DAT (Digital Audio Tape) is currently the standard professional digital format for 2-track digital recording. DAT had a short-lived consumer presence, but never "made it". As digital recorders have no tolerance for clipping, using a DAT recorder takes a slightly different knack. The results can be worth it, however, as DAT format offers the same resolution and dynamic range as CDs. DATs record for up to 2 hours on a tape, and can run at three different sampling rates: 32 kHz, 44.1 kHz (for CD), and 48 kHz (the DAT standard).
Dolby B works mostly with higher frequencies; it increases their levels during recording and decreases their levels, and the levels of high-frequency noise such as tape hiss, during playback.
Dolby B tapes can be played back without Dolby B processing, but high frequencies are over-emphasized and the sound will be excessively bright. This can be compensated for to some extent by turning down the treble control. Audio novices often remark that commercially recorded tapes recorded using Dolby B sound dull when played back with Dolby B; this is because they are accustomed tothe boosted high frequencies they hear when playing these tapes without Dolby.
Dolby C achieves greater noise reduction (about 8-10 db) than Dolby B by working with a greater range of frequencies and altering relative levels more; this means that playing Dolby C tapes back with no Dolby processing or with Dolby B, leads to very bad frequency response and a sound that most people find unpleasent. Dolby C may also be more sensitive to variations among decks in exact frequency response, alignment, etc. Some people find that tapes recorded using Dolby C sound best only when played back on the deck on which they were recorded.
Dolby S works with an even broader range of frequencies than Dolby C, and achieves slightly greater noise reduction. Its has three advantages over Dolby C:
All compression/expansion systems suffer two problems. One is due to the fact that compressors can't compress a loud signal before they have heard a bit of it, so that little bit of loud signal will get through uncompressed. Likewise, quiet passages will not be expanded until after they are detected. These delays give rise to an audible problem often called "breathing".
The other problem inherent in all compression/expansion systems is that if there are any frequency response errors in the tape recorder, they will be made worse by the compression/expansion. For example, if there is a 2dB dip in frequency response at 1kHz in the tape recorder, this will be accentuated to a 4dB dip if the compressor is using a 2:1 ratio. So compression/expansion trades noise for frequency response error. For that reason and the previously mentioned breathing, some people prefer to use their recorder without any noise reduction at all. They prefer a bit of noise to the other errors.
Dolby HX Pro is not noise reduction and does not use compression or expansion. HX Pro is a technique developed by Dolby Labs to increase tape headroom by decreasing the bias when recording signals with a large high frequency component. This allows better transient response, particularly on less expensive tapes, and requires no processing when the tape is played back. Dolby HX tapes can be played back on any system with no decrease in quality.
You CAN hear PASC, but it is very difficult, since it is not a distinctive noise (like a hiss) nor a consistent diminution (like a notch in a speaker's response), but a broad, uncorrelated dropout in a changing collection of sounds that are masked by sounds that you can hear very easily.
Since it is lossy, repeated PASC recording will cause progressive loss, and this signal damage may become easily noticeable. This is a side effect that recording companies hope will have the effect of discouraging piracy via DCC.
You CANNOT hear SCMS.
Many believe that this "tax" is illegal, because it represents an assumption that the buyer will use the recorder and tape to violate a copyright, and not to record their own works. A founding principle of the USA legal system is that everyone is assumed innocent until proven guilty.
If you believe that this law is unjust, write your elected representatives.
It is as of yet unclear whether you own the rights to sell or give away a copy of a recording if you made the copy on media which was sold with an included digital audio tax.
Practical tape head demagnetizers are available for under $10. Try to find one with a plastic coated tip. If you can't find one which is plastic coated. you can slip a drinking straw or plastic tube over the tip for the same effect. This plastic will prevent the demagnetizer from scratching the head. Before plugging in the demagnetizer, remove all tapes from your working area and unplug the recorder. Hold the demagnetizer away from the recorder as you plug it in. Slowly bring the tip of the demagnetizer up to the tape head and slide it back and forth across each tape head for five one-second strokes. Then pull it away from the head slowly and go on to the next. After demagnetizing the heads, use the tip on each metal tape guide with a similar five strokes. Last, slowly pull the demagnetizer far away from the recorder and unplug it. Recording engineers use a demagnetizer before each recording session.
As for setting of record levels, it is best to experiment with different levels on different tape brands. Different formulation will reach saturation for different levels. Generally speaking, the transients on a Chrome tape should peak at about +6 dB above 0, though some formulations can take significantly hotter signals.
Projector-Recorder Belt Company Whitewater WI USA 800-558-9572
J&R Music World 59-50 Queens-Midtown Expressway Maspeth NY 11378-9896 USA 800-221-8180 or 718-417-3737Tascam Rubber Cleaner RC-2 available from:
Tape Warehouse Chamblee GA 1-404-458-1679
Background: When you make a tape recorder, you build electronic circuits which have specific, non-flat frequency response. These circuits correct for the non-flat response of the tape heads, the recording process, and the tape. These circuits can be adjusted after the recorder is made, but adjustment is tricky, and may or may not be successful with every tape made. The designer of the tape recorder picked one tape as their standard when they did the design, and built that recorder to work well with that particular tape. It may work better with a different tape, but it won't necessarily sound the best with what one person calls the best sounding tape.
From a review of frequently given answers to this question, it is obvious that almost every brand of tape has its advocates. Many brands also have their detractors. Maxell and TDK tend to have a strong following, but that is in part because they own a large share of the US tape distribution market.
The major brands in reel-to-reel tape include Ampex, Scotch (3M), AGFA/BASF, and Maxell.
Some Type 1 tapes are more expensive than other Type 2 tapes, and may be worth the extra price. More expensive tapes come in better shells, have better lubrication, fewer dropouts, smoother frequency response, and better uniformity from tape to tape. Even though the types imply a particular tape formulations, the type really refers to the tape performance. For example, some iron oxide tapes have an unusual oxide formulation with very small grains that conforms to the type 2 standard better than the type 1 standard. These tapes will be labeled type 2, but may not have any chrome in them.
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.