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Check this out- RCA Compensator Passive EQ
Old 23rd June 2014
  #1
Gear Head
Check this out- RCA Compensator Passive EQ

Hi, I'm assuming this is the right category to post in since this is of the RCA Vintage. If not, please forgive me.

Check out what I just picked up:

RCA Compensator Panel MI 9302-D

It's got some huge transformers and is all passive in design.

The front confuses me but if I unscrew and mess around swapping connection points for the jumpers I get some interesting shifts in EQ.

Pretty neat!
Attached Thumbnails
Check this out- RCA Compensator Passive EQ-img_1217.jpg   Check this out- RCA Compensator Passive EQ-img_1219.jpg   Check this out- RCA Compensator Passive EQ-img_1220.jpg  
Old 24th June 2014
  #2
Gear Head
Anybody know anything about this?
Old 24th June 2014
  #3
Lives for gear
 
nickelironsteel's Avatar
 

Everyone that did must be over 100 years old
Old 24th June 2014
  #4
Lives for gear
 

Hi
It might be a line 'correction' EQ to compensate for losses on a telephone line being used from a radio station to the transmitter which may have been miles away. I have seen some that were used for 'dial up' lines where the response needed to be changed for each use but in a fixed studio/transmitter setup, screw connections like this would be fine as once done they would not need changing.
Matt S
Old 24th June 2014
  #5
Given the vintage and provenance I wonder if it's simply an RIAA or NAB curve?

Feed in a white noise signal and map the output spectrum to test for this... see what it actually does, then you'll know what it is!
Old 24th June 2014
  #6
Lives for gear
 
emrr's Avatar
It's for film PA system EQ. Various curves possible for theater sound standards and room correction.
Old 24th June 2014
  #7
Gear Head
Anything beyond tinkering with it and using my ears is beyond me. So, if I want to employ it I'll have to use my ears and make some notes of what qualities I like/ can employ.

I'm sure the values are off due to it's age and the look of the inside.

Due to it's passive nature I get quite a drop in dB; nothing that can't be corrected with a makeup gain amp.
Attached Thumbnails
Check this out- RCA Compensator Passive EQ-img_1225.jpg   Check this out- RCA Compensator Passive EQ-img_1226.jpg   Check this out- RCA Compensator Passive EQ-img_1227.jpg  
Old 25th June 2014
  #8
Gear Head
Quote:
Originally Posted by emrr View Post
It's for film PA system EQ. Various curves possible for theater sound standards and room correction.
Do you think this is from the 1940s, Doug?

I'm betting the '40s, a good decade.
Old 25th June 2014
  #9
Lives for gear
 

Hi
You could make it more useable by having a panel adjacent to this unit with switches on it that are simply wires up to the screw pads on the box. This would mean you are not messing up a vintage unit but have something that could be useable today.
Matt S
Old 25th June 2014
  #10
Lives for gear
 
emrr's Avatar
late 30's through '40's for various revisions.
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