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Some Reverb Tips (and why pre-delay is so important)

Posted: Mon May 07, 2012 6:32 pm
by Prime Mover
I just did a bunch of research on reverb application a few weeks back, and I wanted to share a few really cool, simple concepts that I think don't get enough attention. For many people here, this will be old-hat, but I've always felt that reverb was one of the subjects that got the least amount of actual, useful attention in mixing.

Reverb has always been a bit of a black art for me. Of course, I know what all the different types are, which ones tend to work with which instruments, and propper signal-path structure for reverb use. But aside from that, I'll admit, I was mostly playing the reverb game by ear. Especially when it came to things like Pre-Delay and post EQ, I mostly was just playing around until I found something that worked.

Pre-delay is probably one of the most overlooked parameters of any common mixing setup. Most people think, as I used to, that turning up the pre-delay meant lengthening the delay time (which it technically does), so, more pre-delay = bigger reverb, right? WRONG. Believe it or not, it's almost the opposite. Think about a singer in a concert hall. If they're standing at the front of the stage, and you're in the front row of the audience, then the dry sound of their voice is going to hit you far sooner than the first reflection will. So our ears tell us "that person is very close". Now the singer stands at the back of the hall, against the well, suddenly, the first reflection is almost similtaneous with the dry sound, and our brain tells us, "that person is far away". No pre-delay means that an instrument is right next to a reflective surface, which probably means that they're not very close to the listener.

So you can effectively think of the pre-delay as a "distance" control, the shorter the pre-delay the FARTHER the distance. Want to give a lead vocal a close, intimate sound? Use a longer pre-delay. Want to shove the backing vocals into the background? Use a short pre-delay.

So you want to make all your instruments blend together, and reverb is complicated stuff right? Well, understand your limits, and simplify things until you really know what you're doing. I realized I was trying to customize my reverb for every instrument in a mix, but I really didn't know exactly what I was doing. My suggestion: throw them all away, and strip the setup back to a few basic, obvious reverbs that you really understand well. I've started naming them things like "Close Reverb" and "Far Reverb", in order to get a better handle on their function. Drums and percussive instruments often suffer with certain types of reverb, so you may need to give them their own, but aside from that, stick with a few that each serve a specific purpose.

Leave the on-board EQ controls alone, and throw on your favorite graphic EQ. Chances are, a dedicated EQ will give you more control, and be more familliar to use then the EQ stage of a reverb. You'll almost always want to high-pass the reverb to get rid of the lo-mid mud, and you'll often want to shelf-down the high end by a few dB. Where exactly is up to the nature of the mix, but most reverb application will benefit from a bit of low and high-end sculpting.

Another thing that may scare some new people is: only use Convolution if you really have to. Convolution is the newest craze, and it can be damned cool, but is it always the best choice to use? No. Not only is it processor intensive, it's much more complex and can muddy a mix. It also gives you less control than simpler reverbs. Old digital reverbs and plates have the benefits of sonic simplicity, and smoothness that make them much more easy to fit into a mix. Plates, especially, are very diffuse, and will work on just about anything. Digital, 2-stage reverbs are very simple to understand and control, and you can make more intelligent descisions about their effect on the mix. I'd say, until you really understand spacialization well, and really feel like you NEED it, keep the convolution reverb use to a minimum.

My latest find is the good old MOTU "Plate" reverb, I overlooked for so many years because it's that boring old blue color, and emulates an old, completely unnatural acoustic technique. But ya know what? It's perfect for a lot of things, and I now actually feel like I understand what I'm doing, instead of wading through badly-named presets for minutes on end.

Obviously, those of you who have been mixing for decades, this stuff is old hat. But in the modern age where it requires quad-core CPUs to perform seemingly-basic tasks, sometimes it's important to scrape away all the complexity to really be able to get a handle on our tools and techniques.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 1:15 pm
by Todzilla
Great stuff! Nice myth busting and very practical advice!

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 1:50 pm
by FMiguelez
Great post, Prime Mover.

And I really know what you mean about convolution reverbs... I've been working on this new project where I decided to come out of my "comfort zone" and use these convolution Reverb (Waves' IR-1) instead of my usual one.

I've been having a hard time because I don't know the plug-in. I could've cut my mixing time in half if I had used my normal reverb plug (Waves' TrueVerb). So the point is that I'm not sure this convolution reverb is actually much better or not... partly because I'm still experimenting with it and part because it produces a much different sound. Oh, and it's a processor hog, even though I'm using the "low CPU" setting.

I'm still trying to push some instruments to the back (using no pre-delay and a dedicated EQ to cut highs and mids), but I've been having to EQ everything quite differently, mostly because of the CR plug-in.

What frequencies do you find yourself cutting to push instruments to the back? Common sense tells me it's the high freqs, around 8-10 kHz, but it obviously depends on the instrument). Also, some ugly mid-freqs need to go... like for the horns, for instance. I've been cutting A LOT of 250 Hz and 350 Hz, otherwise they sound in-your-face, and I want them all the way to the back.

I really think EQing the dry sound of the instrument (and its group reverb) as important as messing with the delay parameter. But you are right... each plug-in works differently, and it's one's responsibility to learn it to be able to use it to its best.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 1:56 pm
by Don T
Hello,
For me it's all about the phase. Comb filtering from early reflections alter the timbre as well as the spatial placement. Getting all parameters set to enhance rather than destruct is the key. How long a verb tail is in the mix is easy compared to predelay, size, diffusion, spread, density etc. Especially when those words can mean many different things between manufacturers and coders. Fiddling while using your ears is what it all comes down to in the end. Understanding the controls and what they do just makes you faster / better.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 3:10 pm
by jbyerly1
Thanks you sir.

Never fails that i glean another tidbit of info that I wasn't aware of by coming and reading here.
Maybe some one will post about mixing and combing digital delays with reverb as well. My ears like that combo sound but it's trying to get something that doesn't sound like a WTF moment

Once again thanks for the info

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 3:31 pm
by Prime Mover
FMiguelez wrote:What frequencies do you find yourself cutting to push instruments to the back? Common sense tells me it's the high freqs, around 8-10 kHz, but it obviously depends on the instrument). Also, some ugly mid-freqs need to go... like for the horns, for instance. I've been cutting A LOT of 250 Hz and 350 Hz, otherwise they sound in-your-face, and I want them all the way to the back.
Boy, that's a toughy, because distance doesn't always do what you think it will, or what you want it to. Backing vocals, for instance; often I find that a backing vocal part sounds best when it's very bright, lots of air, not a lot of low end, especially open "Ahhh's" in pop mixes. Yet, you still want them to sound like they're behind the lead. Though common sense would say you need to darken them to push them away, that wouldn't neccessarily be the case. Then there's proximity effect for super-intimate vocals, which, again, goes against the "high frequency = close" idea. I guess the biggest problem with the concept of pushing it away is that it also tends to thicken the sound, and usually background stuff calls for a narrow frequency spectrum. So my suggestion is, don't sacrifice clarity for the sake of theoretical realism.

As for high frequency rolloff? I'm weary of using steep low-pass filters. Maybe I'm too squeemish, but common sense acoustics tells me that they're really unnatural. I tend to either use gradual-slope LPFs or high shelf filters.

With 2-stage reverbs like eVerb, RVerb, and I guess True Verb (never used it), you have control over decay time for different frequency ranges. That's another problem with convolution reverbs: you end up with a fairly realistic sounding space, but then to modify it, they have to slap on a dampenning algorythm, which at least for ProVerb is utterly horrific. Between eVerb and ProVerb's "frequency response over time" functionality, there's just no comparison, eVerb wins hands down. But as neat as dampening is, I find that, in reality, what really just matters is the simple, overall EQ of the reverb. Whether it goes from bright to dark over time not as decernable as simply "how bright is it". So yeah, a gradual LPF or Shelf starting at around 7-10kHz is about what I do.

But I'll be honest, I've yet to get TRULY comfortable with EQing distance, it just never seems to work out the way I think it should, and I usually have to go back later and fix it. Either, I make the far stuff too mid-heavy and muddy, or I try to play it safe and high-pass it to get it out of the middle of the mix, and then it becomes tinny and unrealistic. It's a real balancing act, probably one of the toughest challenges I face in mixing.

Ok, let's all admit it, with all the hardware and software units out there, there are always some controls that we don't fully understand. Maybe we understand the basic technical concept, but we don't really know how to use it properly. We'd like to pretend that we understand them, so we never push them to 100% or 0%: pick some specific number like 87%, just to make ourselves feel like we know enough to be that precise. Come on, we've all done it!

For me, that control is density/diffusion. Of course I understand what it does; but seriously, acousticions spend thousands of dollars trying to diffuse spaces as much as possible, so why would I want to make a room sound less diffuse? It seems to me akin to having a "crap" nob, "hey folks, let's give our mix a crappy flutter effect!". My theory is that the programmers just put it there because more controls make the reverb look more important. Maybe someone will come along and set me straight, but for now, I'm just going to admit that I don't know how to use it, and I'll leave it at 100%... no more bullshitting myself with 87%.

EDIT: I just read up a bit on density, and I still don't buy it. The bulk of the psychoacoustic information is going to be contained in the early reflections. Give a vocal track nice, distinct early-reflections, and I seriously doubt it's going to make much of a difference how dense the tail is. I have yet to really experiment with it, but compared to reflection map, pre-delay, decay length, and EQ, this seems like a very low priority control.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 3:57 pm
by Don T
Hello,
I like having EQ before and after reverb only because I get to control the creation of verb and then shape the output too. Sometimes you want to keep that annoying / ugly sound out so it doesn't go round and round creating all kinds of ugliness. EQ essentially is altering time to decay too since an EQ'd frequency will drop below the masking noise floor sooner. Very source dependent, no easy std thing to do, just use your ears to get it where you want it.
The acid test for me is muting the verb return (not bypass) for an A/B test. When I have it correct, un-muting the verb pulls me into the space as opposed to making it "wetter but not better" or further away (unless the latter is the effect you are looking for).

I also like to create some phony stereo processing using DP's stereo chorus or a swept delay to add some image expansion and spatial manipulation. Less is more with that kind of processing but the results can be stunning.

As for Density; it totally depends on the manufacturer / coder. Density on some plugs affect the early reflections too. I know on Alesis products density only affects the time of the first primary reflection and it's proximity to the other early reflections.

On Edit: I tend to take each reverb program / type and explore the affect of each control and compare that to what the manual says it's supposed to do. Most documentation doesn't clearly define terms like "REVERB." Some mean only the dense decay tail, others mean the total algorithm. You have to read between the lines and figure out what they mean. Lexicon, for example, has different meanings between different models and years.

I also test for 3D processing. Some verbs sum L&R to mono before the stereo processor (Lexicon MPX-1) so no matter how you pan the stereo input buss the image ends up in the center. Unfortunately plug-ins work the same way.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 5:41 pm
by FMiguelez
VERY interesting stuff, guys!

My current issue is that when I EQ the instruments to place them far (or close) I feel like a dog chasing its tail. For instance, cutting low-mids make things brighter. If I cut some brightness then it becomes muddier again...
I'm just trying to send the EQ'd signal to the reverb, so it sounds more natural and its placement better... but I'm having a hard time with this reverb plug.

Ok... that's it.

I'm officially tired of not being 100% confident about EQing/Reverb/Distance for orchestral instruments in my mixes.

I just bought Benjamin Britten's The Young Person's Guide to the Orchestra score. I already have a great recording of it, so I decided I will make the full orchestral mock-up and try to match the EQ, Reverb and stage placement by comparison... one by one.

This should work great because there are solo and ensemble passages for every single instrument. It will probably take me a while to do so, but that is one of the very few ways I can think of to become much more proficient at this (and more confident), not to mention a better orchestrator/VI simulator (inevitably, since he is truly an orchestration giant).

I also have the Peter and the Wolf score. This work should also work fine for this same purpose, albeit it has fewer solo instrumental sections (the strings always play together).

If my plan works, I will be able to have a very realistic sounding orchestral template. I know it will be lots of work, but I'm sure it will be more than worth it.

:rtfmmad: , as in Mockup The F... Score!

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 6:15 pm
by bkshepard
A fun little (okay, not so little) experiment to try is to take a single sound source and imagine it on a large, slowly turning turntable in front of you. It takes tons of automation of reverb, EQ, pan, and level controls, but it's a great way to really wrap your brain around what it takes to place a sound in a specific position. I did that a couple of years ago and it was amazingly enlightening.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 6:33 pm
by Prime Mover
FMiguelez wrote:I just bought Benjamin Britten's The Young Person's Guide to the Orchestra score. I already have a great recording of it, so I decided I will make the full orchestral mock-up and try to match the EQ, Reverb and stage placement by comparison... one by one.
Carefull there, unlesss you are using dead dry close-miked samples, the hall and placement is going to be built-in to the recording. Only the very best and very worst orchestral VIs do this. The best because they have to mic every instrument independantly in an expensive hall, and the worst because they do it in a studio and saturate the samples with artifical reverb. I'm not sure what orchestral VIs you are using, but things like EWQLSO close mic version will work.
bkshepard wrote:A fun little (okay, not so little) experiment to try is to take a single sound source and imagine it on a large, slowly turning turntable in front of you. It takes tons of automation of reverb, EQ, pan, and level controls, but it's a great way to really wrap your brain around what it takes to place a sound in a specific position. I did that a couple of years ago and it was amazingly enlightening.
Damn, that's an interesting idea. Are you accounting for the source turning it's back to you, or are you talking about keeping the source oriented toward the front at all times? Not sure how useful it will be to try and achieve the sound of someone singing with their back to you.

BTW: one question I've had is, how well do reverb plugins respond to automating the pre-delay? Will that typically cause glitches and/or pitch shifts, like with modulating delay effects, or will the delay seemlessly change?

BTW2: This is why I think it would be really cool to have a small effects chain inside of the send chain. I'd love to simply drop a delay plugin on my effects send, so that any number of tracks could use this same type of reverb, but with different pre-delays, and then I could automate the pre-delays independantly! Much more CPU efficient, and lots of possibilities! I've thought of manually setting up a template, where every track has a dedicated "Send" Aux track, which I could put pre-delays, and pre-EQs on. But that would use so many busses and screen real-estate, it would be more trouble than it's worth.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 6:54 pm
by FMiguelez
Prime Mover wrote:
FMiguelez wrote:I just bought Benjamin Britten's The Young Person's Guide to the Orchestra score. I already have a great recording of it, so I decided I will make the full orchestral mock-up and try to match the EQ, Reverb and stage placement by comparison... one by one.
Carefull there, unlesss you are using dead dry close-miked samples, the hall and placement is going to be built-in to the recording. Only the very best and very worst orchestral VIs do this. The best because they have to mic every instrument independantly in an expensive hall, and the worst because they do it in a studio and saturate the samples with artifical reverb. I'm not sure what orchestral VIs you are using, but things like EWQLSO close mic version will work.
I see.

I use VSL. They were recorded in their Silent Stage. VERY dry, so it should work well.

Have you checked out their MIR reverb? It's a-ma-zing.
Too bad I can't afford a full computer only for reverb (it requires it), but hopefully soon...

I haven't heard anything more real than that, except for reality :)

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Tue May 08, 2012 10:04 pm
by Prime Mover
Yeah, I'm SOL with EWQLSO. I don't use it enough to cough up the money for the close mic version, and I've grown to dislike it's creator enough that I don't really want to give him my business any more than I have to. Probably for the best, my budget is tight enough as it is.

Back to reverb...

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Wed May 09, 2012 2:52 am
by Dan Worley
bkshepard wrote:A fun little (okay, not so little) experiment to try is to take a single sound source and imagine it on a large, slowly turning turntable in front of you. It takes tons of automation of reverb, EQ, pan, and level controls, but it's a great way to really wrap your brain around what it takes to place a sound in a specific position. I did that a couple of years ago and it was amazingly enlightening.
What a great idea! That sounds like fun!

I've mentioned this before in another thread: When I demo or purchase a new reverb plug-in and want to know what its controls/parameters actually do, or if I'm having trouble dialing in exactly what I need the reverb to do in a mix, I use a trick I learned from the book "Mixing With Your Mind." It entails using a gate keyed to a click on a track with pink noise, but in DP I just use the Pattern Gate to get it done.

1. Put some pink noise on an audio track. Loop it if you need to. Set its output to a dead stereo bus.
2. Send it to an Aux track
3. Put the Pattern Gate on the first insert of the Aux track(set it up as in the screenshot below. If you want a little more "woosh," set the attack to 2 or 3).
4. Put the Reverb plug on the second insert or the Aux track, 100% wet.
5. Solo the pink noise track.
6. Set the Pattern Gate to the note value (speed) you want. Try different ones. Half or whole notes work very well.
7. Now you can really hear what each parameter does, or doesn't do.
8. If you want to adjust the pre delay of the reverb, add in some of the dry signal to adjust it, then set it back to 100% wet.
9. This works great for setting up delays, too.
10. Make it a clipping so you have it readily available.

You can get pink noise here if you need it: http://abluesky.com/wp-content/uploads/ ... tFiles.zip

Image

To be honest, before I started using this trick, I would be adjusting some reverb parameters while being deaf to what they were actually doing. Once I learned what to listen for, I could hear it, and I learned about some damaging parameters that you just don't want to mess with most of the time.

Oh, yeah, I forgot to mention: Once in a while, for some unknown reason, the Pattern Gate will insist on slipping into its default pattern. :shake: This happens mostly when the speed is set to quarter notes. The fastest and easiest way to recover from that annoyance is to remove that instance of the plug and then just reinsert it. So it helps to have a preset saved.

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Wed May 09, 2012 11:46 am
by bkshepard
Prime Mover wrote:Damn, that's an interesting idea. Are you accounting for the source turning it's back to you, or are you talking about keeping the source oriented toward the front at all times? Not sure how useful it will be to try and achieve the sound of someone singing with their back to you.
When I did it, I assumed the sound source remained facing me. I guess that means it's actually a turntable on a turntable :shock:

Re: Some Reverb Tips (and why pre-delay is so important)

Posted: Wed May 09, 2012 7:00 pm
by FMiguelez
Dan Worley wrote: I've mentioned this before in another thread: When I demo or purchase a new reverb plug-in and want to know what its controls/parameters actually do, or if I'm having trouble dialing in exactly what I need the reverb to do in a mix, I use a trick I learned from the book "Mixing With Your Mind." It entails using a gate keyed to a click on a track with pink noise, but in DP I just use the Pattern Gate to get it done.
Hey, Dan.

I just tried your suggestion/trick. You are right! It really helps to make tweaking the reverb parameters quite obvious 8)

But I'm not sure about something... I set the speed to quarter notes or half notes, and the rest of the parameters exactly like your picture. I'm using Waves' IR-1 convolution reverb, BTW.
The thing is that each steps sounds modulated. Like it goes from high to low to high, and I'm not sure why that happens. Almost like footsteps from someone walking towards and away from me. It sounds like that with every IR I've tried. Is this normal? (I'm using the full bandwidth pink noise from your link).

Also, I'm not sure what the "Density" and "Diffusion"parameters are supposed to do (Waves' manual is quite poorly written). I mean, I obviously hear the changes as I tweak them, but in reality, what are they supposed to emulate (in real life)?
I understand Diffusion kind of "spreads" the frequencies all over the place, is this correct? Don't people spend big bucks diffusing their rooms? Or am I not getting this right?

This is very cool, but I want to make sure I understand what I'm doing.

Thanks!