tabulaRasa - Hybrid Wavetable Oscillator [ORDER PLACED]

surgesg · Post by **surgesg** » Sat Jan 15, 2011 12:24 pm

Hey all,

Here's something I've been working on the last few months:

The tabulaRasa is a digital wavetable oscillator with voltage control of frequency, waveform selection, and the amount of interpolation between waveforms. The tabulaRasa consists of two components: a hardware synthesis module which can integrate into a modular synth system, and a software application which allows the user to create their own custom waveforms. These waveforms are then transferred from the computer to the tabulaRasa module through a standard SD card slot.

http://gregsurges.com/circuitry/tabularasa/

Check it out and let me know what you think. I'm planning on doing a run of populated PCBs, and the tabulaRasa will be a Kickstarter project.

Thanks!

- Greg

EDIT:

Just launched a Kickstarter project to fund the production of PCBs, kits etc. Please check it out here: -wavetable-oscillator

It's a great way to get your hands on one when they're done, and help support the production.

EDIT [11/10/2012]:

Taking orders for another run of kits: https://tindie.com/shops/pucktronix/tab ... -chip-set/

At $600 out of the $1000 goal with 2.5 days left!

parasitk · Post by **parasitk** » Sat Jan 15, 2011 12:30 pm

Looks (and sounds) cool! Will it be able to run on +/-15v with some component mods?

surgesg · Post by **surgesg** » Sat Jan 15, 2011 12:35 pm

Yep - there are just a couple of resistors which would need to be swapped.

Jarno · Post by **Jarno** » Sat Jan 15, 2011 12:49 pm

Looks great! On your website you mention the arduino, will the builder need one to build this wavetable osc, or does the pcb contain everything?

surgesg · Post by **surgesg** » Sat Jan 15, 2011 12:53 pm

No - I am using an Arduino to burn the microcontroller chip, and plan on making those available pre-programmed.

Rod Serling Fan Club · Sat Jan 15, 2011 1:15 pm

Glad to see some digital stuff in the DIY modular realm.

fluxmonkey · Post by **fluxmonkey** » Sat Jan 15, 2011 4:06 pm

nice!

mono-poly · Post by **mono-poly** » Sat Jan 15, 2011 4:14 pm

nice indeed!

jbartee · Post by **jbartee** » Sat Jan 15, 2011 4:20 pm

Looks like a really awesome project. I love the logo too -the world always needs more op amps!

stk · Post by **stk** » Sat Jan 15, 2011 8:12 pm

Nice! Keep us posted about populated boards

felixer · Post by **felixer** » Sat Jan 15, 2011 8:42 pm

looks interesting!

- i assume the freq cv is calibrated 1 v/oct? will it go low enough to be used as lfo (not important for me but some people will want to know)?
- how many waveforms can you store?
- seems like the card is flush with the frontpanel. how do you get it out if it is mounted behind a modular synth panel?
- how is the interpolation sounding?
- resolution/max samplerate of da converters?
- and for the ad conv for cv?
- what 's the size of the board? looks like it would fit in a eurorack?
- on which os will the editor software run? (and don't you dare say it's 'pc only'

)
- price point?

if you need a beta tester i'd be happy to be of help ....

mckenic · Post by **mckenic** » Sat Jan 15, 2011 9:29 pm

Watching this with great interest!

surgesg · Post by **surgesg** » Sun Jan 16, 2011 12:32 am

Thanks everyone,

To answer felixer's questions:

I haven't decided on the frequency range. It's limited on the high-end, but could definitely go into LFO territory. I am open to suggestions.

Currently the software supports 32 waveforms at a time. I know this seems like a small number, but I feel like the flexibility granted by the SD card interface makes up for this. Am I wrong?

When fully inserted, the card hangs off the edge of the board by a good amount. This would give enough to remove the card through a panel.

Interpolation sounds good.

All the waveforms are stored as byte arrays, for 8-bit resolution. Output is PWM. The cv inputs are 10-bit.

I don't remember offhand, but the board is right around 4" x 3".

Software has been developed and tested on OS X and Windows 7. The experience is nearly identical on both systems. Another cool feature is real-time audio preview as you draw the waveforms.

Haven't figured out pricing details at this point.

Thanks for your good questions and interest!

mono-poly · Post by **mono-poly** » Sun Jan 16, 2011 2:13 am

Damn this sounds awesome.

Luka · Post by **Luka** » Sun Jan 16, 2011 2:29 am

any room for sync

would be cool to have a wavetable osc that could be properly synced with divisions

sgnelson · Post by **sgnelson** » Sun Jan 16, 2011 2:39 am

looks very cool Greg, good work.

transfixer · Post by **transfixer** » Sun Jan 16, 2011 7:31 am

simply GREAT!

felixer · Post by **felixer** » Sun Jan 16, 2011 10:09 am

thanks for your answers, greg

- if cv res is 10 bit (1024 steps) then over 5 oct (1 v/oct) you would get a pitch resolution of 5 cent. that's on the edge of audible staircase. so some interpolation would be nice. to make it go into the lfo area some switch could be used?
- 32 waveform can sound like many more if the interpolation works well! was kinda surprised by this answer since i figured the card would be able to hold thousends .... so if used as a sample player it is restricted to short sounds? and only 1 sound/set per sd card? if the cards can be switched easily it needn't be a problem, but people will ask for some kind of a 'card switching breakout box' to externally switch 'banks' with cv ....
- seeing the output res i'm wondering what 'musical ground' you intend to cover with it .... do you want to be 'glitchy' and 'effect sound' or 'smooth' and 'tunefull'? either can be great!
- a sync or trigger input with 'one shot' option would enable the use as envelope generator.

maybe you don't need 1 v/oct. wouldn't be a problem as long as it is clear ....
maybe even specialize in low freq/control generator?
or do you intend to market it as a 'raw diy' building block?

surgesg · Post by **surgesg** » Sun Jan 16, 2011 10:19 am

The 32 waveform limit is more a function of the editing software - currently we have a button to select each waveform "slot," and we have 32 buttons. I'm weighing pros and cons of adding additional banks.

I should be clear, the tabulaRasa won't function as a sample player in the traditional sense (i.e. it won't work as a drum sampler). The sample loading function is to allow you to load single-cycle samples for the wavetable.

I'm not sure what you mean about a 'card switching breakout box', could you elaborate?

I'm definitely seeing this as a "digital" sounding device, on the glitchy side of things, probably more useful for drones and noisy sounds than melodies.

For my uses, I don't need 1 v/oct., but if this is something that a lot of people want, I can most likely make it happen.

wetterberg · Post by **wetterberg** » Sun Jan 16, 2011 10:43 am

Very cool - what is the sample length here? I didnt see that anywhere?
The ability to import any play longer looping samples from SD tickles my fancy hehe - either way this is an exciting project and I'd totally be interested in a populated board

EATyourGUITAR · Post by **EATyourGUITAR** » Sun Jan 16, 2011 1:21 pm

so how is this different from the E350? is it the CV'able interpolation. you can burn your own roms for the e350 as well.

I think what he was saying about a sd breakout is to have like 5 sd card slots and a hard switching system. I dont see how your ever gonna run out of space for 1k PCM files even at 2gb FAT16. so its probably just a misunderstanding of where the limitation comes from. your saying its the software and it can probably be fixed for something like 2000 waveforms right?

surgesg · Post by **surgesg** » Sun Jan 16, 2011 1:30 pm

I haven't seen anything about burning your own roms for the e350, but the advantage here is the combination of the wavetable editor software I've developed along with the SD card interface - easier than a ROM chip, I think.

And you're right, the limitation is not the amount of storage. I wanted to keep the waveform addressing system simple. You address 16 pairs of waveforms (each of which you can freely interpolate between) with a voltage/potentiometer. I may bump the limit up to 64 waveforms, but I want to keep the level of voltage precision needed to address a pair to a minimum. Does that make sense?

felixer · Post by **felixer** » Sun Jan 16, 2011 6:16 pm

surgesg wrote:... voltage precision needed to address a pair to a minimum. Does that make sense?

absolutely .... same goes for pitch control. implementing 1 v/oct might be tricky with 10 bits. maybe better leave it off and openly advertise this as a drone/fx machine. it also depends on the price if people will want to get it as a specialized tool. in that case the software will be more important and that seems to look pretty good. i understand it's not a sampleplayer but importing 'real' audio is very usefull. moving thru the successive waves in lineair fashion should give some resemblence to the original. and then you can fsu as you please

more 'musique concrete' then 'hifi dreamy new age e350' .... early ppg ....
switching between different wave banks/sets would be nice (either on 1 card or between several cards). but you would need an extra switch/cv for that. and prob some sort of display. that might go beyond the original purpose/concept. and since the cards are cheap and readily available 8_) much easier than burning roms

EATyourGUITAR · Post by **EATyourGUITAR** » Sun Jan 16, 2011 8:24 pm

just throw a 8 dip switch on the front panel so you can have 2^8 banks of 16 patch pairs per bank. that wouldnt compromise the original design at all.

phase ghost · Post by **phase ghost** » Sun Jan 16, 2011 9:17 pm

Looks cool! I'd be down for a board.

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tabulaRasa - Hybrid Wavetable Oscillator [ORDER PLACED]

tabulaRasa - Hybrid Wavetable Oscillator [ORDER PLACED]