Deluxe Multi Channel Midi to CV converter...

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inlifeindeath
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Deluxe Multi Channel Midi to CV converter...

Post by inlifeindeath » Fri Sep 21, 2012 9:02 pm

Over the past few years, i've been building my synth equipment with a 'sef-playing' mentality. Well, now i'm very curious about playing the synths in a Moog-esque classical sense, using a keyboard.
I've taken the leap into buying a MIDI keyboard and have a Barton Midi to CV board, although I haven't built it yet.

First question is... If I build the Barton circuit into a dedicated module, can I use the single 1v/oct cv output (requires 100k impedance, if I recall correctly) with multiple VCO's, and would it need buffering, or would all of this mess with the scaling?

Second question is whether there is a more complex (~4 CV/Gate channels) DIY MIDI to CV converter that I can build myself (i have Atmel burning capabilities plus it seems one can use Arduino to program PIC18F2/4 chips)?

Has anyone built the old MFOS design (MFOS or Marc Bareille's design MB or this one Here ?
It might be blasphemy but I suppose I'd prefer a microcontroller based design rather than a bulky analog one.
I can burn an AVG chip, but the programming language is beyond me at the moment. There's also the Narbotic versionhere but the code contains a lot more elements and i'm unsure how to revise it to remove theses and create more channels.
Long winded, I know, but you all are my path to knowing success and gaining knowledge, so I appreciate responses I can gather.

Thanks!

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diablojoy
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Post by diablojoy » Fri Sep 21, 2012 11:48 pm

First question is... If I build the Barton circuit into a dedicated module, can I use the single 1v/oct cv output (requires 100k impedance, if I recall correctly) with multiple VCO's, and would it need buffering, or would all of this mess with the scaling?
Into a couple of VCO's may be not too bad as the parallel input impediance is still relatively high compared to the output impedience of the barton circuit.
dont get me wrong it will have an effect on scaling but into a couple you perhaps may not notice it , better to look into adding a CV distributor board. to the output stage of the Midi to CV module its only a few opamps really. check the MFOS site ray has a simple circuit posted there
Second question is whether there is a more complex (~4 CV/Gate channels) DIY MIDI to CV converter that I can build myself
there are quite a few , i could suggest try looking on the midibox site they have i think 3 versions , one of them might be suitable .
It probably wont happen today but if it does it definitely wont go smoothly.

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jonbstevens
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Post by jonbstevens » Sat Sep 22, 2012 1:50 am

Midibox CV is great! I just finished building one with boards and parts from SmashTV. It's well documented, easy to calibrate, and budget friendly. It'll give you 8 CVs, 8 Gates, as well as a clock output with a divider, and start/stop output.

inlifeindeath
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Post by inlifeindeath » Sat Sep 22, 2012 1:10 pm

Awesome, thanks!
So I would just need the AOUT_NG kit correct?
Not really familiar with Midibox and I see some mention of a 'Core'.
Would I need anything aside from the AOUT kit?

inlifeindeath
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Post by inlifeindeath » Sat Sep 22, 2012 1:30 pm

ok, did some more reading on it and answered my own question. Any other interested parties, check this link http://www.ucapps.de/midibox_cv.html

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Post by marvkaye » Sat Sep 22, 2012 3:33 pm

Thanx for pointers to MIDIBox... cool stuff....

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jonbstevens
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Post by jonbstevens » Sat Sep 22, 2012 5:03 pm

You need an lcd, core module, AOUT ( AOUT NG is available as a kit from Smash TV), DIN board if you want buttons, and Bankstick if you want patch memory.

I bought this LCD:
SSC2F16DLNW-S 16x2 Blue HD44780 STN LCD

from 411techsystems.com, it was like $8 or something.

The rest of the boards I bought from Smash TV as kits, and i'm using an MFOS wallwart power supply. I haven't built the bankstick yet, but Jameco has the Atmel 24LC512 for $2, which should work fine according to the midibox wiki.

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Luka
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Post by Luka » Sat Sep 22, 2012 5:54 pm

i have an all-in-one midibox cv pcb here from a run on electro-music from the member sonicwarior (who is on muffs i think)

i think i might be keen on selling it as i dont have a music laptop to use it with anymore. i need to raise some cash for my vocoder anyway
let me know if you want it

Image

notes for the pcb

http://electro-music.com/forum/viewtopi ... ox&t=27166

marvkaye
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Post by marvkaye » Sat Sep 22, 2012 6:26 pm

jonbstevens wrote:You need an lcd, core module, AOUT ( AOUT NG is available as a kit from Smash TV), DIN board if you want buttons, and Bankstick if you want patch memory.

I bought this LCD:
SSC2F16DLNW-S 16x2 Blue HD44780 STN LCD

from 411techsystems.com, it was like $8 or something.

The rest of the boards I bought from Smash TV as kits, and i'm using an MFOS wallwart power supply. I haven't built the bankstick yet, but Jameco has the Atmel 24LC512 for $2, which should work fine according to the midibox wiki.
XLNT! Thanx for the list.

I bought a couple of these LCDs off eEbay back when I started working on the Thomas Henry AY Voice project, so have a spare available, ought to work just fine. Maybe even be able to do something trick with it using its RGB functionality... should be interesting.

I hadn't considered preset storage until you mentioned it... seems that would be something nice to have to streamline things. Thank you for the suggestion.

Which PIC did you use for the Core?

<marv>

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diablojoy
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Post by diablojoy » Sun Sep 23, 2012 1:49 am

Luka wrote
i have an all-in-one midibox cv pcb..... think i might be keen on selling it
Hi Luka I see it looks complete , I managed to get one from that run also but I would like to increase my midi to CV capability further
how much would it take to make you part with it ?
It probably wont happen today but if it does it definitely wont go smoothly.

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Luka
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Post by Luka » Sun Sep 23, 2012 2:29 am

someone jumped on it already :)

ill let you know if they pull out

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diablojoy
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Post by diablojoy » Sun Sep 23, 2012 5:04 pm

someone jumped on it already
Ok not surprising.
I may do my own layout eventually , i was heading that way myself anyway , i have enough MAX525 chips to do another 2.
It probably wont happen today but if it does it definitely wont go smoothly.

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neilbaldwin
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Post by neilbaldwin » Sun Sep 23, 2012 5:45 pm

With the AOUT NG kit, do you know what it contains exactly? There's no parts list on SmashTV site.
jonbstevens wrote:You need an lcd, core module, AOUT ( AOUT NG is available as a kit from Smash TV), DIN board if you want buttons, and Bankstick if you want patch memory.

I bought this LCD:
SSC2F16DLNW-S 16x2 Blue HD44780 STN LCD

from 411techsystems.com, it was like $8 or something.

The rest of the boards I bought from Smash TV as kits, and i'm using an MFOS wallwart power supply. I haven't built the bankstick yet, but Jameco has the Atmel 24LC512 for $2, which should work fine according to the midibox wiki.

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fluxmonkey
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Post by fluxmonkey » Sun Sep 23, 2012 6:09 pm

www.fluxmonkey.com

BUILDER FOR HIRE - kits or custom, email me with your needs

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jonbstevens
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Post by jonbstevens » Sun Sep 23, 2012 9:58 pm

@Marv; I used the PIC18F452

The Aout NG kit has the D/A converter chip, a couple of TL074's, resistors, caps, trimpots, ic sockets, and headers.

I haven't built the Bankstick yet, but have some space on a perfboard inside the box where i'll put it. It looks really simple to add, just waiting to make my next jameco order.

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keninverse
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Post by keninverse » Mon Sep 24, 2012 10:32 am

I have a PolyDAC and it's worked well for me. I had one issue that came up a few months ago but wasa able to get it back on track. Not bad for a 5 year old build.

inlifeindeath
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Post by inlifeindeath » Tue Nov 06, 2012 3:01 pm

multiple posts, sorry!
delete
Last edited by inlifeindeath on Tue Nov 06, 2012 3:17 pm, edited 1 time in total.

inlifeindeath
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Post by inlifeindeath » Tue Nov 06, 2012 3:04 pm

delete
Last edited by inlifeindeath on Tue Nov 06, 2012 3:17 pm, edited 1 time in total.

inlifeindeath
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Post by inlifeindeath » Tue Nov 06, 2012 3:05 pm

FYI, I built the MiniCV into a stand alone box powered by a nine volt and the long banana cable ground connection doesn't seem to be an issue. I emailed Roman and he confirmed it should be ok, but did recommend building voltage buffers for multiple outputs. Videos here:
http://www.youtube.com/watch?v=XJDF8M5d ... kvqhiXeQHg
http://www.youtube.com/watch?v=bD7CY5uz ... kvqhiXeQHg

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