KeVlaR's Audioworld

The compact cassette tape was introduced by Philips back in the early 1960's.

It was was originally intended for use in office dictaphone machines but it soon found its way into the home recording market. Because of its compact size it became popular as a replacement for the many reel-to-reel recorders that were in use at that time.

It can be argued that the sound quality of the new compact cassette was a step backwards in sound quality as the speed of the compact cassette was a steady 1 7/8ips (Inches Per Second) and many reel-to-reel recorders could be varied upto 30ips in speed. As you may already know the faster the tape runs the wider the bandwidth and the better the recording.

You may be asking yourself; do cassette decks still have a place in a modern hifi system given the many new formats available boasting super high quality performances? Absolutely! The main reason being that you can record whatever you want and play it wherever you want.

You can record from any source: CD, tape, radio, or records. You can record custom mix tapes, with any songs, in any order. You can easily and quickly make multiple copies for playback at home, in your car, or in your portable. Or you can simply enjoy any of the thousands of available pre-recorded cassettes.

Many mini and midi systems still ship with cassette decks along with virtually very motor car built over the past fifteen years. With the advent of the new formats personal cassette players have dropped to ridiculous prices while their performance has soared. It's no wonder cassettes continue to be so popular.

Considering this incredible versatility, as well as the improved sound quality and value of today's cassette decks, now is a better time than ever to invest in a new deck!

One popular type of cassette decks that is available are Dual well models, or "dubbing decks," that can hold two tapes in separate wells. The main advantage of these is easy tape-to-tape copying. High-speed dubbing cuts copy time in half (but copy at normal speed for best sound quality).

Many dubbing decks let you play two tapes, one after the other, non-stop (called relay play). Some of the better models include two auto-reverse record/play transports that let you record four sides non-stop (relay record), such as those from Pioneer and Yamaha. A few of these models can even make two identical recordings simultaneously! The only drawback to these types of decks is that the sound quality of them suffers and they are not as accurate as a single deck recorder.

If like myself you're somewhat of a purist when it comes to recording quality, you may want to look for decks with Dolby S noise reduction. And if you don't need a dubbing deck, look for a 3-head, single-well model. Whilst recording a cassette tape, a 3-head deck lets you compare the tape to the source and adjust bias for optimum accuracy!

Just as a footnote. Undoubtedly (in my opinion) the king of the cassette market is Nakamichi, closely followed by Revox and Teac.

TAPE TYPES

Cassette tape consists of a backing material such as PVC and on this is bonded a number of different coatings, all of which are capable of being magnetized.

Playing time is denoted by the code numbers C-30, C-45, C-90 and C-120 with the numerical digits denoting the playing time in minutes if both sides are played in sequence.

C-120 cassette tapes are very prone to stretching and breaking and their usage is generally frowned upon by most users and cassette deck manufacturers. C-90 is the most popular/common cassette available as it will accommodate a full LP or CD on each side. The reason for the failure rate on these is that the tape is much thinner.

These are IEC (International Electrotechnical Committee) standards. They provide broad standards for all tapes, and end the need to align a deck for an individual tape.

TYPE 1 - Ferric Tapes

A flexible base with fine particles of iron adhered to it, which can be magnetized by the record head. The quality of this tape is variable but is probably the most common and cheapest around. Sometimes referred to a 'IEC Type 1'.

TYPE 2 - CRO² Chrome Tapes

Capable of higher frequency response than standard ferric tape and should only be used on equipment with the facility for the playback of CRO²/Chrome tape. Also referred to as 'IEC Type 2'.

TYPE 4 - Metal Tapes

Even better quality. By using pure metal as a coating, recordings can be produced with even less background noise and a better frequency response. Again the tape deck must be equipped with the facility for the playback of metal tapes. Also known as 'IEC Type 4'.

Most modern cassette recorders sense the tape type by the holes in the back of the housing and adjust bias and equalization to compensate for the differences. A few top cassette recorders (the Revox and several Nakamichis) automatically align to a particular tape by recording test tones and then setting their own equalization.

In practice, each brand and model tape is slightly different. For the very best recordings, adjust your recorder for the tape you use most, or buy the tape which works best in your recorder. Manufacturers adjust each recorder for a specific tape at the factory. So the best tape might be the one referenced in the recorder owner's manual. In a recording studio, it is common to align the bias and equalization for the specific tape used, and stick with that tape.

While they differ in the details of their operation and the degree of noise reduction they provide, all three Dolby noise reduction systems answer the same question: how can noise be reduced without harming the music?

Unlike simple noise filters, Dolby NR makes no attempt to remove noise once it has been mixed in with the music. Rather, it prevents noise from being added to the music as it is recorded in the first place.

This two-step process first encodes the music when it is recorded, and then decodes it when the tape is played back. This is why the Dolby noise reduction system in your recorder should be switched on both when you make a cassette and when you play it.

In recording, the Dolby NR circuit makes the quiet parts of the music, which are most susceptible to noise, louder than normal. When the encoded tape is played back, the Dolby NR circuit is switched around to in turn lower the previously boosted parts of the music.

This automatically lowers any noise added to the music by the recording process, and it restores the music to its original form so that nothing is changed or lost but the noise.

As simple as it sounds in theory, highly sophisticated technology is used in all Dolby NR systems to ensure their unique combination of effective noise reduction and freedom from side effects.

Dolby B-type noise reduction is the original Dolby system designed for consumer tape recorders. It is inlcuded in all but the least expensive cassette machines today, and is used in the preparation of the vast majority of prerecorded cassettes. It is also incorporated in many stereo VHS videocassette recorded to improve their linear audio tracks and, in a modified form, in Dolby Surround decoders. Dolby B-type provides 10 dB of noise reduction at the higher frequencies where tape hiss predominates.

Dolby C-type noise reduction was developed to improve the cassette medium still further by providing twice the tape hiss reduction (20 dB) of Dolby B-type. It is offered along with Dolby B-type in a variety of mid-range and premium cassette decks and players. Dolby C-type is also used in many professional videocassette recorders.

Intoduced in 1990, Dolby S-type is based upon the principles of the professional Dolby SR (Spectral Recording) process. It not only provides still more tape hiss reduction (24 dB), but also reduces low-frequency noise by 10 dB. Thus, it permits recording high-level signals at the frequency extremes more accurately and cleanly. In listening tests conducted during 1995 it compared very favorably with compact disc recordings, with most listeners judging the quality of Dolby S-type encoded tapes as comparable with or in some cases superior to the playback quality of the CD. Dolby S-type is steadily gaining momentum and is being incorporated first in state-of-the-art decks for the most discerning listeners.

Not a noise reduction system, Dolby HX Pro makes it possible to record loud musical passages with fewer high-frequency losses and less distortion. It is available in better cassette decks and is also widely used by the recording industry to improve the quality of prerecorded cassetes, through its process of reducing the effects of tape saturation. As no encoding of the signal takes place, no playback decoding circuitry is required to realize the benefits of Dolby HX Pro.

Jargon Buster - modern Cassette Deck features

Bias
An inaudible high-frequency tone (typically around 100 kHz) which is mixed with the input signal and passed through the recording head to excite the tape particles, preparing them to record effectively.

Each tape formulation requires a particular bias level to maximize its recording response. If too much bias is used, high-frequency response will be impaired, causing the recording to sound dull. If too little is used, high frequencies will be accentuated, causing the recording to sound overly bright and harsh. In addition, distortion will increase and the amount of signal the tape can accept at middle frequencies will decline.

Some decks automatically optimize recording bias for whatever tape you're using. Some decks let you make manual adjustments.

Dolby® HX Pro
This circuit adjusts cassette tape bias during recording to extend dynamic headroom and improve the tape deck's ability to record high frequencies without distortion. Dolby HX Pro requires no decoding.

Dolby® Noise Reduction

Dolby® noise reduction systems reduce cassette tape hiss and background noise. Dolby B reduces high-frequency hiss by 8 to 10 dB. Dolby C works over a wider frequency range and reduces hiss by 15 to 18 dB.

Dolby S the most powerful version of all, covers the full range of audible frequencies, reducing hiss up to 24 dB in the higher frequencies, up to 10 dB in the lower frequencies. Dolby S noise reduction is the most effective at increasing the signal-to-noise ratio of the deck.

Dolby noise reduction is an "encode/decode" process -- both the recording deck and playback deck must have the same type of noise reduction (B, C, etc.) for best results. An exception to this rule is Dolby S, which was specially designed to also provide good sound when played back on any deck with Dolby B, including portables and car decks.

Dolby S is the consumer version of Dolby SR (Spectral Recording) -- the noise reduction system used by professional sound studios worldwide. Dolby S uses several of Dolby SR's proven techniques to achieve:

increased headroom
lowered distortion
greatly reduced noise (up to 24 dB at higher frequencies, 10 dB at lower frequencies)

Because its encoding and decoding are done in a more sophisticated way than the earlier Dolby B and C systems, Dolby S allows a much purer signal with a cleaner sound to be recorded and reproduced across the full frequency range.

During the encoding process, S-type dynamically alters the signal as little as possible. This makes it much easier to decode the signal accurately, resulting in greater purity of sound. And though the benefits of Dolby S-encoded recordings can only be fully realized with S-type decoding, you can play back Dolby S-encoded tapes on B-type players (your car deck or portable Walkman) with fine results.

Frequency Response
The portion of the audible frequency range (20-20,000 Hz) a deck can reproduce. Several values are shown: one for standard (type I) tape, one for high-bias (CrO ₂); one for superior metal tape.

Full-Logic Transport
A microprocessor-controlled electronic tape mechanism that stops between functions, decreasing the possibility that the tape might be stretched or become entangled in the mechanism. Often referred to as a "soft-touch" design, a full-logic transport's controls require less effort to use than older style mechanical transports.

High-Speed Dubbing
With dual-well decks, it enables you to make recordings at twice the normal speed when dubbing from one tape to another. The disadvantage to this is the slight drop in quality.

Multiplex (MPX) Filter
All FM stereo broadcasts contain a 19 kHz pilot tone that tells the receiver to decode stereo. This tone can interfere with the operation of a cassette deck's Dolby noise reduction circuits. An MPX filter removes the pilot tone for better recording. Switchable MPX filters allow for higher frequency recordings with sources other than FM.

Music Search
Automatically locates the beginning of a song from fast forward or rewind, by finding the silent spaces between songs. Decks with multiple music search let you skip to the beginning of a song several tracks away.

Number of Heads
With 2-head cassette decks, one head is a combination play/record head and the other is an erase head. 3-head decks use separate heads for play, record, and erase, so you can monitor directly off the tape while recording from another source. You'll hear exactly what your recorded tape sounds like.

Real Time Counter
An especially useful feature when recording, it gives you an estimate (in minutes and seconds) of how far into a tape you are.

Relay Play
A dubbing deck feature which automatically begins playing the second tape when the first tape is finished. You can play up to four sides non-stop.

Relay Record
A dual-record dubbing deck feature which automatically begins recording onto the second tape when the first tape is finished. You can record up to four sides non-stop.

Signal-to-Noise Ratio
A measure of how well a cassette deck silences background noise. Higher ratings -- in decibels (dB) -- indicate less noise.

Wow and Flutter
Measures how accurate the cassette deck's playback speed is. The lower the percentage, the better the performance.

The single most important thing you can do to maintain top performance is to keep head clean and regularly demagnetized.

Rather than using one of those dodgy cassette type demagnetizers, I have been using one of the wand type demag units for the past 15 years. I find that regular usage coupled with the use of good quality cassettes helps to keep my decks in good working condition.

Regular head cleaning is also recommended. Around about every forty to fifty hours is recommended. There are two types of head cleaners currently available;