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Here's one for you historians.At work we have an unused radio/PA distribution/amplification cabinet made by the Commercial Radio Sound Corp. based in NYC.
It appears to be from the 1940's - it's a self contained rack-type metal cabinet that's a dark olive green color, is about 2 feet wide, 1.5 feet deep, and stands about 7 feet tall. There is a hinged access door on the back.
On the front are controls for selecting inputs, outputs to 20 different speakers, a radio tuning console, and a monitoring speaker.
I work at a university in NYC, so this was used at one point for taking radio feeds, or microphone feeds, and routing them to different rooms within the building.
Inside is are two mono amps that are driven, I believe, by a pair of PP 6L6 output tubes. The transformers, both output and power, are produced by the Langevin Corp., also from NYC. The pots for the 20 speakers are pretty beefy Clarostat units.
Does anyone know anything about these transformers or about the Langevin Corp? I was wondering whether these transformers were any good for use in a modern tube amp setup.
From what I could find on the web, the Langevin Corp. produced transformers and circuits for professional/studio applications. They started in NYC but later moved to California.
Later, the Manley Corporation bought the Langevin name and circuits and are now producing studio recording gear under the name. Apparently these devices are highly regarded.
At least I think that's right.
If anyone knows anything more, it would be great to hear from you.
Follow Ups:
please email me offline, i have an off topic question for you, i need access to a wind chamber in the NYC area.
hi KT:We have close to two dozen of the Langevin audio transformer designs in our archives though this represents just a smaller fraction or sampling of their body of work.
On a related note, would you happen to have any documentation for the Langevin 312A output transformer? I have a pair of mystery Langevin amps, that most closely resemble the model 128 using a 6sJ7-6v6- PP 6l6 configuration with the common 317A output transformer. However, my amps appear earlier, with a slightly different chassis layout, and the 312A transformer. I can't seem to figure out if it has capabilities for 8-16 ohm operation, as strapping info for 500 and 125 ohms is given only.
Doug, your amps look like 610a Muzak amps.
See if this is how your 312a is.
opt imp, connect to, (strap)
500ohms, A-D, (B-C)
125ohms, A-D, (A-B,C-D)
2-8ohms, 0-4,
The three windings are,
D-B, 125ohm
C-A, 125ohm
4-0, 4ohm nominal
as of 5-26-47
If you have 101a power transformers,
For 20w power use taps #1 and #5 (as shipped)
For 15w power use taps #2 and #4
Hello,Yes indeed, those would be my amps! No wonder they didn't seem to fit the normal 128 layout, although the circuit is pretty close. I had a feeling the 0-4 taps were for 4 ohm nominal, but I didnt want to find out they were not by blowing something up. I wonder how they will sound. They have really nice transformers for Muzak amps, or any amp for that matter. They look very similar to a Western Electric 124
Doug wrote,
They have really nice transformers for Muzak amps, or any amp for that matter. They look very similar to a Western Electric 124
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You could get 30 of those 755c's? and wire the house for stereo :-)
I must say, distributed sound systems have taken a turn for the worse in my opinion. Muzak listeners used to get treated to Altec 755's powered by Langevin amps like mine. Now you walk into a department store and you get some 20 watt Bogen solid state thing powering cheezy 6" Atlas drivers!
Arrgh, what happened to the quality?
Hi Doug: we don't have the 312 engineering folder. Sorry.
Doug--Many years ago in Ca. was given a Langevin amp that I think had 6L6 outputs and output imp of 125-500 ohms. Its output imp was measured and was quite low --enough to work well with 15 ohm JBL speaker system. I was told it was designed to be used in the premium music remote feed telephone lines of the time. Good luck. Max
Yes, The transformers are very high quality. Their tube stuff was very nice! The Langevin Company made a transfer to solid state about 1966. They introduced one of the first silicon solid state Class A push pull amplifiers. They also introduced solid state microphone amps and booster line amps as well as sliding attenuators. Then they faded out mostly from foreign competition. The Rupert Neve Company in England as well as Neumann in Germany was making great inroads here with comnpletely configured mixers and consoles where Langevin, RCA, Altec, and Fairchild had previously been dominant. The first American solid state amps and preamps were not as good as the Europeans partly due to the avaliability of low noise silicon transistors. American transistor makers always reserve their best for the defense and the space programs and everyone else suffers. The best! James
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