Midi and DAC

Here is a project i hope come true…
It is a Midi interface for the famous TR-808 Drum Machine.

Can someone guide me on how to make a Midi to CV Inteface with Arduino?

Here is atached my Diagram to give you an idea of what i need to built.

Best Regards, Tilemachos

You've really got two sub-tasks so best break it down that way:

Not sure if there are MIDI shields, but if not hopefully there is some library or code in another post that will go through sorting the protocol and electronic spec (opto-isolators if I recall) - but anyways, I think you'd be ditching the USB part in that diagram - no need for it.

Have you searched for: MIDI + arduino ?

Once you have that protocol sorted the CV (that's synthesiser speak for 'analog control voltage' for those interested) and gate/note-on/note-off stuff should be easy - likely some buffering and amplifying op-amps and/or transistory carry-on. Pretty much just variable to arbitrary analog output, and a bool (or similar) to digital I/O.

As you've got timing involved learn to avoid 'delay()' read up on the stickies for this forum - they may not be 100% relevant at first glance, but they will teach you valuable insight to how best deal with timings - may as well get the learning out of the way now before you hit your first bottleneck of no can do

You've got an 808 ? very nice! I've always wanted a 909 (went through a techno phase) - but now I see equal value in both. I've only used an 808 once for a track, the kick certainly has some, er, kick (!) if you let it out huh

I am building a TR-808 clone from the begin based on original schematics but with many sound mods available. There will be some extra voices on it. Like Guiro from Roland CR-78 and some 909 voices.

It will be available on the market from the time i will built a midi interface with the specs i need.

-= IF SOMEONE HERE CAN HELP, I CAN PAY HIM WITH ONE OF MY TR-808 CLONE UPCOMING=-

Best Regards, Tilemachos

As much as I'd love one of your clones and also to build MIDI>>CV controllers for them (mate has lots of analog synths incl. a sweet ARP2600 (ex Cat Stevens!)) - with two projects on the go I don't have the time.

Grumpy Mike has suggested he knows a lot about MIDI - CV side the slightly less hard component to this, depending on your skill set, anyways> he talks the talk - maybe scope him out? He could have missed this thread...

Thnk you very much. I emailed him.

Anyone else here can take the job??

Best Regards, Tilemachos

IF you want something a bit less intimidating, there is a kit from PAIA: http://www.paia.com/midi2cv.asp

This is a Midi to CV and it uses Demultiplexer. I need real time Channel with no any Delay and only a DAC can do the job Properly for real analog sound. PAIA Midi to CV device is too expensive for what it does....

KeithRB: IF you want something a bit less intimidating, there is a kit from PAIA: http://www.paia.com/midi2cv.asp

Demultiplexer where ? read the webpage and the manual - and what is inherently wrong with 'demultiplexing' (in it's variations) ?

Been a while since I played with MIDI, but what is 'real time channel' ? No delay huh? Maybe you mean to say 'delay within a spec that you define as acceptable'.

only a DAC can do the job Properly for real analog sound

Well, um - er, would have thought only an analog originated CV would do the job properly for a real 'analog' sound?

Besides it's not so much the control voltages that give the sound but the oscillators, envelopes, filters and so on, I can see that having unnecessarily quantised/bit-steppy CV won't help, but it's not the main concern. If I recall MIDI mod-wheel for instance is 8bit anyway, so what is your DAC going to do with that? It can (theoretically) smooth it (LPF), but then you've got a delay...

Once you factor in time costs the PAIA kit looks good, but then you won't have all that learning under your belt, and the ability to alter your project for your needs - up to you :)

-- Maybe my time away from synths has made me forget the details, or I never knew them properly in the first place?

I was talking about Delay yes. PAIA is using demux. Also the DAC is using is a low cost R2R-Ladder. you can see it here in the schemas. Check both pages. http://www.paia.com/prodimages/midi2sch.pdf I need no delays and i need all channels to be updated at the same time.. Even the Demux time is so small when sequencing for long time delays are going to be bigger..

Also with the term real analog sound i mean :

1) If i use an R2R-Ladder or PWM with LPF each time a new voltage is selected there will be some "zipper noise". The intensity of this noise depends on the bits which are toggled when a new voltage is selected - the leftmost bits (most signifigant bits) will produce the highest "zipper noise".

I need a smooth operation when voltages are changing for best results. The midi to cv/gate device i need will be used to other future projects, it is not only for my TR-808 clone. It will be used for 303 and Juno-60 and later for other analog synths. Quality is my target.

'Even the Demux time is so small when sequencing for long time delays are going to be bigger..' I've read that a few times now, sorry, can't crack it...

Anyways, you realise that MIDI is serial?

With that in mind, how exactly do you propose to 'update all channels 'at the same time' yet with 'no delay'?

Anyway i prefer a DAC with 32 channels to do the job...

Best Regards, Tilemachos

Seems like we’re losing something in translation here.

You could conceivably get a 32-channel R2R-Ladder DAC - so I’m not sure what 32 channels has to do with things, aside from the fact that 32 channels affords you… well, 32 channels …

And again, there will be a delay - how do you get 32 channels worth of info at which to 'update all channels ‘at the same time’ without a delay?

It’s the nature of serial comms.

Maybe I’m not understanding things - but at the moment it seems like you’re making some odd connections between specifications - I stand to be corrected of course, maybe it’s me that is getting everything backwards, and it’s ok if you don’t want to hold my hand through it all. But just be aware, your communication indicates (at least to me), that while you’re bang on in some regards, there is some apparent confusion.

When you play a chord on the piano, it’s vital that all of your fingers go down together at exactly the same time. MIDI is built with this in mind. It can send ‘setup’ information to let you know what the next group of notes are going to be, before playing that group.

But the only piece of MIDI hardware I have is a Tesla coil, so I could be wrong.

I don't want to use R2R-Ladder or PWM with LPF. I wanna use that : http://www.analog.com/en/products/digital-to-analog-converters/da-converters/ad5372.html Chech the page for details about simultaneous update of DAC outputs.


Anyway is someone here that has the knowledge to built a High Quality MIDI to CV??

1:1: Seems like we're losing something in translation here.

You could conceivably get a 32-channel R2R-Ladder DAC - so I'm not sure what 32 channels has to do with things, aside from the fact that 32 channels affords you... well, 32 channels ...

And again, there will be a delay - how do you get 32 channels worth of info at which to 'update all channels 'at the same time' without a delay? .

Yes, I understand that...

OK, now I'm 99.5% sure you need some more conceptual background to understand what I'm trying to say.

For a serial stream of data to be parsed (demuxed) and updated simultaneously, every bit of data up until the last in any given 'window' (32channels worth in your case) will have to be held in some kind of storage medium until it is all accounted for.

This amounts to a delay.

You never replied when I suggested "maybe you mean to say 'delay within a spec that you define as acceptable'." ... (?)

Google parallel vs serial :)

Anyways, it's not a deal breaker for your project, but holding onto this conceptual block (or at least continuing to not state that you don't want my input anymore) won't get you anywhere in the meantime.

The dissenting opinions is what make us human being…
This is why forums exist… Opinions leading to replies…!

Best Regards
Tilemachos

But we seem to be stuck with me saying the same thing over again - that serial comms (MIDI) excludes your required project spec - then you not replying to the (apparently) new information (from your perspective) I have brought to the discussion.

But instead kind of tangentially swimming around the original spec as if you say it often enough it'll come true...

Anyways, I'm out of the discussion - (I'm not even sure I was in it) - have fun ;)