Tape Machines (Part 4)
Conclusion of the survey.
Top of the Technics range, the model RS-1500US, is an unusual machine. It features an 'isolated loop' transport design which uses a direct-drive dc-servo capstan coupled to two pinch wheels. Difficult to describe, but a look at the photograph will reveal all. The outcome is a truly remarkably low wow and flutter figure of only 0.018% rms at 15in/s. Full logic interlock of deck functions and motion sensing is provided, and a fourth head offers ¼-track playback if that's your need. Both mic and line inputs are included, with front-panel mixing. Frequency response is claimed to be within 3dB from 30Hz to 30K Hz at 15in/s (3¾ and 7½in/s being the machine's two other speeds) and signal-to-noise better than 60dB at the same speed. An optional accessory allows the RS-1500US to be powered from two 12 volt batteries — a useful facility for remote recording where no mains power is available. Basic price is around £600. Two new versions are currently under development: an improved stereo machine to be known as the RS-1520, and a 4-track machine with full sel-sync. These two are so new that no prices are available yet.
Although, like the Schlumberger F400, the 1400 Series machines from Telex are designed mainly for use by broadcast organisations, their price/performance may make them of interest to smaller studios. They are of a very rugged construction to withstand hard continuous use. One possible drawback, however, could be the fact that they won't take 10½in reels. Full logic interlock of deck functions and motion sensing ensure smooth tape handling, and separate mic and line inputs are provided on each channel. Frequency response is quoted within 2dB from 35Hz to 22K Hz at 15in/s, and signal-to-noise ratio 60dB at the same speed. Which for a price range that begins at £1200 can't be bad.
The Telefunken M15A range of tape machines is available in all of the normal formats from stereo on ¼in right up to 24 or even 32 tracks on 2in tape. Construction is to the very highest of professional standards, with full logic interlock of deck functions and motion sensing (of course). A novel feature is the specially timed record and bias switching to ensure that drop ins are click-free and do not leave any gaps or partially erased portions of tape. Basically it works by using ramp-shaped voltages to provide some overlap between the erase and record heads turning on and off going into and coming out of a drop-in, to make up for the time taken by the tape to pass from the erase head to the record head. Tape speeds on stereo and 4-track machines are 7½ and 15in/s, while larger format machines are available with 15 and 30in/s. Frequency response is claimed to be within 1dB from 60Hz to 16KHz at 15in/s, with wow and flutter under 0.04% at the same speed. Optional extras include various autolocator and varispeed units, plus Telefunken's very own noise reduction system, known as Telcom c4. Space is provided within the pull-out lower drawers on larger machines for up to 24 channels of noise reduction. Like Studer though, Telefunken tape machines do not come cheap. A stereo machine costs about £4000, a 4-track £5300, an 8-track £10600, and a 16-track around £16000. Each channel of c4 noise reduction that you may want adds approximately £250 to the total price.
The M79 Series from 3M are built round the unusual Isoloop differential capstan drive, which reduces the unsupported length of tape to just 3½in and as a result reduces wow and flutter to exceptionally low values. A look at the spec — 0.06% rms flutter at 15in/s — would seem to confirm that it does work. All machines in the series, from two to 24 tracks on the normal tape widths, use the same basic transport, and can be expanded very easily (from 2 to 4-track, for example). Speeds are 7½ and 15 ips or 15 and 30 ips, selectable by changing a couple of links on the capstan servo board. Varispeed runs from 5 to 45 in/s with a choice of two equalisations to compensate for hi or lo speeds. The transport has full logic control and motion sensing (as one would expect from a fully-professional machine) with spec to match: frequency response within +1, -2dB from 50 to 15KHz at 15 ips for all track formats in sync and normal playback (think about it), and signal-to-noise ratio of 64dB.
3M and the BBC are currently co-operating on the development of a digital mastering (two or 4-track) and multitrack system. The multitrack records up to 32 tracks on 1in tape, and sports a quoted frequency response within 0.3dB (sic) from 30 to 15KHz and a signal-to-noise ratio of greater than 90dB. The system won't be cheap though — estimates run to about £85000 or $150000. It's the shape of things to come.
mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.
If you value this resource, you can support this project - it really helps!