Sie sind hier : Startseite →  Hifi Magazine + Zeitschriften→  (32) US "off duty"→  US off duty - 1985→  off-duty-1985-09 Taperecorder I

"off duty" 1970 - 1997 - eine Werbezeitung für's US Militär

Die in diesem amerikanischen (Freizeit-) Shopping-Magazin angeprie- senen Produkte waren auschließlich amerikanischen und kanadischen Militärangehörigen ausserhalb der USA zugänglich - also zu kaufen - vor allem zu ganz ungewöhnlich (verblüffend) niedrigen US $ Military-Preisen. Zu der einführenden "off duty" Seite geht es hier lang.

.

KEEP ON TAPIN' - OFF DUTY/EUROPE/SEPTEMBER 1985

written by DEAN ROCHE AND MIKE MICHELS
.

Introduction zu den Listen mit den Kassettengeräten von 1985
"KEEP ON TAPIN"

They don't make cassette decks like they used to. They make them better now. With the technological advances in such areas as noise reduction, memory, and microprocessor controls, the cassette decks of today are almost unrecognizable beside their brethren of just a few years back.

As the performance quality of the home cassette deck has increased, so has its prominence in the home audio system.

In most cases, it is no longer simply a source of music tapes for your car stereo (or taping a letter to your dreaded Aunt Edna, so you don't have to phone); it's a major source of music in the system.

However, there is no such thing as a free lunch. With all the advances in technology comes the major undertaking of determining what features are available and which ones are important to you.

This point is driven home on your very first visit to an audio showroom. You may come to the stunned conclusion that your average Boeing 747 doesn't have as many knobs, lights and buttons!

But take heart, with a little research as to what will satisfy your personal listening requirements, what's available and what you can afford, you'll be on your way to owning and operating a home cassette deck that's just right for you.

FEATURES

The multitude of features available on today's home tape decks can probably be divided into two distinct categories: performance and convenience.

In the performance category, you would find quite a number of items, such as tape heads, noise reduction, record-level meters, transport systems and bias adjustments. All of these features will have a very direct influence on the quality of the signal that passes through your home cassette tape deck.

This is opposed to the variety of counters and timers, auto-reverse, and memory or "search" features, which can really be viewed as being geared primarily for the convenience of the operator. (We do realize that one person's convenience is another person's luxury, but we will claim literary license for the purposes of this discussion.)

PERFORMANCE ITEMS

.

  • • Tape Heads:
    The heart of the tape recording process can be found in a tiny electromagnet that senses the magnetic signal pattern on the tape and converts it into an electrical signal which can be decoded into sound.
    This marvel of science is called the tape head. Most decks are equipped with two heads: one for the combined record/playback functions, the other to erase. It is increasinqly common to find a third head added. This allows for a separation of the record and playback heads, which yields optimum performance and provides the ability to monitor directly from the tape that is being recorded.
    This feature is certainly a big plus to the less than-casual audiophile.
    Studies have shown that correct tape head alignment (called azimuth) is critical to getting maximum high frequency performance out of the cassette deck. To this end, several models features automatic azimuth adjustment.
    A section of the tape is scanned and the head alignment is fine-tuned for each individual cassette. Azimuth accuracy is especially important on auto-reverse decks and can often vary slightly from one side of a cassette to another.
  • • Noise Reduction:
    The goal of any music fan is to obtain music reproduction that is a lifelike as possible. A tape recording should be, to borrow a line from Ma Bell, "the next best thing to being there." A major stumbling block to the attainment of this goal comes in the form of a four-letter word: hiss. Tape hiss is a condition that results from the cassette tape's narrow width and the slow speed at which it is played. The most common prescription for this illness is the Dolby system, which consists of circuits that artificially boost the treble frequencies during the recording of the music, thus overshadowing hiss, which is a product of the tape and not the music. Upon playback, the treble is restored to normal, with the tape hiss far less audible.
    Virtually all decks are equipped with a system called Dolby B. Of increasing availability is the newer Dolby C system - which has double the noise-reduction capacity of its predecessor - and Dolby HX, which maximizes the high-frequency storage capacity of the tape.
    Though most common, the Dolby system is not the only game in town. The dbx system provides approximately 10 decibels (dB) more noise reduction than Dolby C. It provides excellent dynamic range and virtually eliminates the noise problem. However, there is a catch. A tape recorded on the dbx system can only be played on a deck with dbx. It would sound very flat and tinny on a deck without dbx. Such is not the case with Dolby. Something to consider if you record tapes for your car or portable stereo.
  • • Record-Level Meters:
    Tape decks provide record-level meters to assist you in recording at the highest volume without distortion. Virtually all decks now come with fluorescent bar-graph level indicators. As a rule of thumb, the more segments in the display, the greater opportunity for accuracy and consistency in recording level.
  • • Transport Systems:
    As the tape is pulled across the heads, any irregularity in the speed and pitch in the tape movement will be relayed through your sound system. The result: flutter and unsatisfactory sound. Manufacturers combat the malady by adding to the number of motors and capstans used to drive the tape. Generally speaking, a two-motor, dual-capstan transport system should do the job.
  • • Adjustable Bias:
    Normal bias, high bias and metal cassettes each require different adjustments to the current and equalization fed to the recording head. There are industry standards for these values, and all cassette decks will be adjusted at or nearly at these standards for each position of the tape selector switch. Nevertheless, different brands within each category (high bias, for instance) can exhibit slightly different bias requirements.
  • Some decks provide a fine bias adjustment control to allow for maximum compatibility between tape and deck. In some the adjustment is performed according to the user's ear. On more deluxe computer-equipped models, the deck can actually perform the adjustment itself, after recording a brief test signal on the tape and analyzing the results. If you like to use several different formulations and makes of cassettes, there are decks that will store this bias info in their memories.

.

CONVENIENCES

.

  • • Counters and Timers:
    Many would argue, justifiably, that the tape counter is essential to finding a music selection's location on a tape. Manufacturers agree, so all decks come with a tape counter and virtually all now are electronic digital readouts. Some decks provide independent scan and memory search features tied in with the counter to provide automatic retrieval of specific selections on the tape.
    Timers are becoming increasingly available on cassette decks. They're great for automatically recording a radio broadcast at a specific time or if you wish to wake up or fall asleep to a tape.
  • • Auto Reverse:
    At tape's end, this feature will automatically reverse the direction of the tape and allow you to continue recording or play back the other side of the tape without interruption. This can be a big plus to anyone who appreciates long-play capability once available only in reel-to-reel.
    Tape deck manufacturers, like automobile manufacturers, are continually striving to come up with features that are one better than the competition-features that you just can't live without.
    Additional lights, remote control, the liberal use of microprocessors-all are there for the asking at the right price. If you're trying to budget, consider focusing your attention and resources on features that will maximize performance. For example, when considering a car, you can buy a Volkswagon or a Porsche. Both get you where you want to go. It all depends on how you want to travel.

.

OPEN REEL DECKS

Since cassette decks have become so advanced and convenient, why bother with the cumbersome threading of an open reel machine? Well, just take a look at the specs of a good open reel unit and the answers to this question become obvious.

For example, frequency response is typically 25 to 33 kHz, wow and flutter less than 0.02 percent signal-to-noise ratio (without noise reduction) greater than 65 dB and, most noteworthy, the playing times can go as long as 3-1/2 hours per side.

Besides, those big open reels just look professional. For those who have serious musical aspirations, need to edit by splicing or who would just like to make multi-track, studio-quality recordings, there is no other answer.

Finally, when equipped with dbx noise reduction, a quality open reel deck can provide dynamic range well in excess of what the digital compact disc can deliver, making an open reel machine an excellent choice for dubbing from CDs.

Open reel decks utilize 1/4-inch wide tape, usually divided into four separate tracks. The most common arrangement is with two tracks running in each direction, one for each stereo channel. When one side is recorded, the reels are reversed on the tape deck's hubs and the other two-channel program is recorded in the opposite direction. Splicing of this four-track tape is impractical since cutting one program will ruin the tracks in the reverse direction.

Professional half-track decks are available, with two single-direction channels all the way across the tape. Better separation and frequency response also result. Still other machines can be converted to four-channel recording, with all of the tracks running in the same direction and played simultaneously. They can also be converted back for bidirectional stereo use. Four-track machines are the best choice if you want to do some serious multi-track music recording.

THE TAPE HEADS

The critical point of contact between the tape and the rest of your audio system is the tape head. These heads are used to erase, record and play back, depending on how they are wired to the recorder electronics. Sometimes the same head is used for both recording and playback, but the preferred way is to have heads dedicated for erase, record and playback functions. Auto-reverse decks (also known as bidirectional) may have as many as six heads, duplicating the record, playback and erase heads for each direction of tape travel.

Individual record and playback heads permit immediate monitoring of material as it is being recorded. Certain models feature sound-on-sound capability, which lets you take previously recorded music from one channel and mix it with a live performance onto the other channel.

Fancy studio-type multi-track productions are possible with "simul-sync." For example, a guitar track can be recorded on the left channel. It is then played back and the vocal track is recorded on the right channel in perfect synchronization. With this feature, the two tracks remain unmixed, permitting "retakes" or adjustments to mixing volume.

THE BENEFITS OF SPEED

Most open reel decks move the tape along at 3-3/4 inches per second (ips), with a second setting for 7-1/2 ips. A cassette tape deck operates at 1-7/8 inches per second, so obviously open reel decks tend to consume tape quite a bit faster. But these higher speeds permit wider frequency response, reduced tape hiss and a greater headroom for high volume levels. Seven-inch reels holding 1,200 to 2,400 feet of tape are most common, but there are also 5-inch and 10-1/2 inch reels. The largest size can only be used on machines fitted with NAB (National Association of Broadcasters) hubs.

For truly professional results, many decks feature 15-ips tape speed. This is useful if elaborate cueing or splicing is to be done, but for the most part, 7-1/2 ips will provide all the recording performance one could reasonably need.

The deck's transport system is a team of motors driving the reel hubs and the capstan, which pull the tape across the heads. Exact tape speed and braking, along with safe handling, are best insured by logic-controlled buttons which guarantee fool-proof handling. Most designs employ dual capstan systems. This method features a drive capstan and rubber roller at each end of the row of tape heads to further isolate the tape from vibration, bent reel flanges and other speed irregularities. Direct-drive capstans utilize a precise servo-controlled motor whose shaft is the drive capstan of the tape deck. This eliminates the need for drive belts, thus removing a potential problem area.

SPECIFICATIONS

The three most commonly quoted specifications for open reel tape decks are frequency response, wow and flutter and signal-to-noise ratio. As we mentioned above, the typical open reel deck will exhibit outstanding frequency response, from below 30 Hz to beyond 35k Hz at 7-1/2 inches per second tape speed. By comparison, the range of human hearing is from 20 to 20k Hz. Any variation from perfect frequency response is expressed as a plus or minus decibel figure, ±3 dB for example. The smaller this number, the better. Frequency response will vary slightly depending on the taping speed. Expect slower speeds to yield somewhat less high frequency, although one would not hear the difference.

Wow and flutter is one area where open reel and cassette tape decks are very similar. This measure of speed irregularities is usually in the 0.03 to 0.05 percent range, making it essentially inaudible. It is customary for wow and flutter to be slightly worse at the slower tape speeds, although with good mechanical design the figures can be well within the acceptable range.

Signal-to-noise ratio is the difference between actual recorded sounds and the background hiss that is an undesirable part of the recording process.

Thanks to the higher tape speed of open reel as compared with cassettes, the open reel deck will have S/N ratio superior to that of a cassette deck, when neither uses noise reduction. Some open reel machines have dbx noise reduction, and it's also available as an add-on accessory, making it pretty much the noise reduction standard in the open reel league.

The 30 dB improvement created by dbx can combine with a top-notch open reel deck and EE tape for a total dynamic range of over 100 dB, making open reel superior to even digital compact discs in this respect.

written by DEAN ROCHE AND MIKE MICHELS in Sept. 1985
.

.

- Werbung Dezent -
Zurück zur Startseite © 2007/2024 - Deutsches Hifi-Museum - Copyright by Dipl. Ing. Gert Redlich Filzbaden - DSGVO - Privatsphäre - Zum Telefon der Redaktion - Zum Flohmarkt
Bitte einfach nur lächeln: Diese Seiten sind garantiert RDE / IPW zertifiziert und für Leser von 5 bis 108 Jahren freigegeben - kostenlos natürlich.

Privatsphäre : Auf unseren Seiten werden keine Informationen an google, twitter, facebook oder andere US-Konzerne weitergegeben.