Reader T.F. sent me this scan from AUDIO ENGINEERING c. 1952: the introduction of the RCA BC-2B Console.
LEFT: The BC-2B incorporated the RCA MA-11241 dual mic pre-amp unit; a two-stage circuit, each channel used a single 12AY7 for, I would suppose, about 25 – 30 db of gain. The schem for the 11241 is posted below here. Notice that, similar to the earlier octal-pentode based RCA mic pres, the full B+ current flows through the output transformer; this severely limits your choice of output transformer: the only vintage full-fidelity units that I am aware of are the UTC A-25 and LS-27. Lundahl makes a modern unit that satisfies this spec, as does Hashimoto (HL-20K-6); very expensive pieces tho! Any of you fellas know of other 15k:600 1/2 watt transformers that handle 8ma unbalanced DC and still pass 40 – 20K?
Here’s a dude that’s cloning the BC2B preamp; price is $650 for the preamp plus another $450 for the power supply. Assuming that the build-quality is good, $1100 is a pretty fair price for this thing; I know how much those Lundahls cost ( I use the same O/T in my BRDCSTR as well) plus phantom power is a pain in the ass to build in.
7 replies on “RCA BC-2B Recording Studio Console c. 1952”
What is the B+ you are operating at?
300 vdc or thereabouts.
The old RCA “Radio Age” magazines are available online at http://www.vacuumtubeera.net/RadioAgeMagazine.html now.
40 dB gain, output is 30K:600, they are wired 150 out in the consoles. 285VDC for B+. Passes well below 40Hz. That particular schematic should be banned from the universe, I have no idea where it came from, definitely not the official schematic from the manual.
Hi Doug. Do you have a more accurate schem for this device that you can send us or link to? c.
Just found full manual here:
(for this, and other old RCA consoles)
http://vintagewindings.com/products/RCADVD.html
Hey Chris.
Another update from downunder. .
I just picked up the AWA equivalent of this consolette .. it’s an exact clone (probably licensed from RCA).
It’s called the BCU-1. Same enclosure, same layout, same amp modules (just with with locally Oz made transformers, looks like). Will be interesting to check the sound when i get it going one day! Have to get one alongside the RCA somehow to compare (!)
Mine is missing the smaller labelled panel plate from the top right side function area (where the CUE selection & VU Meter function switches are, etc) ..
If you hear of anyone that might have a spare, I’m all ears!
Cheers,
Evan