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Jl Cooper Sync-Link

Macintosh MIDI Interface

The new line of cheap Apple Macs sees them Ending more music applications; now the search is on for a cost-effective MIDI interface. Vic Lennard checks out a strong contender.

If you're used to using an Atari as part of your MIDI setup, you've been spoilt by its onboard MIDI interface - but choosing an interface for a Mac has just become a lot easier.

IT'S A SAD fact of life that unless you have an Atari ST or a Yamaha C1, you have to buy a MIDI interface for your computer. Owners of PCs, or compatible machines, require more than a simple interface due to the slow nature of their computer's serial port. In contrast, Apple Macintosh users don't have the same problems. The various Mac MIDI interfaces start at around £65 with Opcode's Translator and JL Cooper's MacNexus, each providing a single MIDI In and three MIDI Outs. As there are two serial ports on most Macs, one for modem and the other for printer, you can effectively drive two such units and have access to 32 independent MIDI channels with two-way MIDI merging on input for around £130.

The problem facing Mac users is how to generate SMPTE or FSK code for tape, and then convert it back to one of the MIDI synchronisation methods. This either requires an additional piece of hardware, or a combined MIDI interface/synchroniser. And while such units are available, they have usually been expensive.

JL Cooper are renowned for MIDI hardware devices such as Fadermaster and the PPS1 FSK-to-MIDI Clock converter. While they have had a device as described above available in Syncmaster, the RRP of £315 is rather steep. Consequently, the company's Sync-Link represents a low-cost alternative.


MEASURING JUST 21CM x 12cm x 4cm, Sync-Link is about a half-U rack size and can be racked by using the optional JL Cooper Rack Tray. Controls on the front panel are sparse: a three-way toggle for Tape Code mode, another for MIDI sync mode and a power push-button. There are also five LEDs: two each for the modem and printer ports (showing in/out activity) and one to show tape code activity. The rear panel has two sets of MIDI connectors along with their associated serial port sockets, tape sync in/out and the socket for the external 9 volt psu - far more sensible than an internal one for a unit of this size, for reasons of heat and possible transformer interference.

The psu is included, as are two Mac serial cables which usually cost at least a fiver each. It's good to see a manufacturer being prepared to include all necessary cables.

By using both of the Mac's serial ports, Sync-Link gives you the opportunity to effectively use two different systems with it. Separate keyboard and MIDI modules can be connected or alternatively, two MIDI Ins and Outs from a MIDI patchbay can be used for signal distribution to an integrated system - I suspect most people will use Sync-Link this way. This leaves the awkward question of how to access the Mac ports when you're not using them for MIDI applications; after all, they're primarily for a modem and printer respectively. You could spend your time disconnecting and reconnecting the various leads, but you can get hold of an ingenious switch "box" which has a flying cable going to the Mac, two sockets and a single switch encased in grey plastic. All you do is mount it near the Mac and switch between the two devices by pressing the button. The fact that it has a flying lead reduces the number of cables you need by one - important when you consider that Mac serial cables aren't usually available from your local computer shop.

Sync-Link can transmit one of two tape sync codes - SMPTE or FSK. The decision on which to use will depend on whether the Mac sequencer you are using recognises MIDI Time Code or not (more soon). The right-hand toggle switch lets you choose whether FSK is used or not by selecting either the bottom position for FSK, or the middle or upper for SMPTE. This selection has to be made before turning the unit on - alteration after this is not recognised.


SMPTE MODE IS used if the sequencer can recognise either MIDI Time Code (MTC) or Direct Time Lock (DTL). The latter is a proprietary system used by Mark of the Unicorn's Performer, which now responds to MTC as well. The right-hand toggle is set accordingly and the sync in/out connections are made between Sync-Link and the multitrack recorder. The signal level to tape should be around -7dB, although higher levels can be used for reliability if the adjacent track is left blank as a buffer.

Tape striping starts from and at 30fps as soon as you flick the right toggle to Stripe. What if you want a different start offset and frame rate? One of the short-cuts taken with Sync-Link is in the use of a Desk Accessory to configure the striping operation instead of providing the relevant switches and readouts on the front panel. The Start Time and Frame Rate can be set on-screen as can the relevant serial port and MTC/DTL. The current SMPTE time can be displayed - and continues even when the DA window isn't the active one - and can happily co-exist with any Mac sequencer as long as the box with MIDI Application Running is selected. This is fine if these are the settings you always use, but Stripe has to be selected on the front panel, and a click on the Download option on-screen stops Sync-Link from transmitting tape code. A further click on the Download option then sends the relevant info to Sync-Link and transmission starts. Simple and practically bullet-proof.

The manual explains the setup procedure for the sync pages of most of the Mac sequencers, including DTL for Performer, with the serial port invariably being set to 1MHz.

Once the tape is striped, flip the right toggle to Read and either MTC or DTL will be transmitted back to the Mac on the port set by the DA or to the modem port by default.


THERE ARE ONE or two budget sequencers which cannot recognise MTC, such as Passport's Trax. For these, JLC have included the FSK-to-MIDI Clock conversion option which also includes Song Position Pointer. This allows a song on tape to be started from somewhere other than the beginning, and the sequencer to lock to it. This type of FSK is often referred to as "intelligent" FSK or FSK2. The left-hand toggle is set to FSK and the right-hand one is used as for SMPTE - Stripe or Read. When striping, the sequencer has to be playing the relevant song so that any tempo changes are recorded. This is, of course, one of the reasons why you only use FSK with a sequencer when you have to - if the sequencer can use MTC or DTL, then the SMPTE mode of Sync-Link should always be used.

"Having looked around for a suitable Mac synchroniser/MIDI interface for a month or so, I can only wonder how JL Cooper can produce Sync-Link so cheaply."

Copying SMPTE timecode from one tape to another shouldn't be done by simply re-recording the track. The code should be regenerated. Sync-Link can do this. In fact, it does it all of the time - whenever it receives SMPTE at the sync in, it automatically transmits a regenerated version from the sync out. It also has the ability to do basic Jam Syncing, which again occurs automatically. This is when the original time code has faults and the generator continues to transmit SMPTE even though the input code is corrupted. Sync-Link can handle up to six frames of corruption - if the drop-out is longer than this, the generator stops.

Additionally, the MTC or DTL conversion continues through a minor drop-out - again for up to six frames. Remember that six frames is between a quarter and a fifth of a second depending on the frame rate, and dropout beyond that is certainly substantial. Tape damage or corruption through a mains spike should be handled OK.

Finally, Sync-Link can operate in Free Run mode - the upper position of the right-hand toggle. In this mode, SMPTE is output from the sync out and MTC or DTL are output from the modem (default) or printer port. This allows you to synchronise devices requiring SMPTE, MTC or DTL without needing a tape machine.

The only problem I encountered when using Free Run was in changing the code start time or frame rate. Using the DA in Stripe mode, this can be changed, but you have to be certain to close the DA before moving the toggle to Free Run mode otherwise the Mac locks up. If you are using Passport's Pro4, the serial leads have to be changed round and the printer port selected, because Pro4 will only recognise MTC from this port.


I TESTED SYNC-LINK with most Mac sequencers with complete success. The comments in the manual about usage with various programs is accurate and very necessary - you have to be aware of the slight quirks in the synchronisation of your sequencer; trial and error working is not recommended. JL Cooper have done their homework. One sequencer not mentioned within the manual is Steinberg's Cubase, but there are no problems here.

Having looked around for a synchroniser/MIDI interface for a month or so, I can only wonder how JL Cooper can produce Sync-Link so cheaply.

One point worth making here is that if your sequencer is using MTC and is jumping during playback, the odds are that the frame rate set for the sequencer and Sync-Link are different. It's a shame that European versions of Sync-Link can't be set to 25 frames by default, but it's easy enough to alter from the DA.


DID I SAY Sync-Link was cheap? Yes I did. With a RRP of only £150, it can hardly be described any other way. (Who says that everything for a Mac is expensive simply because of the name?) Sync-Link is practically the same price as a free-standing SMPTE-to-MIDI Clock converter and yet it offers two MIDI Ins and Outs, SMPTE and FSK, MTC, DTL and MIDI Clock along with free-running time-code generation, jam sync and SMPTE regeneration.

Needless to say, I bought one. Now at last I can get down to some sequencing on my Mac.

Price £150 including VAT.

More from Sound Technology, (Contact Details).

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Waxing Lyrical

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IMS Report

Music Technology - Copyright: Music Maker Publications (UK), Future Publishing.


Music Technology - Sep 1991

Gear in this article:

MIDI Interface > JL Cooper > Sync Link

Review by Vic Lennard

Previous article in this issue:

> Waxing Lyrical

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> IMS Report

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