alison research gain brains

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pucho812

pucho812

Well-known member
Joined
Oct 4, 2004
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third stone from the sun
Due to speedy service I was given some alison research kepex 500 gain brains 4 in total. They came missing a PSU but are in a real nice rack that can hold up to 8. on the back I see 2 different voltages connections 24V and 100V.  They also appear to be unbalanced? Does anyone have info on these?



 
edit found some info....


here is a photo

gb1-1.JPG


gb1-2.JPG


http://www.cmaudio.net/gainbrain_schematic.png


now just need some balancing transformers for the i/o :)
 
Good if you like gritty sound.
These things showed up in the '70s in many radio stations.
One station where I worked was still using them in the late '90s to ride gain on the studio and control room mics!
They were terrible when compared to any modern gear and they were unbalanced, which in broadcasting, is just asking for trouble in picking up hum and RF.
They do, as I mentioned, have a "sound" and they may have a place in making music.
 
Mike Cleaver said:
Good if you like gritty sound.
These things showed up in the '70s in many radio stations.
One station where I worked was still using them in the late '90s to ride gain on the studio and control room mics!
They were terrible when compared to any modern gear and they were unbalanced, which in broadcasting, is just asking for trouble in picking up hum and RF.
They do, as I mentioned, have a "sound" and they may have a place in making music.
Click to expand...

I know... I have used them before. just never had to service them.
 
Mike Cleaver said:
IIRC, they run on 24 volts.
Don't recall any 100v connection or supply but this is going back to the '70s for me.
Click to expand...

The original rack mate Kepexes used neon bulbs, thus the 100V.  This one uses LED's, and 24V.  The newer ones use +/- 15V.
Best,
Bruno2000
 
Bruno is right

I got some kepexs that have neons instead of LEDs
The 100v is the drive voltage.  You don't need the 100v connection pucho.
I had 4 allison brains in my FOH rack that I used for vocals
around 1980. They worked well.  Yes unbalanced but so were my inserts on my
soundcraft in those days.

I have been looking to buy one of these guys if your in a selling
mood pucho.

GARY
 
gar381 said:
Bruno is right

I got some kepexs that have neons instead of LEDs
The 100v is the drive voltage.  You don't need the 100v connection pucho.
I had 4 allison brains in my FOH rack that I used for vocals
around 1980. They worked well.  Yes unbalanced but so were my inserts on my
soundcraft in those days.

I have been looking to buy one of these guys if your in a selling
mood pucho.

GARY
Click to expand...

I think there is an old Gain Brain, and a couple of old Kepexes in our graveyard.  You want them, make me an offer via PM!
Best,
Bruno2000
 
I have one racked in a case with a calrec. Had two bad transistors for a couple LED's, couple bad LED's too.
Tracked the transistors down and replaced all the LED's. May get around to recapping it soon.
Also put an input trans on it...utc 08 if i remember right? Works good. Another toy!
 
There's a pdf of the full manual online somewhere.  Might already be in the gmail.

Gain Brain's rule for certain rock drums.  Drums is all I ever use mine for, and not all the time. 
 

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