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TM3030 calibration and sound references
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Author TM3030 calibration and sound references
tvh
Finally got my panel today and assembled so started to calibrate. Sounds amazing so far.

Only a few issues:
Having trouble tuning with the knob dead center. Trimmer bottoms out and I have to adjust the tune knob another 90degrees. Last note by default should be a C4/65.406Hz, right? Is there something I should look at...I know the PSU affects it but I have it set to 5.333V and it's holding steady for a few hours.

V/Oct seems to have little practical effect on the upper octaves, it seems like it isn't a linear scale as you move up and down the keyboard. I know this isn't like your 1of3 VCO in terms of accuracy so just wondering if that is par for the course for 303's?

Last question re: reference audio from acidvoice.com - are those example riffs just laden with effects? I played their example pattern 7 for a real 303 and then the midi file in ableton...different to say the least. I added some overdrive and it's closer but not being 100% familiar with a real 303 I am looking for advice on the effects they might have used (if any)?

Thanks!

PS I could list the various parts I chose if that helps
Synthbuilder
tvh wrote:
Trimmer bottoms out and I have to adjust the tune knob another 90degrees. Last note by default should be a C4/65.406Hz, right?


Lowest note on a real TB303 should be C2 at 65.4Hz. So you should be able to get it with the pot set central. Not quite sure what could be pulling your's high. C9 could be wrong but it could be a leaky JFET. Check also that you have a 4066 in there as U8 and not a 74HC4066.

Quote:
I know this isn't like your 1of3 VCO in terms of accuracy so just wondering if that is par for the course for 303's?


It's not as accurate partly because of the VCO design itself and the DAC used. But it should be good enough; +/-5 cents worse case between top C and bottom C if I remember correctly. Be sure to have used 0.1% or better resistors in the DAC (R15 to R26) though.

The V/OCT trimmer gets less effective the closer the DAC's CV is to +5.33V. From bottom C to top C the DAC goes from 1V to 5V respectively. I tend to trim scaling in the middle two octaves of operation.

Quote:
re: reference audio from acidvoice.com - are those example riffs just laden with effects?


Sounds like the output has been put through a distortion pedal of some sort. Apart from giving you the infamous overdriven mixer input stage sound it also stops the loss in signal level when resonance is turned up. Insert your favourite pedal to get this sort of sound. I use a Tubescreamer clone. An Oakley Overdrive in 'overdrive' mode could be used but I've not tried it... it maybe that the TM3030 doesn't have a big enough output to fully get the overdriven sound.

Tony
tvh
Thanks Tony. I think I have it figured out - the midi "C1, C2" etc seems to be different depending on where you look. I am now going by the piano roll in ableton and made C2 65.4hz and that worked with the TUNE pot in center position.

For U8 I have a CD4066BE. I looked up quad analog switches 4066 and found this one, I guess mine is "revision E". I will admit the suffixes/prefixes can confuse me so please let me know if you recommend a different part.

I double checked the 0.1% resistors and they are correct (at least labelled correctly). Pretty sure I have the right polystyrene cap (10000J).

So far I'm very happy with it, I'll post some photos and sound example at some point once I find a good distortion. Tried my Nova Drive and that was just ok sounding.
Synthbuilder
tvh wrote:
the midi "C1, C2" etc seems to be different depending on where you look.


Yeah, it's silly. The simple way I remember it is that A4 is 440Hz. The lowest note on a piano is A0, but midi will take you down to C-1 at note number 0.

Quote:
For U8 I have a CD4066BE.


That's perfect.

Tony
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