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"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.


Die Bandmaschinen und Kassettenrecorder von 1972

Hier kommt erst mal die Einführung in die Feinheiten der Eigenschaften der angebotenen überwätigenden Vielfalt der Magnetbandgeräte in den Military Audio Clubs. Die Zielgruppe sind ja gelangweilte junge in den Kasernen wohnende oder aber direkt im Vietnamkrieg befindliche oder zurückkehrende Soldaten, die amerikanischen GI's.

Wenn ich als begeisterter Tonbandler schon überfordert war, mich durch den Wust an publizierten und dabei nicht immer glaubwürdigen technischen Details durchzuarbeiten, wie sollte ein GI das können.

Die völlig irre Typenvielfalt verblüfft genause wie bei den japanischen Receivern einen Monat später. Die Japaner brachten beinahe wöchentlich neue Modelle heraus, sadaß auch der Fachmann am Staunen war. Daß das ganze später mal ein beinahe tödlicher Bumerang wurde, ist in den Boom-Jahren ab 1970 bis 1978 noch nicht abzusehen. Man hätte es aber erahnen können, daß es auch in diesem Markt kein grenzenloses Wachstum gibt.

"annual survey" - (zu bezahlende) jährliche Marktübersicht


Off Duty Europe / September 72 - Is Open-Reel a Closed Case?

What manufacturers are doing to save an endangered species

ARE THE DAYS NUMBERED for open-reel tape recorders? It's a logical question to ask in the face of the events during the past year - one of the fastest moving years the audio industry has ever known. Consider, for instance, the development in the unitized-tape field.

cassette equipment.

The first big threat is from cassette equipment. Here is a field that has developed dramatically over the past year and can truthfully be said to have achieved full stature in the audio business.

Some of the new cassette machines coming onto the market actually have better specifications than some (older) open-reel machines. While they are still a bit weak on frequency response, they have amazingly good flutter and wow figures and highly respectable signal-to-noise ratios.

Cassette machines have long had the low-price market wrapped up and the general feeling now is that they will sew up the medium-price market, too. In view of this fact, you'll see that almost every open-reel manufacturer, even some of the old-line conservatives, have edged into the cassette business.

open-reel machines

The second threat for open-reel machines came from the cartridge people who jumped into 4-channel sound with astounding speed.

Overnight, 4-channel cartridge units for home and car were on the market along with a fair variety of prerecorded cartridges. Again, like cassettes, cartridges have their shortcomings, but the lower end of the 4-channel tape market has been pretty well covered by cartridge manufacturers.


The future for open-reel machines, then, was clearly spelled out -4-channel and high performance machines.

Both areas take advantage of weaknesses inherent in unitized tapes. A high-quality system whereby cassettes can handle discrete 4-channel is not yet available and it's unlikely that unitized tapes will ever reach the heights of performance available from an open-reel machine.

Therefore, open-reel machines designed for the high-quality market are becoming prevalent and this year you'll find that over 50 per cent of the machines in our SHOPPER cost over $250 (add $100 for Stateside price).

Ein Verweis auf die 1972er Chicago CES show

Using that as a clue and scanning the OFF DUTY coverage of the 1972 Chicago CES show, you can see that many of the new open-reel models have features that used to be found only on professional studio machines.

At the same time, it also delineates the audiophiles who will be interested in open-reel machines - the ones who do a lot of tape work and who demand the very highest quality.

Special features.

The latest machines on the market have professional features straight out of the recording studios. Some are pure luxuries while others make substantial contributions to the performance of the machine.

Synchronized record/play.

Here is a feature designed for the person who wants to do some really serious recording. It allows him to switch various tracks of the record head to the play mode thus giving the capability of recording on one track in perfect synchronization with whatever track (or tracks) is being monitored.

It's the exact same technique used by all the leading recording studios to produce low-noise first-generation multi-track recordings. In the consumer market this feature is known by a variety of names such as Simul-Sync, Sel-Synch and Synchro-track, and is available on several of the new machines. Remember, though, that probably even the most ardent audio buffs will find little use for this complicated feature, so make sure you understand it thoroughly before you decide to invest in it.

Dolby system.

As of this writing, only a few machines offer built-in Dolby circuitry, but look for the situation to change. Dolby IC modules are now being produced for just a few dollars each and will soon start appearing in all sorts of equipment including open-reel tape units.

The current machines with built-in Dolby circuitry are from European manufacturers and boast incredible signal-to-noise ratios in the high 60s. (Anmerkung : das betraf zu dieser Zeit fast nur die Revox A77-Dolby) Of course, there are many add-on Dolby units available, too, so this does not have to be a crucial factor in your buying decision.

Transport control.

The trend in the latest top-of-the-line machines is toward completely electrically controlled transport functions. This means that the machines are controlled through a combination of relays and solenoids (relay/solenoid control) and the control buttons on the machine have no mechanical linkages. This allows complete remote control whereas mechanical controls or simple solenoid controlled units may not have this capability.

Frequency response.

This is one of three measurable parameters which you should take into consideration when selecting a recorder. Many units today can deliver a record-playback response of 30 to 20,000 (20k) Hertz (Hz) with variance limits of plus or minus three decibels (±3 dB). Needless to say, this is excellent performance, and if the recorder you're considering has a frequency response close to this, you can be assured that it will deliver hi-fidelity sound. The frequency response figures given in our SHOPPER are for a tape speed of IV2 in. per second (ips) unless otherwise noted.

Signal-to-noise ratio.

Because of the natural character of tape, noise has always been a big problem in tape recording. Compared with a standard signal level, this noise is expressed in a signal-to-noise (S/N) ratio such as 50 dB. S/N ratios have steadily improved (gotten higher) over the past few years - they were commonly in the high 40s but now it's not unusual to find machines with S/N ratios of 60 dB even without special noise reduction circuitry. With careful use of a recorder, low noise tape and Dolby noise reduction circuitry, today's audiophile can expect S/N ratios of 65 to 70 dB.

The importance of low noise (high S/N ratio) is even greater if you plan to do a lot of dubbing or secondary recording. Every time you rerecord a piece of material you add the noise generated in the recording process to whatever previously existed. Therefore, after several dubs, the noise level may be objectionably high and it's for this reason that major recording studios developed the synchronized playback/record technique.

When selecting a recorder, your lower limit for a S/N ratio should be 50dB and, of course, as much higher than that as possible. Some of the small portable or inexpensive machines may not be able to meet this limit, but most of the quality stereo units listed in this SHOPPER will pass the test easily.

Flutter and wow.

To measure the stability of movement in a recorder's mechanism, manufacturers measure the amount of average deviation and express it as a percentage called flutter and wow. The idea is to have as little flutter and wow as possible since it has a definite and adverse effect on sound quality.

As with other parameters, manufacturers have made great progress with flutter and wow. Here again the trend toward super specifications is evident, with flutter and wow figures for home recorders being almost a third what they were just a few years ago.

While a flutter and wow figure of 0.15 to 0.20 per cent (at 7/4 ips) used to be normal, now it is not unusual to find units with as little as 0.07 per cent. All of which means that home machines of this caliber are quite professional in quality. When selecting your recorder look for flutter and wow figures under 0.15 per cent and, even better, under 0.10 per cent when possible.


The heads on any tape recorder are tremendously important and very tricky devices since this is where mechanical and electrical activity merges. Not only do the heads have to be extremely well designed, but they must be held in an absolutely rigid predetermined position.

Construction of the heads has received a lot of attention from manufacturers and many are now offering long-wearing ferrite heads as standard equipment on their recorders. These ferrite heads have the same basic core construction as previous heads but have, in addition, a ferrite cap on the front of the head which gives much longer wear than conventional heads. In some cases, glass coatings are also used with the ferrite for added durability.

The number of heads in your recorder may be important to you, but in some cases is difficult to determine. If your machine is designed for playback only, it will probably have only one head.

If it is designed for record and playback then it will probably have at least two heads - one for erase and one for recording and playback. On the other hand, if it has three heads, it will probably have separate record and playback heads, giving the advantage of reduced switching and providing tape monitoring during recording. If the machine is a bidirectional model it will probably have more heads - up to six in all - to take care of the additional functions.

Some manufacturers are using multi-heads to save space. These are heads which have more than one core group mounted in one case - actually two heads (such as erase and record) in one. Therefore, a machine which appears to have only two heads may really qualify to be a three-head machine. And, finally, there is the crossfield bias head which is used only during recording to apply the bias signal but which is not usually included in the number of heads possessed by a machine.


The current trend is toward three-motor transports. This provides one motor for each reel and a separate (usually hysteresis synchronous) motor to drive the capstan. One major advantage of this type transport is that it eliminates the need for various complicated mechanical arrangements such as gears and pulleys. The three-motor system also is usually controlled with solenoids and relays which, while it may cost more, offers the recordist definite advantages.

Other transport features.

There are many other features offered on tape recorder transports which are perhaps not standard nor new and which vary from manufacturer to manufacturer.


More and more models are using a rigid cast frame (oft Alu-Druckguss-Rahmen wie bei Revox und der TEAC 3300 Serie) as the basis for their machines, having realized that durability is essential for long-term quality performance. A cast metal frame can hold the heads, motors and accessory components in perfect alignment, whereas a thin gauge plate or multi-piece chassis cannot guarantee to do so.
Vertical operation. It's rare to find a unit today which cannot be operated in the vertical position. Almost all have some kind of reel locks to hold the reels in position during operation.

Bidirectional operation.

There is a wide selection of machines, today, with automatic bidirectional operation. Some can only playback in both directions while others can record and playback. In either case, the transports are usually controlled by a bit of foil attached to the recording tape and will continue to run a tape back and forth as long as you wish. Or they can be programmed to make just one reverse and then stop after both sides of the tape have been played. These machines are usually more complicated and a bit more expensive, which has to be taken into consideration when buying your recorder.

Automatic fast reverse.

A few machines are provided with an automatic fast reverse mode which automatically rewinds the tape at the end of the reel and may also have a provision for playing the tape repeatedly.

Cue mode.

This feature is not found often on home-type machines since audiophiles have little occasion to do precision cuing. But, in the machines which do have it, it consists of an arrangement whereby the tape is held against the head when the machine is not in operation so that you can locate selections by manipulating the reels by hand.


The bias frequencies being used in modern recorders are all satisfactorily high enough that there is little point in studying the matter. A few manufacturers are providing bias adjustments on the front panel of their machines - you may be interested in this if you intend to use tapes which require different bias levels.

Special effects.

In addition to the synchronized record/playback feature, some manufacturers include sound-on-sound and sound-with-sound circuitry into their machines. These circuits allow you to take material which is on one track and mix it with new material to be recorded on a second track or to record on a second track in approximate synchronization with the first track. While these circuits are not as sophisticated as the synchronized record/play circuit, they are still meant for the individual who intends to do a fair amount of recording work.


Almost every machine has connections for line inputs and line outputs. Most of the European machines will use the DIN-type jacks exclusively, while the other machines will have a variety of phono-pin jacks, DIN jacks and phone jacks. In any event, the irritation in having to adapt from one type plug to another is usually small and short-lived, so it is little problem in your selection process.

Nachdenklicher Nachtrag im Okt. 2020

Wenn ich als 22 jähriger Student mit ein paar Verbindungen zu beinahe gleichaltrigen jungen Amerikanern auf diese off-duty Magazine Zgriff hatte und sogar der deutsche Zoll die off-duty Magazine anforderte und auch die off-duty Jahrbücher bekam (es war ja ein Frankfurter Verlag nach deutschem Recht), um die realistischen Warenwerte der Einfuhren aus Japan und Korea besser abschätzen zu können, warum hatten die deutschen Elektronik-Hersteller diese Magazine nicht gelesen ?

Dort konnt selbst der unbedarfte Laie erkennen, daß ein DUAL Bandgerät oder eines der billigen von Grundig oder Philips nicht die geringste Chance hatte, von den Amerikanern akzeptiert zu werden - und seien sie noch so billig und noch so schwächlich.

In den Beschreibungen wurde ausdrücklich erwähnt, welche Anschlüsse an den Geräten dran waren. Die Japaner hatten immer DIN und Cinch (auch mal die 6,3mm Klinke) und später XLR, die Deutschen und die Europäer seltenst. Nur die Studer Entwickler hatten das von Anfang an kapiert und folgerichtig den gesamten Weltmarkt mit der A77 und der B77 aufgerollt.

DUAL konfektionierte alle amerikanischen Export-Plattenspieler mit Cinch- Steckern. Die Tonband- und Verstärker-Kollegen bei DUAL hatten es offensichtlich nicht oder erst viel zu viel zu spät mitbekommen.

Der europäische Niedergang war durchaus "hausgemacht" !!



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