Urei 175B

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Thinking about this one, a very nice compressor....

It is a fantastic and much-underated compressor, as is the 176 which is basically the same except that it has variable ratio's.

I tried to buy one of these recently and the only one I could find was a non-working specimen which still went for £1000 !
 
[quote author="NewYorkDave"]the drawings I have indicate that it's a UTC A-19 run backwards.[/quote]

correct
 
the pa-5946 is the output transformer, not the interstage. it is some kind of custom UTC that i've never been able to find any info on, beyond some speculation that it is something like a 7:1 output. the version in the later 176 and 177 has taps to get different ratios.

ed
 
I have a copy of the 175B schematic, when I had the actual unit in hand I noted the transformers:
input: UTC O-17
interstage: PA 5946
output: UTC A33

BUT as far as I know an "A33" is a mu metal can.....with nothing in it

the output primary is center tapped & fed B+, the secondary has 6 taps, two are tied as a center tap (unused) and two are un used
this is very different than the 176/77 output posted, does this sound correct?
 
the A-33 is a shield can covering the A-19, which is the interstage transformer. similarly, the O-17 is a shield can covering the O-1, which is the input transformer. the PA5946 is the output transformer.

ed
 
Just as a matter of interest I was talking to an engineer friend who recorded some classic stuff in the 60's and 70's (including Hendrix, Fleetwood Mac etc.) and he told me that they used to use the Urei 176 all the time on pretty much everything. A very flexible and great sounding compressor.
(The 176 by the way is the same as the 175 with the addition of different compressor ratios via taps on the output transformer).
I noticed that Retro make a new version of this great compressor:
http://retro176.com/
Further to that I was working at a studio in Italy last month and they actually had one of these Retro units and it sounded absolutely fantastic!
The owner told me that they have comissioned Retro to make them a stereo version.
So, if you are intending to do a 175 or 176 project, it might be a lot of work - but it would ultimately be very worthwhile.
 
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