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[kits/PCBs] ACXSynth MIDI2CV -- an accurate DIY MIDI-CV
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3 ... 25, 26, 27  Next [all]

What format/how many are you interested in?
PCB set x1
28%
 28%  [ 32 ]
PCB set (more than one)
11%
 11%  [ 13 ]
PCB/euro panel set x1
13%
 13%  [ 15 ]
PCB/euro panel set (more than one)
8%
 8%  [ 10 ]
FULL euro kit x1
33%
 33%  [ 38 ]
FULL euro kit (more than one)
3%
 3%  [ 4 ]
Total Votes : 112

Author [kits/PCBs] ACXSynth MIDI2CV -- an accurate DIY MIDI-CV
hexinverter
Hey guys!

I've come to post about yet another project coming about from me in the not-too-distant future!

To receive an email when these are available, place your email on my list here: http://eepurl.com/pDf_5

EDIT: PCB sets, kits and panels are now available!: http://shop.hexinverter.net/category.php?id_category=17

User/Assembly manual, schematics, BoM: http://cv.hexinverter.net/?projects=midi2cv-v10


It is a very accurate 4 channel polyphonic/full monophonic MIDI-CV interface developed by the wonderful Alain of ACXSynth! I found that there is a serious lack of quality MIDI-CV designs that aren't really hard to build or require you to etch your own PCBs for do it yourselfers! There are loads of great expensive commercial modules, but I wanted something for DIY, so here it is thumbs up

Alain of ACXSynth has given me full license to make a DIY eurorack project of his great design. I will be offering:

- PCB sets (with eurorack control surface board -- simply omit the control board for other formats and wire the panel parts by hand. It will be designed to be easy to follow if you don't want to use the eurorack board!)

- PCB sets w/ nice eurorack panels (see render below)

- Full eurorack component sets (complete with panel, power cable, everything you need except tools)

...all of course supplemented with easy to follow build documentation.

This thread will serve as an interest check to know how many panels and PCB sets I need to order, as well as a comments/suggestions/discussion thread for the project. Please USE THE POLL to tell me if you are interested (instead of responding and clogging up the thread with "one for me" posts and the like!) Thanks guys thumbs up applause

Here are details about the module and the eurorack panel rendering! I will be posting in this thread as I have updates about the progress of the design and prototyping of the module, and of course demo videos in the future.





Reposting this here for any new people to this project (so it's not missed):

!!READ THIS!! -- HANGING NOTES:

In Monophonic mode, if you bang a whole bunch of keys at once, the module will sometimes get the GATE output stuck open. Seeing as how this occasional error is Monophonic mode, this shouldn't be a problem for most users since you play one or two keys at once only in Monophonic operation, but, if it is a problem for you I strongly encourage you to abstain from building one of these as it is a problem that cannot be solved without deleting other features (to free up processing power).

The beta testers agreed that it is not a huge issue, but you may feel differently, which is why I am telling you. smile

You have been warned! I am the full-disclosure type and while I wish that the firmware was 100% perfect in every way, sadly the little PIC microcontroller isn't quite up to doing everything it does do in Monophonic mode with absolute perfection.


ACXSynth MIDI2CV Features

12bit DACs with Intersil tunable opamps mean great CV accuracy (many commercial MIDI-CVs have only 8bit DACs)

This module has three modes, selectable by the mode select switch. This switch is a THREE position switch (Up, Centre, Down) and its functions are as follows:


Up = Polyphonic 1 Channel
Centre = Polyphonic 4 Channel
Down = Monophonic 1 Channel

In the Poly 1 or Poly 4 states, the 8 lower output jacks function one way, as indicated, and in the monophonic mode, they function another way for full control of one voice. That is, there is one "full" channel of CV (ie: with mod wheel, keyboard velocity and normal CV), a gate and a trigger output.

A special note about operation in Monophonic mode:

The way in which note/gate data is handled is unique for most MIDI converters, and different people like different styles, so, I will do my best to explain exactly how this one works, here.

The module operates in LEGATO operation during monophonic mode. This means that if you slide two notes together, the gates will tie together. In other words, if you want two notes to generate two independent gates, you MUST completely let go of the last note before starting a new one. The "TRIG" output of the module in monophonic mode always sends a trigger pulse whenever a key is hit, so, in this way you can patch it up to get STACCATO style playing be re-triggering your envelopes, if that is your fancy smile

If you play one note and play another while still holding the first note, it DOES revert to the note played previous. Yay applause


Sync jack:
This jack outputs an analogue version of the MIDI clock in the digital data stream. It is 24ppqn and can be divided down for use driving sequencers and the like. It can be used alongside the run/stop and reset outputs to control a sequencer while playing in Monophonic mode.

LEDs down the centre of the lower jacks:
Each of these LEDs corresponds to the respective Gate/Trig/digital output.

MIDI In jack:
This is where the user plugs their MIDI cable into.

LED to the left of the MIDI input jack:
This LED is a status indicator for the module. It is lit when the module is first initialised and has yet to detect a MIDI channel. When MIDI clock is being received, it blinks along with the beat.
Isaiah
I'm interested in a PCB or two for polyphonic purposes.
How are the voices allocated in Poly 1 mode? Most recent note "steals" from the oldest note?[/list]
hexinverter
Isaiah wrote:
I'm interested in a PCB or two for polyphonic purposes.
How are the voices allocated in Poly 1 mode? Most recent note "steals" from the oldest note?[/list]


Woot! This is fun! It's peanut butter jelly time!

Yes indeed! From ACXSynth's page, I quote:

ACXSynth wrote:
POLYPHONIC MODE

One MIDI channel ("Poly1")

In this mode it is possible to play up to 4 notes simultaneously. The first output is sent to the CV1, the second on the CV2 output ... Each CV output has its own gate output. The 5th exit Trig / Gate provides a signal of type Trigger whenever a note is played. Finally, the value of the Pitch Wheel is added to each of the 4 channels.

4 MIDI channels ("Poly 4")

Each output is driven independently by its own MIDI channel. Channel numbers must be followed (eg 3,4,5,6). This mode is very useful when the module is controlled by a sequencer


MONO MODE ("Mono")

In this mode, only the last note played is taken into account. Its value is sent simultaneously to both outputs CV1 and CV2, plus the value of the Pitch Wheel. CV3 output provides the voltage and the output velocity CV4 voltage modulation. Gate signal is present on the 3 outputs Trig / Gate, and Gate1/Gate Gate2/Gate. The last two outings and Gate3/Trig Gate4/Trig Trigger output signals.
whitewulfe
My obvious question is will there be a universal or MOTM/MU/5U/Frac compatible version available? Asking out of MU curiosity ^_^
wbkennedy1
any idea on how much they would be?
wbkennedy1
is that 6hp? i cant accurately guess hp sizes yet..
frequencycentral
Interested! Great idea. Looks like 8HP? Any idea on cost yet?
hexinverter
whitewulfe wrote:
My obvious question is will there be a universal or MOTM/MU/5U/Frac compatible version available? Asking out of MU curiosity ^_^


The PCB is other format friendly and will be easy to follow like all my other PCBs, with a universal wiring diagram. This is fun!

To make a different format, you simply omit the eurorack control surface PCB. There is NO active circuitry on the control PCB so no panel kludging is needed. thumbs up

I will NOT be making MU/other format panels! Sorry! Dead Banana
hexinverter
frequencycentral wrote:
Interested! Great idea. Looks like 8HP? Any idea on cost yet?


Yes indeed! It is 8HP exactly.

Not 100% on the cost yet, but it won't be too bad! If you just want the PCB/panel/microcontroller set and source your own parts it will be pretty cheap indeed!

The full kits will obviously be a bit more as the DACs and Intersil high quality opamps are quite expensive. They're the most expensive part of the project, for sure.

I will have exact pricing as soon as I have an idea of how many I will be making, but, expect it to be cheaper of course than a commercial module thumbs up
rico loverde
def interested in a kit w panel
ABC
I am potentially very interested in this, dependant on price of course.
kinrat
I can't vote in polls yet, but I would be interested in one complete kit
diablojoy
been wanting to do this one for quite sometime
never got to it yet .
I will want to grab a couple at least but probably more.

edit: Hey Hex have you got a very rough estimate of price on those DAC's and intersil opamps , dont worry i wont hold you to a price just trying to guage how many i can afford . if they are a fair bit cheaper then
max525 then its all good lol
filterstein
So only midi clock is output to the sync jack and there is no way to put out a start or stop signal?
This means you'd have to reset a synced sequencer by hand once you stop and start your midi source.
raisinbag
Hey Hexy, I'd be down for a few pcbs for sure and if panels are good price Id get panels as well.
terrafractyl
YES!

I'm definitely down for 1 PCB

I've been waiting for something like this to come along for yonks!
Thanks a lot Hexinverter MY ASS IS BLEEDING
ejr27233
As I havent enough posts to vote I've got to clog up the thread by saying I'm interested in 1 PCB
hexinverter
filterstein wrote:
So only midi clock is output to the sync jack and there is no way to put out a start or stop signal?
This means you'd have to reset a synced sequencer by hand once you stop and start your midi source.


Your observation is correct!

I think there were just extra pins on the microcontroller and Alain decided to use them for this purpose. Here is the text regarding this output from his site:

ACXSynth wrote:
Output Trig / Gate now called MIDI Sync is a 24 ppqn synchronization that meets MIDI clock signals (codes F8 Clock Start and Stop FA FC)"


Maybe it's just MIDI sync? wink Certainly it has limited uses without a start/stop and reset output, but I figured I would include it sad banana
hexinverter
diablojoy wrote:
been wanting to do this one for quite sometime
never got to it yet .
I will want to grab a couple at least but probably more.

edit: Hey Hex have you got a very rough estimate of price on those DAC's and intersil opamps , dont worry i wont hold you to a price just trying to guage how many i can afford . if they are a fair bit cheaper then
max525 then its all good lol


Right on smile

Ah yes -- nowhere near as bad as the MAX525!!!

The DACs are about $5.00 (depending on quantity/interest) to build one MIDI2CV module, then the opamps are another $4.50 per module -- then you need eight cermet style 12 turn trimpots which are another $10 or so...so it adds up quick smile Those are the most expensive parts other than the hardware and panel of course though!
whitewulfe
hexinverter wrote:
The PCB is other format friendly and will be easy to follow like all my other PCBs, with a universal wiring diagram. This is fun!

To make a different format, you simply omit the eurorack control surface PCB. There is NO active circuitry on the control PCB so no panel kludging is needed. thumbs up

I will NOT be making MU/other format panels! Sorry! Dead Banana


Good to know, was hoping you would make it universal ^_^
hpsounds
No reset output when a MIDI sequencer is stopped ? hmmm.....

Hédi K.
diablojoy
Quote:
The DACs are about $5.00 (depending on quantity/interest) to build one MIDI2CV module, then the opamps are another $4.50 per module -- then you need eight cermet style 12 turn trimpots which are another $10 or so...so it adds up quick


ahh very good .

i guess you can put me down for 5 then thumbs up

Quote:
No reset output when a MIDI sequencer is stopped ?

hmm not too big a problem for me i think, I use my M2C's and slaved Fonik master clocks for Sequencer clocking duties.
arrmcbain
(Edit) sorry - I just read the first post properly and voted instead :doh: (can't see the vote when using a phone app)
hexinverter
hpsounds wrote:
No reset output when a MIDI sequencer is stopped ? hmmm.....

Hédi K.


I have just spoken with Alain about this, and this is the way it will work:

The MIDI Sync output will stop outputting clock when a stop message is received on the MIDI bus. So, in this way it is pseudo stop/start/run control. It is the best available solution with only one port. I realise it won't meet everyone's needs perfectly, but, the main focus of this module is keyboard/note event data (not running sequencers). There are other solutions available for sequencer sync out there (that take up more panel space of course ^__^ ) thumbs up
hpsounds
I understand the "target", but why providing a clock output in this case ?

twisted hihi

Hédi K.
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