This week’s Identify It Challenge was guessed pretty quickly, and one fan even found a picture (until this post the only picture I know of this device on the internet today!) So great work everyone. I took the liberty of obscuring the IBM logo on the original picture when it was posted in order to make it a little harder to look up the item. Here is the object without the IBM logo obscured.
This item is an IBM Magnabelt Dictation Machine (model number 224) also sometimes called an “executary”. IBM first introduced these machines in the early 1960’s. It was used to record dictation in the office and also as a method to record audio in the field by reporters. These machines are fully transistorized which lends to their smaller size and ability to be operated by battery. They did suffer from sound quality issues partly due to tracking problems with the recording belt, but also due to the poor quality of the included microphone. Today’s microphone technology is light years ahead of what was possible in 1960. In spite of these problems these units were a commercial success.
As you might know Thomas Edison invented the record player. He first marketed the record player as a business tool to record dictation. Early models used wax cylinders. As time went on other methods to record sound were devised including wire recorders and eventually tape recorders. The “executary” uses “magnabelt” technology where audio is recorded as a helical stripe along an endless magnetic recording belt. The belt is a mylar plastic belt with ferromagnetic material deposited on its recording surface.
The unit could be used in the field on battery power, or in the office connected to a base station via a proprietary power, audio, and control cable. For use in the field the unit had a thick leather carry case (which was the style at the time for portable electronic equipment like transistor radios). The leather case is held to the unit with a large captive thumbscrew. The picture above shows the unit with its leather case removed. Its exterior is a thin steel shell case with a flat gray paint job. The end piece is a black plastic.
To gain access to the magnabelt recording media or in order to adjust the recording level (a curious design limitation given there is a recording level meter in the operating controls) you can press a metal button on the back of the case and simultaneously pull the actual mechanism out of the case. There is a stop inside the case that keeps you from removing the entire case.
To get to the magnabelt you must first release a catch on the recording head mechanism and it swings open to about 25 degrees.
You can then gently lift up the portion of the belt that is pressed down by the recording mechanism and slip it off of its feed rollers. One benefit of the magnabelt over other kinds of tape (reel-to-reel, cassette, or cartridge types) is that it can be folded flat and sent through the mail to another person with another machine at normal postal expense, taking up much less space. One drawback to the technology though is that the physical alignment and tracking on a magnabelt is lost once it is removed or replaced, requiring the use of indexing and pitch controls. Getting a totally accurate reproduction of the sound is more difficult.
The “executary” used a single head for recording and playback and does not include an erase head. Recording over used magnabelts would be possible but you would have to have used an external degaussing machine to scramble the magnetic domains on the tape to erase it first otherwise you would likely have had a mixture of old and new sound recorded. (especially if the belt had been removed and replaced… due to the tracking problem as mentioned above). The head is visible in the photograph above. The head is moved from left to right by a rotating threaded rod, this rod is geared to the motion of the magnabelt’s drive by a toothed belt. As the mangabelt moved below the head the head slowly moved to the left thus recording a helix around the belt. There is a tone/tracking adjustment wheel on the body of the recording mechanism (indicated with a tuning fork symbol). This adjustment moves the head slightly to the left or right in relation to the screw mechanism so that you can find the track if the belt is moved or if a belt from another machine is being played back.
The “executary” was powered by a proprietary 10.7 volt non-rechargeable battery that is marked with the IBM logo but manufactured for IBM by the Mallory corporation.
The unit was typically used by holding in the right hand and using the thumb to operate the controls. Inside the recessed blue square are the following controls and indicators: A tiny recording level meter, the power and playback volume control knob, the record button (which can be used as on/off or locked on for continuous recording), and a manual tape advance control lever that starts the tape moving for playback or recording. Also on the unit is the tone/tracking control, an indexing control that in some way marks the index strip of paper to indicate a start/stop/edit point and a manual release that disengages the tape head mechanism from its drive screw so that you can advance the listening/recording position on the tape. This is all relative from 0 to 100 on an index strip of paper that is held in place by friction inside the tape record head mechanism. This strip would be kept with the magnabelt if removed and used to label it.
In the later 1970’s advances in micro-cassette recording technology, integrated circuits, and better microphone technology replaced the “executary” style magnabelt recorders for office and portable use. Today micro-cassettes are still used but are largely being replaced by tape-less technologies such as recording directly to flash memory. In fact most cell phones have a recording capability for audio notes!
To learn more about the Magnabelt “Executary” and other older and proprietary audio recording technology check out this website: http://www.videointerchange.com/audio_history.htm
Check back again in the future for more Identify It challenges and their answers.