Atari Multi-Port MIDI Expanders

Martin Russ investigates why you might need more MIDI Outputs.

One of the subjects which is guaranteed to get me talking is multi‑port MIDI expanders. Since price and availability both seem to be excellent at the moment, this looks like a good time to promote their use by every Atari MIDI musician.

The reason that this article is targeted specifically at Atari users is that they have only one MIDI output. But why would you need more than one MIDI Out socket? Sixteen MIDI channels sounds like quite a lot, after all...

Multitimbrality

It all comes down to multitimbrality. Just about any MIDI sound source these days has at least 8‑part multitimbrality, which sounds like a wonderful idea, and it is — until you realise what it means in terms of MIDI channels. Suppose you have a workstation and a synth expander module, both with 8‑part multitimbrality. Obviously this means that if you use all the available parts, you've already used up all 16 MIDI channels. Even if you only use half the parts, you could end up needing more than 16 channels with only four devices. And many MIDI sound sources now have 16‑part multitimbrality and 64‑note polyphony, which means that one box could use up all of the available channels on its own.

Getting around the 16‑channel limitation of MIDI is easy — you just need a second MIDI Output to provide another 16 channels. At first glance, you might think that a Thru box could provide this, but all that a Thru box does is provide copies of the input at several Outs — useful for wiring up a 'star' configuration MIDI system, but no use for increasing the number of MIDI channels. What is really needed is a completely separate MIDI Out port which can provide 16 additional MIDI channels.

The simplest way to get more channels is just to hook up one of the many single‑port devices which connect to the modem port — most sequencers will drive these directly. This gives you 16 extra channels from the modem port. For more MIDI ports (and thus even more channels) there are three‑port expanders which match the extra channels which are available in Cubase and Notator/Creator. Three ports equals an extra 48 channels, making 64 in all when you remember the Atari's own Out. As well as the 'generic' expanders, there are also those which are produced as accessories for the well‑known sequencers. Emagic Logic is supplied complete with its own multi‑port expander, and the Emagic Xport expander allows you to add extra Outs to Notator/Creator, whilst Steinberg's Cubase can be expanded with their own Midex expander.

With four separate ports to play with, you can really simplify your wiring — no need for Thru boxes or daisy‑chained cables tying up Thru sockets on equipment. This makes it easier to remember where something is — with a master keyboard, two expander modules and a drum machine you can dedicate a port to each. If you have a sampler as well, adding that to the same port as the drum machine should cause no major problems — how many channels do you need for drums, and how many samplers are 16‑part multi‑timbral with a comparable polyphony? You probably only need a couple of channels for drums, and 14 channels for samples seems more than adequate. Because the Outs are separate, you're effectively reducing the amount of MIDI information that needs to travel down each cable — half for two ports, and a quarter for four. This can improve the timing and make using continuous controllers much less troublesome.

Eight Ports

If you have more equipment than the above example, an 8‑port MIDI expander like the Friend Chip MM1 might be the answer. This provides eight separate MIDI output ports and connects into the Atari's (Centronics) parallel printer port — and can still provide access to a printer via a switch. Other 8‑port units might use the DMA or SCSI ports. Having eight separate MIDI Outs is seriously powerful, but with the current proliferation of affordable expander modules, it is not as unlikely a need as it might at first seem.

What large numbers of channels offer you is the ability to be in charge of a large orchestra without any hassle. Setting up eight pieces of equipment to have 16 different sounds assigned to the 16 parts may take a while, but once this is done, you then have instant access to 128 different sounds without even needing to send a program change. By allocating your favourite sounds to the available channels, you can produce your own customised orchestra, where it is the port and channel that determines a sound. With such a palette, you can double up parts, cross‑fade between sounds using velocity, create composite sounds, and a whole host of other tricks that would probably eat up too much channel‑space on a 16‑channel, single‑port MIDI system.

Multi‑port MIDI Interfaces can be the key to avoiding the time smearing or 'flamming' that can happen if you have an overcrowded MIDI port. They make wiring up and changing MIDI systems easier, since there is less need to use Thru sockets to daisy‑chain equipment together. They enable you to access a wide range of sounds merely by selecting a port and a channel, which can make arranging a piece of music much quicker. With all these advantages, why are you still here? Buy a multi‑port interface and make some more music...