Rebis Noise Gate

Noise gates are useful devices, especially in the smaller studio. They enable you to cut off disturbing ambience, noise and the odd synthesiser hum, and so on, all of which have a nasty tendency to pop up even in the best-equipped recording facility. Noise gates are quite easy to make, but they're relatively hard to make well at a reasonable price.

Rebis Audio in Stourbridge, however, have succeeded in producing a noise gate module with an excellent spec and a sensible price tag (£62). Rebis, you may remember, were responsible for the mixers used by Mike Oldfield on his current world tour. They also supplied the mixer for his Gloucestershire studio and are well known as custom console designers.

The new RA201 noise gate is the first in a range of modular units designed to be desk or rack-mounted. A 16-channel rack mounting unit can be supplied for £50, and a suitable power supply is also available. The module itself is 5¼in x 1in in size, and has variable sensitivity (setting the level at which the signal is cut off, or 'gated') ranging from -60 to +20dBm, a variable degree of attenuation from 5dB to 40dB, and the attack and decay times are also front-panel adjustable, the attack ranging from a usefully fast 15μs (so you don't lose the initial transient of a signal, like, for example, on a vocal) to 4ms, and the release time can be set between 40ms to 10ms.

The front panel also features red and green LEDs to indicate gating, and in/out bypass switch, and a 'key' switch which enables the unit to be triggered by a second input (other than the signal being gated) if desired. The unit has a very low distortion and noise level and the frequency response is a good 20Hz to 20kHz ±0.5dB.

For further info on the RA201, contact Rebis Audio, (Contact Details).

Tomorrow's Disc

Philips have finally announced their new digital disc format, which looks as if it's going to set a firm trend for the future. The Compact Disc (CD) is a vinyl disc a mere 4½in (115mm to be precise) in diameter. That's a lot smaller than a single, of course. The disc offers an hour of stereo on its single side (if you wanted mono, you could get two hours, and if you wanted to produce a 4-channel B-format Ambisonic disc including height information — periphony — you could obtain half an hour's playing time per disc).

The CD utilises a helical track of laser-etched 'pits' beginning at the disc centre; the tracks are a mere 1.66 microns apart and the disc speed is controlled by the position of the pickup head; at the centre it rotates at about 500r/m, and while tracking the edge of the disc its speed is about 215r/m. This produces a constant linear velocity. The pulse-code modulation system of digital recording employed uses a 14-bit code sampled at 44.33kHz, with a 50μs pre-emphasis. The disc player uses a solid-state laser to track the disc (so there's no physical contact between disc and head, and thus no playing wear), and the system offers a dynamic range in excess of 85dB, a signal/noise ratio of better than 85dB, harmonic distortion less than 0.05% and an audio bandwidth of 20Hz to 20kHz. Very impressive.

The disc itself is pressed from a photo-etched master in a more or less conventional way, although the information-layer is aluminised and then coated with a transparent layer to protect it.

All in all, the system looks set for success. It's obviously difficult to introduce a new system from scratch, but then Philips did it with the Compact Cassette, so with luck they'll succeed with the Compact Disc. Philips are confident that the CD will be competitively priced with the conventional analogue disc but it won't appear in the shops until at least 1983. The player is very small — about the size of an average cassette player and should cost £150-£200 at today's prices. What remains to be seen is how soon Philips will be able to persuade other record manufacturers to follow suit. Obviously, there's no point in having a system which no-one can use! However, Philips say that they will operate a similar 'liberal' licensing policy to that operated when they introduced the compact cassette.

But we wish Philips the best of luck. Discs haven't changed for almost 30 years: maybe this new system will last as long...

Sescom Goodies

Good news for those of you requiring mic-splitters, direct-injection boxes, extension cords and other microphone goodies. Atlantex are now marketing and distributing the entire range of Sescom products in this country. Smiling Bob Wilson of Atlantex (he of the bizarre attitude to the retention value of certain monthly music magazines) tells me that he has already sorted out dealerships in most large centres of population. And for those who don't favour urban living, he even offers a postal service from his opulent Hertfordshire HQ. You've no excuse not to buy something from him now.

Sescom's range is probably best described as 'extensive', there only being space here to mention but a few of the more interesting goodies. Prices may seem a touch high, but remember that all the units are made to the highest mechanical and technical standards, and are built to withstand a lifetime of abuse (it says here).

The MS-1A mic-splitter (£32.55) allows a single low-impedance microphone to be connected to two inputs (or, working in reverse, to combine the output of two microphones into a single desk input), while the MS-2 (£27.94) does a similar job with high-impedance mics. Also available are the SM-1A passive DI box (£32.55) and SM-2 active DI box (£34.71), the former featuring two inputs for amplifier or instrument plus a switch to select one or the other. The active box is powered by a 9-volt battery and can be set for unity gain or 6dB gain or attenuation.

Microphone patch cords, comprising sturdy Belden cable terminated in XLRs are available in a variety of lengths from 5ft (£7.26) to 100ft (£26.88). And for testing cables and connectors for shorts, open-circuits, continuity and phasing, the battery-powered CT-1A unit (£28.10) is extremely useful.

The IL-Series of microphone and line matching transformers and accessories comprise a wide selection of high/low impedance matchers, phase reversers, high and low pass filters, plus mid-range boosters and attenuators. Each device is built into a short metal barrel terminated at either end in an XLR connector.

For a copy of the current Sescom catalogue, plus the name and address of your nearest dealer, contact Bob Wilson at Atlantex Music Ltd, (Contact Details). Mel Lambert

Bass Amp Nicker

People who nick instruments and amps from musicians should, of course, be impaled on a sharpened Telecaster neck and put on show in the local music shop. In the meantime, our Bass correspondent Steve York has had his Ampeg SVT top halfinched from the Bridge House in Canning Town, east London. Serial number is 106084, and its most unusual feature is the fact that it exhibits two mains leads, a 110 and a 240 (for the fan). So keep yer eyes peeled and sharpen yer Tele neck — any info to Steve c/o SI (a reward will be etc etc).

SCM 381-8

As mentioned recently in our News pages, Soundcraft Magnetics, a sister company to the one that manufactures those lovely mixers, now has a working prototype of its new 8-track on 1-inch tape machine. To be known simply as model SCM381-8 (how do manufacturers manage to think up such designations, I wonder) the new machine incorporates (naturally) full logic interlock of all transport functions with motion sensing, and even comes complete with a very sophisticated remote control unit and varispeed. Either or both of these devices can be located in the machine's front panel or, much more usefully, mounted up to 30 feet away on your recording console. UK price of the 381-8 is £5250 (excluding VAT) which, for a machine with such advanced design features and full remote control, would appear to be not unreasonable.

I had the opportunity recently to tinker with the new machine at a small homebuilt studio belonging to Nigel Stokes. Nigel was trying out the machine for Soundcraft with the aim of hopefully providing some useful feedback on how it stood up to regular (and sometimes merciless) use in a real recording environment. Also on hand during my trying out of the machine was John Eustace who, with his partner Alex Nicholas, has been working on its development during the past two years.

And I'm happy to report that the result of their labours is a true delight to use. While the new machine fairly bristles with useful features, I'll talk first about the remote control unit, since this really is an extremely elegant device. It houses not only the normal rewind, fast forward, play, stop and record buttons, but also a tape counter with minutes and second display linked to a very handy stop-at-zero facility. Additionally, the transport can be set to search to zero and then drop into play or record, all on the prod of a couple of buttons. In the search mode, the transport is very accurate at returning or advancing to the zero position, with practically no overshoot. The logic system selects the appropriate rewind or fast forward mode as zero is approached, hunting by repeated applications of either mode until it is satisfied with the final location.

Switching between line-in/sync/replay modes on all tracks is handled by a set of three master pushbuttons and associated LED display, while eight more pushbuttons take care of the record/ready switching for each track. All pretty straightforward and conventional, with the 'sync' mode automatically changing the tape machine output from off-tape sync to line-in as you drop-in on a particular track.

But suppose you want to be able to override the automatic switching for some reason. For example, you may want to monitor line-in on certain tracks all the time, the musicians taking their cue off other previously-recorded tracks. Or, more likely, because the producer wants to do a drop-in without the musician knowing about it, without possibly fluffing a reasonable take by being momentarily thrown at the point of drop-in. Or you may want to use a track for tape delay or to achieve a special effect.

It is for these not so unusual circumstances that a second set of eight pushbuttons and one labelled 'master' come into their own. With them you can set up any combination of line-in, sync or off-tape monitoring for any or all the tracks. Selection is achieved by pressing sequentially the required mode and the chosen track. Couldn't be easier. Switching between the 'normal' mode of operation and the specially-tailored combination is simply a matter of hitting the 'master' pushbutton.

The varispeed unit has a range of +15, -50% at the machine's single operating speed of 15 in/s. Other useful features include separate sync output on each track — handy for triggering noise gates in advance of the signal from the replay head making its appearance, or for providing an easy method of tape phasing. Another useful feature is the ability to drop out of the record mode by simply pressing the record button for a second time.

All transport controls are duplicated on the machine's top plate, with the exception of the record button. Instead its place is taken by an edit button that reduces the voltages to the spool motors, thereby allowing the tape to be rocked backwards and forwards more easily during sessions with a splicing block.

Comprehensive facilities for routine adjustment are provided on each of the electronic modules, including front-panel adjustments for bias, record/sync/replay level and high-frequency trim, plus the normal line-in sync and line^out levels.

An uncluttered tape path makes for easy threading, the heads themselves being mounted from above with grub-screw adjustment for azimuth and zenith. Guides before and after the headblock, and between the record and replay heads, ensure accurate tape alignment. Interestingly, the pinch wheel is mounted inside the tape path to prevent the oxide coating being damaged by contact with the capstan shaft.

Tape handling is extremely well mannered, as was demonstrated by the transport's ability to cope with a loop measuring at least 10 feet that John Eustace pulled from between the capstan and motion-sensing roller. Not a protest was evinced from the deck, and there didn't seem to be any additional wow and flutter on the output. A creditable performance.

And so to an assessment of how the machine stands up in operation (apart from its ability to put up with obstacles being put in the tape path). Suffice it to say that the machine is extremely well behaved and moves tape round very gently. No amount of fast switching between rewind, fast forward, play etc could produce even the hint of a thrown loop.

Switching between operating modes is entirely click-free, and I was pushed to detect much of a difference between sync and off-tape replay (although, to be fair, this may have something to do with Nigel Stoke's control room monitors which, at the time, hadn't been fully equalised). Even track bouncing to adjacent tracks proved to be no problem whatsoever.

Colour scheme is a restful brown with white lettering for the electronics, remote control and varispeed, the ½-inch thick transport deck plate, guides and headcover being left in pristine polished alloy.

Soundcraft quote a very respectable frequency response of +1, -2 dB from 30 Hz to 20 kHz, replay signal-to-noise ratio of 76 dB (reference: 510 nWb level and IEC curve A-weighting), and wow and flutter of only 0.03% (IEC-weighting).

I understand that Soundcraft are currently working on a 16-track on 1-inch version of the 381-8. I look forward to the completion of that project with great anticipation.

A complete rundown of the new SCM 381-8 can be obtained from Soundcraft Magnetics Ltd, (Contact Details). Mel Lambert

AKG Your Revox!

We don't usually talk about turntables, but of course we all use them more or less every day, to listen to music on (or whatever your particular ears like to receive off disc). A good turntable is certainly a necessary requirement for most of us, both for work and pleasure. Apart from reviewing albums or listening back to test-pressings, both of which require top-quality gear, it's nice to be able to listen to things for fun. So when we heard that Revox and AKG had got together we thought it worth a mention — both companies are, of course, eminently respectable and produce a range of vairy nice products indeed.

Revox produce the innovative linear-tracking turntable, the B790. It's an excellent machine although it doesn't like warped discs — but then nor do I — and has a servo-controlled 'arm' which allows the cartridge to track across the disc so that it's always properly tangential to the grooves. No tracking distortion and none of those horribly distorted last-tracks-on-side-n. And of course, not having a conventional arm, the only mass is that of the cartridge. Add to that the fact that a linear-tracking turntable most closely approaches the way in which a record is cut, and you can see that it'll be a good idea in theory. And being Revox, the B790 neatly puts a good idea into practice.

Formerly, the B790 has been fitted with an Ortofon M20E magnetic cartridge: the one we have is like this, and it certainly behaves very well indeed. It has a smoothness which emulates the remarkable sound of Ortofon's more expensive moving-coil cartridges with none of the usual problems of low-level outputs produced by this type of device (which requires a transformer — which picks up hum if you're not very careful — or an expensive low-noise preamp).

Now Revox and AKG have got together and future B790s will be fitted with the AKG P8ES magnetic pickup. AKG lent us one to test a few months ago, and it's certainly an exceptional cartridge, with excellent tracking and once again, the 'smooth' sound you associate with a moving coil device. While I'm quite happy with me Ortofon, it certainly looks as if this new combination will be eminently suitable for high-quality reproduction.

And while we're talking about AKG, AKG Acoustics are about to conclude a deal with Rose-Morris. AKG will be distributing some of the vast range of Rose-Morris musical gear directly to the industry.