Disa 91b21 preamplifier

rotation · Jul 9, 2006

Hello!
I found this http://www.gyraf.dk/schematics/Disa_91_b21_micamp.gif link with schematic of Disa preamplifier. I would like to know more about this design, it's sound qualitiys, history..I searched over the interenet and can't find nothing really helpful. The only thing i know is that moonly was or is using it, but nothing more.
Can anyone tell me more.
Thanks Miha

gyraf · Jul 9, 2006

Nope, I think you got it wrong: The DISA compressor was mentioned to be the inspiration for the moonly vari-mu - not the DISA mic amp..

http://www.gyraf.dk/schematics/Disa91n_02_limiter.gif

Jakob E.

rotation · Jul 10, 2006

Sorry for mystake; i couldn't find that writing before posting to check if i'm correct.
But i was asking for preamplifier. I would like to know more even if it was not used for moonley compressor..I like to discover stories about old designs, people who done them.
Btw, is tubes (diodes?) like EAA91 hard to find and use? Can they be changed with diodes we use today? I'm wondering how would be design like Disa comp done today.
Miha

gyraf · Jul 10, 2006

DISA was a Danish company - Dansk Industri SyndikAt - (Danish industry syndicate) that developed a range of modules for our national radio before NTP and NP took over in the sixties/seventies.

The "star" part of the DISA range are the audio transformers, made by a Danish transformer-guru named Jørgen Schou. Company name was "JS". These transformers - and their drawings and info - was all lost at a bankrupcy in the late 80'es. I've tried for a long time to trace any information, but no luck. Some of the HiFi-related transformer designs are still around though (MC step-ups and such) - but that's not really exiting to us.

So a direct DIY of the DISA's is sadly out of the question currently. But you may want to experiment with available parts - it's a good construction.

EAA91's are easy to find and very cheap.

Jakob E.

rotation · Jul 10, 2006

Thanks for the reply. Maybe i will try preamplifier when i find out what transformers i can use there. Another interesting hting is their compressor. But that's far away. Right now i'm starting to buy parts for the 1176..
Miha

Michael Tibes · Jul 10, 2006

Jakob,

Can you describe, how the preamps sound? (If you have some?)

Michael

gyraf · Jul 10, 2006

Michael,

Sorry - I'm not really into describing sonics.. :?

But they're good for sure - though a bit limited in their gain control range.

We don't have any of the modules here, but a local studio has some of them..

Jakob E.

chrissugar · Jul 10, 2006

How rare/expensive are these DISA comps?
If they are that good, it would be interesting to find one, and send CJ the transformers for some exact reversing info. Probably the only way to save this comp from disapearing. :sad:

chrissugar

Disa 91b21 preamplifier

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