Difference between wavetable and sample-based generators?

[urlwolf]

I've read the wiki pages, but still cannot get my head around this one.
What's the difference between wavetable and sample-based generators?

There are plenty of synths that let you load your own samples as generators. I'm using linplug crx4 (great synth btw). The same sample played as a wavetable sounds different from it played with the loop sampler or the time sampler. Why is that? The manual is not clear on what's going on behind the scenes. I suspect the wavetable playback (1) requires a periodic wave, and (2) is a shorter wave. It may truncate any longer sample than say 1 sec.

[aciddose]

A wave-table is a "table" as in a spread-sheet of samples. That is it.

Perhaps it expects 256, 256 sample periods making one 65536 length sample.

No way to tell other than by the manual though.

[BertKoor]

Wavetable synths use very short samples, typically of only one cycle long. If the base sample is a 100Hz tone sampled at 44kHz, then it's just 0,01 secs or 441 samples long. So the sound is rather static and you need modulation of some sort (envelopes on amp & filter) to get some life and realism into it.

Sample players use relatively long samples, with optionally loop sections after the initial transient/attack defined. The looping section could be very short or very long.

But nothing withholds you from taking a typical wavetavle sample and use it in the same way in a regular sample player. And vice versa: you can take very short portions of a long sample in a wavetable synth.

[foosnark]

A wavetable synth has a table of (usually) short samples. The index into the table is a parameter that can be modulated -- so for instance, you can morph from a saw to a square, or a pulse to a double pulse (thus an octave higher), or from one squiggly thing to another squiggly thing, via envelope and/or LFO.

Some synths blur the line by letting you modulate playback and loop positions within a longer sample.

[Peter from LinPlug]

CrX4 has 3 sample based generators, from which loop sampler is closest to a traditional sampler, just that you can modulate the loops points and thus create pretty weird results already. Time sample uses a proprietary time stretching that also can be modulated and wave table builts a wavetable (in the way foosnark explained) from any sample you load.

[urlwolf]

Thanks Peter.

Still, Crx4 is too much of a black box, without having to.

How long is the default slice in wavetable? Some kind of visualization there would not hurt.

Once I load a preset with samples, can't help but wonder 'how does the sample sounds alone?' (no filter, effects, other generators). The interface doesn't invite you to answer the question. you could have a explorer window always open on the sample folder, and play it, but really?? This is the task of the vst.

Switching off everything else is convoluted at best (go through any effect, turn off button). A global 'bypass effects and mod elements should be there.

These days I really wonder if there's not a single person alive in the vst world caring about UX. Most plugins are primitive as hell, years away from how we interact even with default file browser. Preset managers? Pfff! horrible (crx4 no exception). Why you no can search? no favorites? No moving across banks?

[Aural Chaos]

Modern meaning is a lot different than it was 15-20 years ago. Aciddose's answer above is basically true.

These days, people except the term to mean scanning through a bunch of short samples, as in PPG synths.
But originally it just meant that it stored a bunch of samples, and could look up a specific one and play it back- a ROMpler basically.

[fmr]

Modern meaning is a lot different than it was 15-20 years ago. Aciddose's answer above is basically true.

These days, people except the term to mean scanning through a bunch of short samples, as in PPG synths.
But originally it just meant that it stored a bunch of samples, and could look up a specific one and play it back- a ROMpler basically.

The term "wavetable lookup" is somehow abstract, and it only means that the oscillators will "look" for the waves (whatever that means - samples, single cycle, shorter, longer - in a table, and exists, if I'm not mistaken, since Max Matthews created the first of these kind of oscillators in his Music series programs.
The term "wavetable" with the meaning of a "bank of samples in ROM" is actually more modern than the meaning of "dynamic wavetable scanning" that was the term when applied to the technique used by Wolfgang Palm (PPG/Waldorf), and I saw it used firstly in the boom of soundcards for the PC in the eighties. Before that, I never saw it used with that meaning (Korg M1 and Roland D-50, for example, were never called "wavetable synths")

[Ingonator]

AFAIK the term "wavetable" was introduced by Wolfgang Palm at PPG with the Wavecomputer 360 back in 1978 and then with later models (PPG Wave 2/2.2/2.3 and finally continued at Waldorf).
The Wavecomputer 360 already had 30 wavetables with 64 waveforms in each wavetable.

If we speak about products published by Wolfhgang Palm himself (besides beta tetsing and doing new wavetables for Waldorf PPG Wave 3.V) the "evolution" after around 35 years was leading to the PPG WaveGenerator which was first released for iPad and later for PC/Mac:
http://wolfgangpalm.com/new-products/wa ... ac-and-pc/

The term "Wavetable" was later "misused" for "usual" sample playback synths and also soundcards with samples. Also Cakwalk Rapture was marketed as a "wavetable" synth but no wavetable scanning possible there. It's more or less less an advanced "ROMpler".


An advanced form of wavetable scanning is maybe the wave sequencing of the Korg Wavestation (also in combination with the vector synthesis) which could use both single cycle waveforms and longer samples and you also have bigger control over which waveforms/samples are played at which time (and crossfading between two waveforms/Samplesis possible too).

In PPG WaveGenerator you could set a "path" whch sets the way how the waves in the wavetable are played which could be comparable to "wave sequencing". In usual wavetable synthsusing ADSR envelopes or LFOs there was less control at the wavetable scanning.


Ingo

[cornutt]

The term "wavetable lookup" is somehow abstract, and it only means that the oscillators will "look" for the waves (whatever that means - samples, single cycle, shorter, longer - in a table, and exists, if I'm not mistaken, since Max Matthews created the first of these kind of oscillators in his Music series programs.
The term "wavetable" with the meaning of a "bank of samples in ROM" is actually more modern than the meaning of "dynamic wavetable scanning" that was the term when applied to the technique used by Wolfgang Palm (PPG/Waldorf), and I saw it used firstly in the boom of soundcards for the PC in the eighties. Before that, I never saw it used with that meaning (Korg M1 and Roland D-50, for example, were never called "wavetable synths")

Yeah, the terms "wavetable" and "wave scanning" sort of overlap but they don't necessarily mean the same thing. You are correct in that the MUSIC programs had (and Csound, its descendent, still has) a software construct called a "wave table" which you can write code to index as you wish. The wave table is basically a chunk of memory that you can write code to index it however you wish. Back in the day this would most likely have been single-cycle waveforms given the severe memory limitations of computers of that era. The term "wavetable" sort of got extended in the 1990s to refer retroactively to earlier synths that stored short cycle waveforms or pieces of waveforms because they didn't have enough memory to store more complete samples.

And "wave scanning" was what the PPG machines, the Waldorf Wave series, and the Ensoniq Transwave machines did. You take a bunch of single-cycle waveforms, join them together in memory, and then you have a sliding playback window that moves back and forth across the string. Building a table and scanning algorithm that makes useful sounds withtout producing a bunch of popping and buzzing noise as the window moves is not the easiest thing in the world. The early PPG factory wavetables were hand-massaged by Palm to make them play nice together.

[aciddose]

The argument makes sense if you try to use a very concrete meaning. What you need to realize though is you're defining "wavetable" to have a very limited meaning specific to "collection of looped single-cycle samples used as a direct look-up for the shape of the waveform from a ramp oscillator".

What you should do is instead use the widely accepted definitions for "table" and "wave".

Given this, the most specific part of the definition is going to come from "table" actually. We all know what a table is, I hope?



Wave however is a slight bit more complicated.

http://en.wikipedia.org/wiki/Wave

We should examine the etymology of the term as well. What was actually being described when it was used? Was it intended to be so narrow a definition?

I argue that no, it was obviously not ever intended to be ridiculously narrow. The reason for the use of single cycles was simply the cost of memory at the time and the invention of "scanning" of wavetables was the result of asking the question: "What can we do with these shitty single cycles that isn't entirely pointless and boring?"

Note that "LA - linear arithmetic synthesis" is a ridiculous name for scanning wavetables with larger samples and combining this with digital linear filters rather than analog ones. This name was chosen obviously for two reasons. First, to differentiate it from the meaning taken on in the commoner's brain for "wavetable", and second to denote the fact that the filters were linear and implemented with simple digital arithmetic.

[fmr]

Hi aciddose:
Exactly which argument are you answering?

[electro]

hand-massaged by Palm

but of course!

Wouldn't expect a hand-massage from anything else.

[aciddose]

Hi aciddose:
Exactly which argument are you answering?

Any against the definition of "wavetable" as a simple combination of the terms "wave" + "table".

While I think it is fine, really if you want to be so specific just use "single-cycle wavetable scanning ...", not "wavetable", and any objection to "wavetable" as "wave" + "table" is completely ridiculous, in my opinion.

[fmr]

Hi aciddose:
Exactly which argument are you answering?

Any against the definition of "wavetable" as a simple combination of the terms "wave" + "table".

While I think it is fine, really if you want to be so specific just use "single-cycle wavetable scanning ...", not "wavetable", and any objection to "wavetable" as "wave" + "table" is completely ridiculous, in my opinion.

Yes, I agree with you (read what I said about "wavetable lookup"). The reason why first wavetables only had single cycle waves was just memory limitations.

But the name used that way is so broad it is almost meaningless. Any synth that comes with sounds pre-recorded is a "wavetable" synth. Actually, even the DX7 was a wavetable synth (with a table of just one single cycle wave - sine), as well as any FM synth (any digital synth?), for that matter.

And definitley any ROMpler is a wavetable synth. So, to answer the OP: Any sample based synth is a wavetable synth, but not all wavetable synths are sample based.