Question about Choosing Reverbs

[Debutante]

With panned instruments, most reverbs I've come across provide their wet sound straight down the middle, while only a minority, it seems, are able to give a wet signal relative to the panning position of an event. Firstly, why is that?... and secondly, what is the "convention" on the choice of reverb for mixing based on that element. Also, all of the verbs I have are freebies or relatively affordable demos, so how does this element relate with super high-end VST and hardware units; are the ratios the same as I've seen?

It seems to noobie me that it's probably wiser to pick a reverb that will help isolate your sounds as opposed to dumping them in whith a whole load of other stuff. I'm definately seriously in the market for a good verb since hearing that CSR thingee somewhere, and I'm curious as to how you guys handle yourselves with this matter. CHEERS!

[living sounds]

It's called 'true stereo'.

[93143]

I suspect people code unpanned reverbs to avoid having to deal with stereo inputs - double processing power for some parts of the algorithm, phase problems to solve, etc... I've never programmed a reverb, so I don't know...

I usually use SIR. There's a control for how much of the input stereo spread gets used; I always set it to zero. There's another control for stereo spread of the reverb; I always use 100%. This ensures that the late tail sounds realistic (centre panned), but there's no pan tracking for early reflections - the lesser of two evils.

If I'm using a true-stereo reverb impulse, I run SIR on each side separately with stereo input ignored and stereo IR on max. This produces a summed signal where the early reflections track the input pan and the late tail doesn't (ie: realistic).

If I were to mix something where some of the sound was coming from another room, the reverb of that room would be panned according to the position of the door, so I would use full input pan and no IR pan (and then use my conventional techniques on top of that for the room/hall the listener is supposed to be in).

If I want a specific pan position for a source sound, and a realistic reverb around it, I might design the reverb with Voxengo Impulse Modeler. Or I might go for RaySpace. Those tools do direct physical modeling of the reverb, and have more realism than just dynamic panning. But will anyone notice? (They're good reverbs anyway; one might want to use them for other reasons.)

There are algorithmic reverbs that track pan with early reflections: Ambience (I think), definitely AAR, also the E-MU PatchMix DSP reverb (which actually kind of sucks - it's better in some ways than most freeware, but in other ways it sucks)... The Creative EAX reverb on the Audigy does NOT track input pan as far as I can tell, but it sounds great (pre-EAX4.0 of course, I don't know what they did to it in that update but it was awful), and it's easy to modify an impulse of it to be true-stereo. No reverb worth anything will ONLY work with the late tail tracking input pan, because that sounds stupid in most cases (see above for the exception).

[pethu]

Well, if you think about it functionally, the main function of a "full" stereo reverb is to simulate what happens to the sound when it bounces around off the surfaces in the space that surrounds the listener: The original instrument is the only directional point source, the reverb is purely the "surround information". Going further, the common way to "fuse" instruments so that they seem to be played in the same space is to use various amounts of the same reverb on them -- all the reverberated sound will be pretty much "directionally dispersed" in the room before it reaches the listeners ears. Hoe much directional information is left will depend of the dry/wet balance and the type of reverberation used.

There's nothing here to say that says you can't use a reverb as a single instrument effect though. And who is to say that you can't put the listener in several spaces at once, if you want to?? Many reverb effects are dedicated to single instrument/mono use (guitar stomp box/amp simulations, etc.) Or, you can "monofy" or narrow down a too-wide 1) stereo reverb with more or less good results, using dfx monomaker and other plugs of that kind. 2) (The question of 100% mono-compatibility of modern reverbs was briefly discussed in the CSR-pants down thread recently, I believe...)

(1 Edit: Make that too non-directional, cause I guess too wide could equally well mean a reverb that kept a more precise stereo position... which I guess was your point!

(2 Edit: So what I meant was, narrow it down... pan it to the position of the original instrument to make it meld with just that source... And then I'd probably put another general send reverb on it to make the whole package blend into the same space as the other instruments!

[tahome]

Those tools do direct physical modeling of the reverb, and have more realism than just dynamic panning. But will anyone notice? (They're good reverbs anyway; one might want to use them for other reasons.)

I like the realism that tools like Rayverb provide. Like I said elsewhere, I especially like Rayverb ( www.rayverb.com IIRC) because of its incredibly precise localization and the way it works (you can take any existing IR and reverse engineer a room that creates such an IR, and then edit it wrt. position, size etc.).

Good stuff,
--th

[93143]

@pethu: I'm not used to mixing for listenability as opposed to realism... that's why I don't use compressors. It's a different way of thinking about the tools. Good points. Some people do like to use different types of reverb on each track, or techniques like that, but I like to pretend my stuff was recorded live, perhaps because none of it is...

You CAN tell from the early reflections of a real reverb where the sound is coming from, but the late tail in most reasonably symmetric rooms is not panned, unless the listener is near a padded wall or something. This doesn't mean there's no width to it, but the average is usually the same in both ears long before T60.

@tahome: I forgot about Rayverb; that sounds awesome. I remember thinking this when it came out. Unfortunately my budget is more comfortable with stuff like the Ultimate Bass Kit...

[kritikon]

I quite like the effect of stereo reverbs - it can enhance the clarity of a busy mix - especially on something like drums. But as ever, it's all down to personal taste.

The long and short of it is that to use alot of true stereo reverb, you have to account for CPU use etc (if you're using plugin reverb). You gain and you lose. To use a true stereo reverb in most hosts, then you need to use the reverbs as inserts...which means using alot more reverbs...unless you use it over a whole group (say the drum group), but that might not be how you want to mix - it's not unusual to want a snare reverb, some ambience on certain drums and even some tails on some other drums. So if you use inserts, that can add up to alot of CPU and might mean alot more bouncing (no problem to me, as I render alot anyway...but not everyone works that way).

The down side of a generic send reverb is that the reverb takes no notice of where the source is and gets split to L/R irrespectively. Which can bugger up your mixing.

Although I do like true stereo reverbs, I have to admit that I don't use them that often...it just gets to be alot of work, and sometimes for very little gain. As already mentioned - even with a true stereo reverb, if it truly is stereo, then much of the reverb will be split L/R anyway - it's mainly the early reflections that will give you any hint of stereo placement.

And you also have to hark back to alot of good mixes done many years ago...did they all use true stereo reverbs to get their quality mixes? No...in fact, most of them used simple mono->stereo sends. They may have used flashy reverb units, but still only had mono sends with a simple stereo return. And achieved excellent results with it. That doesn't stop you using true stereo sends, but I personally find it tedious. In fact the most effect you'll get is not from a true stereo reverb, but from a simple stereo reverb as insert - it returns the reverb directly in accordance with the placement of the source (i.e. if your source is 25%L, the return is 25%L too). That will give you obvious stereo effect...but it's not true stereo reverb. And it seems like almost all plugin reverbs will do that trick. You don't need to buy an expensive one to get simple stereo reverb.

I have an old Digitech TSR24S - it was expensive at the time, and Digitech were trying to compete with the likes of the DP4 and even Lexicon (they failed miserably at competing with Lexicon, of course)...but...it came with 4ins/4outs. You could split it up as a combination of mono/stereo sends and returns, as 1 big FX unit or as 2, 3 or even 4 smaller ones. Some of the specialist reverb settings are pretty fancy, and do actually give great results - you can have different stereo returns for front/back and use a 3rd send as a feedback mix control between the two returns and all sorts of other fancy goings-on. You can even set different shape envelopes for the early reflections for the front and back walls - even have to same halls, but completely different early reflection algos to imitate a hall with, say, a wooden front but tiled back wall (odd, I know, but can give some strange and eerie reverb effects!). Anyway - I don't use it now much as I got rid of my last big desk (sadly). But I didn't even use it that way much when I did have a big desk - I had a huge enough set of channels/sends/returns that I could actually set it up that way and with true stereo sends. And...in a mix, it really wasn't worth it, I hate to admit. If I ever did a really sparse ambient mix with very little instrumentation, and maybe no drums at all...then it was f**king superb (if I say so myself)...it really did give stunning effects, but anything uptempo, anything dense, even slow dub, it just wasn't worth the hassle and wasn't that noticeable. Maybe if the actual reverb was up to the quality of a decent Lexicon, then maybe it might have been worth it, but I honestly doubt it.


So...I'd say don't worry about true stereo reverb. Possibly only the ambient lot, or the symphony people would have need to use it. Listen to some of the classic good mixes done in the past and the odds are they used a simple stereo return fopr reverbs and used mono sends. Sad but true. Those mixes were great because they were done by great mixers, not because they used fancy technology (although that did help, for sure).