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Fostex RD8

Article from The Mix, July 1994

Assessing the alternative ADAT

Why spend more on a Fostex ADAT? That's the question the adverts ask. Bob Dormon spends some time with the Fostex RD8 digital multitrack and comes up with some intriguing answers

Cream of the crop: 'Professional' (ie. not black) colour scheme immediately sets RD8 apart from its Alesis counterpart

Compatibility has never been the strong suit of the multitrack tape recorder industry. In the early days of four-track cassette multitrackers, there was the Noise Reduction Question. Did you want Dolby, in which case you had to go for a Fostex machine, or would you opt for Tascam's favoured dbx system? Either way, all you could do if you wanted to use the latter to play a tape recorded on the former was to disable the noise reduction on both machines.

That's still the case today. Further up the scale, Dolby have managed to put the brakes on the digital revolution with their SR and S-type systems, while dbx has been further refined. The choice now is between 16-tracks on half-inch tape and 24-tracks on one inch, with dbx or Dolby S. But again, once you've made a commitment to one of these formats, you have to live with it. And woe betide you if a mate offers to lend you a multitrack master made using an alternative format.

The situation is hardly ideal. But if you take a look at what's happening on the digital side of the fence, you soon begin to realise that it isn't all bad.

Here again, Tascam and Fostex seem destined to walk different paths - no doubt a legacy of their personal history. Fostex have adopted the Alesis ADAT S-VHS format for digital recording, while Tascam have pioneered their own system, with Hi-8 tapes the chosen medium of their DA88 recorder. ADAT designers and manufacturers argue that the larger VHS format reduces the strain on digital error-correction systems; yet it offers only half the recording time.

Clearly, there are pros and cons on both sides. What matters perhaps most of all is that, with either format, you can sync up 16 of the buggers to get 128 tracks of digital recording - not that you'll be able to hear much when they're all whirring in the background...

Until now, the Tascam DA88 was the only digital multi track recorder of this class to provide an integral synchroniser. True, you still need to buy the SY88 synchroniser card. But the alternative for Alesis ADAT users was (still is) the BRC or 'Big Remote Controller'. It's definitely big, and perhaps a little over-specified for some.

What Fostex have managed to do now is cram in some of the better BRC functions, along with a few of their own, with the introduction of their own ADAT-format digital multitrack, the RD8.


The RD8 looks every inch a Fostex, while dispensing with the traditional black of the company's analogue multitracks. The creamy-grey colour scheme is easier on the eye than the black of the Alesis.

Below the Fostex logo in the top left-hand comer lies a dark, sunken panel of meters. The 12-segment LEDs represent a range from -60dB to the digital hard-wall of zero decibels. Metering can be deceptive on digital multitracks of this type because the designers are inclined to give quite generous amounts of headroom. The thinking behind this is that it's better to be safe than sorry, as you don't get a second chance with digital recording in a live situation.

This explains why 0VU on a +4dB mixer going in on the +4dB inputs (or a mixer running at -10dB plugged into the -10dB inputs) will illuminate the sixth LED around -15dB on the RD8. In theory this gives you 15dB of visible headroom, but often what happens is that signal gets recorded right into the last red LED. Unfortunately, some desks can't cope when switched into tape mode for mixing, and there's no way of attenuating this steaming tape return other than bringing the tape returns back through the line inputs. All in all, perhaps not what these diligent designers had in mind...

Beneath each of the eight meters are record and input LEDs. Selecting a track for record illuminates a blinking red 'record ready' LED and a steady green one indicating the input status of the track.

Further along is a solitary timecode section, where just three LEDs are used to show the presence of timecode and the record and input conditions.

The metering may speak volumes, but you'll have to record something first. Just below the meter panel lie ten small squares. The first one initiates tape formatting, the last one selects timecode recording. The eight buttons in between choose individual tracks for recording.

Further down is another row of lights and function buttons, the most obvious being the large power switch. Adjacent to this are six more LEDs to relay details of clock sources and sampling frequencies.

A little way along is the 'Chase' button. This toggles on and off, for slaving the RD8 to an external source, an LED below flashing until you're in sync. This is far more helpful and obvious than the Alesis's decimal point in the counter display.

'Digital In' is next along. ADAT users will be familiar with this function, which allows 'ping-ponging' of tracks via fibre-optic cable, either within the machine itself or from another ADAT. The last two switches on the first half of the RD8 front panel are for input monitoring. 'All' puts all channels into input, while 'Auto' toggles selected tracks between input and replay, when in stop or play respectively.

The bevelled mouth of the RD8's tape transport makes tape loading quite a lot smoother than on the Alesis machine. Underneath it are two screens.

Timecode frame rate adjustment takes place here
The data save/load page

"Ascertaining which display should have your attention is not easy, with a minuscule dot bouncing across the screen beneath cryptic legends"

On the left is a 32-character LCD readout which displays itemised edit pages and locate positions. Three function keys steer the cursor and provide direct access to different options available on screen. The edit pages are accessed with the 'Data Edit' key adjacent to the function keys.

A red LED warns when you're in Edit mode, and another press returns you to either the main menu or the current locator position. Generally, when you hit edit, it'll take you to the last edit page you were using. To actually change the edit screen, simply press the button for that particular function. However, not every function has a dedicated key and this is where the Main menu comes in.

Directly below the Data Edit and Function keys are four keys to assist the selection process: two for up/down scrolling and the main menu 'Home' and 'Next' keys. Home takes you back to the start of the Main menu, and Next simply moves on to the next page. Using the function keys above takes you further into Edit.

Curiously enough, the dedicated Cursor key is some five inches away from all of this. Maybe it's to encourage two-handed editing, but being so far from the action, it's easy to mistake it for something else.

The remaining small keys are more or less what you'd expect to find on a machine of this calibre. There's varispeed, along with remote/local control selection - the RD8 can be in both at the same time - with two LEDs indicating the status. In fact, there's a choice of three remote-control types.


The Locator Edit screen

The RD8's locator functions are slightly disappointing. There are only two buttons to weave your way through 40-odd minutes of tape, and one of those is Locate Zero! The other takes you to the currently displayed locator position. You can have as many as 100 locate positions stored within the RD8 and, at first glance, only one key for them all.

Help is at hand, however, in the form of the Mark In and Out keys. Press one of these buttons, and you go directly to their current 'marked' position. You can set these up on the fly so long as you're in Edit mode, and then loop around them or drop in and out. But the 'mark' that you wind on to is not displayed in the locator LCD unless you happen to be in Edit. And even then, you have to select the appropriate marker key after you've gone into Edit, though you can't start the search for the marker while you're there. The ultimate wind-up, or what?

Play and display

The tape counter sits above the Auto Record, Marker, Cursor and Display keys. The Display key itself cycles through the half-dozen time and position modes. This is where the RD8 comes into its own as a serious sync workhorse. The six modes are as follows.

Absolute Time - Refers to the time reference created when an ADAT tape is formatted.

Relative Time - Can be used to show elapsed time. Used in conjunction with the Reset button, this display will notch up the time from that point.

Tape Timecode - Reads out the timecode recorded on the RDX's own timecode track, even if it is not being utilised.

The internal timecode generator can produce all six frame rates and also sends out MIDI timecode - are you listening, Alesis? If only it responded to incoming MIDI timecode, the RD8 could slave to hard-disk recorders and the like. Ah, well.

"It's the same old story: seemingly infinite functions but only a finite number of buttons to tackle them with"

Absolute Offset - Displays the current offset set-up within the RD8, and is used to create the correct timing interval between the RD8 relative to another incoming timecode source.

Relative Offset - This is how far off the tape is from where it should be when being slaved to an external timecode. It should read all zeros when the machine finally locks/syncs.

Generator - Displays the timecode generator's output.

Ascertaining which display should have your attention is not easy, with only a minuscule dot bouncing across the screen beneath cryptic legends. And it only cycles forward, so blink and you'll have to go around again. Nevertheless, the options are very useful, in some cases essential.

External Timecode - Any incoming timecode such as SMPTE or VITC will be shown here.

Back panel has loads of options in the form of video, sync, and MIDI sockets - but why are the standard audio connections different from those on the Alesis ADAT?


A glimpse at the back panel gives a real sense of the applications of the RD8. Only the first two audio inputs need to be connected. The input signal then appears at all the respective odd and even channels - very useful with small mixers such as a Mackie CR1604.

Aside from the array of phono connectors for -10dBV operation and the DB25 (25 pin D-type) connectors for +4dBu use, the RD8 has a variety of sync interfaces. A row of three nine-pin D-types allow sync in and out to daisychain multiple ADATs and/or a remote controller.

The RS422 interface means that third-party software developers can have direct access to the 'brain' of the RD8. This appears to be a very real possibility, as at the time of writing there was no information available regarding a Fostex 'BRC'. Another D-type feeds an optional meter bridge, and along from there are three BNC connectors, MIDI in and out, and two XLRs for timecode in and out.

The first BNC has a 75ohm terminating switch, providing the option to terminate the video signal chain coming from video/VITC sources. When the clock source is set to video, the RD8 detects the video standard being used (PAL, SECAM, or NTSC) and will lock to composite video, black burst, or video sync. Alternatively, you can use the Word Clock for other sync needs. The word inputs and outputs allow the RD8 to utilise sample rates as a clock source, so the machine can synchronise to digital clock information from a DAT or hard-disk recorder, provided there is also a timecode source as a locate reference. You can use the optical input/output instead of the BNC word interface. Simply select BNC or Optical in the clock source page.

The MIDI in and out basically supports MMC in and MTC out, while the Timecode in and out reads or generates SMPTE.

S-VHS tapes are essential at this level (ex-rental shop horror movies are out), but even with an Alesis-approved cassette, our reviewer suffered a burst error

In use

It's the same old story: seemingly infinite functions but only a finite number of buttons to tackle them with. In particular, there are tasks which take an inordinate number of prods and would really benefit from an alphanumeric keying option. Entering offset and locate values is an obvious candidate, and there are plenty of others. You soon resign yourself to this tedium, as no (local) alternative exists. But what a shame that a machine of this extraordinary power should make you feel like a supermarket checkout operator who's just had their barcode reader disconnected.

On a more positive note, the transport buttons respond immediately, sending the RD8 whirring into action like a vintage movie projector. Formatting an ADAT tape takes time, but you can format while recording, or just format as much of the tape as you need. An 'End of Format Search' facility allows you to continue the process as you require. From there you activate 'Format Extend'.

It isn't, alas, entirely clear whether you can stripe the tape simultaneously with the formatting. Absolute time is written during the formatting process, but the creation of a longitudinal timecode track (LTC) only seems to be possible afterwards.

Timecode can be striped to tape as you record, or in one fell swoop in 'Rec-Run' mode. You can use the generator to just stream out timecode regardless of what the RD8 is doing in 'Free' mode, and you can set the frame rate and start time as you wish. And regardless of the generator's mode, MIDI timecode is simultaneously produced with a corresponding time reference.

"In extensive listening tests, it sounded indistinguishable from the Alesis ADAT"

Main Menu 9 - this was used during the review to check the error rate on a tape that suffered a drop-out

As for the tape itself, the S-VHS cassette provided suffered a huge burst error. The result was that the RD8 dropped out of record and began a series of stop/start shuttling manoeuvres - continually trying to reposition itself to to an absolute time reference. A check of the error rate (on Page 9 of the Main menu) confirmed this sad state of affairs, so I reformatted the tape and checked the same area afterwards. This time there was no problem.


'Little Remote' model 8312 is standard fare; there are no official plans for a Fostex 'Big Remote' because the machine has so many additional sync options onboard already.

Performing as an 8-track digital recorder is the RD8's most basic function, and this it does without complaint. The meters are responsive, and in an extensive head-to-head test, the sound quality proved indistinguishable from that of the Alesis.

But the features included on the RD8 are rich and varied, extending its role far beyond that of basic audio tracking For instance, you can delay individual tracks by up to 170mS (Track Slip) and 0.1% pull up/down varispeed, for when the RD8 is slaved to an external sync. This is particularly useful for film-to-NTSC video transfers, as the sample rate can be slowed to compensate, while the timecode format remains the same. User bits can be employed, as well as MIDI and tape for storing data.

Being able to switch sample rates is handy, too - the Alesis will only do this with vari-speed.

I began this review talking about compatibility. Well, before the RD8's arrival rumours were rife that the Alesis and Fostex variations on the ADAT theme would not quite speak the same language in various critical areas. Yet in my experience (see the Compatibility panel) the two machines can hold a range of coherent conversations that would make an Irish pub sound like a Trappist monastery.

The one compatibility problem I encountered was that the 'Save data to tape' feature on the Alesis BRC wasn't recognised by the RD8, though I wasn't too surprised by this - the two machines have quite different features, after all.

All in all, this is an extremely versatile machine that will find favour in many small studios - particularly (but not exclusively) those that often find themselves dealing with sound-to-picture work. Dedicated audio/visual facilities will likewise lap it up.

The RD8 has every aspect of synchronisation more or less covered, and the inclusion of an RS422 port should ensure that its front-end shortcomings will not have to be endured for too long.

It would have been interesting to see a jog/shuttle wheel implemented, as on the Tascam DA88, but it is still unclear whether the S-VHS format can be coaxed into responding to such a wheel.

My main grumbles are the noise the RD8 makes in play mode (it's very quiet in stop, but that's not what you bought it for) and the garbled sound it produces as it locks up to any external sync. I'm sure Fostex could take (another) leaf out of the Alesis book here.

Some people will prefer the audio connections (phono and 25-pin D-type) offered by the RD8; others will be infuriated that neither are instantly Alesis-compatible. New looms will have to be made for those wishing to marry Fostex with Alesis (yes, it's time to get the soldering iron out again). So, while the two machines can talk to each other quite happily, persuading them to sit either side of the same table is not as easy as it should be.

Then again, the RD8 is at least offering you a choice - and in an increasingly lookalike world, that has to be good news. In many ways, the RD8 is the intelligent digital multitrack choice - and a choice piece of kit at that.

The essentials...

Price: £4559 inc VAT

More from: Fostex, (Contact Details)

Their spec


Recording format: ADAT rotary head Tape: S-VHS cassette
Heads: 4 (2 read, 2 write)
Recording time: 40mins typical per 120min cassette
Fast wind rate: 20 x play speed (unwrapped)
10 x play speed (wrapped)


No. of channels: 8 plus timecode
Audio conversion: A/D - 16-bit linear audio, delta-sigma 64-times oversampling, single converter per channel
D/A - 18-bit linear, single converter per channel
Sampling rate: 44.1/48kHz, switchable
Varispeed range: ±6.0%
Freq response: 20Hz-20kHz, ±0.5dB
Dynamic range: 92dB, A-weighted
Distortion: 0.09% THD
Channel crosstalk: 90dB @1kHz
Wow & flutter: "Unmeasurable"
Reference level: -15dB


Dimensions (mm):132 (h) x 482 (w) x 355 (d)
Weight (kg):9.0

The compatibility question: a rotary head-to-head

Alesis vs Fostex. Would they talk? And if they did talk, would they argue? And if they did argue, what the hell would they argue about? Seconds out, round one...

The simplest test was to just swap tapes. No problem. How about the Alesis BRC with the Fostex? Again, no problem. And with another (Alesis) ADAT plus BRC? Well, it would appear that the Alesis mutes its output until it locks in sync, whereas the RD8 doesn't. As it strives to lock, a fragmented and highly disturbing sound of what should be sweet music is heard for a couple of seconds before locking. I was so alarmed by this noise that I opened up the RD8 to check that the tape tension was consistent. It seemed OK, so it must be an over-zealous playback mechanism.

The next test was to split a stereo signal with one side on the Fostex, the other on the Alesis, and then sync them up and check for phasing in mono. Initially the stereo signal was recorded on the Fostex, then one side was digitally bounced over to the Alesis. When each side was returned independently from each machine, there was absolutely no sign of phasing. Hooray! Got it right, lads. And the digital bouncing went smoothly, as did creating offsets between the two machines - a chorus could be seamlessly repeated by bouncing it over from one to the other, dropping in and out automatically at specified points entered on the BRC.

Alright, so the BRC works with the RD8, but what about SMPTE? Seconds out, round two...

Removing all visible traces of remote synchronisation, I hooked up the RD8 to the BRC's SMPTE out. Selecting 'Chase' followed by 'Edit' on the Fostex allows you to choose external timecode as your clock source. Ensure that the RD8 is in chase mode, and it will respond to incoming timecode, by shuttling to sync up with it. This process will, of course, be set by the appropriate offset time - the time (in hours, minutes, seconds, frames, and bits) that is needed to match the incoming timecode position with that of the RD8's position. The RD8 can refer to its own longitudinal timecode, or absolute time. I used absolute time, and by having all zeros as my offset, I attempted to synchronise the left and right stereo tracks on the separate machines as mentioned above. This time there was some phasing, so I adjusted the Fostex to run at three bits ahead of the Alesis, and the phasing virtually disappeared.

Winding the tape back and restarting with such a small offset meant that the RD8 didn't always respond to the offset, and needed reminding with a prod of the edit cursor. Larger offsets of minutes and seconds were tried, and all was well except on one occasion when the RD8 dropped out of sync and then caught up. Going over the same area didn't produce a repeat performance.

I particularly liked the Relative Offset display, which shows how far off the RD8 is from locking right down to the bit. In this sync mode, the RD8 takes about ten seconds to lock, which is about half the time taken by most analogue multitracks. But you only get a third of the tracks, and it remains to be seen how quickly three RD8s would respond to external SMPTE sync.

Finally, I checked the RD8's response to different timecode rates. The edit screen accurately followed the changes, as I flipped through them on the BRC. As expected, the RD8 couldn't tell 29.97fps from 30 fps. When you're in the Offset Edit page, things don't go so smoothly. As offsets are frame-specific, changing the incoming timecode produced Japanese characters and a frame range up to 99.

It is, admittedly, a bit sadistic to wilfully give the RD8 such major headaches - but as with all dirty jobs, somebody has to do it...

Previous Article in this issue

Laurie load

Next article in this issue

Falling into line...

Publisher: The Mix - Music Maker Publications (UK), Future Publishing.

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


The Mix - Jul 1994

Donated by: Colin Potter

Coverdisc: Mike Gorman

Control Room

Gear in this article:

Digital Tape Deck (Multitrack) > Fostex > RD-8

Review by Bob Dormon

Previous article in this issue:

> Laurie load

Next article in this issue:

> Falling into line...

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