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Analogue keyboard synths as new MIDI modules...

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Analogue keyboard synths as new MIDI modules...

Postby Elephone » Sat Jun 08, 2019 11:34 pm

Hi. How difficult are the old analogue keyboard synths to make really, as in the actual internal electronics (not the keyboard and all)...?

I mean, surely nowadays you could copy the components, probably miniaturise the circuits and have them placed in small panels or boxes that can be played with a MIDI keyboard and/or controlled with a MIDI mixer?

Guitar effects pedals seem to sell pretty well (despite VSTs) so I wonder why this is not being done for keyboard players. I'd buy some if they were reasonably priced.

I'm thinking of units like the Jen SX-1000 and the like. I remember opening one up to repair a key and there was hardly anything in it in terms of electronics. The containing box was far larger than it needed to be (I suppose for playing purposes) and the components can probably be made far smaller now.

Should be pretty straightforward? I know there are copyright issue but I expect it wouldn't be difficult to modify circuits or mix and match bit from the various budget synths.

I know you can buy those Japanese synth kits and the Krischer boxes and get into all that circuit modifying thing, but I think that's for those who are into electronics rather people who want the instruments just to make music from the go.

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Re: Analogue keyboard synths as new MIDI modules...

Postby Folderol » Sun Jun 09, 2019 7:46 am

I wouldn't like to try it :o
It would be an incredibly complex task Even just replacing the keyboard with some other control input would be hard work, and you can't just replace components without unintended consequences - which may not show up immediately.
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Re: Analogue keyboard synths as new MIDI modules...

Postby Sam Spoons » Sun Jun 09, 2019 9:05 am

Behringer are cloning 'vintage' synths, some are not far off what you are requesting. The Model D is a box with controls but no keyboard and probably as compact as you could go while retaining all the functionality of the original.
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Re: Analogue keyboard synths as new MIDI modules...

Postby fruitcake » Sun Jun 09, 2019 1:29 pm

Also the IC chips in those vintage synths were responsible for a lot of the sound. Curtis comes to mind. Their SSM and CEM chips weren’t being made for some time. I believe the patent ran out recently now reproductions are being produced.
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Re: Analogue keyboard synths as new MIDI modules...

Postby Chevytraveller » Sun Jun 09, 2019 9:10 pm

Elephone wrote:I'm thinking of units like the Jen SX-1000 and the like.
Cheers

Quite ironic you mention this synth as it had DCOs...
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Re: Analogue keyboard synths as new MIDI modules...

Postby The Elf » Tue Jun 11, 2019 4:57 pm

As above, what you're suggesting is actively being done by Behringer - and very successfully, from a commercial point of view, from the number I'm seeing in my travels.

But don't go running away with the idea that because something looks simple it actually is. If you take a look at the innards of a humble ARP Pro Soloist, for example, you might deem it a very simple synth, but try finding anyone who can explain how it works - and some of those humble little ICs (most people might refer to them as 'chips') will be extremely difficult to replicate short of buying your own manufacturing plant, even assuming you can decode what they are doing!
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Re: Analogue keyboard synths as new MIDI modules...

Postby James Perrett » Tue Jun 11, 2019 8:30 pm

The Elf wrote: - and some of those humble little ICs (most people might refer to them as 'chips') will be extremely difficult to replicate short of buying your own manufacturing plant, even assuming you can decode what they are doing!

And that's exactly what Behringer did - they acquired Wavefront Semiconductors when they bought TC Electronic and renamed it Cool Audio. They've also re-created some of the old Curtis chip designs.

http://www.coolaudio.com/prod-coolaudio-semi.php
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Re: Analogue keyboard synths as new MIDI modules...

Postby Folderol » Tue Jun 11, 2019 8:48 pm

Makes it a bit difficult to criticise them when they do things like this. Now if they'd just do the same for some of those old transconductance amps...
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Re: Analogue keyboard synths as new MIDI modules...

Postby The Elf » Tue Jun 11, 2019 10:31 pm

James Perrett wrote:
The Elf wrote: - and some of those humble little ICs (most people might refer to them as 'chips') will be extremely difficult to replicate short of buying your own manufacturing plant, even assuming you can decode what they are doing!
And that's exactly what Behringer did - they acquired Wavefront Semiconductors when they bought TC Electronic and renamed it Cool Audio. They've also re-created some of the old Curtis chip designs.
They certainly did. And, as I understand it (?) are actually selling Curtis chips back to the likes of Sequential!
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Re: Analogue keyboard synths as new MIDI modules...

Postby nathanscribe » Fri Jun 14, 2019 6:24 pm

The Elf wrote:
James Perrett wrote:
The Elf wrote: - and some of those humble little ICs (most people might refer to them as 'chips') will be extremely difficult to replicate short of buying your own manufacturing plant, even assuming you can decode what they are doing!
And that's exactly what Behringer did - they acquired Wavefront Semiconductors when they bought TC Electronic and renamed it Cool Audio. They've also re-created some of the old Curtis chip designs.
They certainly did. And, as I understand it (?) are actually selling Curtis chips back to the likes of Sequential!

The CEM chips are being remade by the current Curtis Electromusic, Behringer/CoolAudio, and Alfa – who are also making reissue SSM chips. I'm not sure which ICs are used in current Sequential gear, but I know which I hope are in there...

Legal and moral positions aside, I'm glad we can now buy a new set of affordable ICs for repair purposes, as prices for those old ones were getting very high.
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Re: Analogue keyboard synths as new MIDI modules...

Postby nathanscribe » Fri Jun 14, 2019 6:29 pm

Folderol wrote:Makes it a bit difficult to criticise them when they do things like this. Now if they'd just do the same for some of those old transconductance amps...

You mean the 3080? You can buy the current Rochester product, which I believe is made from old ex-Intersil (?) stuff. https://www.thonk.co.uk/shop/ca3080/
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Re: Analogue keyboard synths as new MIDI modules...

Postby Folderol » Fri Jun 14, 2019 6:58 pm

nathanscribe wrote:
Folderol wrote:Makes it a bit difficult to criticise them when they do things like this. Now if they'd just do the same for some of those old transconductance amps...

You mean the 3080? You can buy the current Rochester product, which I believe is made from old ex-Intersil (?) stuff. https://www.thonk.co.uk/shop/ca3080/
Well that's nice, but it is still a very limited supply. There are no new wafers being made and once they're gone they're gone :(
There was talk about using modern methods to create enhanced but compatible devices, but I don't see anyone actually doing it.
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Re: Analogue keyboard synths as new MIDI modules...

Postby DGL. » Sat Jun 15, 2019 7:38 pm

Coolaudio do have a dual transconductance amplifier in their range, the V13700 (functionally compatible with the LM13700).

http://coolaudio.com/docs/COOLAUDIO_V13 ... ASHEET.pdf
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Re: Analogue keyboard synths as new MIDI modules...

Postby Folderol » Sat Jun 15, 2019 9:09 pm

That's very interesting indeed. Just checked the specs and it is virtually identical, and relatively cheap too. However it would take a lot of surgery to use it in place of an LM3080, and that's one that is in a lot of old designs.
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Re: Analogue keyboard synths as new MIDI modules...

Postby nathanscribe » Sat Jun 15, 2019 9:46 pm

Folderol wrote:That's very interesting indeed. Just checked the specs and it is virtually identical, and relatively cheap too. However it would take a lot of surgery to use it in place of an LM3080, and that's one that is in a lot of old designs.

Like this?

https://shop.pedalparts.co.uk/CA3080_LM ... 21572.aspx
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Re: Analogue keyboard synths as new MIDI modules...

Postby Folderol » Sat Jun 15, 2019 9:51 pm

I really should learn to keep my big mouth shut :lol: :bouncy:
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Re: Analogue keyboard synths as new MIDI modules...

Postby nathanscribe » Mon Jun 17, 2019 9:51 am

Heh. You can get replacements for the BA662 as well now, based on little surface-mount circuits adapting off-the-shelf new OTAs and adding a few parts to match differences. The 13700 is still current (pun unintended) and even if the Rochester 3080 is made from old wafers, the market is synth and pedal heads, for a few DIY and repair jobs, so they should last a little while yet. :)
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