[78-L] Mail-a-voice

[David Lennick]

Found out a little more about this:

Brush Mail-A-Voice and the Recordon

A small disk based recording device, broadly similar to a small portable 
turntable or a disk cutter but had a magnetic head instead of a 
pickup/cutterhead, the recording quality was pretty abysmal. Brush Development 
Company started manufacturing the device in 1946 and utilised 9" paper disks 
coated with magnetic particles developed by the company in association with 3M 
but actually manufactured by Shellmar. The disks and the coating were fairly 
rugged and paper was chosen instead of a more durable format because the idea 
was that you could mail it directly without packaging and the long term 
durability was not a problem since the format was intended for a dictation 
recording only (this idea resurfaced with dictation belts), but in the 50's 
disks made out of plastics were available. The unit was not a hit but sold 
reasonably due to the relatively low price of 40USD which made it one of the 
cheapest dictation products that you could buy at the time (there was in fact a 
cheaper model available, the 501), it can be seen in operation in at the least 
2 Film Noir movies from the early 50, it died out sometime in the 50's 
primarily due to the fact that it was difficult to use compared to a tape 
recorder but there were also problems with lifetime of the magnetic heads, and 
it was a bit primitive, erasing was done by holding a permanent magnet over the 
disk. The Mail-A-Voice was manufactured under license by the British company 
Thermionic Products as the Recordon.
http://audiotools.com/oldf.html

Mail-A-Voice Disc Recorder
MAIL-A-VOICE. The model BK-503 Mail-A-Voice (Fig. 6-52), manufactured by The 
Brush Development Company, represents an entirely different approach to the 
problem of storing information on a magnetic medium. The recording material in 
this case is in the form of a 9-inch disc, and the sound track is a spiral 
running from an inner diameter of 5 inches to the outer edge. The recording 
track has a width of 0.014 inch, and the pitch of the spiral is 0.025 inch. 
Despite this close spacing, no noticeable crosstalk can be detected. The 
powder-coated paper discs can be folded and mailed like an ordinary letter. No 
guide grooves are provided on the coated discs. The recording-playback head
is guided on a spiral path along the disc by a stylus located on the tone arm, 
which tracks the guide disc. The amplifier, the circuit of which is shown in 
Fig. 6-53, covers the voice frequency range only. With a minimum of tubes (two 
double triodes), all the necessary functions are performed. No level indicator 
is employed. Even with close and loud talking into the microphone, the 
distortions are not sufficient to impair intelligibility. Alternating-current 
biasing is used in making recordings,
but erasing is effected by d-c saturation of the medium by means of a permanent 
magnet. A previous recording is erased by holding this magnet on the disc while 
the turntable revolves several times. The turntable rotates 20 r.p.m., 
resulting in a total recording time of slightly over 3 mm. This instrument 
deserves special mention because it presently represents the most simple and 
basically the most inexpensive mechanical 'rid electrical design for a magnetic 
recorder that has been produced commercially. A single crystal headphone is 
used both as a recording microphone and as a playback earphone.

The model BK-503 Mail-A-Voice shown in the illustration is intended primarily 
for dictation purposes. A solenoid, shown in the underneath view of the 
instrument in Fig. 6-54, retracts the driving idler from the turntable rim when 
the "stop" switch is opened and simultaneously applies a brake to the 
turntable. This stops the turntable so quickly that practically no time is lost 
in 'coasting." Another model of the Mail-A-Voice, the BK-501, not shown, is 
intended primarily for correspondence and dispenses with the solenoid.
http://history.sandiego.edu/GEN/recording/begun6.html

dl

David Lennick wrote:
> Okay, people..does anyone know anything about the Brush "Mail-A-Voice" Magnetic 
> Recorder? This is the one reference I've been able to find..
> http://ech.cwru.edu/ech-cgi/article.pl?id=BDC
> 
> Today I picked up a nearly complete package of Mail-A-Voice Recording Blanks. 
> 16 of them (there were originally 20 in the envelope)..about ten-inch, thin 
> paper, shiny black on one side and brownish on the back..very much like paper 
> tape. The link refers to this device being popular with servicemen during WWII 
> (so popular I've never heard of it or seen anything related to it, and 
> presumably any "letters" made on it would require another machine at the 
> recipient's end to play them back) but the blanks mention Brush as manufacturer 
> of the Soundmirror, which was post-war.
> 
> dl