Tony Wride checks out a device which can relieve many of the MIDI-induced headaches associated with even the most modest MIDI system.

If, like me, you own a MIDI set-up and have often been faced with the common problem of trying to put two MIDI data inputs into one instrument, you will be pleased to learn that it can be done. In my case I have often wanted to feed sequencing data from my computer and note data from my master keyboard into the same expander module. The problem is that you end up with two plugs trying to fit into one socket, and no matter how hard you try it just cannot be done - even if you use the universal fixing method of a size ten boot! What is required is some way of combining the two sets of MIDI data into one, and this is achieved by using a device called a MIDI merger. The MIDI Merge+ from 360 Systems is one of the latest products on the market that can perform this feat of magic, but as the '+' suggests, it will also perform several other handy operations.

Working on the principle that everybody owns a rack (I actually use a few bits of suitably spaced chipboard), 360 Systems supply the MIDI Merge+ in standard 19-inch rack-mount format. There's an array of pushbuttons and LEDs on the front panel and no less than six MIDI sockets at the back. The front panel layout is fairly logical, and once you understand what the unit can do the two rows of LEDs become a very quick way of seeing exactly what you have set up. The rear panel connections comprise of two input channels, each with a MIDI In and a Thru, plus two output sockets labelled 'Merged Outputs'. There is also a socket for an 'All Notes Off' footswitch (a useful addition), plus my least favourite item - the 9-volt DC input socket. Yes, you guessed it; this is yet another unit requiring a separate power supply, with all that that entails. I have a strong dislike of them (not helped by the fact that within my current set-up I have no less than four of the little blighters littering my floor!), but I suppose if 360 Systems had included an onboard power supply it would have added to the cost. One day somebody will design an external power supply unit that can be easily attached to the back of a rack unit and has a long lead on the AC mains end with a short lead on the DC end; not the other way around.

WHAT IS MERGING?

'Once you supply power to the MIDI Merge+ and switch on, any valid MIDI data arriving at either Input 1 or Input 2 will be sent to both outputs, providing it is not affected by any filters (see later) that may be active. When data arrives at both inputs simultaneously, the Merge+ becomes a sort of traffic controller and forces each input to take turns sending complete MIDI messages to the output, while saving any data arriving on the input that is locked out.'

Confused? When I first read the above quote I had visions of there being a sort of motorway contra flow, where two lanes of traffic suddenly become one. As those of you who have experienced such things will know, you tend to get delays while people wait for a gap in the traffic. I imagined that if there was a continuous flow of MIDI data on one input, there would be very few gaps that the other input could slot into. The delays that I thought might occur could have horrendous results. However, after some pretty severe testing it seems that the Merge+ unit copes. What you have to remember is that all the MIDI data that flows is travelling at some incredible speed, which (if we continue with the analogy of cars at a motorway contraflow) equates to something like a one mile gap between cars on the busy lane! You would only need to store a car (bit of MIDI data) for a short while in the not-so-busy lane if both cars arrive at the same time.

To test the Merge+ I had one input supplied by my computer playing a fairly rapid sequence of chords, while on the other input I played a lead line from my master keyboard. Listening to the results when the merged output was fed into my expander, I couldn't notice any delays. The owner's manual actually states a case where problems might occur, which is when a System Exclusive message is detected on an input. In this case, the second input is not allowed access to the output for the duration of the System Exclusive message. Since such messages can be very long, it is possible to introduce noticeable delays if performance data arrives on one input while a System Exclusive message is being transmitted on the other. The worst case would be if you tried to merge two sets of lengthy System Exclusive messages. This might cause data loss because the buffer memory in the Merge+ is not big enough to hold it. That said, using the Merge+ for the job it is intended for, ie. merging two sets of performance data, did not seem to present any problems.

THE PLUS FACTOR

One of the most useful things about MIDI data is the fact that it can be manipulated to a far greater degree than, say, a recorded tape track. Unlike sound, MIDI data is a stream of numbers which can be rearranged if you have the necessary piece of equipment to do so. The Merge+ lets you carry out several useful data manipulations plus a whole host of MIDI data filtering, as follows:

MIDI Transpose: This can be independently set for each input source simply by selecting the required transpose interval from a connected keyboard. The 'Set', 'Transpose 1' and 'Transpose 2' buttons are used to carry out this function, and once the interval has been set it is stored in memory so that at a press of a button you can activate the transposition.

Channel Bump-Up: This automatically increments the channel number of any incoming MIDI Channel messages by one. Thus, channel 1 becomes channel 2, and so on. This gives new-found freedom to owners of synths with fixed transmit or receive channels (such as the original DX7).

MIDI Filters: There are seven individually selectable MIDI filters on the Merge+. These allow the user to selectively filter out any combination of Pitch Bend, Modulation, Aftertouch, Program Change, Real Time, and System Exclusive data that is received at the MIDI In. The 'User Filters' switch lets you define up to eight filters at any one time for each input line.

Specifying what user-defined controller you want filtered is simply a matter of pressing a couple of buttons and then moving the desired controller. The two 'Input Enable' buttons allow you to choose whether the appropriate filters are active on an input channel, and the row of LEDs above the filter buttons supply an instant indication of what has been selected.

As a word of caution, 360 Systems make a point of highlighting a couple of potential problem areas when using the Merge+, which basically warn against making any changes to a set-up during performance. If, for instance, you had a sequence playing and then suddenly decided to switch the Transpose function on or off, you are likely to end up with some 'hung' notes. This is because the Note-Off commands will also be transposed and, consequently, will not match up to their corresponding Note-On messages, leaving you with hung notes.

For the same reason, switching filters on and off or channel bumping when playing will also cause problems. If you do happen to make this mistake then you have the facility to press either the 'All Notes Off' button or footswitch to remove the unwanted drone.

CONCLUSION

I found the MIDI Merge+ to be a very useful piece of equipment for the MIDI musician to own, since apart from solving the merge problem you have the added benefit of transposition and data filtering. In use I encountered no real problems, and at £199 the MIDI Merge+ represents fairly good value for money.

Price £199 inc VAT.

Contact Argent's, (Contact Details).