MIDI interfaces come in many different shapes and sizes, with most slotting inside the PC. External interfaces, however, such as those made by MOTU, can offer certain advantages, as Martin Walker discovers.MIDI Interfaces tend to be heard and not seen — if they work reliably, once installed they're forgotten about. And so they should be.
<h3>PLUGGING IN</h3>
So, onto the items under scrutiny, Mark of the Unicorn's PC‑MIDI Flyer and Pocket Express PC MIDI interfaces. Each is built into a solid, stove‑enamelled metal case which should withstand the proverbial roadie's boot. Both also have LED readouts for each of their two available MIDI Ins and Outs (32 MIDI channels in total), which is always a useful way of checking that data is actually passing through the unit. In addition, a computer bypass switch lets you use each interface as a Thru box even when the PC is not powered up (very useful when you just want to play a keyboard without firing up your sequencer). The Flyer is powered from the parallel port, and the Pocket Express comes complete with its own plug‑in power supply. Like them or loathe them, the dreaded 'wall warts' do help to keep the price down, and as long as you keep them well out of the way of audio cables, they'll do their job perfectly adequately.
Parallel‑port interfaces seem ideal as the insides of our PCs continue to fill up with multiple soundcards, SCSI controllers, fax modems and the like.
The main differences between the two interfaces are that the Pocket Express can be connected to a Mac as well as a PC, each of its two MIDI Outs is duplicated (giving a total of four DIN output sockets, which could well save having to use a Thru box), and it's also equipped with a comprehensive set of SMPTE sync options for use with analogue tape machines and video tape, including 30, 29.97 drop, 25, and 24 frame rates. It can also be used to stripe SMPTE onto audio tape decks, although for video, MOTU recommend their Digital Time Piece, which has genlock facilities to ensure accurate matching (for more in‑depth info on this subject, look no further than Paul White's feature on SMPTE and MIDI Time Code in the June 1996 issue of SOS).
Connection to the PC is via a standard DB‑25 lead that is included with each unit. Unfortunately, there is no through‑port, so unless you have multiple parallel ports on your PC, there will be nowhere to plug in your poor old printer. You could try a switcher box (available from most computer suppliers for about £15) which will allow either device to use the single parallel port. Alternatively, I use a parallel port expander card (again, about £15) which adds two more ports to the basic one. This allows three simultaneous parallel devices to be connected (LPT1, 2, and 3), although, of course, it does take up one of your precious slots.
Installation of both devices proved easy enough in my case, taking about half an hour. The supplied drivers incorporate Express Setup software, which correctly identified which of my three parallel ports the interface was connected to. They also attempt to intelligently allocate an interrupt (IRQ) setting from a choice of 4, 5, 6, or 7, and will default to IRQ7, as this is normally used by LPT1 (the default printer port). This, again, worked fine on my PC, although I do know of other people whose machines reported no IRQs free at all from the four provided. Although four options sounds generous, IRQ4 is already used by the first serial port (normally connected to the mouse), and IRQ6 is permanently tied up to the floppy disk controller. This leaves IRQ 5 and 7, and if either of these is currently unused, Express Setup will use them. If neither are available, the dreaded shuffle of resources starts — finding another internal card that uses IRQ 5 or 7, that also has other available unused settings. Parallel port connection avoids the need to set I/O addresses (the locations in memory used by the PC to read and write MIDI data). Normally a selection of alternatives are needed, but in the case of parallel ports, the address is already decided by the operating system, giving one less potential source of conflict.
In Use
When you fire up your sequencer after having installed either of these interfaces, you'll find two new MIDI outputs (A and B), two inputs of the same variety, and an additional input labelled 'Sync'. Any MIDI Time Code (MTC), MIDI sync, Song Position Pointer, or real‑time related messages received at either input are routed to this port for sync'ing your sequencer to any external hardware. I found that some MIDI applications recognised and were able to use the interface first time (Cubase Score v2, ReSample Professional) but others refused to co‑operate. These included Sound Forge 3.0's SDS MIDI sample dump ("An unknown error occurred opening the Flyer:A device") and the shareware sample converter Awave 2.5 ("Couldn't open MIDI input device"). Both of these problems disappeared immediately I installed the updated set of drivers that arrived during the course of this review (version 1.02, released August 1996, and also available via the MOTU website).
During use, I did have one big problem, which took a great deal of solving and which had the same totally bizarre symptoms with both interfaces and both sets of drivers. Trying to run an existing sequence resulted in total silence until I stopped Cubase, whereupon most of the notes from my melody would sound simultaneously, almost as if they'd been hiding inside and trying to pluck up courage to emerge! I examined the MIDI data emerging from the interface: there was plenty of it, but all nonsensical, such as 'All Notes Off' and random controller messages. This odd problem was finally cured by ticking the 'Force interrupts' option in the interface setup window (see screenshot, left). MOTU say in their readme file that "this option is intended for trouble‑shooting only. If your MIDI interface is working properly, you should not check it. However, if you experience trouble receiving System Exclusive messages (especially if your computer has a slower 486 processor) try checking this option." Well, no SysEx was involved in my file, but ticking this option cured my notes of their shyness, and everything worked perfectly from then on. From conversations with Musictrack, the UK distributors of MOTU products, it seems that hundreds of people have bought these interfaces and no‑one has reported suffering from my particular problems. It just goes to show that PCs take no prisoners when it comes to installing new hardware!
Conclusions
Both of these interfaces are rugged and, despite my own initial teething problems, reliable in operation. The PC‑MIDI Flyer is recommended if your interfacing needs are straightforward, while the Pocket Express is the one to go for if you need the four MIDI Outs and/or the sync options. The use of the parallel port can be a godsend if you're running short of internal slots, and the LED status readouts make any fault‑finding a lot easier. The biggest advantage of buying one of these has to be the two Ins and two Outs, which make using several synths a far less complex operation. My only niggle is the lack of a through‑port, since most people still only have one parallel port on their PC, and unplugging the interface whilst still powered up, in order to attach your printer, might prove too tempting for some, resulting in possible electrical damage.
MIDI interfaces are not glamorous, even when fitted with multiple flashing lights, but parallel‑port devices seem ideal as the insides of our PCs continue to fill up with multiple soundcards, SCSI controllers, fax modems and the like. By placing the box on the outside of the PC, you can ensure that valuable resources still lie untapped within — this has to be the way forward!
Serial Box
The use of serial ports for MIDI has generated some problems in the past, and many manufacturers have now stopped trying to squeeze high‑bandwidth MIDI data (especially SysEx) in and out of a port which would normally see use with a mouse or modem. Windows 95 users have a further problem here, as reports are that serial MIDI ports tend not to be very reliable using this operating system. Even using buffers, the data can still arrive at the In port faster than it can be removed. The buffer helps, but with large SysEx dumps or SDS sample dumps, the data keeps on coming, and even with a buffer the system may eventually fall over. Sound modules such as the Yamaha TG300 do have serial port interfaces, but since the rate at which SysEx data arrives at the PC is set by Yamaha, it can ensure total reliability with its own data. For general‑purpose interfaces, using the parallel port tends to be far more reliable, as it was designed to transmit and receive data at much higher speeds in the first place.
Pros
- Two inputs and two outputs.
- Uses no internal slot!
- Useful bypass switch.
- Easy to install for most people.
Cons
- Ties up printer port.
- Occasional clashes with existing hardware.
Summary
Both these devices are rugged, reliable, and an ideal way to expand your MIDI setup without filling up the inside of your PC.