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What the Heck is Wavetable Synthesis?


BbAltered

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Hello. I am trying to satisfy my curiosity. What the heck is wavetable synthesis?

 

I was first introduced to analog synthesizers in the 1970s. I learned the principles of subtractive synthesis and used them to create sounds on Moog Model Ds and Arp Odysseys. I was at Dartmouth College in the early '80s when NED created the Synclavier and so I learned the principles of additive synthesis. I learned the principles of FM synthesis when Yamaha introduced the DX series of synthesizers (and later owned a TG-77, which combined FM synthesis with sampling). And with a computer, I have become familiar with sample-based synthesis.

 

But I never got close enough to wavetable synthesizers to fully understand what is going on. My rudimentary understanding is that wavetable synthesizers store in digital memory many examples of a single cycle of a periodic audio wave and various permutations of that single cycle audio wave. And so when one selects a waveform and applies a LP filter to it for playback, one is essentially instructing the computer in the synthesizer to seek the memory location of a previously calculated wave altered by a filter, and loop it repeatedly to create the tone we hear. So it seems to me that this is little more than a digital version of subtractive synthesis.

 

Can anyone here enlighten me further?

 

J.S. Bach Well Tempered Klavier

The collected works of Scott Joplin

Ray Charles Genius plus Soul

Charlie Parker Omnibook

Stevie Wonder Songs in the Key of Life

Weather Report Mr. Gone

 

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I've never really had a chance to explore a wavetable synth, but the purpose of the wave table is not simply to be able to recall a single wave shape to be used like a standard analog oscillator. The point is to be able to interpolate between 2 wave shapes, the aural equivalent of Michael Jackson morphing into a panther ( remember when that was cutting edge?).

 

According to the wikipedia article, things like pulse width mod could be simulated by having waves of varying pulse width adjacent in the wavetable, and interpolating between them. But you can do much more radical interpolations, including between harmonic and non-harmonic waves.

 

Wendy Carlos critiqued the limited number of waveform options available to analog synths in her CD Secrets of Synthesis. She asserted that if you judge waveforms strictly by ear, there's no musically significant difference between sine and triangle. Perhaps because her focus has been mostly on imitative synthesis, she praised the new digital synthesis options available in the 80s, but didn't mention Wavetable at all.

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I was at Dartmouth College in the early '80s when NED created the Synclavier and so I learned the principles of additive synthesis.

 

Wow. We may have some friends in common. How terrific. Will send you a PM.

 

I have done some wavetable synthesis in softsynths like Thor and Alchemy. Not much, but enough to have a way of thinking about it.

 

My easy way of doing so is to assert that wavetable synthesis is confined to the oscillator (tone generator) section of a synth. If you want to filter what comes out, that is up to you. So, to extend the vocabulary you could have a patch which employs both wavetable and subtractive synthesis. For example, Animoog has wavetable and subtractive capabilities.

 

And so when one selects a waveform and applies a LP filter to it for playback, one is essentially instructing the computer in the synthesizer to seek the memory location of a previously calculated wave altered by a filter, and loop it repeatedly to create the tone we hear.

 

The filter isn't involved. In wavetable synthesis you have a table of waves and you scan between them to the sound. Early wavetable synths like the PPG didn't have interpolation so you would have this typical "crinckly" sound as you swept across the tables. Modern wavetable synths read the wave into memory and then allow you to morph between waves to smooth things out if you prefer.

 

To me the closest analogies to "wavetable synthesis" in the typical analog synth are Pulse-width modulation and oscillator sync. Both techniques allow you morph between (potentially) harmonious sounds, but the manner in which you do so can create discordance if you like.

 

I enjoyed this video and I hope you do also ...

 

[video:youtube]nQ16WeCqla4

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I wonder if there are any classic tracks that use wavetable? I was totally immersed in classical music between 80-86 and hardly heard anything else. When I got back to pop music somewhat after that, the DX and sampling had taken over.
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A single cycle wave played over and over is static. It can reproduce just about any overtone spectrum you want.

 

If you filter it after, you can get dynamic timbre changes in the standard manner.

 

A good wavetable synth has banks of waves that allow you to control which wave in the bank is being played. Put this under modulatable control, and you can sweep a bank with an envelope or lfo.

 

If the waves next to each other are musically or harmonically related, you will get a smoothly changing sound as it sweeps.

 

If they are random or unrelated, you get rhythmic timbre changes.

Moe

---

 

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I vividly remember the ads for the Keytek CTS-2000 in Keyboard during the late 80s. As far as I can tell, it uses samples in the wavetables. I think it was built by Siel, but marketed under the Keytek Brand. Never saw one in person.

 

 

http://4.bp.blogspot.com/_bYze_R6XM18/SjUQ6nAiRgI/AAAAAAAAAEw/LM2Gz_stQLo/w1200-h630-p-nu/keytek_cts-2000_nov_1987_mt.jpg

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I wonder if there are any classic tracks that use wavetable?

 

IIRC, Thomas Dolby shared that the bass line for Windpower was wavetable PPG - the pulsing bass synth isn't from a delay or similar effect, it's built into the wavetable used. That's what I remember at least. Perhaps someone here can clarify, correct or amend. I've been a TD fan since he dropped Wireless.

 

[video:youtube]

..
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Good timing, I just looked it up myself (along with other types like Granular, Spectral, and Additive) since I've been getting interested in possibly getting a new virtual synth. That's the first point of any discussion about them (on kvr/gearslutz/etc): what type(s) of synthesis can it do.

 

I give programmers a lot of credit. Knowing just one way of synthesis on one deep synth (take Zebra for instance) takes a lot of time and patience...some of those guys seem to be able to program the sounds they want regardless of synthesis type. My patches always seem to end up worse than when I started LOL

 

Where it gets really crazy are all the synths that can do multiple types and blend them all together.

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IIRC, Thomas Dolby shared that the bass line for Windpower was wavetable PPG - the pulsing bass synth isn't from a delay or similar effect, it's built into the wavetable used. That's what I remember at least. Perhaps someone here can clarify, correct or amend. I've been a TD fan since he dropped Wireless.

Sounds right:

http://www.bigbluewave.co.uk/ppg_340_380.htm

 

http://www.electricity-club.co.uk/html/int_dolby.html

"On top of that, the PPG also had a wavetable synthesizer in it which had some pretty extraordinary sounds. Some of the wavetables were so disparate that you'd hit a key and the note had a sort of rhythm inherent to it... like the bassline in Windpower which has this slapback effect. I think I actually wrote that song because I'd dialled up that sound. That's what I made the song with."

 

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Thanks for the replies and info.

 

OK: what is the "table" when one speaks of wavetable synthesis? Does this simply refer to the collection of single-cycle audio waves?

 

 

J.S. Bach Well Tempered Klavier

The collected works of Scott Joplin

Ray Charles Genius plus Soul

Charlie Parker Omnibook

Stevie Wonder Songs in the Key of Life

Weather Report Mr. Gone

 

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Thanks for the replies and info.

 

OK: what is the "table" when one speaks of wavetable synthesis? Does this simply refer to the collection of single-cycle audio waves?

 

 

It appears that's what the online resources generally say.

 

The basic benefits of wavetable synthesis in its most basic form seem to be 1) the single-cycle waves can be all sorts of different waves and, 2) there can be mechanisms to interpolate between different waves over time.

 

#1 doesn't require any more storage or computational capabilities than other traditional types of synthesis (of the era), and #2 can produce interesting timbre morphing or "movement".

..
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It's a confusing world of information out there Tim. We appreciate the time you put in filtering it for us and giving the us just the 'need to know'. :thu:

(For the avoidance of doubt no sarcasm implied or intended)

A misguided plumber attempting to entertain | MainStage 3 | Axiom 61 2nd Gen | Pianoteq | B5 | XK3c | EV ZLX 12P

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I once got to "demo" that one, if you can call it that with such a flimsy synth. I think it was trying to be a poor man's Korg DW8000, but failed badly. The build was klack city, the samples excruciating and the envelopes and filter quite limited. It was a synth you'd give to a kid whom you wanted to discourage from playing music. I hate to speak ill of the dead, but the smell was terrible. :rimshot:

 "You seem pretty calm about all that."
 "Well, inside, I'm screaming.
    ~ "The Lazarus Project"

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"The basic benefits of wavetable synthesis in its most basic form seem to be 1) the single-cycle waves can be all sorts of different waves and, 2) there can be mechanisms to interpolate between different waves over time.

 

#1 doesn't require any more storage or computational capabilities than other traditional types of synthesis (of the era), and #2 can produce interesting timbre morphing or "movement"."

 

 

 

To me, this is the real benefit of wavetable synthesis. I used to own a Waldorf Microwave XT (a descendent of the PPG Wave, which was probably the earliest (or at least most common) wavetable synth), and aside from the massive number of individual waveforms you had access to, you could modulate the waveform with an envelope or LFO, which allowed you to create evolving sounds, in particular, pads that would constantly change over time.

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The Kawai K1 was also a wavetable synth, and quite a cool little piece of kit. The K1 II added effects, so it's the more desirable, and they can be had generally for well under $150.00.

 

With a velocity and touch-sensitive keyboard.

 

I love mine to bits.

 

..Joe

Setup: Korg Kronos 61, Roland XV-88, Korg Triton-Rack, Motif-Rack, Korg N1r, Alesis QSR, Roland M-GS64 Yamaha KX-88, KX76, Roland Super-JX, E-Mu Longboard 61, Kawai K1II, Kawai K4.
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