Click for homepage
Lorenz Textophon
Audio wire cartridge recorder - under construction

Textophon was an early wire recorder 1 , introduced around 1933 by by C. Lorenz AG in Berlin-Tempelhof (Germany). The device was used for recording audio onto a thin steel wire, and play it back afterwards. It was unique in that no open reels (or spools) were used, as the wire spools were contained in a large metal cartridge, or cassette, that could be swapped and resused easily.

Although it was a large device that was originally intended as a dictation machine (dictaphone) or telephone answering machine, it is listed here as a covert recorder, mainly because it was used by the German Federal Police during World War II, for making covert recordings of interrogations of prisoners of war, and arrested agents and spies.

The image on the right show the leftovers of a Textophon BE-4/III that was rediscovered in 2015 in Germany. The device shown here was made in 1947 and is very similar to (but a bit smaller than) the earlier BW-4/II model of 1941.

The device is based on the Telegraphone [3], invented in 1898 by Valdemar Poulsen in Denmark [1] and also on the Telephonograph, inventend in the same year by the French engineer Jules Ernest Othon Kumberg [4]. It was used from 1933 onwards for telephone answering systems and for central office dictation systems. The machine was also adopted by the German Nazi party, and – in 1935 – by the Reichs Rundfunk Gesellschaft (RRG), the German Broadcasting Corporation.

It is known from statements made by former engineer Semi J. Begun — who worked for Lorenz in the 1930s before moving to America — that the German Nazi government purchased thousands of Textophons for tapping and recording telephone conversions of people under surveillance [8].

In 1936, the Textophon was used as a major recording device during the controversal Olympic Games that were held in Berlin that year [5]. In many ways, the Textophon was based on a similar American device – the Dailygraph – of which the rights had been acquired by the American ITT corporation. ITT, who had become the major shareholder of Lorenz in 1930, passed the device on to Lorenz for further development. It is likely that its design was incorporated into Textophon.

  1. German: Stahltondrahtmaschine (steel sound wire machine), Stahltondrahtgerät (steel sound wire device), or Stahltonmaschine (steel sound machine).

1 / 1
1 / 1

  • BW-1
    First commercially available wire recorder from Lorenz, housed in a large wooden enclosure that was usually placed on the floor. The top section contained the wire cassette with the recording heads, whilst the lower part contains the amplifiers and main power supply unit. This version was developed in 1933 and was delivered in large quantities to the German Nazi Government in 1935 for telephone surveillance.

  • BW-4/II
    Improved design, housed in a wooden enclosure that is similar to that of the BW-1 [6]. It would usually be placed on the floor and requires a different – improved – design of the wire cartridge. The initial design was made in February 1941, but the device was probably not released commercially until 1942 [F].

  • BW-4/III
    Smaller variant, also housed in a wooden enclosure, that could be placed on a table top. Based on the BW-4/II, but probably not released until relatively late in the war, probably 1945. The machine featured on this page is a BW-4/III with serial number 47-038, that was manufactured in 1947.
The Textophon can be used as a stand-alone audio recorder — operated with the controls at the front of the top surface — but also as a remote-controlled unit, by adding the optional Steurstelle (controller) and the optional Abhörstelle (play-back device). In such cases, the actual Textophon was commonly placed in a centralized facility, depicted in the diagram below as the control room.

In such cases, the controller is commonly placed on the desk of, say, a company director, who dictates latters to the Textophon in the control room. The controller is also suitable for the direct connection of a telephone set, so that conversations can be recorded without a microphone.

A secretary can transcribe the recorded text directly from her own desk, by using a small remote control unit known as the Abhörstelle (play-back device), with a pair of headphones connected to it. The push-buttons on the play-back device can be used to start, stop and rewind the wire.

German Police during WWII
During WWII, the German Police used the Textophon for covert recording of interrogations of prisoners of war (POW) and – more importantly – enemy spies and agents that had been caught while operating on German territory. The diagram below shows a typical setup as it was used by the German Police Department of Vienna (Austria), recreated after the orignal WWII diagram [C].

In this setup, the microphone is hidden from view. Its signal is first amplified in a sensitive pre-amplifier, after which it is amplified to line level by an extra amplifier that also drives a relay, which means that it uses voice actuated recording. The relay takes over the function of the RECORD-button on the control unit, that is also hidden from view, perhaps in the next room.

The signals from the control unit are fed to the Textophon, which is located in the monitoring room, or in a centralized facility elsewhere in the building. An extra amplifier and loudspeaker are placed in the monitoring room, so that people can observe the interrogation 'live'. Furthermore, a line feeds the signals to the transcription desk (in the same room or in a separate office), where a secretary can play-back the recording later, in order to produce a complete transcription.

Textophone was initially developed by Semi Joseph Begun, whilst working as an engineer for the Ferdinand Schuchardt Fernsprech- und Telegraphenwerk AG in Berlin (Germany), at the request of the Echophon Maschinen AG company – at the time owned by Kurt Bauer – who had acquired the manufacturing rights for magnetic recording from Kurt Stille. The major shareholder of Ferdinand Schuchardt AG, was Kurt Blattner, who also made the Blattnerphones for the British BBC [9].

In May 1930, Begun's device was ready, and from June 1930 onwards, it was sold by Echophon AG under the name Dailygraph. For the wire spools he had used a cassette, or cartridge, based on US Patent 1,665,784 of 1925 by Willy Hornauer [10]. The device was well known under the name Dailygraph in the English-speaking world, in particular in the UK and in the United States.

Around the same time (1930) the American ITT corporation, acquired the majority of shares of all three companies: Ferdinand Schuchardt AG, Echophon Maschinen AG and C. Lorenz AG, and brought the development of all magnetic recording activities under the umbrella of Lorenz.

The Dailygraph was renamed Textophon and was manufactured from 1933 onwards by C. Lorenz AG. From 1934 onwards, the Textophon was further developed by Lorenz and in 1936, the wire cartridge was changed for a version that was open on one side. Textophon was initially marketed as a dictation machine, which had the added ability to record directly from a telephone line. For this purpose, it had been approved by the German telecom authority Reichspost in 1936 [11].

  • SP-1/I
    Wire cartridge
  • BW-1/St
    Control unit
  • ?
    Playback unit
Removable wire cartridge
Control unit   Steuerstelle

Play-back unit   Abhörstelle

Wire cartridge   Spulenträger
Conversation are recorded magnetically onto a steel wire that has a thckness of just 0.22 mm.

The device is unique, in that it is one of the first devices on which the wire was not supplied on open reels, but in a cartridge, that could easily be replaced by a non-expert. As far as we know, there were two designs of this cartridge, that are very similar, bot not compatible with each other.

The first design was used with the original Textophon BW-1, whilst the improved version shown in the image on the right was supplied with later models, like the BW-4/II and the BW-4/III.
Original tape cartridge SP-1/I

Wooden case with two spare wire cartridges Inside the wooden box Original tape cartridge SP-1/I Rear view Close-up of a wire spool The other spool Serial number tag Note pad
1 / 8
Wooden case with two spare wire cartridges
2 / 8
Inside the wooden box
3 / 8
Original tape cartridge SP-1/I
4 / 8
Rear view
5 / 8
Close-up of a wire spool
6 / 8
The other spool
7 / 8
Serial number tag
8 / 8
Note pad

  • Wire thickness
    0.22 mm
  • Recording speed
  • Wire length
  • Recording time
    20 minutes (later: 30 minutes)
  • Rewind speed
    2 x recording speed
  • Mains voltage
    110, 120, 150, 220 or 240V AC, 50 Hz
  • Rectifier valves
    Telefunken RGN-1064 (or Valvo G-1064) and Philips 328
  • Amplifier valves
    Telefunken REN-914 (or Valvo W-4110, or Philips E-499)
  1. Textophon Brochure (German)
    Lorenz AG, date unknown. 11 pages.

  2. Bedienungs-Anleitung für das Lorenz Textophon BW-1
    Operating instructions (German).
    C. Lorenz AG, Berlin-Tempelhof (Germany). 15 pages.

  3. Textophon interrogation system, block diagram
    Bundespolizei Wien (Federal Police Vienna).

  4. Textophon, circuit diagram snippets
    Author and date unknown.

  5. Dailygraph Type A and B, circuit diagram
    Original blue prints (German). 16 March 1933.

  6. Textophon BW-4/II, circuit diagram
    14 February 1941 - 29 November 1944.
  1. Wikipedia, Wire recording
    Retrieved January 2018.

  2. Wikipedia, Valdemar Poulsen
    Retrieved January 2018.

  3. Wikipedia, Telegraphon
    Retrieved January 2018 (German).

  4. Wikipedia, Telephonograph
    Retrieved January 2018 (German).

  5. Wikipedia, 1936 Summer Olympics
    Retrieved January 2018.

  6. Günter Hütter, Lorenz Textophon BW-4/II, S/N 8255
    Personal correspondence, June 2017 — January 2018.

  7. Smithsonian Institute, Telephone Answering Machine
    The National Museum of American History. Retrieved January 2018.

  8. David Morton, Sound Recording: The Life Story of a Technology
    ISBN 0-8018-8398-9, 2004-2007. Recording in World War II, p. 113.

  9. Museumsstiftung Post und Telekommunikation, Textophon mit Zubehor
    Full title: Drahttonaufzeichnungsgerät 'Textophon' mit Zubehör.
    Inv. nr: 4.2004.211.0. Retrieved January 2018.

  10. Willy Hornauer, US Patent 1,665,784
    Electromagnetic Talking Machine. Filed 20 June 1925. Published 10 April 1928.

  11. Reichspost, Ambtsblatt 1936 Nr. 51, Mitteilung 1216
    Mitteilungen des RPM, 1216—1218. p. 219.

  12. Recording on a Steel Tape
    The Wireless World, 29 June 1939. p. 611.

  13. H. Wildbolz, Das Textophon
    Schweizer Archiv fur angewandte Wissenschaft und Technik (German),
    Appendix Betrieb und Wirtschaft, No 10, 1943. pp. 9—12.

  14. Dr. Hans Joachim von Braunmühl, Magnetische Schallaufzeichnungen
    Fortschritte und Spitzenleistungen.
    Date unknown, but probably 1936. pp. 184—186.

  15. Von der Tonwalze zur Bildplatte
    Audio (Magazine). Date unknown. pp. 43—44.

  16. Eduard Schüller, Das Magnetophon
    pp. 428—431.
Further information
Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Created: Monday 08 January 2018. Last changed: Tuesday, 09 January 2018 - 14:20 CET.
Click for homepage