And now....the CS(R)-80 project

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oldcrow
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And now....the CS(R)-80 project

Post by oldcrow » Sun Oct 06, 2013 9:22 pm

For 15 years I've been wanting to make the CS-80 in a rack-mount format, but using discrete equivalent circuits instead of the Yamaha IG-series custom chips. Since that time I've slowly determined the necessary elements: my circuit for the filters turned into the MOTM-480, The VCO-III turned into the cs80.com CSVCO, the VCAs became the JH00151 and the envelope generators, after a lot of thought, I have decided to use "electric druid" power, that is, PIC-based PWM/sigma-delta modulation derived envelopes as developed by Tom Wiltshire of electricdruid.net.

But this is just the voice card. The magic of the CS-80 is less about the sound engine and more about the user performance controls. I intend to keep the modulation routing and provide for the relevant user interface inputs not only as MIDI controller messages, but as good old physical analog devices like pedals, breath controllers, etc. The advent of the programmable control surface as seen in ipads, nexus tablets, and so on makes some of the trickier parts of CS-80 user performance less of a problem for me.

One important detail in the original CS-80 is the analog audio processing that comes after the voice cards. There are the expression/wah circuit, the balanced modulator circuit and the chorusing circuit along with the stereo splitter, final volume VCAs and so on. A fair bit of this has to be re-created as they affect the final sound, even in bypass mode.

And so, it begins. I will most likely make my experimental voice card not in the form factor of a CS M board but rather in the form factor of a crOwBX voice card. This is because I am currently set up to test crOwBX voice cards. :sb:

More later.

--Crow
/**/
Last edited by oldcrow on Mon Oct 07, 2013 12:05 am, edited 1 time in total.

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Post by synthcube » Sun Oct 06, 2013 9:25 pm

Sigh :eek:

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diablojoy
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Post by diablojoy » Sun Oct 06, 2013 9:37 pm

A CS-80! :hail:
dont think :75: is gonna cover it
I should probably start saving up now then.
It probably wont happen today but if it does it definitely wont go smoothly.

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Post by beesting » Sun Oct 06, 2013 9:49 pm

OMG! :)

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Dr. Sketch-n-Etch
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Post by Dr. Sketch-n-Etch » Sun Oct 06, 2013 9:56 pm

A worthy project, Oldcrow! Best of luck with it (and I'm a little jealous -- I haven't worked up the courage to do anything that ambitious yet).
They always said I would be nothin' but a fishhead -- look at me now!

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Isaiah
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Post by Isaiah » Sun Oct 06, 2013 11:15 pm

Scott, you are a wizard!


Will it be possible to make a monotimbral 4-voice with your voice cards, a la CS-50?

Not that I'll tackle either until next year, but the only difficult part now is deciding whether I'd like to (can afford) to build the crOwBX and this CS(R)-80 as mono or 4-voice variants.

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Post by oldenjon » Sun Oct 06, 2013 11:53 pm

YES
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Peake
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Post by Peake » Mon Oct 07, 2013 12:49 am

Something about dilithium crystals and cannot change the laws of physics...!!!!!
This is not the place I'd imagined it to be.

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Post by Jarno » Mon Oct 07, 2013 2:53 am

:yay: :hail:

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oldcrow
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Post by oldcrow » Mon Oct 07, 2013 3:32 am

One remark: the CSR-80 is going to go at a slower pace than the crOwBX. :guinness: :guinness: (I have actual work too you know) :goo: :goo:

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Post by Jarno » Mon Oct 07, 2013 3:51 am

Ah yes, still only human, how disappointing :hihi:

Retaining the crOwBX architecture seems sensible.

Edit:
Well, maybe a little bit bat-like, it's 4AM at your end right? :goo:

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Post by nvining » Mon Oct 07, 2013 4:47 am

I've been waiting for you to do this one for ages now. Even more so now that I actually have a CS80 and am concerned about the relative aging of its voice cards...

Let me know if you still need a voice card for form-factor measurements. I have a spare from a CS50 I can donate.

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Post by nickster » Mon Oct 07, 2013 5:53 am

:banana:
:nana:
:bacon:
:sadbanana:
:ripbanana:
:nana:
...we tiptoe amongst giants. Incredible. :hail:

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Post by tron23 » Mon Oct 07, 2013 5:57 am

wow my dream machine to have in a rack! :hyper: :hihi:

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Post by Moog$FooL$ » Mon Oct 07, 2013 10:33 am

my god. :woah:
i use to drink & smoke.
that fat cat had to go..... wasn't even mine.

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Post by logicgate » Mon Oct 07, 2013 11:18 am

:party: :cloud: :party:

:drunkhomer:


Me wantz

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Post by mOBiTh » Mon Oct 07, 2013 11:50 am

totally inspiring stuff, can't wait!

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magman
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Post by magman » Mon Oct 07, 2013 11:56 am

I will be watching this project with interest.

I picked up a set of CS80 service manuals a couple of years ago and occasionally enjoy tracing through some of the circuit diagrams, so I really appreciate the effort that this will take.

Are there likely to be any more fall out projects of this development, like the revised version of the MOTM 480?

Regards

Magman

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oldcrow
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Post by oldcrow » Mon Oct 07, 2013 2:47 pm

480 mark 2 is actually first as I want it finished before incorporating it into a voice card. --Crow
magman wrote:Are there likely to be any more fall out projects of this development, like the revised version of the MOTM 480?

Regards

Magman

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Post by limpmeat » Mon Oct 07, 2013 8:21 pm

I can't take it........ttoooo mannnyyy......projectsss..... :deadbanana:

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Synthsense
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CS-80

Post by Synthsense » Tue Oct 08, 2013 7:15 am

I have been waiting ages to get a decentlly priced Yamaha CS-70M just because it was the most similar synth to the CS-80 I could afford, but ...... Oldcrow you made my day! :yay: :nana: :w00t: :stg: :hyper: :wookie: :bop: CHEERS!

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Post by oldcrow » Wed Oct 09, 2013 12:08 am

As an example of the scale involved, the crOwBX filter has about 20 parts. The CSR-80 filter has about 60. Of course a CS-80 filter is 2 SVFs, but it is still a pile of parts. :goo: :goo: The trade-off is one VCO.

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Isaiah
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Post by Isaiah » Wed Oct 09, 2013 12:56 am

oldcrow
Will this project permit construction as a monotimbral synth (like the CS-50 & CS-60),
as opposed to the CS-80's duo-timbral architecture?
If so, I guess it would only need half the number of voice cards, and the Mix control would be hardwired instead of variable, right?
Would this leave half the control panel PCB unpopulated, or do you plan to have a multiple PCB solution for the control panel?

Are you sticking with slide potentiometers?

Will the builder be required to source their own MIDI-CV convertor, or will there be one specific to this project?
Maybe I misunderstood your opening post...



I realise you're in the early stages of development, I'm just curious how you're going to execute this.
I'm really looking forward to watching this develop!

Looks like 2014 could be the year I build a 4-voice OB-X and a 4-voice CS-synth!

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Post by Dude163 » Fri Oct 18, 2013 7:57 pm

wow!! this would be the radness
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Chok
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Post by Chok » Sun Oct 20, 2013 1:54 pm

Two years ago, I also dashed into this adventure. I used at first two NEIL JOHNSON'S SVF (18dB) to realize the filter. The envelope generator of the filter was rethought by a companion of forum ( Anafrog), as well as by Yves Usson himself. The shape of particular wave of the sawtooth was realized with a small circuit with 555 and it works well. The ring modulator was reproduced as before with the LM1496 which is a recent version of µA796... It works very well ( monophonic prototype). The second version of the filter was made with LM 13700 as on the filter Omega 80 of the Code... The particularity of Cs-80 being its keyboard, I think that the most difficult will be to redo such a controller... I am going to make a polyphonic version 4 voices with monophonic aftertouch....

For the aftertouch, I have realized this system:
[video][/video]

Sound without aftertouch and spécial sawtooth waveform
https://soundcloud.com/chok66/cs55

I think that Scott's version will be still clearly more realistic and I look forward to hearing it....

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