Bell System Memorial

 

About Porticus Porticus Home Page References & Links Testimonials & Member Site Disclaimer
 
  Western Electric Products- Mirrophone
 
Home Page About This Site What's New References and Links Bell System History Life in the Bell System Capsule History of the Bell System Bell Canada Bell Operating Companies Bell Labs AT&T Long Lines AT&T Historical Financials Historical Photos Historical Film & Video Bell Telephone Magazine Articles What Killed Ma Bell "The Day the Bell System Died The Rape of Ma Bell AT&T Divestiture The Decision to Divest Odds & Ends The Eastland Disaster Bell System Employee Stories Bell System Property - (Not) For Sale Bell Logo History Trading Post - Bell System stuff wanted, for sale, for trade, etc. Bell System Advertisements Don Lively's Essay and More Miscellaneous Retirees Info Trademarks and Copyrights Visitors Comments Dew (Distant Early Warning) Line Project "Yellow Pages" Site Map The Western Electric Store Books Bell System Practices (BSP) & Technical Manuals

 Western Electric "Mirrophone"
Wire Ribbon Recorder/Player

 

Sewing Machine - Automatic Answering Service
"Mirrophone" wire ribbon recorder/player
Telephones - PicturePhone - Bell Chime

 


This page submitted by Steve Shepard who put this item up for auction on eBay.
Click on hyperlinks below to view photos of the unit.

"Of all the strange things that have been manufactured by Western Electric, this extremely rare "Mirrophone 213-A Reproducer Set" has to be one of their most unusual. It's called a Mirrophone (that's the correct spelling). When I found this at a recent estate sale, I thought the label said "microphone", and assumed that it was some kind of public address amplifier. It's not. Instead, it's a one-minute continuous loop wire recorder/playback machine. It may have been used as a voice training instrument. It was made by Western Electric for its subsidiary, Electrical Research Products, Inc. (ERPI). Notes found with it indicate that it was made no later than 1944. I have no other documentation.

In operation, one plugs a microphone (not included) into the input jack on the front of the instrument and sets the controls to the "record" mode. The correct recording volume is set with the aid of the built in "magic eye" cathode ray indicator, which displays the amount of modulation present. A message of up to about a minute in duration may be recorded. After recording, the controls are switched to the playback mode and the message will be played back continuously, either through its internal speaker or to an external amplifier (not included). There is a motorized pointer, just below the Magic Eye, that rotates once per minute as the message is being recorded or played back. It indicates the time remaining/time elapsed of the message. .

There are many unusual and unique features of this device. As near as I can estimate, there is a seventy-seven foot endless loop of metal recording wire, wound 28 times around the spools and wheels of its transport mechanism (for another view click here). The entire length passes over the unit's record/playback head once per minute. This works out to be pretty close to a wire speed of fifteen inches per second: The wire really flies around its circuitous path at a good clip. You may be familiar with wire recorders of the forties and fifties that preceded today's tape recorders. Those reel-to-reel recorders used wire that was round in cross section. In contrast, the Mirrophone's wire is flat, like the tape in a modern tape recorder. Its approximate dimensions are 0.05 inch wide by a few thousandths thick (maybe about 0.003 inch). I did not want to risk damaging the wire with a micrometer, so did not take an actual measurement. The recording and pickup heads are very primitive. They look very much like small solenoid coils.

Several features lead me to believe that this may have been a prototype or of very limited production. The entire cabinet is made of wood, except for the metal back panel. There is a brown wrinkle-finish paint applied to the sides and top, and gloss brown paint on the front panel, both of which give the impression of a metal cabinet. Also, if you look at the close-up pictures of the front panel controls, you will see position markers around the "Volume", "Repeat/Record", and "Timer" knobs. These are simply little brass round-head nails pressed into the wood. Surely a high-production machine would have been made differently. The low serial number (201) is another indication that there may not have been many units produced.

This is not a hi-fi however, and the sound quality is inferior by modern standards. The Magic Eye tube is bright and functions properly. I used a magnetic microphone to do my recording, but I believe that a ceramic type would work as well. I don't see why any other audio source could not be used as easily. The four tubes used are 6X5, 6V6GT, 6B8, made by RCA and Philco, and the 6E5 Cathode Ray Indicator, made by Emerson.

It still has a Railway Express shipping label attached, over which has been placed a shipping label from the Mountain States Telephone and Telegraph Company (click here for photo). 

I received an email from Dave D. referencing a book that appears to exactly describe the Mirrophone. The book is "Magnetic Recording" by S.J. Begun (Vice President and Chief Engineer, the Brush Development Company), Rinehart and Company, NY, 1949. 

Here are some excerpts from page 159 of that book (there is a also a schematic and a photo of the device) :

"The Mirrophone... was manufactured by the Western Electric Company in the beginning of 1940 and was intended primarily as a voice-training device and for use in the telephone system for weather-announcing purposes. 

"The recording medium consisted of 0.050 inch wide Vicalloy tape in the form of an endless loop, supported on three rollers... The medium was wound over the three rollers in a manner somewhat similar to a reversible threaded screw so that no crossover path was necessary. A spring-biased pulley maintained the medium at constant tension. A belt drive was employed, driving one roller to propel the tape. 

"The recording time of this instrument was about 1 minute, and a time indicator on the front of the panel informed the user when to switch from recording to reproducing. Direct-current bias was used. The instrument covered a frequency range of from 100 to 5,000 c.p.s. and had a dynamic range of about 40 dB."

There is also a small, blurry photo and passing mention of the Mirrophone in Appendix A of "Magnetic Recording Handbook" by Marvin Camras (Van Nostrand Reinhold Co., 1988). The photo credit is "Wireless World" magazine, Feb 1942, so it's possible there's more info there (or possibly not; some of the old magazines had only short blurbs about amazing new devices).

Uncrated, the Mirrophone weighs 60 pounds. It measures 15-1/2"H x 19"W x 13"D. The shipping/storage box weighs 35 pounds, measures 22"W x 22"W x 16-1/2"D."

Other photos not linked from text above:

Electronic (tube) circuit

Corner view of unit

Internal backside view

Left side view

Power switch and label

Magic Eye in "off" condition

Heads - Close-up 1

Heads - Close-up 2

Heads - Close-up 3

Speaker grill


Here is an old black and white movie on the www.archive.org website that had the words "Western Electric Mirrophonic Recording" in the movie credits and have not yet proven if this relates to this Western Electric Mirrophone equipment depicted on this page. If anyone knows if there is a connection, please write to us.

 

The Western Electric Store

 

 

Contact Beatrice  Careers  About Us  Site Map  Disclaimer  Legal Policy  Privacy Policy

Copyright ©MDCCCXCIV-MMXV Beatrice Companies, Inc., All rights reserved.

Porticus Home Page