The piece you see above is my homage to the Western Electric 43A.  The 43A, as far as I can determine, was the first audio amplifier developed specifically for cinema sound.  According to online sources, it was released in 1928 or 1929 – a year or two after the first optical-track sync-sound film was shown publicly.  (source, and source).

(image source)

Above is the original context in which the 43A would have been found – it’s the piece on the bottom – and this entire massive apparatus represents a single 20-watt audio playback channel, with all associated power supplies, preamps, and control devices.

Above, a pair of these systems, as seen recently via a dealer in Japan.

I don’t have a clear sense of how many 43A were made, so I don’t want to add to internet ‘swirl,’ but there can’t be too many out there. Above is a pair of 43A that sold in 2016 on eBay for $32,000.  IMO This is a very fair price for such an incredible piece of history, but it’s not a sum I, or many people, are prepared to spend on a hifi amp; hence the idea to create this tribute piece.

Back to my piece (above)… my goal was not, in any way, to make a copy of a 43A – it would be a fool’s errand, and not very practical – but rather to create a great-sounding and powerful stereo amp that honored the aesthetics of that iconic piece.

I wanted to use large, dramatic NOS tubes, but at a low cost; coke-bottle 6L6G would be nice but two matched pairs of those would be very pricey.  So I subbed 6BG6GA instead.  Basically a 6L6 with the plate in the top-cap.  I chose the Altec 353A circuit (above), as I have built several Altec 323 and they sound great, and this is essentially the same circuit but using one fewer tube per channel.  Since the mechanical construction of this thing was going to be a major PITA, I wanted to keep it as simple as possible electrically.  The nameplate is a beat NOS “Northern Electric” mirror-finish plate that I found at Radio Hovsep a few years back.

Here’s a shot of the rear.  In order to keep hum induction to a minimum, I used aluminum wherever possible in the build.  The output transformers (awesome nos 70s40-watt  Schumachers with a great vintage look) are suspended from the top chassis in order to keep the plate leads as short as possible.  The PT is a pull from an Eico ST70, which has more than enough current-handling ability for this device.   The meter is a NOS 1930s 500VDC meter that displays plate voltage.  The knob in the center is simply an on-off power control.  I am assuming that this will be used with a preamp – probably a ’42 homage’ when I get around to it  -although it gets plenty loud as-is with just a CD player connected to the RCA inputs.

This was a very difficult build in terms of the metal work.  Getting all the various subchassis to line up was difficult but worth it in the end.  It’s incredibly solid and has an imposing aura to it.  The use of all Hammond-brand metal components ensured that the black finish(es) would all match and thereby present a unified appearance.

The Western Electric 755A speaker

In a previous post, we looked at some early Western Electric cinema-sound equipment and the cult that surrounds this early kit.  Here’s a series of print ads from 1948 that describe some of the last-ever pro audio offerings from Western Electric.  WE was soon to be broken up by the government, and many of these products would then re-surface as Altec-branded components.

The Western Electric 756A speaker

The Western Electric 25B mixing console

The Western Electric 141, 142, and 143 audio amplifiers

The Western Electric speaker line up, featuring the 757A

Of all the cults and sub-cults of audio-equipment collecting, few are more rarefied and costly than collecting antique movie-theatre equipment; especially equipment made by the Western Electric Company (hf. WE).  I won’t go into WE; the company had such a complicated history filled with intense government regulation, so tightly intertwined were they with the communication industries in American life; check out wikipedia for the details.  Suffice to say that, along with RCA, WE was a main manufacturer of the equipment used to playback sound in movie theatres at the dawn of the sound-film era (late 1920s).   Since the equipment was designed for such purpose, quality and reliability was very high.    Also massive.

(from “Recording Sound For Motion Pictures,” McGraw-Hill, 1931)

Here’s RCA’s theater system from that era:

(from ‘Audels New Electric Library,’ Audel+ Co, 1931-1958)

Mr. Yashima had quite a collection of this stuff.

(scanned from “Makoto Yashima Collection,” Seibundo, Japan)

It’s hard for me to say what the value of these WE components is, but i can easily imagine single pieces trading in the 5 figures.

Getting back down to earth, WE stopped making theatre-sound equipment in the late 1940s due to anti-trust regulations (complicated, right?), but RCA kept on building it.

This brings us into the realm of more accessible (even downright cheap!) devices.  Even though this later hardware may be inexpensive nowadays, we are still dealing with equipment that is designed for ultimate reliability, and really very good fidelity.  After all, tens of thousands of people sat in these theaters every year, paying a good fee in order to watch and listen to the latest films…  this is a case where quality really matters.

I  picked up this circa 1960 RCA 9362 booster amp for…  maybe… $70?  on eBay a while back.  I had no idea what it was, but it looked like it might be useful in the studio.  And here is where it gets technical….

I could not find any technical information on the web about this device.  The only info i did find was from www.widescreenmuseum.com:  apparently these 9362s were used after the photocell amp, but before a 4-ganged volume pot, in RCA’s “four channel magnetic track motion picture film of the “CinemaScope Type”.

I did see one other fellow on eBay who had built a couple of them into a little line-preamp….

(this is the unit someone else had built and sold on eBay)

…but a studio microphone pre-amp is more practical for me.   It seemed pretty clear to me that the shielded cable on the top of the unit was likely a hi-Z input (it was), so the only work i had to do was decipher the pin-out of the Jones connector on the bottom of the unit (1, 2= heater, 3= ground, 4= B+, 5, 6= balanced output).  Well, that and build the thing.

Since it was pretty clear from the circuit type (phase inverter- push-pull output amp) that the 9362 would not have enough gain (level boost) to use as a mic pre-amp, i took the opportunity to build this little RCA 5879-tube mic preamp from their manual RC-25.

I had never built a 5879-based mic preamp, and i have to say… it’s really pretty great sounding!  I used a Jensen 115 mic input transformer, which are great btw, and the whole unit sounds really great.

The horizontal switch / ¼” jack in the front of the unit allows the user to select either the balanced input-5879 preamp-500k pot chain OR simply go hi-Z directly into the RCA 9362 amp.

Does anyone out there use old WE theater equipment for tracking/recording?

Is there any de-accessioned theater sound equipment from the 70s/80s/90s that we should be digging into?