Model: Mail-A-Voice BK-503 (BK503)

Antique radios, Old Time Radios

Mail-A-Voice BK-503 (BK503)

Country: United States of America (USA) Manufacturer/Brand: Brush Development Co.; Cleveland, Ohio
Year: 1948 ?? Type: Music/speech recorder and/or -player.
Tonspeichergerät im weiteren Sinn, also auch Kassettengerät, CD-Player, Tonbandmaschine, Video-Maschine etc. möglich.Recorder and/or Player Mod.-ID = 129443 previous | Result List | next | New search for Radios etc. Schematics etc.: 1 (for members) Principle AF (audio) amplification only, one, two or three stages etc.
Niederfrequenzverstärkung.
Meist als «Nachsatz» zu einem Empfänger verwendet, um das Tonsignal zu verstärken - z.B. für Lautsprecherwiedergabe statt Kopfhörer.Audio-Amplification
Details It is not a Phonograph, Record changer, Tape Recorder, Wire Recorder, CD-Player or Minidisc, Cassette plaser or -recorder but something like 8 channel player, manchette player, Tefifon etc.Other Recorder/Player
Power type and voltage AC set plus voltage range.
/ = 2 different voltages
- = voltage from-to
* = «Special»
Apparareil à courant alternatif. Tensions mentionnées.
/ = 2 Spannungswahlen
- = von-bis
* = Fabrikwahl/«Spezial»
Trafo ist nicht immer mit Primär- undSekundärwicklungen versehen. Dadurch kann das Chassis ein gefährlichesPotential führen.Alternating Current supply (AC) / 110 Volt
Loudspeaker/pwr.out Permanent magnet type moving coil speaker (principle by Rice-Kellog, without field excitation coil).
Haut-parleur avec système dynamique à aimant permanent (sans bobine d`excitation).
Permanentdynamischer Lautsprecher, also (modernes) Tauchspulenprinzip mit Selbsterregung bzw. Permanentmagnet statt Magnetspule. Siehe «Radios von gestern» Seiten 329ff.Permanent Magnet Dynamic (PDyn) Loudspeaker (moving coil)
from Radiomuseum.org Model: Mail-A-Voice BK-503 (BK503) Valves / Tubes 3: 6SL7GT (more for members)
Notes The model BK-503 Mail-A-Voice from "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 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.

This model was suggested by Ernst Erb.

from: http://history.sandiego.edu/GEN/recording/begun6.html

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Mail-A-Voice BK-503 (BK503) (Brush Development Co.; Cleveland, Ohio)