Through most of the 20th century, recordings were made on adevice called an analog tape recorder. The professional analog recorder has its own unique sound, described as warm, gutsy and raw.
This retro-specialty tool is more expensive then digitally based recording equipment and quite a bit heavier. However, it is still highly regarded in the recording industry and sought after by many recording studios and artists.
Basically, all analog tape recorders (ATR) use the same principles to record and play audio signals. “A length of plastic tape coated with a magnetically sensitive material is unwound from a supply reel, drawn past tape heads at a constant speed, and wound onto a take-up reel. During recording, the record head encodes a representation of the incoming audio signal in the tapes magnetic material. During playback, the repro (or play) head reproduces an audio signal from the magnetically encoded information on the tape.” From: Anatomy of a Home Studio, by Scott Wilkinson (1997).
Multi-track analog recorders behave as if there were several independent, mono recorders within one machine. Professional ATRs can be found in 2-, 4-, 8-, 16-, 24-, and 32- track formats. The erase, record, and repro heads can be activated independently for each track.
Multi-track analog recorders use tape that is ¼ to 2 inches in width. The more tracks, the wider the tape needs to be.
8-tracks machines typically use ¼” – ½” tape, 16-track machines normally use ½” – 1” tape and 24-track to 32-track machines use 2” tape.
The faster the tape is drawn past the heads, the more magnetic particles are affected in a given amount of time, which improves the recorded quality. Adversely, the faster the tape speed, the less recording time you have on a given length of tape.
Some analog recorders offer variable speeds, which also adjust the pitch of playback as well as speed. Common open reel speed are 3-3/4, 7-1/2, and 15 ips, however, professional units can go up to 30 ips.
For a great book that includes a chapter on analog tape machines, check out: Analog Recording: Using Analog Gear in Today’s Home Studios, by Dave Simons. Dave he maintains a basement studio at his New England home, complete with live echo chamber and an arsenal of aging equipment.
Despite the advances in digital technology, many recording enthusiasts argue that the sound produced on a analog tape recorder using ½” tape running at 15ips is more accurate and has a better frequency response that digital audio. And I agree…it really, really sounds good.
As of this writing I found exactly two of these devices available. However, I do believe that since analog recording is coming back it is just a matter of time before someone starts making them again .