How is "Delay" different from "Reverb", and what is its best use?

David,

Delay and reverb are two different manifestations of the same phenonemon: sound bouncing back from reflective surfaces.
In the case of delay — which, in real life, is typically an outdoor thing —, the distance between the source and the reflective surface is so big that those reflections can be heard seperately. (For example: the echo in the mountains.)
Reverb, on the other hand, is what happens indoors: the short distances and the enclosing space make the sound bounce around on all the surrounding surfaces of the room and this results in a very complex, diffused blend of reflections which we call reverberation.

In other words: with delay, you can hear each reflection seperately (until they die away), and with reverb, the reflections dissolve and blur into a wash of sound.
(That is: as far as the natural occurences of these two is concerned anyway. Things are a little bit different when discussing digital emulations of both reverb and delay.)

And it’s also a bit more complex than just that, because, in reverb, we often distinguish between the so-called ‘early reflections’ and the ‘tail’. The early reflections are the first to reach our ear and it’s the part of the reverb that happens right before the blurring (=the tail) starts to occur. As such, these reflections are still faintly delay-like: less diffused, less dissolved than the tail.

Which leads us to the most common use of delay in virtual spatialization: the simulation of the ‘early reflections’. That’s what a very short delay (with a short feedback) actually does a pretty good impression of: the initial response of a room.
Early reflections are vitally important when it comes to suggesting a room. It’s the early reflections, much more than the tail, which give us an idea of the sort of room that the source sound is happening in, and where in that room it is happening. Especially for smaller spaces (rooms, studios, chambers, small halls), you really can’t afford to ignore the importance of the early reflections.

If you look at many of the piano presets in Pianoteq, you’ll find that the delay effect is already often used in precisely that way: to increase the sense of space around the instrument.
The danger with using delay like this however, is that, when you overdo it, you end up with a sort of enclosed, boxy sound which makes the instrument sound like it is trapped in a small space. Not a very appealing sound (unless you want it as an effect). So you have to be extremely careful with the delay settings. Set right, delay can be a very powerful ingredient of the total illusion, set wrong however and it’ll cause all sorts of trouble. If in doubt: better have too little than too much.

Also: the bigger the space you hope to suggest, the less delay (early reflections) you need. Because: the bigger the room, the more the early reflections become part of the tail.

All in all, a fairly complex matter and one that, if you’re unfamilar with it, takes quite a bit of excercise and experimenting before you’ll feel totally comfortable applying these effects.
But … there’s no way around either of these effects: you really have to master them both completely if you ever hope to be able to create convincing simulations of spatialized sound sources. And the better you know them, the more you can control them and apply them with complete accuracy to your mix.

_

Things like what Piet De Ridder is talking about must be put into PTQ's manual, or gathered in some big guide and put into a sticky topic. I was close to ditching Pianoteq because I couldn't find a way to make it produce live, reverberant, fragrant sound I liked and heard many times in different piano records - something I could easily do with some sampled pianos out there by spinning some knobs a bit. It's only in this last days when I delved deep into the effects pane and understood importance of room's sound profile I finally was able to achieve something similar to what I want from it. No ready sound preset seemed "live" or "authentic" to me. They were dull, uncharacteristic, too "muddy", too "synthetic" etc.

At least it's for me who always use headphones for playing (I believe it may be different for those who use good external sound systems with speakers; but, you know, headphones as an output device SHOULD be the default assumption when creating these presets, as it's one of the selling points of digital pianos, a lot of people buy them because they can play it with headphones on)

That's not a good thing, IMO. If I understand Modart's marketing strategy correctly, Stage version (which I poses) must be comparable very closely with popular sampled piano libraries out there (because they are in the same price range), while providing some benefits also, to "hook up" a customer (like much better dynamics, full-range support of pedals, "extensibility" and "tweakability" in case you'll upgrade to Standard later etc). So it must right out of the box, with as little changes as possible, provide the same quality of sound these libraries do. User must not spend several days in the settings before he'll be able to achieve that.

I honestly think Pianoteq could benefit a lot if these standard profiles and presets would have been revisited by Modart with all the wisdom they have on sound profiling, and would have been "tweaked up" until resulting sound's richness become similar to the one shown by best sampled libraries out there. Or at least a definitive official guide should be published which shows how to achieve that.

I guess I'm the opposite. I often turn off the delay of a preset and diminish the reverb (smaller room or less of the reverb effect added to the model in the "wet/dry" mix) even when wearing headphones. I like the additional clarity, especially when playing a piece with complex chords (chords that include many notes or have complex frequency interactions between notes).

Although you might prefer a particular type of sound, others may disagree and have different preferences. You may prefer to have the sound of your piano drowning in the complex reverberations of a huge cathedral or gigantic cave, or echoing strongly from a relatively flat, rocky surface of a mountain, for example, while others may prefer a clearer sound. There is also the matter of how close or how distant you are (or rather, one is) from a sound source. Sitting at the piano in a large cathedral, one primarily hears the sound of the piano itself (which is louder than its reflected, reverberated sound), but sitting in the balcony furthest from the piano, one may primarily hear the sound reflected from the walls, windows, columns, wooden objects, all of the complex surfaces facing different directions and of different surface textures and forms, all of which affect the reflected sound and the complex interactions of that reflected sound from all the surfaces. In that distant balcony, the sound produced by the piano itself might be obscured by or submerged within the reflected sound the listener hears.

It is a great advantage (for performers, recording engineers, etc.) to have an isolation between sound and effects, so that the pure sound produced by an instrument or any sound source can be heard clearly, or alternatively altered with precise control. One of my personal complaints against sampled sounds is the reverb and delay and other sound colors that are introduced into and included to some degree within most of them (all of them that are recorded with microphones). I tend to prefer dryer samples (those made with close mics in small rooms with sound-absorbing wall, floor and ceiling treatments), so that reverb and delay and other effects can be added to the sound as one wishes, rather than incorporated into the samples in their raw, original form.

There are already some Pianoteq presets that make heavy use of delay or reverb or both, such as the "cinematic," "new age," "dreamy" type presets, which I usually find have too much reverb and/or delay for my taste, and it's easy to make any preset sound dripping wet with reverb and delay using Pianoteq's very versatile and finely-controlable effects. I rarely use the "cathedral" or "Taj Mahal" reverbs (very spacious rooms or structures with many reflective surfaces) in Pianoteq, for instance, although they are nice for certain effects or for people who like a lot of reverb, nor delays long enough to hear distinctly and separately from the original sound, nor either effect added to any great degree to the dry or pure sound of an instrument (using the reverb's "Mix" and "Duration" sliders, for example).

If you desire a lot of delay or reverb, it's always possible to choose a more intense reverb (larger room and routing a greater percentage of the dry sound through the reverb using one of the reverb effect sliders) or longer delay and a wetter (more pronounced) ratio of original sound to delayed or echoed sound. Reverb and delay are both affected by a combination of the type of effect (such as the size of room or type of reverb (including artificial electronic "plate" or "spring" reverbs)) and the amount of influence that effect has upon the instrument sound, determined with great control by the sliders in the effects area of Pianoteq.

Traditionally, this sound coloration or alteration is what the rack-mounted effects processors, microphone placement, and room treatments were used for by recording engineers and performance-space designers, and I think it is nice to keep those effects separate from the sound source itself, which in my view is one great advantage of Pianoteq over sampled sounds that already include reverb, delay, etc. which cannot be removed, but only added to.