and seconds you use less of your CPU, as you can always send more signal into one return. When I use insert FX, I usually print it.
Super indepth reply, thank you, I can see your points.
I have personally almost only used reverbs as sends, but I also seen some composers add an insert FX per each instrument group, with different settings on each. It can also help with stems, as the entire group will have reverb on it for each group you stem out.
The problem I see with this approach is that letâs say you add an insert on the brass group bus, then you decide that well the trumpets should be more dry to stick out more. Well then that is not possible as you have the same reverb on the entire group.
So I guess there are upsides and downsides with both models. But I will experiment with this as I find it fascinating. There are no rules in music, especially if you want to be more creative, and not just do what everyone says you should do
What I tend to do when mixing dry orchestral instruments is basically the group approach, although I just set up multiple reverb buses, and then each track sends to one (or more!) of those. So, for example, all brass would be sending to the same reverb bus, but each instrument/stem has its own send level.
Either way, I think the key here is to know the traditional âbest practices,â but also understand how and why they work, so you can build tailored solutions when you run into unusual problems, or need to spice things up with some interesting sound design.
If you want to have a complete control of your production, you can have send-returns for individual sections as well. So you have: One return for solo instruments, one for the 2nd chairs, the groups, and so forth. With this you can as flexible as you want. Studio One for example can print your FX-Return. So itâs not a problem for me to deal with âreal timeâ reverb-printing like still Logic does, am I right?
I love Logic Pro, and this is the DAW I have chosen to âmasterâ so I wonât switch, but there are still some annoying things they havenât fixed. Like stemming is a problem in Logic when dealing with sends. I want to be able to just select all groups and have a one button press to export all stems automatically. Does not work in Logic, you need to solo each one, and do it manually group by group. =/
Yeah, itâs better to stick with one for sure. You will be much more efficient. The only reason why I stopped using Logic was the pure cheekiness to pay for a full version. I had 8 / 9 and had to pay another 200$ for a new upgrade? I am aware how much good things you get with Logic, but I donât like these kind of upgrade-approaches where you just do whatever you want as a developer with your âcustomersâ. Doesnât seem right and fair to me. Look for Fruity Loops. Everybody loved a couple of years ago, but today most people use it, as well trailer composers. Why? You pay only one time for the full version and all the next versions are completely free for the rest of your life! Itâs doesnât mean that they will stick forever with this model, but until now (20 years) they did!
I tend to have at least one small and one large reverb (plus a couple of delays) on a bus and send all instruments to them in varying amounts to help âput them in the same roomâ (top tip: change your âSENDâ setting to post-pan so that panning also affects the reverb).
And then if I want to use reverb as more of an âeffectâ to alter the sound of something, Iâll use it as an insert.
I try to be as minimal and streamlined as possible with my inserts and sends though. Interestingly, as a recent study showed:
âIn a nutshell, surprisingly the fewer plugins an engineer used the better the mix tended to get rated and the best mix used primarily stock plugins, whereas the lower performing mixes were overloaded with pluginsâ
It would be interesting to know, what mixes (which artists) were part of the study/reseach. I believe that the less the artists and producers are experienced, the more the engineers use more plugins to fix the recordingsâŠ(my experience at least)âŠ