9090 (909 clone) - Adding automation to parameters (Machinedrum style)

[SubContractor]

Hi All

As a proud owner of an Elektron Machinedrum, I love the parameter lock function – quick extract from the user guide:

“2. Now it is possible to lock parameters to a specific note in the pattern. In

grid edit mode, hold a [DRUM] key and then tweak a parameter. The

parameter adjusted will be inverted to indicate that it now is locked to the

value you set. The corresponding <DRUM> LED will flash rapidly to indicate

that a parameter is locked for that step.

3. In live recording mode, you can lock parameters by tweaking the knobs

while recording.â€

I’d love to build the 9090 (http://www.introspectiv.eclipse.co.uk/) and add this functionality to it. As for the MidiBox side, I guess (a modified) MB SEQ or MB808 would be the right brain for it. Ill probably wait for the new core module before hitting this side of things. As for the ability to add the tuning, I need to find a way of replacing the mainly logarithmic pots on the front panel. Circuit diagram at http://www.introspectiv.eclipse.co.uk/download/9090_schems_10june02.pdf . I thought of:

1. Digipots, but from what I gather, they will not go well with the negative half of the waveform, and the waveform will probably be too high voltage for them (only found 5v ones)

2. Mixer chip like in MB Mixer, but there are 30 parameters in the 9090 which would mean 15 chips at more than AU$20 each, that’s not viable.

3. AOUT_NG (multiple x AOUT NG?) driving VCAs – currently the only solution I can see.

I’d love to hear if anyone has any better ideas for this!

FYI: These are the original values

470ohm Log x 1

100K Log x 4

10K Log x 10

1M Lin x 2

470K Log x 4

47K Log x 9

Regards

Andrew

[stryd_one]

1. Digipots, but from what I gather, they will not go well with the negative half of the waveform, and the waveform will probably be too high voltage for them (only found 5v ones)

A resistor is a resistor is a resistor ;) You might find that 5V is the operation voltage, but you can pass more through the analog I/O. AOUT_NG is always nicer though ;)

[Ashiman]

theres a guy on interwebs who modded a roland dr or boss dr something, plus there are some good photos off the xbase something innards. Probably new voicecards would be better ???

[moogah]

This was part of the original idea for the MB808, a long long time ago.

To make a long story short, this really just isn't possible* You will need to use a combination of digipots, voltage controlled resistors (CA3080's) and vactrol's to cover all the parameters that need to be modified.. and that is drastically understating the amount of engineering and prototyping that will be involved... I would estimate that you'd nearly double the amount of PCB involved with a 9090, before adding the standard MBHP modules. 

Assuming you *do* find a suitable way to get all the parameters under voltage or digital control you will need to have quite a few AOUT channels running to control the VCRs and vactrols. 

If you get all that done, you will probably be just in time for the new core module to provide you with enough sequencer tracks to actually sequence the parameters...  All in all, this would be one of the most difficult projects I've seen around here..

*of course everything is possible, somehow..

[stryd_one]

Yeh after chatting (nagging, begging) with moogah during the early days of the MB808, I came to the conclusion that the 'right' way to do this, is to do a near-clone, from the ground up, with digital control in mind. Adding it as an afterthought (to the original x0x design) always seems to result in much misery.

[moogah]

Yes, it will take some thought and effort to make it work.. but it's probably worth it :D

SubContractor: stop by chat sometime if you want to pick my brain, but you probably don't want to start with a whole 9090, I think it would be reasonable to tackle one instrument at a time, possibly end up with a "lite" version which still gets quite a bit done!

[SubContractor]

Hmmm. Ok, well if its going to be that much work, I guess I'll have to admit that I dont really have that much time to do it then. When I first started thinking about it, I thought it would be relatively straight forward. Bummer. Thanks for the feedback guys!