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Fostex G24S

SSSH... From You Know Who

Article from Sound On Sound, March 1991

Following last month's review of the Tascam MSR24S, Dave Lockwood turns his attention to Fostex's new one-inch 24-track with Dolby S: The G24S.

Finally, Fostex's long-awaited offering in the 24-track 1-inch format has been revealed. Derived from their latest generation 1/2" 16-track, it is designated the G24S, the 'S' being an indication that, like the latest version of its rival MSR24, it too features the new Dolby S-type noise reduction. Like its 16-track predecessor (the G16), it has a 10-point autolocator on-board as standard, with a detachable control panel which can be used as a remote, and a host of synchronisation functions. With the optional 8330 card installed, the G24S is able to offer the unique facility of an on-board chase synchroniser — timecode can be output during fast wind modes, and incoming high speed code can be both read and chased by the system, making hook-up for synchronised use with machines with a similar capability very simple.

As on a number of recent Fostex models, MIDI control (including MIDI Time Code implementation), both of transport and record functions is possible, given appropriate software. Some sequencers already include the necessary functions (Steinberg's Cubase has a driver for the 8330 built-in), and for users of other systems I understand that a separate control program is likely to be made available by Fostex (possibly a DA called MIDI Remote).

When Tascam's MSR24 introduced the 1-inch 24-track format just over a year ago, the big surprise for many was that Fostex hadn't got there first. Having been the initiators of both 1/4" 8-track and 1/2" 16-track, it seemed only natural to look to them for the next step. Fine machine though the Tascam was, it undoubtedly met with a certain amount of resistance simply due to its use of dbx noise reduction — its relaunch with Dolby S, in the guise of the MSR24S, will certainly alleviate resistance to the format based on that particular prejudice, and the fact that the new Fostex machine uses the same track and noise reduction formats can only be good news for both companies.

Fostex's somewhat delayed entry into this market apparently seeks to compete not in terms of sound quality, for I will say at this stage that I feel there is simply nothing on that front to choose between the two machines, but in terms of control sophistication. Even disregarding the optional sync board and the MIDI features, the basic G24S gives you a lot of functions to play with, and indeed at times the two 9-figure 7-segment LED displays seem barely adequate as a means of conveying the information necessary to follow the procedures taking place. LCDs may have their own limitations, but they are certainly an awful lot better than half-formed LED characters and having to interpret the presence or absence of a number of small flashing dots!


Remarkably, the G24S is no larger than its 16-track forerunner. Unlike the the MSR24, the G24S has its power supply on-board as opposed to in a separate casing. In spite of this, it is still just about light enough to lift (35kg), although I wouldn't like to carry it any distance! Large detachable rack-ears permit the remarkably compact chassis to be mounted in a standard 19" rack or trolley. The deck-plate and head-block assembly seem appropriately substantial, with a flip-up section in the centre of the plastic head cover assisting with access and visibility, when the machine is mounted in the vertical plane. The 10.5" reels are mounted on deeper, but otherwise standard, plastic NAB centres, with an acceptably positive lock for the weight of reel involved.

A simple, 4-guide tape-path is employed, with a conventional pinch-wheel/capstan assembly, although the pinch-wheel is, unusually, located within the head-block cover and none too easy to get at for cleaning. Precision roller bearings on the tape guides, plus substantial reel motors and sophisticated capstan drive create the impression of a quality transport, capable of withstanding the rigours of demanding usage. Below the head block and transport assembly is the main control panel, with large transport controls, a keypad for data entry, and all the meters and displays.

The control panel is hinged at the top and can be tilted upwards for more convenient operation, or even de-mounted from the machine altogether, and by means of an optional extension cable connected at the rear, used as a full remote control unit. The most basic transport controls — Stop, Play, and the two fast wind modes — are duplicated on the main chassis, thus giving an essential measure of local control when the remote is in use.

Access to line-up controls is good, with the control panel removed or tilted up. This is an important feature in machines that are going to see service in a professional environment, and proper maintenance of this side of the machine should not be beyond even the less technically orientated user. All you need is a test tape, a few basic tools, and a decent manual. Like seemingly all narrow-gauge multitracks these days, the G24S is a 2-head design, with just an erase and single combined record/play head. Economic factors of course dictate this approach, and it has, in practice, few limitations for most users, beyond perhaps those of operational convenience on the odd occasion, such as when lining-up (given a separate Play head one can make continuous record alignments, monitoring via the previously adjusted Play head, obviating the need to rewind to check the results).

Audio connection is via 24 pairs of phono connectors running the width of the rear panel. All inputs and outputs are therefore unbalanced, and at the -10dBV nominal operating level. Curiously, in my opinion at least, the inputs are paralleled in two groups of 12 — there must be an awful lot of 8 and 16-group desk owners out there for whom a more convenient number could have been chosen! Full 24-group operation is still possible however, for the higher numbered inputs use switched sockets, and are therefore only paralleled when not connected themselves. Dolby S can be disabled on track 24 alone, for timecode use, or switched out on all tracks, should the need arise. A front-panel 'NR Off' LED flashes when in either of the disabled modes — given that the machine is likely to spend most of its time with NR On, but disabled on track 24, I found this rather distracting, and indeed potentially misleading.

Like the MSR24, the noise performance is actually quite tolerable without the NR, provided sensible noise management techniques (high levels on tape, close-down any tracks not in use etc.) are used — always a healthy sign, indicating a good basic performance merely enhanced by the NR, not dependent upon it.

Multi-pin interfaces are provided for the Fostex 4030 synchroniser (Accessory 1 terminal) and for using the optional 8330 card (via the Accessory 2 ports). A further multi-pin allows connection of the extension cable for the control panel. Connection facilities are completed by MIDI In, Out and Thru sockets, for remote MIDI control of the transport and MTC functions, and two 1/4" jacks for footswitch control (one for drop-ins, while the other offers the very convenient function of activating Play from Stop, or Locate from any other function).


In addition to the normal transport controls there are four large locate function controls, offering Auto-Return, Auto-Play, Locate and Locate Zero. Locate can be used as a 'one touch' transport control, to automatically find whichever of the 10 memorised locate points is presently active. Auto-Return facilitates automatic cycling between any two points, for convenient rehearsing, and Auto-Play can be used (either with or separately from Auto-Return) to automatically set the machine in Play mode whenever a memorised point is found via Locate. Memory data is displayed in the lower of the two LED windows, whilst the upper one always handles the real-time tape position function. Locate positions can be entered either 'on the fly' via the Hold key, which transfers the present time down from the upper display to the lower, or via direct entry of a time from the numeric keypad.

Despite one or two minor anomalies hopefully peculiar to the review model (serial number 001!) the autolocate functions of the G24S are simple to operate and effective in use. The number of memories available is more than adequate to mark out the various sections of the average song, but may be less so given a more complex program. The ability to cycle between any two of the memorised points is very useful for rehearsing different sections of a song, one at a time, with the minimum of programming once the initial locations are entered. Automatic pre-programmed Drop-In and Out however, is only available via the 8330. This appears to be because the facility uses the timecode reader, which naturally offers much greater accuracy, rather than relying on the counter.

In fact, the G24S counter, which is driven by the rubber-coated left hand tape guide, seemed to be tolerably accurate in practice, over a short run at least. It would surely have been better to have implemented at least a basic Auto-drop, using the counter on the un-enhanced machine, allowing the timecode system to offer a greater level of accuracy for those who want it. However innovative it may be to have synchronisation facilities on-board a machine such as this, some people will not actually be particularly interested in them. Auto Drop-In however, will surely be expected of any version of the machine.

With an 8330 present, Auto Drop-In and Out can be performed with great precision and reliability. You can program In and Out locates either on the fly, or via direct entry from the keypad. A Trim facility allows these, or any other numbers to be edited, without reprogramming the whole set of figures. A rehearse function, giving Input monitor during the duration of the programmed Drop-In allows not only rehearsal of the part, but also optimisation of the locates, before committing to the actual event.

"...manufacturers are actually prohibited at present from using Dolby S on 'professional' format machines, but fortunately for us, that does not preclude its use on 1-inch 24-track."

Like a number of functions on the G24S, the programmable Drop facility may suffer, in the eyes of some users, from apparent over-complexity. Any piece of equipment can seem complex until you have properly mastered its procedures, but I am sure musicians in particular will expect a basic function such as this to be more immediately accessible. Audio performance of the G24S during a Drop-In proved to be excellent — being both quiet and fast. No mention is made of any special timing circuitry to aid with 'glitch-free' dropping-in, so perhaps it's just the proximity of the two heads that is responsible for the good performance in this area.


You switch tracks to Ready either via individual Safe/Ready switches located just beneath each meter, or via programmed selection using the numeric keys in conjunction with a dedicated master Safe/Ready key. This procedure works well enough in practice, but is again a little more obscure than most users would prefer. For example, you can't enter '16' as '1' followed by 6 — you have to use the dedicated '+10' key. 24 must be entered as '+10', '+10', '4'; not really as intuitive as '2' and '4'.

I must admit that there are times when the relative obscurity of some of the commands, and the limitations of the display, make instructing the G24S distinctly heavy going. This machine is going to need a good manual if users are to get the most from it — unfortunately I can't say whether or not it has one, as the review model was supplied with a rather inadequate temporary adaptation of some G16 documentation.

Once you've switched tracks to Ready, normal (as opposed to programmed) dropping-in is accomplished by hitting Record whilst holding Play, in the accepted manner. Dropping-out however, must be done either via Stop, or if you don't wish to interrupt playback, by pressing Stop whilst holding Play. Once again, I find this less than intuitive — I expect Stop to over-ride anything else that may be pressed at the same time, as a safety measure (extensively microprocessor controlled machines do go wrong sometimes!). Why not simplify drop-out of record on the fly by pressing Play on its own, like most large format multitracks?


Edit Mode, accessed from the dedicated Edit key, allows the reels to be easily rotated by hand, in either direction, for very precise cueing. Alternatively there is a rotary cueing control (shuttle wheel), which allows playback at between zero and several times normal playing speed, which can be used for running the tape backwards and forwards over specific points, under fingertip control. Either mode can be used in conjunction with the Spot Erase facility (a function that works well on the G24S, with the usual proviso that you can not get away with entering or leaving record unless the tape is in motion).

The G24S fast wind buttons also allow signal monitoring for cueing purposes, for if either of these are pressed and then held, the system enters a slow wind mode. Subsequently pressing Play retracts the single tape lifter to let the tape pass over the head, enabling a cueing signal to be heard. The slow wind mode lasts only as long as the button is held — releasing it reverts to normal high speed wind. It does not however, defeat the cueing signal (you must press Play again to do that), which surely creates the risk of some damaging high energy HF getting through to the monitoring?

A Zone Limit function prevents accidental spooling-off. This is especially useful where machines are used with synchronisers, because unless you are working to the same reference on each machine, it is easy to forget to allow for the effects of any offset when locating the master transport, sending the slave spooling-off! The Zone Limit can be calculated automatically, (the tape base thickness is assumed by default, although you can change this), but it can also be altered by manual entry of amended figures.


The G24S allows access to various system parameters via what it calls 2nd Mode, entered by means of simultaneously pressing RCL (Recall) and STO (Store). Functions are then selected with pairs of numbers from the numeric keys — there is no particular logic to these, you simply have to remember them or look them up each time you want to use one. Parameters which have a practical effect, such as set-up of reel diameters (independent for take-up and supply), and set-up of timecode frame-rate, are intermingled with more esoteric ones such as display of software version number, and cumulative playing time (useful as an indication of wear on mechanical components).

I found Direct Locate to be the most immediately useful of the 2nd Mode functions. This allows 'one touch' location to any of the memorised cue points simply by pressing the appropriate number on the keypad. You can also determine the maximum speed of the fast wind modes — the default value, represented by the apparently arbitrary figure of 253, can be edited down to as little as 20 to give a 'library wind' function for tape storage. All 2nd Mode parameters are battery backed-up, and the whole system can be re-initialised by powering-up whilst holding down both Play and Stop on the duplicate controls on the main chassis.


Monitor source selection is governed primarily by a single master status switch, giving All Tape or All Input, but there are also two Individual Input Monitor Modes, selectable from within software, according to your preferred working practice. Individual Input Monitor Mode 1 maintains input monitoring on any tracks switched to Ready, irrespective of the transport status, so you can always hear live input from the performer during an overdub, even prior to entering record. Individual Input Monitor Mode 2 conforms more closely to the accepted practice of an Auto Input mode, giving input monitoring in all modes other than when it is possible to monitor tape (ie. during Play). This is my preferred method, for it allows maximum communication whilst never causing any confusion as to what is live signal and what is on tape.


Dolby S, which draws to some extent on techniques employed by the professional Dolby SR format, was developed primarily for use on cassette machines. Presumably to protect the market for SR, manufacturers are actually prohibited at present from using Dolby S on 'professional' format machines, but fortunately for us, that does not preclude its use on 1-inch 24-track.

Space precludes a detailed look at how the system works (see last month's MSR24S review), but essentially it consists of five active elements, which can be sub-divided into high and low frequency stages, with a single fixed band operating at LF, below 200Hz. The other four elements all operate from 400Hz upwards, with both fixed and sliding bands being employed simultaneously. Two 12dB companders with staggered thresholds, operating in series, are used to form separate high and low level stages at HF. The fixed and sliding bands are able interact via a technique called 'Action Substitution' which seeks to take advantage of the beneficial characteristics of both types, without suffering the disadvantages of either. Like Dolby SR, Dolby S produces a noise floor that is not only very low, but which remains apparently unchanged whether there is signal present or not.

Other techniques such as Spectral Skewing and Modulation Control seek to mitigate the effects of tape saturation at the frequency extremes, and other potential sources of side-effects, such as transient overshoot in the compressor stages. The remarkable absence of discernible side-effects attributable to NR operation would seem to indicate that it all works rather well!

"Even disregarding the optional sync board and the MIDI features, the basic G24S gives you a lot of functions to play with..."


There is no getting away from the fact that the primary question that will inevitably be asked of this machine is 'how does it compare with the MSR24S?' I suppose there is some logic in the conclusion, given that both Fostex and Tascam are highly respected manufacturers of tape machines, and have now produced machines of an identical format, that these machines sound substantially the same. To my ears, allowing for the fact that I was unable to have both machines at the same time, there is simply nothing to separate them on intrinsic sound quality. I performed the same tests with the same sources, and produced the same results, and must therefore draw the same conclusions; given today's head performance, 1-inch 24-track is capable of providing a most respectable specification, whilst Dolby S is extremely kind to signals and virtually incapable of generating unwanted side-effects. The G24S simply sounds great.

With all 24-tracks open, I would say that there was significantly less tape noise than with a 2-inch 24-track running Dolby A. Above all, the sound is simply effortless, and 'big' as opposed to the slightly 'pinched' quality that seems to characterise most narrow-gauge multitracks in comparison with a 'pro' format machine.


Does the arrival of quality performance from 1-inch 24-track herald the end of the road for 2-inch 24-track? Certainly not, for there is always a role for the best in any field, and there is no denying that Dolby SR on a 2-inch machine, or even a 2-inch machine at 30ips without NR under certain circumstances, is still the best we have in the analogue domain. But the gap is now so narrow as to surely make many potential buyers who might once have aspired to a 2-inch machine think again. This is particularly true of those working in fields such as A/V, where their end result is going to finish up on a less critical medium, who must surely see the cost/compromise ratio coming down in favour of these new machines. The fact that the G24S is so well geared up for use in this type of environment, perhaps to the extent of compromise in other areas, surely indicates Fostex's belief that their product is able to compete for this market.

Lower tape costs are unlikely to mean all that much to the potential purchaser of this type of machine. Lower maintenance costs, in terms of greater reliability in the mechanical components simply due to the physically smaller size of the system, well might, but only time will tell. Remember that maintaining an ageing 2-inch machine can be a very expensive business!

Compatibility has never really been an issue in the narrow-gauge multitrack market before, for it is of comparatively little importance in machines that will see use mostly in private studios, where projects are generally seen through from start to finish. In the commercial world however, the ability to take a tape from one location to another is essential. In the past there must surely have been many professional commercial studios who might have been tempted to acquire a narrow-gauge multitrack of some sort to cater for clients who wanted to finish in a pro environment a project started at home.

However, the problem has always been which machine to choose. The big two, Fostex and Tascam, have always been divided by the gulf of incompatible noise reduction formats fragmenting the market. Now we have full compatibility, and the more widespread these machines become, the safer it will be to use them on a project, and indeed the more confident the purchaser can feel of buying into an on-going format.

The Fostex G24S is a machine of great sophistication and potential. The fact that it is packed with features on the control side should not be allowed to overshadow the high quality audio performance — even if you have no interest whatsoever in synchronisation or MIDI control, the G24S is still a great recorder. Any reservations about aspects of the operating system should be tempered by a realistic appreciation of the machine's full capability — the more options you make available, the more difficult it becomes to present them clearly. Whilst it is possible that one or two potential purchasers might initially be discouraged by the apparent level of complexity in the implementation of some functions, for the rest, I am sure the G24S will seem like a dream come true.

At last, with the arrival of Dolby S, Fostex and Tascam have finally come together, and they will surely both benefit as a result. In the wider view, there can be practically no-one (except perhaps one or two manufacturers of 2-inch machines!) who will not welcome this development wholeheartedly, for we are surely now seeing the birth of a new format of some significance.


Fostex G24S £8395 inc VAT.
8330 Synchroniser card £595 inc VAT.

Fostex UK, (Contact Details).


Machine Format: 24-track, 1-inch
Dimensions: 428mm x 488mm x 230mm
Head Configuration: 2-head, Erase + Record/Play
Tape Speed: 15ips (38cms) +/-0.2%
Varispeed: +/-12%
Record Reference Fluxivity: 320nWb/m *
Frequency Response (ref 0VU): 40Hz to 18kHz (+/-3dB)
S/N Ratio (CCIR ARM Wtd): 88dB with Dolby S
THD: <1% (1kHz)
Erasure: >70dB(1kHz)
Crosstalk: <55dB (1kHz)
Wow & Flutter (IEC/ANSI Wtd): +/-0.05% peak
Line In: 30kOhms impedance, -10dBV (0.3V), Unbalanced
Line Out: >10k0hms load impedance, -10dBV, Unbalanced
Start-up Time: <0.5s
Wind Time: <140s (740m tape)

* There is no great significance in the fact that Fostex have chosen to align their machine to 320nWb/m, whilst the MSR24S operated at 250nWb/m. The latter figure is probably nothing more than a legacy of that machine's dbx origins (dbx is very dependent on tape linearity and benefits from playing safe with level) — I am sure an MSR24 with Dolby S would be quite happy at 320nWb/m. Indeed, I shall be quite surprised if that level is not adopted on production models.


The 8330 sync card and the use of the G24S in a multi-machine set-up merits far more detailed examination than is possible within the confines of this initial review. However, the main features are as follows: The 8330 consists of a timecode generator and a 2-channel timecode reader, allowing the G24S to be locked to the transport of another recorder — audio, or video. In the simplest system, where the master recorder can output code during fast wind, timecode from the master source is compared with timecode on track 24, and the transport instructed accordingly. In many instances however, other transport sync pulses also have to be read in order to chase the master during wind modes.

All functions required for basic chase synchroniser operation are implemented. There are three lock modes: Frame Lock (attempts to match the timecode values of the two sources, providing the most accurate lock, but accurately transferring any wow or flutter in the master directly to the slave); Sync Lock (a slower lock state which does not transfer any momentary speed variations or code drop-out to the slave); Auto Lock (automatically switches between Frame Lock and Sync Lock to give the optimum sync performance). Other functions include: Lock On/Chase On (Combined Lock and Chase mode — if the slave transport departs further than a user-determined distance from the master, fast wind modes will be used before attempting to achieve lock-up); Park And Start (advances the slave ahead of the master when stopped, in order to overcome the inevitable time lag on start-up); Auto-Record. No data was supplied on MIDI functions.

Also featuring gear in this article

Previous Article in this issue

The Missing Lync

Next article in this issue

Roland MV30 Studio-M

Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

The current copyright owner/s of this content may differ from the originally published copyright notice.
More details on copyright ownership...


Sound On Sound - Mar 1991

Donated by: Bert Jansch / Adam Jansch

Review by Dave Lockwood

Previous article in this issue:

> The Missing Lync

Next article in this issue:

> Roland MV30 Studio-M

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