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Expand your DX

Yamaha's DX7 may well be a classic keyboard but its MIDI implementation and small onboard memory are starting to look decidedly limited compared to newer generation keyboards. What's needed is an upgrade, and the add-on E! board from America's Grey Matter Response is certainly that! Martin Russ enthuses over its features.

DX-pert Martin Russ travels to London in search of the ultimate expander for his DX7 and finds it in the guise of an add-on PCB called E! made by America's Grey Matter Response.


Camden Town tube station: out of the shadows our intrepid reviewer approaches two policemen who are busy cautiously eyeing the Saturday afternoon football supporters. "Can you tell me where Take Note are?" "Sorry son," said a broad Yorkshire accent, "we aren't local - we've been drafted in." (Pulls A-Z from his pocket) "Carol Street, you said... mmm." Once on my way (it's actually only a couple of minutes from the tube station), I ponder upon my assignment: Why bother to review an expander for the DX7? There are already several on the market giving you lots of extra internal voice memories as well as that rather superfluous MIDI Omni Mode, so what else is there left to add?


The answer is the E! board from Grey Matter Response (don't ya just lurv that name, man!). This is much more than just another expander for the DX7. It gives you what amounts to a new instrument, because instead of just adding a few extra bits of RAM and editing the Yamaha Operating System ROM, the whole of the DX7's software has been rewritten from scratch. And so you get access to lots of extra controls within the DX7, as well as very comprehensive control over MIDI input and output, in addition to more internal memory.

In this review I will talk mostly about the software in the Generation 1 E! board - by the time you read this Generation 2 should be available, and I have included a summary of its features so you will know what to expect. Don't forget that the Generation 2 software will be an update to the existing hardware, and it will also be free to existing owners, so there is no need to wait before buying - you get the updates anyway!


As with most internal expanders for the DX7,the E! sits over the DX7's main 'DM' board, with a couple of flying leads which need soldering to LS138 address decoder outputs, but with all the other connections made via two ribbon cables and headers which you push into a ROM (27128) and a RAM (5118) socket. Since the RAM chips used are CMOS devices, you need to take some precautions against static when fitting. The board itself comes well packed in anti-static bubble-packing with some black conductive foam on the trailing end of the ribbon.

Mechanically, the board is supported by a bracket and a bolt and spacer, as well as being protected against vibration by a couple of sticky foam pads. Fitting the E! PCB (Printed Circuit Board) takes about 15 minutes if you take your time and check everything thoroughly, as I did. (As there are two soldered connections to be made, as well as the CMOS and a little bit of disassembly work, you may well prefer to delegate the installation task to a studio or service engineer. London's Take Note - who distribute the E! will, of course, fit the board for you, if you ask.)

The board itself is a double-sided, plated-through hole, flow-soldered, solder resist and silk-screened board. [This boy knows his PCBs! - Ed.] Components used are all from well-known semiconductor makers - NEC, Fujitsu, AMD and Intel - and overall there is no doubt that this is a quality product. As I expected, there were no problems in fitting the board myself and it worked first time - there are, however, instructions in the user manual to help you discover and eliminate any possible problems before you re-assemble your DX7.


When you power up the DX7 with the board in place, you now get a message that says:

...and the LED display shows'E!' instead of the old random two-digit number. After a few seconds the display reverts to the conventional Play mode and you get your first surprise - it now says INTERNAL BANK 1 on the LCD. Pressing the DX7's Yes/No buttons or moving the Data Entry slider now runs through 8 banks of voices, each voice being equipped TX-style with its own function memory as well as a new programmable volume feature (very useful in live performance). 8 banks of 32 voices = 256 voices = 8 Yamaha RAM Cartridges - the Generation 2 E! will have 10 banks (= 320 voices) by using the available RAM more efficiently.

Selecting a voice is easy: you choose the bank and press one of the 32 green buttons, just as usual. When you change a bank the LED display shows 'En' for a few seconds, then you can skim along the green buttons to find the voice you want, as usual. If you select a cartridge voice, a special set of 32 function memories is also loaded from the internal RAM. This is the same for all cartridges - so you need to plan carefully how you use your memory. In practice, it is probably best to have the cartridge functions set to 'normal' settings suitable for most voices, and leave any special effects function settings to the internal voices. It took me only about 30 seconds to get used to selecting voices from the banks, then I began thinking about life after I return the review E! — all that swapping of cartridges... yuk!


MIDI was very young when Yamaha originally released the DX7, and so it has a simple implementation of the standard. In fact, Yamaha's interpretation of some of the MIDI standard has resulted in the recent appearance of an extra MIDI Mode - Mode 2. Early DX7s also had a problem with aftertouch being used as a controller, but this has since been cured by a software update.

To summarise then, the standard factory DX7 always transmits on MIDI channel 1, and can receive on any of the 16 channels. E! significantly adds to this meagre specification. The MIDI controls are accessed via the page system: pressing the brown Function button on the DX7 now enters the page mode; pressing the purple Operator Select button now cycles through the available pages. At the time of writing, these were: the Function Control page, the MIDI Control page and the Memory Control page. The MIDI page uses the upper row of green number buttons to set the receive options, and the lower buttons for the transmit options. You can send and receive on any MIDI channel and filter out the incoming and outgoing MIDI data - options are Notes, Program Changes, Pitch Bend, Foot Control, Breath Control, Modulation Wheel, Aftertouch, Sustain Pedal and System Exclusive.


Merge facilities can also be found on the MIDI page: the Generation 1 software only gives limited merging, but Generation 2 will implement a full note merge. The two current options available are, firstly, a 'Controller' merge, which lets you use a DX7 as a Yamaha MCS2-type controller for external 'piano' type keyboards with no pitch bend and modulation wheels of their own, by letting you use the DX7's controllers in addition to playing the external keyboard. Secondly, a 'Sequencer' merge, which allows MIDI timing clocks and sequencer on/off commands to be merged with the output from the DX7.

Further controls allow you to optimise your DX7 for use with other equipment. Things like a Running Status toggle; a TX-type bulk dump toggle; a Key Off code toggle for slaves which don't believe that a 'note-on' command with a velocity of zero equals a 'note-off' command; and an Aftertouch toggle which enables you to emulate the early controller-based aftertouch so that you can use a QX-1 sequencer to record and play back aftertouch. (As I mentioned above, early DX7s had the aftertouch implemented as a controller, and some QX-1s still think that this is the case.)


Also on the MIDI page are extra controls over the keyboard: Key Velocity Processing and Keyboard Assignment. The Velocity Processing allows you to 'tone down' the velocity of incoming MIDI data so that it matches the velocity range of the DX7. (The keyboard velocity algorithm used in normal DX7s only gives a maximum output level of 112, instead of 127.)

You can also select the velocity curve, ie. how the sound responds to velocity. You can reverse the sense so that keys struck with fast velocity will sound as if they had been struck with slow velocity and vice versa. You can also alter the curve to make the velocity effect more compressed in the upper values, so that slow and medium key velocities sound as if they had been played slowly, but with a sudden increase in the upper range of velocities. There is even a curve where everything except very fast velocities sounds like fast velocities, and only the very fast velocities sound like slow. The portamento pedal can be changed using the E! board's MIDI page so that it functions as a sequencer stop/start or a keyboard preset selector (of which more later).

However, the most interesting controls over the keyboard are those for Keyboard Assignment. Four modes are available in Generation 1:

- Normal emulates exactly the normal DX7 mode - all keys played are voiced by the DX7 and output to MIDI Out.

- Rolling alternates notes played between the DX7 and MIDI. This is very effective using, say, a couple of Yamaha FB-01s on odd and even note numbers in stereo, where notes jump around the stereo image, coming from the DX7 or one or other of the FB-01s.

- Floating High Split gives you a keyboard split that plays notes above the split on the DX7, while notes below go to MIDI - only there isn't a split point. The E! magically figures out where your left and right hands are and splits accordingly. So you can do things like holding a left hand chord and crossing it with the right hand, without the DX7 getting confused. It takes a bit of getting used to the constraints of this system though - for example, the first note you play seems to be assigned to the DX7, and any further notes within a musical tenth are assigned to your left hand (even when you have held down more than five notes!). I can only assume that the algorithm that E! uses makes a compromise between complexity (= time to figure out where the split should be) and speed of keyboard response. Having said that, for legato playing - with sustained left hand chords and right hand contrasting sounds - this 'floating split' is really effective and very confusing to anyone who knows the DX7 but not the E!. No bothering with a split point that is one note too low! (The Generation 2 E! software also implements a fixed split point.)

- Track High gives you a Mono Highest Note Output, giving a sort of automatic melody line - very good for brushing up on your chord inversions so that the lead line sounds right! And also very good at showing up your playing, because if you don't slightly legato your top chords, then the mono line hops down to whatever your left hand is playing. Again, a useful mode within the constraints it imposes, but whatever happened to Track Low, the automatic bass pedal board? [This is NOT a 'Home Organist' magazine-Ed.]

- Last but not least is the Local Control Off mode, where only the MIDI output appears, the DX7's output then being accessible only via MIDI In.


Oops! - another 'Home Organ' term. The Keyboard Presets are actually memories for keyboard set-ups - so you can have 16 different stored settings of parameters like the Keyboard Assignment, the MIDI Filters and the Velocity Curves. You can select the Presets by using the portamento pedal in its controller mode and pressing a green (1-16) button while the pedal is held down. You store the Presets while in the MIDI page by using the pink DX7 Store button - as with all the other additions to the original Operating System, you do it exactly as you would expect. Obvious Presets that you could store would be a 'normal' DX7 emulator in Preset 1, a floating split in 2, a master controller in 3 and reserving Preset 16 for bulk dumps and other MIDI System Exclusive activities. (As per channel 16 in MIDI, which seems to usually get assigned to bulk dumps etc.)


The E! Functions page is very similar to the original DX7 function controls except that all the memory management and MIDI controls have been moved to their own pages. So the brown functions on buttons 1 to 7, and 17 to 32 remain as usual. Button 8 now has Programmable Volume instead of MIDI, and the Edit Recall and Voice Initialise are now on the Memory Control page. The programmable volume is a TX-type facility which has a range of 0 to 7, for soft to loud, and can be very useful in preparing for live performance. Unfortunately, because of the way that the cartridge storage works, you can't have programmable volume in Cartridge Voices.


An impressive term for the actions available on E!'s Memory Control page. Here you have access to controls which enable you to transmit any of the internal banks of voices, in either DX (bulk 32 voice only) or TX formats (where voice and function data are sent); as well as format cartridges; recall edits; initialise voices (and function memory); and save and load cartridges into internal banks.

All the E! memory is battery backed up, using the original system from the DX7, so when you replace your battery you will have to back up all your banks! It takes a bit of lateral thinking to figure out how to choose banks for saving and loading to and from the cartridge socket, since the display sits there displaying 'LOAD BANK 1 ?' - to which you can answer only 'YES' or 'NO', not 'I WANT BANK 2'! In fact, you have to select the bank whilst in Internal Play mode, and then go into the Memory Control page to load or save a bank. (File under 'useful tips'.)


The user manual is well-written, clear and precise with no superfluous padding. There is lots of practical help and guidance to enable the user to effectively use E! with patch librarian software as well as with TX816s and QX-1s (and other sequencers). When used with sequencers, E! neatly uses the LCD and LED displays to show MIDI Beats (the red dot on the LED flashes at the beginning of a beat, and the LCD shows the beat number between 0000 and 9999) along with the sequencer status (LCD shows 'SEQPLAY' or 'SEQSTOP' as appropriate). The manual also gives clear instructions on how to successfully install the E! board into your DX7 in the first place. The inside back cover even gives advice on the 'Social fear of creativity'!


Steve and Jack Kellogg, the Grey Matter Response designers of E!, have certainly come up with a rather good piece of work here! Generation 2 software extras include: microtonality - for users who want keyboard tunings other than 'equal temperament'; a MIDI Mono Mode; Patch Mapping; and the already famous Timbre control - which enables you to alter the brightness of a DX7 sound without getting into editing.

Grey Matter Response promise further products from their Illinois Product Development Department; hints so far mention ROM voices for the E!, together with the software to prepare your own voices for blowing into EPROMs, and DX5 Operating System re-writes - look out for them.


E! really is wonderful! It does almost everything that the standard DX7 doesn't allow you to do, and the fact that it could save you the cost of a MIDI filter unit (eg. Yamaha MEP4, Roland MPU103), keyboard splitter box (eg. Akai ME25S) and MIDI merger (eg. Yamaha MCS2), as well as giving you 256 or more internal memories (saving you the cost of RAM cartridges), makes it even better value.

Using the DX7 in the studio is made lots easier because of the control E! provides over MIDI input and output, as well as the sequencer monitoring. The Keyboard Presets enable very quick changes to be made to the keyboard mode etc, making the DX7 much more usable as a master controller. In short, I loved it! (It will be a sad day for me when it goes back to Take Note.) Whoever said that expanders were boring?

The E! board costs £399 inc VAT from the UK distributors:
(Contact Details)

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Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Jan 1987

Gear in this article:

Expansion Board > Grey Matter Response > E!

Review by Martin Russ

Previous article in this issue:

> The Shape of Things To Come

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