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Hi-Tech Xpansion

Article from Electronics & Music Maker, April 1985

As Yamaha's 'X' range of hi-tech hardware continues to grow, Dan Goldstein and Trish McGrath present an exclusive appraisal of two of the range's most affordable additions, the TX7 FM Expander and QX7 MIDI Keyboard Recorder.

If you've achieved the implausible and exhausted the possibilities offered by the DX7 on its own, Yamaha can now supply you with the means both to make it sound better and to make it play your music automatically.

Yamaha TX7 FM MIDI Voice Expander

Now that world domination is the only outstanding item on the Yamaha DX7's List Of Things To Do Today, its creators are seeking some means of making sure those who've succumbed to the FM poly's undoubted charms don't get all over-confident and lose interest as a result. Hence a range of new goodies, unveiled by the company at the beginning of the year, aimed fairly and squarely at the DX7 owner who thinks he knows it all.

Believe it or not, there are limits to what the DX7 can do. They're not rigidly definable or even easily visible, but they do exist, and once you've come up against them, it's all too easy to think that's all there is to FM Synthesis, Life, the Universe and Everything.

For a start, the 7 has no built-in sequencer, which is why Yamaha have introduced the QX7 digital keyboard recorder reviewed in the following pages. It also has a finite number of sound-generation possibilities. True, six Operators and 32 algorithms is a pretty flexible arrangement, but even that has its limitations, so Yamaha have come up with an elegant solution in the form of the TX7, a voice expander that duplicates the DX7's internal circuitry without burdening the end user with the cost of a second (unnecessary) controlling keyboard. Given that the new unit communicates with such keyboards via the ubiquitous MIDI, it should theoretically be possible for owners of compatible analogue synths to add it to their systems as a means of producing FM-type sounds, but the configuration of the TX7 is such that its most logical partner is a DX, as we'll see.


I could take the easy way out here and say no more than 'it's a DX7 in a box', but that would be unfair not only to Yamaha's designers but also to this magazine's devoted readership (thanks for everything, Jim), so I'll go into details.

The first point worth making is that the TX7 is remarkably small, light and neat, considering the amount of synthesis power it incorporates. Four circular indentations at the top of the box allow you to stack other TX7s (or a similarly-constructed QX7) on top without fear of the whole lot toppling over, but it's unfortunate that none of the DX synths have a suitably flat panel that would allow a selection of these add-on modules to be tidily and conveniently stored on stage, for instance. A rare production oversight on Yamaha's part, I fear.

And talking of oversights, DX9 owners are going to be left a little out in the cold by the TX7, not because it's electronically incompatible (the two should link up fine), but because no printed diagrams of algorithm configurations (or indeed any other in-depth synthetic details) are in evidence on the TX. Which means you've got to be pretty familiar with the workings of a DX7 to get anything like the best out of its keyboardless brother: and I can't think there are too many DX9 owners who have that sort of working knowledge of a synth they don't possess.

What you get instead is a flow chart of how TX functions marry up with DX ones, but although this will undoubtedly be of value to first-time TX users, it is entirely obscured as soon as you stack up any additional modules in the above-mentioned fashion. Pity.

The TX7's front panel is laid out with even more economy than that of the DX7, which means fewer switches than ever before, and a corresponding plethora of functions for each switch. To their credit, Yamaha have made things as straightforward as possible by colour-coding sets of functions in a familiar fashion, but my guess is that it'll take even DX devotees a while before the process of programming the TX becomes second nature.

Of the 12 identical green pushbuttons on offer, the two most crucial are probably the Function and Mode switches. The former moves the editing process on by one parameter (the new parameter is then displayed, in somewhat abbreviated form, on the accompanying LCD), while the latter is used to instigate the switch array's second set of 'Shift' functions. And although the various modifiable parameters are accessed in a set sequential order, the Shift function does at least allow you to move through those parameters in either direction, using the Function key.

Parameter values are adjusted using Yamaha's now customary +1 and -1 data selectors (and as is usually the case, these double as Yes/No selectors), but in order to store any new values, you have to ensure the TX's Memory Protect circuit is off: better safe than sorry, I suppose.

Four switches to the left of the front panel allow you to program upper and lower preset levels for the TX's output as a whole - and there's also programmable attenuation for each of the voices you create with your Expander, which should save all that tedious mucking about adjusting levels between connected synth modules.

"The TX7's front panel is laid out with even more economy than that of a DX,
which means fewer switches than ever before."

TX7's operational flowchart, neatly - if short-sightedly - printed on the machine's top panel.


Rear panel features are confined to the Power switch, three MIDI sockets (In, Out and Thru, all on standard five-pin DIN connectors), an eight-pin socket for linking the TX7 with a mono cassette recorder with a view to facilitating some means of data storage, and Line Out and Headphone jacks. The cassette interface is obviously slower and less convenient than competing disk-based storage systems, but it has the clear advantage of cost, especially so in the case of the TX7 because of its ability to dump 128 data files (each one comprising a complete set of 32 sound patches and a similar number of function sets) on just one tape. So you shouldn't need too many C60s, all things considered.

The synergistic relationship between TX and DX is demonstrated by the extent to which the former uses MIDI System Exclusive commands to transfer data to and from a connected Yamaha poly. For example, Yamaha are making a big fuss over the fact that the TX7 stores a set of individual performance functions not only for each of its own sound patches, but also for those programmed into the connected DX. This usefully extends any DX's programming power (only the DX1 has this facility normally), because it means you don't have to adjust the list of parameters you've assigned to the synth's performance controllers (say) every time you change a voice.

The MIDI interconnection means you can also make program changes in one of two ways. Individual program change has effect only on the voices currently in residence inside the TX, while the Combined mode enables you to select a new voice on both TX and DX simultaneously. So if you've got a glockenspiel sound assigned to Patch 15 on the TX and a vibraphone in the corresponding memory location on the DX, selecting that number on either unit will call up both voices at once. This Combined mode will also come in useful for users of MIDI remote keyboards that have no sound-generating circuitry of their own, as it will let you change TX voices remotely from the keyboard, leaving the module itself tucked safely out of the way.

Clever use of MIDI codes has resulted in a number of other refinements in the dialogue between TX7 and DX synth. For instance, an Edit Voice Out facility is built into the TX, and this transfers all the Expander's parameter-modifying codes to the controlling synthesiser so that said parameters can be varied remotely from the synth, assuming it's capable of decoding the System Exclusive information.

There's even a facility that allows you to program the area of the keyboard over which the TX is operating. So if, for example, you've created a patch in which you want to hear the Expander's output over the bottom two octaves but the DX's output over the whole keyboard, you can program a split point at the appropriate place just for that patch.


It's neat, it's useful, it's well-designed and it's what the people want. All those things apply to the TX7, but the full story isn't quite so clear-cut.

For starters, its RRP of £699 doesn't exactly make it cheap. Attractive, maybe, but by no means a bargain: the removal of a five-octave, touch-sensitive keyboard, its associated controlling circuitry, and the case to go round it should have cut a bigger hole into the selling price of a DX7, make no mistake.

Soundwise, the TX is a delight. Then again, no machine that duplicates the DX7's sound-generating hardware has a right to be anything less. Fans of FM programming will revel in the extra possibilities a TX opens up, but as I've already intimated, 16 characters of LCD don't provide the world's most comprehensive information service, and working your way thoroughly through the TX maze is going to take a lot of perseverance. And if you've got an analogue poly from A N Other Manufacturer that you want to add FM sounds to, the TX7's internal configuration won't make your life any easier.

"Soundwise, the TX7 is a delight... but no machine that duplicates the DX7's sound-generating hardware has a right to be anything less."

Yamaha QX7 Digital Sequence Recorder

Its design lacks the spark of imagination that would have taken it from the status of nicely inconspicuous add-on to that of possible Expander of the Year. But it'll still make a lot of people happy.

It was only a matter of time before Yamaha applied the proven data recording technology of their elaborate QX1 MIDI sequencer (still to be reviewed by E&MM pending Yamaha-Kemble having a spare sample to send to us) to a simpler and more readily affordable unit of more modest, but still extensive, capabilities. Such a device is the QX7, a dedicated sequencer that'll be of interest to most MIDI synth and drum machine owners, save those already bitten by the computer software bug. Yamaha CX5M users, for instance, will no doubt opt to save their pennies in anticipation of the company's forthcoming icon-driven four-track sequencer package.

Quite simply, the QX7 is a two-track digital sequencer capable of recording MIDI data polyphonically on all 16 MIDI channels and in either step or real time, with velocity, aftertouch, pitch-bend, modulation, foot control and even breath control parameter information intact. Overdubbing can be carried out by merging the machine's two tracks as many times as necessary up to a total of 16 simultaneous notes, using a wide range of editing features.

Designed to fit snugly on top of the TX7 FM Expander unit, the QX7's sleek black metal and plastic casing is decorated in traditional Yamaha hi-tech colours. The various editing functions are called 'Jobs' (as they are on the QX1), and are arranged in four banks labelled A to D. Yamaha have thoughtfully provided a comprehensive Job Guide on the top panel for reference purposes, while the front panel has a rundown of Jobs A and B, complete with accompanying LED indicators.

The remainder of the front panel controls comprise a two-digit LED display and a range of buttons with titles like Reset, Stop, Job/Step Size, Track 1, Track 2, Data Measure (-1 and +1), Record, Stop/Continue, and Start: there's also a large rotary Tempo control.

The sparsely-populated back panel offers the usual set of MIDI sockets (In, Out and Thru) as well as an eight-pin DIN socket for saving and loading sequences to and from cassette. And that's about it.

Real-time Recording

If you've got faith in your own ability to play music in something resembling the intended order and tempo, you go into real-time record mode, in which the QX7 will faithfully record exactly what you play to the remarkably fine resolution of 1/384th of a measure. Recording is always carried out on Track 1 (since only playback is possible on Track 2), and some Job conditions are worth setting before recording actually commences.

The Metronome function offers you a choice of hearing the metronome during recording and overdubbing or recording and playing: alternatively, you can have it permanently on or off. A flashing dot at the lower right-hand corner of the display indicates the chosen tempo, but to be honest, the metronome is a bit on the quiet side for comfort, so a MIDI drum machine will certainly prove handy in the keeping time department.

The Beat/Measure option lets you set a time signature from 1/4 to 16/4 and 1/8 to 16/8 inclusive (that should satisfy just about everybody), while accessing Clock Select gives you the option to choose between internal or external MIDI clock. Moving on, Recording MIDI Channel lets you receive and record on any channel between 1 and 16, while Change Channel gives the QX7 the go-ahead to ignore the reception channel and assign incoming data to the channel number of your choice: handy if you've also got a DX7 and TX7, as the DX transmits on Channel 1 only. If you want the latter function to take place in real time, you simply select Echo Back - see later.

"The QX7's metronome is a bit on the quiet side for comfort, so a MIDI drum machine would certainly come in handy in the keeping time department."

Once these recording functions have been fiddled with, selecting Track 1, Record and Start sets off the two-bar lead-in, after which recording can begin in earnest. No matter what you play, this process is always carried out in full bars, so if you stop recording in the middle of a bar, the QX7 will insert spaces until Measure End.

Then there's the promised Echo Back feature which, when activated, transforms the QX's MIDI Out socket into a second MIDI Thru. But the difference between this MIDI Thru and the one next-door is that the data passing through it can be MIDI channel-shifted by the QX7's internal software. Mind you, it would have been nice if the QX7's designers had also given the existing MIDI Thru the ability to act as another MIDI Out. That way, you could have sequenced two MIDI synths (or synth and drum machine) together directly from the QX7. A small point, perhaps, but there'll be somebody out there cursing that omission, particularly as there's no logistical or financial excuse for it.

To economise on memory space (quoted as an approximate 8100 notes without key velocity, 6000 notes with), Job C allows you to switch out any unwanted (and memory-intensive) functions such as polyphonic aftertouch, aftertouch, pitch-bending, and key velocity. Incidentally, the first-mentioned applies to owners of instruments such as the Yamaha DX1 and Prophet T8, as it enables the QX to recognise aftertouch pertaining to each individual note played when the synth is in Mono mode (the facility needs a separate MIDI Channel for each voice in order to work properly).

QX7's Job Guide is an essential reference point for musicians experiencing difficulty getting the sequencer to do as it's told.

Step-time Recording

The new Yamaha will also happily record in step time, and available step sizes (ie. values of entered notes) range from half-notes to hemi-demi-semi-quavers, and triplets of either crotchets, quavers or semi-quavers. And whereas the standard gate time is about 80% of the length of these notes, the QX7 also offers the means of entering crotchets, quavers and semiquavers with 100% gate times. In step-time mode, the Job lists on the front panel double up to indicate your chosen step size, and can be cycled through using the Step Size buttons.

You probably won't be flabbergasted to discover that pressing the Rest button inserts a rest equivalent in length to that of the step size, and only marginally more inspiring is the fact that notes can be prolonged by pressing the Tie button.

Although program change and key velocity information may be entered during step time recording, you can't - for obvious reasons - execute pitch-bend, aftertouch and control changes in this mode. But the really good news is that step- and real-time recording can be mixed at will, and the editing functions (see below) can be used to exploit this further.

Logically enough, pressing Start replays your recording from the beginning (or you can set playback to begin from a specific measure), while the Stop/Continue switch can be used to halt the playback operation temporarily and then restart it.

Editing Facilities

It's in the editing arena that the QX7 really scores. Because far from clinging to the belief that so long as you provide musicians with the means to record information and make mild alterations to it once it's been stored, they'll be happy, the QX7's designers have taken notice of the fact that today's keyboard player demands rather more in the way of compositional versatility, and given the sequencer a whole host of helpful and easy-to-use editing facilities. For instance, Quantisation (the means of correcting out-of-time notes) is offered to the nearest crotchet, quaver, or semiquaver and their respective triplet values. A factor of 1/32 would also have been a useful quantisation option, but apparently, the Japanese don't agree. If you're anxious to avoid committing any musical faux pas, you're best off setting the quantisation level to the lowest note value recorded, and once you've done that, pressing Start lets quantisation commence.

There's another nice feature incorporated within the QX7 that goes by the name of the Temporary Buffer. It's here that your original recorded data is automatically transferred as part of the quantisation process. Thus, if the results of the quantisation prove aesthetically unacceptable, the original data can be swopped intact back to Track 1.

"Once you've overdubbed the second part to your satisfaction, the QX7 offers a number of scintillating options."

If you've decided to go on, the Chain function joins Track 1 onto the end of Track 2, the result being transferred to Track 2 automatically. If you desire the reverse running order (ie. Track 1 before Track 2), you simply press Exchange before chaining. The QX7's most critical function revels in the name Trackdown, and merges the data on Track 1 with that on Track 2, transferring the result to Track 2.


Generally speaking, you do your first overdub by swapping the contents of Tracks 1 and 2 (using the Exchange function), and recording another sequence on Track 1. And once you've recorded this second part to your satisfaction, the QX7 offers a number of scintillating options. If you're happy with things the way they are, you can commit your two tracks to posterity by activating the Memory Protect function. If you aren't, you can gamble what you've won and try for this month's Star Prize of multitrack musical satisfaction (no, not a ten-year subscription to Electronic Soundmaker).

In fact, the Save Temporary Buffer function can be selected at any point during recording or editing, and allows data on Track 1 to be saved within the buffer, while any data previously in the buffer is transferred simultaneously to Track 1. Which means a pattern that repeats itself many times during a song can be stored in the Temporary Buffer, retrieved whenever it's needed and chained to Track 2.

If, by some mysterious quirk of fate, you make a mistake at some crucial stage of the recording process, you can clear the contents of Track 1 either in their entirety or from a specific measure using the Erase and Delete Measure functions. Conversely, the Insert option allows data from Track 1 to be inserted at a specified measure position on Track 2.

Among the QX7's less commonly used modes are Cassette mode (in which sequence data can be saved to and loaded from cassette tape, and the former procedure verified), and Local Device Number, which allows you to specify the MIDI channel used for System Exclusive data. Pressing Start in the latter mode sends the sequence data currently within a specified track to an external device along MIDI Out, assuming that said device is capable of decoding the System Exclusive information: another QX7 will do just fine...

Yamaha's new YMC10 MIDI tape sync converter.


There's no doubt that Yamaha have scored again with the QX7. It looks good, it's (relatively) easy to use, and it offers a lot more in the facilities-against-price battle than its nearest competitor in the dedicated sequencer market.

Its two-track format means you can create an overdub on a separate track, taking as much time and as many attempts as you like, and merging tracks together only when the new track is to your liking. In fact, an awful lot of the way the QX7 does its job adds weight to the impression that it's been designed to serve the musician, rather than acting as an unwanted source of operational distraction.

My only major criticism is that the QX7's designers haven't given it any more than one MIDI Out socket. Why not two, or even three? Is it because Yamaha are just about to introduce a new MIDI Thru Box? Your guess is as good as mine.

Speaking of new devices, Yamaha's YMC10 MIDI Converter should be just the job for anyone wishing to sync the QX7 to tape, while owners of non-MIDI drum machines can avail themselves of the Korg (shock, horror) KMS30, which'll convert the QX7's MIDI clock to the standard sync format as well as syncing everything to tape. Take your pick.

With so much sequencing software for both conventional home micros and Yamaha's own CX5M becoming available, it's nice to know that musicians unwilling to join the computer revolution have a feasible and cost-effective alternative. Because the QX7 is just that: there's nothing else to touch it.

RRP of the TX7 is £699, while the QX7 retails at £499, both prices inclusive of VAT.

Further details from Yamaha-Kemble, (Contact Details).

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Pearl DRX1 Electronic Drums

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Publisher: Electronics & Music Maker - Music Maker Publications (UK), Future Publishing.

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Electronics & Music Maker - Apr 1985

Donated & scanned by: Stewart Lawler

Previous article in this issue:

> Pearl DRX1 Electronic Drums

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