Digital migration of Reel-to-reel audio


There is no doubt that storing old reel to reel audio tape in low temperature and humidity archival storage conditions slows down the physical tape degradation process, however regardless of the storage conditions, most audio tape that is presented for digital migration shows signs of aging. Broken splices, shrinkage, delamination, shedding, mould, dirt and physical damage are all signs of age and degradation. With few manufacturers left supporting the format, tape decks and the parts for maintaining them are becoming scarce, as are the technicians to keep them operative and the cost of maintenance continues to rise pushing up the cost of digital migration.

If your content is valuable and justifies the cost, we recommend you consider the transfer sooner than later to more modern digital file formats that can be digitally shared and backed up. You will benefit from preserving your valuable assets and being able to back up, edit and share the content electronically over the internet.

Open reel audio tape comes in 4 widths. ¼”, ½”, 1” and 2”. All widths can run at several different speeds and have various numbers of recording tracks and configurations. FATS offer digital migration of all formats of open reel and cassette audio however we limit our discussion here to ¼”.

¼” open reel audio is by far the most common of the open reel formats accounting for greater than 95% of the market. Developed in the 1930’s and improved during the war era to the point that the recordings surpassed the quality of most radio transmitters, allowing Generals to use ¼” recordings to make broadcasts, that appeared to be live, while they were safely away in other cities.

The ¼” format was embraced for commercial recording applications in radio and television and inexpensive reel to reel recorders were widely adopted for voice recording in the home and schools before the Phillips compact cassette was introduced in the mid 60’s eventually displacing reel-to-reel recorders for consumer use. ¼” tape was popular from the 50’s until the turn of the century, when digital formats such as DAT became available. Some artists still prefer the use of analogue open reel tape with its natural and warm sound.

¼” analogue tape is capable of recording and playing back up to eight tracks of audio.

The larger the surface area of tape used to create the recording, the higher the fidelity of the recording. The two methods of increasing the area of tape used are to speed the tape up, or increase the width of the recording tracks. Obviously a 2 track recording has much wider track recordings than an 8 track recording.

The most common ¼” format is 2 track and was widely used in radio, film and television. Content can be recorded in either mono or stereo. In production a synch pulse was used to synchronize the recording on tape with the film camera.

4 track recording was commonly used in music for either stereo or multi track recording. The 4 track format can record 2 stereo pairs, the first on one side of the tape and the second on the opposite side. This was commonly known as split track stereo.

¼” 8 track recordings were used in small non-professional music recording studios and used in the same way as the professional studios would use a 2” 16 or 24 track machine.

In general, the faster the speed, the better the reproduction quality. In addition, higher tape speeds spread the signal longitudinally over more tape area, reducing the effects of dropouts that can be audible from the medium. Slower tape speeds conserve tape and are useful in applications where sound quality is not critical.

  • 15/16ths of an inch per second (ips): used for very long-duration recordings (e.g. logging).
  • 1⅞ ips: usually the slowest domestic speed, best for long duration speech recordings.
  • 3¾ ips: common domestic speed, used on most single-speed domestic machines, reasonable quality for speech and off-air radio recordings.
  • 7½ ips: highest domestic speed, also slowest professional; used by most radio stations for “dubs”, copies of commercial announcements. Through the early to mid-1990s, many stations could not handle 15 IPS.
  • 15 ips: professional music recording and radio programming.
  • 30 ips: used where the best possible treble response and lowest noise-floor are demanded although bass response might suffer.

¼” Reel to reel running times (minutes):

here will be a table


Durations above are based on 1 direction recording for 1 track mono or 2 track stereo.

Double the above durations for 2 direction recordings for 2 track mono or 4 track stereo

Quadruple the above durations for 4 track mono

1/4 inch open-reel tapes come in a variety of formats but generally fall into two categories: “domestic” and “studio” tape. Both types have various playing speeds and tape lengths, giving a range of playing times as indicated in the table above. Generally reels up to 7” in diameter are manufactured from plastic and have a hole in the centre that fits over a ¼” shaft known as a cinespindle. 10.5” reels were almost always manufactured from aluminium. These reels were known as NAB reels and were designed to fit onto 3 ½ “ NAB hubs.

Audio Reel

Domestic reels: Typically spool diameters are 3 ¼”, 5” and 7” recorded at 1 7/8 ips, 3 ¾ ips, or 7 ½ ips and are often quarter-track mono or stereo.

Studio reels: Typically spool diameters are 7” and 10.5” and are usually half-track (2 track) stereo recordings running at 15 ips or 30 ips.

FATS specialize in migrating good quality output from old and degraded tapes to digital files. We use special ovens to dehydrate absorbed moisture from tape oxide and tape cleaners to clean the tape surface prior to digital capture. If you need help, please give us a call.

tape cleaner

dehydrating oven







FATS uses a range of Otari, Revox and Sony professional ¼” audio machines.

All are connected to RME ADI-2 PRO analogue to Digital converters, as used by the National Film and Sound Archive.

The audio is captured via AES and recorded on digital recorders.


Our Otari machines have been modified to replay recordings from 1 7/8” to 30 ips at their correct recorded speed. We can handle every format of ¼” recording.

The professional tape recorders are connected via balanced audio to professional audio capture cards and the digital files are captured without the addition of any artifacts.

Post capture, and generally as an archival requirement any specific custom metadata can be added to the files. Smaller lower resolution access versions (i.e MP3) can be created for ease of distribution and sharing.

quarter inch reel machine 1 quarter inch reel machine 2







Occasionally, tapes are sent to us that are encoded with dbx noise reduction – these are decoded using an outboard dbx decoder unit.

The quality of the recorded files depend on the quality and condition of the equipment used, the configuration of the file format chosen and the expertise of the operators.

Whether we are working on material for the National Film & Sound Archive or your precious memories, at FATS Digital we use the best professional equipment and personnel to guarantee archival quality transfers. Every transfer uses the same professional standard and the same professional care because at FATS Digital that’s what we do.