The first usable Magnetic Recording Tape was made in 1928, using a strip of paper with magnetized steel particles. However, in order for the strip to survive repeated playback and recording, a new material was needed.

Now, the standard base material for most tapes is a plastic-type material, along with a coating of metallic particles. The metallic particles are applied with a binder substance, and they retain their magnetic properties almost indefinitely. So, you can expect the recording and playback capability of most audio tapes to last more than 30 years, especially with proper care-compare that to an iPod battery life expectancy between 2-4 years.

Audio Tape Recording
A standard audio cassette tape has two sides, A and B. These "sides" actually share the same tape surface. Tape recordings are made in the form of magnetic paths or "tracks" laid down on the tape. A device known as an audio tape head lays down the tracks. Magnetic tape can be recorded in formats called monaural, stereo, or multi-track. The audio tape head determines the format.

Monaural Recording-or sometimes called "mono" means only one track is laid down per side. An example of monaural recording is an inexpensive "shoebox" recorder. Monaural recording is called "half-track, two-channel" because each track is allowed one-half the tape surface, and there are a total of two channels.

Stereo Recording-has a "left" side and "right" side of the audio. Both sides A and B of the tape can carry a left and right track. Stereo recording is called "quarter-track, four-channel" because each track is allowed one-quarter of the tape surface, and there are a total of four channels.

Multi-track Recording-involves using the entire tape surface in one direction to lay down "multiple" tracks. This is useful for recording separate audio inputs for instance, vocals, keyboard, guitar and drums, and then retrieving them later to mix each one in a non-multi-track format.

Since all the tracks are laid down in only one direction, there is no side "B" in multi-track format, which means sacrificing one-half of your tape time when you record in multi-track. Almost all professionally recorded music is first recorded in multi-track and then mixed down into the final product.

Tape Bias
Bias is a special signal (usually from 40 to 150 kHz) added during recording that makes audio tapes more receptive to magnetic fields. Although this frequency is beyond the scope of human hearing, every audio tape has "lazy" magnetic particles that need a "boost" to help them retain magnetic information. Bias moves the signal being recorded into the "linear portion" of the tape's magnetization curve, meaning your tape will reproduce recorded sound more faithfully.

There are two bias types:

Type I (Normal) Bias-is standard ferric-oxide tape, also referred to as "normal bias."

Type II (High) Bias-is "chrome" or CrO2 tape. The ferric-oxide particles are mixed with chromium dioxide and have a stronger bias level that makes for a better frequency response.

Which one is best for my high-speed duplicator?
Many manufacturers do not recommend using Type II tapes for high-speed duplication. This is due to the thinness of the tape and the possibility that it may break under high speeds. If in doubt, check your User Manual! While Type II is generally considered better for music, Type I has been around a long time and sounds fine with music without very high frequency contents such as cymbals, violins, flutes…and they cost less.

Maintaining Sound Quality And Frequency Response
The magnetic information stored on your cassette tape is extracted by means of a device known as a tape head. This head is a very small electromagnet. In the record mode, it places magnetic information on the tape as it travels by the head. In the play mode, magnetism on the tape causes an electric current to flow from the head.

Another type of head, called an erase head, exhibits a very strong magnetic field on the tape as it passes by. This magnetic field "cleans" or "erases" any existing magnetic information by neutralizing it.

Cleaning Heads
Cleaning your record, play and erase heads on a regular basis is very important. Proper cleaning removes build-up of polish flakes that come off magnetic tape and keeps the heads free of dust and dirt. For cassette duplicators, tape heads should be cleaned approximately every 10-20 recording passes. For consumer tape recorders, cleaning should be done about once a month as a rule. To clean heads, use de-natured alcohol, or acetone using a soft cotton-tipped swab.

Demagnetizing Heads
Another important key to maintaining good audio play and record quality is to periodically demagnetize all tape heads. The constant passage of tape over the guides and capstan shaft can produce a build-up of magnetism. This build-up results in increased high frequency distortion hiss and clicks, as well as low frequency noise such as rumblings or popping. Demagnetizing is a process of neutralizing magnetic build-up on the heads.

Demagnetizing should be performed on a regular basis, about once every 1,000 tape passes.

Give New Life to Used Cassettes!
For cassette ministries, nothing saves money better than being able to re-use those cassettes. However, nothing is worse than background noise or hearing old recorded information that's still on the tape-even after your tape deck was supposed to have erased it.

A Bulk Tape Eraser uses a stronger magnetic field that will erase tapes and get them back to a clean, like new condition…if not better. This not only allows you to make better recordings, you can even erase reels or floppy disks, which contain your business or personal information.

Copyright © 2005 by Long's Electronics. All rights reserved.