David Mellor samples Yamaha’s version of the ‘ultimate instrument’, the MIDI sampler. Does it improve on all that have gone before or have Yamaha taken technology beyond the point of usability?

Although the TX16W is Yamaha's first MIDI sampling module, it is not their first foray into the professional sampling field. Their range of PCM drum machines shows that they already have the technology to store sounds digitally for replay on command. It may be one or two steps up the technological ladder to make an instrument that can play a sample at several pitches simultaneously, and to add all the other bells and whistles that the well-dressed sampling module needs these days, but Yamaha have shown time and again that they have the ability to compete in the forefront of musical innovation. They were first with FM for the working musician. They may well be among the last to join the ranks of the sampled digits, but they can be certain that a lot of people will still be interested in what they have to offer.

The obvious next question is, just what can they offer? A sampler is just a device for getting real sounds to respond to a MIDI keyboard, surely? Can it be judged purely on its bit-quotient and memory capacity? Or perhaps a sampler needs a unique feature of some sort to differentiate it from others in the same price range.

The Roland S550, for example, has the unique feature of its partnering video monitor, which compares to an LCD display like Frank Bruno to an amateur featherweight. Yamaha's unique feature is a system of digital filtering. In fact, the full name of the TX16W is a Digital Wave Filtering Sampler or Echantillonneur a Filtrage de Donnees Numerique, if you'll pardon my French. Rather than the more usual variable top-cut filter, Yamaha have employed a series of digitally-implemented equalisers which may be statically and dynamically altered. It certainly sounds interesting on paper, but more of that later.

Something rather more important than the digital filter is the actual sound of the machine. 'The sound of a sampler?', you ask. Yes, different samplers do sound different. Everyone knows that synths sound different, but with samplers that seems rather more unlikely.

My first serious encounter with MIDI samplers was a hired Prophet 2000. Not too easy to operate, but it had a damned good sound. I could never figure out why I couldn't get the same kind of sound from my Akai S900. I just couldn't get the 'presence' that the 2000 had. I still don't know the answer, obviously something to do with the digital workings, but as soon as I played the Yamaha I knew what I had been missing since those Prophet 2000 days. I should say now that it's a subjective matter, and you may not like the bright sound of the TX16W - less 'realistic' you might think. I would recommend auditioning the Yamaha unit against either the Akai S900 or the Roland S550, taking identical samples on each and playing them back at different pitches. You will hear a difference, and you'll know straight away which machine you prefer. Soundwise, I'll go for the Yammy.

SPECS

You won't need specs to see that the TX16W has a lot of what it takes to be big in the sampling world. A 1.5 megabyte memory for one thing, 16-note polyphony for another - not forgetting stereo sampling, and mixed and individual outputs on the back. It puzzles me sometimes why samplers are specified in terms of megabytes instead of their maximum sampling time. Perhaps one and a half million bytes is supposed to sound more impressive?

The sampling time available at 33.3kHz sampling rate is 22 seconds, according to my experiments. Not that you can take a sample this long, unfortunately. The longest continuous chunk of sound you can record is 7.9 seconds at this sampling rate, or 16.3 seconds at 16.7kHz. A sampling rate of 16kHz, remember, means an audio bandwidth of less than 8kHz. Considering that one of the major uses of samplers is to 'touch up' recorded vocals, I prefer the S900's ability to sample at 12kHz audio bandwidth for up to 15.8 seconds. 12kHz is adequate for vocals, 8kHz usually isn't.

Although the TX16W may be short(ish) on maximum continuous sampling time, it obviously isn't on total time available. And seeing that the memory is expandable up to six megabytes, you could have a hell of a lot of performing power in there all at once. Don't expect to fit six megabytes onto one floppy disk though! Two DSDD 3.5 inch disks are needed to fill the unexpanded TX16W's hungry belly.

As is common with many instruments, the operating system of the TX16W must be loaded anew from disk each time you switch on. The usual warnings regarding losing/damaging the disk, and buying the unit expecting the system to be updated to include further features that you want, apply. There is a function for copying the system disk, so sensible users will have no problems in making a backup copy. The TX16W is a fully functioning system already, so I wouldn't imagine anything more than minor changes via updates. Yamaha may not forgive me for mentioning that it takes one and three-quarter minutes to load the operating system and the digital filter tables before you can do anything. In comparison, the Akai S900 (which has its operating system in ROM with updates supplied on disk) is ready to go in seven seconds.

Other matters which are worth mentioning, spec-wise, include the TX16W's maximum sampling rate of 50kHz. One could say that since Compact Disc only has a sampling rate of 44.1 kHz that this is overkill, but if you think that transposing the sample down a couple of octaves reduces the rate to 12.5kHz - and the audio bandwidth to around 6kHz - then I could think of applications where you need all the initial bandwidth you can get.

Stereo sampling is an important feature too. Sometimes I do it with my mono-only sampler, with a lot of fiddling around. However, once you have made up the necessary lead for the TX16W (it's a stereo jack on the front panel) stereo sampling is as simple as mono. And if I mention that the maximum sampling time is still 7.9 seconds (at 33.3kHz), the same as mono, then you'll want to pat Yamaha on the back too. Stereo sampling should, in my opinion, be included on any serious machine from now on.

STRUCTURE

If I keep referring to the Akai S900 it's (a) because I have one, (b) because it's a damned good machine. The manual I got with mine, back in 1986, was a bit nonexistent, but I was up and running with it in no time. The S900 has two variables to play with: the sample and the program. The sample is what it says, the program is the way samples are treated and mapped onto the keyboard.

Yamaha, for reasons of their own, have chosen to have five variables. Phew! It's a lot for the simple mind to cope with, but if you like the sound of the machine then cope with it you will. Apparently, Yamaha UK are producing a simple English version of the manual to better explain how to get started. I hope it has some sort of tutorial section so that you can follow through step-by-step the procedure from sampling to performance. It's a lot to handle.

The five variables of the TX16W are:
• WAVE - the truncated and looped sample
• FILTER - a digital filter setting
• TIMBRE - the Wave with Filter, LFO and envelope settings
• VOICE - an arrangement of Timbres across the keyboard
• PERFORMANCE - a combination of Voices

As you can see, the opportunities for complication are inherent. Hopefully, as the various parameters and procedures are explained, all will become clear.

Sampling mode is entered by pressing the Sample key. That's straightforward enough. The TX16W's backlit display then presents you with a short menu: Frequency, Level and Record. 'Frequency' is where you set the sampling rate and the expected length of the sample. The available rates are, as I mentioned earlier, 50kHz mono, 33.3kHz mono, 33.3kHz stereo and 16.7kHz mono. The sample length is set in blocks, where each block is just under two milliseconds (at 33.3kHz sampling rate). This is a clear example of complication for its own sake. You have to enter the time in blocks, but you are immediately given the equivalent in milliseconds. So you quickly learn how many blocks make a second, but why not enter the length directly in milliseconds? There is no advantage to the way it's done here.

Available sample triggering options are Auto, Yes Key, Foot Switch, External, Input-Foot, and Ext-Foot. 'Input-Foot' obviously means that you have to give the machine a kick to start it off! Seriously, it means that if the footswitch is pressed, and the level of the signal coming in exceeds the triggering threshold, then sampling will start. 'External' is where a trigger signal must be applied to the front panel Ext Trig jack socket. A fairly versatile series of options, but no 'Previous' function like on the Roland S550 and S330, where the sound already in the memory is held when a key is pressed - useful for sampling words or phrases from old films on the TV, as is the current trend.

In Sample Record mode, there is a bargraph display of signal level together with a threshold indicator. Two oddities appear here. Firstly, the threshold level for auto-triggering is strangely unalterable. I would have thought this was essential. Sampling sounds with a slow attack phase has to be done here by manual triggering instead. Secondly, although an indication of clipping (distortion) is given before sampling begins, there is no indication of peak level whilst the sample is being taken. Result: you don't know that you have overdriven the input until you replay the sample. Strange.

The Wave Edit function has seven menu items. Before I go on, I must explain something else that seems odd to me. The TX16W has things called 'Edit Buffers'. With sample editing, the sample has to be entered into the buffer memory before it can be altered in anyway, ie. truncated or looped. You cannot work directly on samples which are in the section of memory normally accessed from the MIDI keyboard. This is okay while you are taking new samples, because samples are placed directly into the buffer memory as you take them. After editing, they are copied to the normal memory - 'Internal Memory' as Yamaha call it. But... remember when I said that the memory capacity of the TX16W is 1.5 megabytes? That memory has to serve both internal memory and buffer memory. Total memory capacity is 22 seconds at 33.3kHz bandwidth, but that is spread between the two memory areas. If the internal memory is full you can't copy anything to the buffer memory. If the buffer is full, vice versa. Once again, this does nothing but complicate matters. I found that I had to keep erasing samples and swapping them around to do all the editing I wanted. It also means that you can't actually fill the entire 22 seconds of internal memory by sampling alone. There would always be a little bit left in the buffer that you couldn't transfer because there wasn't the space to make a copy. You can, thankfully, use the entire internal memory capacity when loading sounds from disk. I just don't see the benefit of the buffer. If it's meant to be there as some sort of backup - well, isn't that what disks are for?

Having got that off my chest, the Wave editing functions are as easy to use as you would wish. There is a nice 'normalising' feature which brings samples recorded at too low a level up to full strength - not helping the signal-to-noise ratio of course, but a handy function nonetheless. Looping is also a straightforward matter. Not as good as the Roland S550 where you hear alterations to the loop as you make them, making it very quick to find good loop points. On the TX16W, you have to play the note again to hear the change. Once you have set up rough loop points, the TX's Autoloop function can be brought into play. A sniff better than the S900's autoloop I would say. There are also a selection of Crossfade Loop, Reverse, and Sample Mix functions. When the sample is edited to complete satisfaction, it may be named if you wish.

DIGITAL FILTERS

The filters of the TX16W are all digitally implemented in real time. Not like the Akai S900, where the filter is analogue, or the Roland S550, where the filter is digital but does not work in real time (ie. filtering as you play). The benefits would seem to be that the noise ought to be lower and the variety of filter shapes more versatile.

The system disk supplied with the TX16W contains 16 different basic filter shapes. Yamaha call them 'tables', but this seems rather confusing to me so I'll stick to the way I can best explain them. Figure 1 shows one of the filter shapes, which is a fairly typical example. This is a notch filter with two variable parameters - the centre frequency of the notch, and the depth of the notch. All the filters have two variable parameters. Most have frequency, which corresponds to the notch's centre frequency here, and level, which corresponds to notch depth in this case. A few of the filters offer frequency and the slope of the filter as the two variables.

In use, one of the two variable parameters can be statically controlled. That means you set it when you edit the filter and it stays set. The other parameter can be dynamically controlled via the filter's envelope generator and LFO, or by MIDI controllers such as modulation wheel, breath controller etc.

So far, it seems that there is a wide choice in the way you can filter a sampled sound. What you probably want to know is what the filters sound like. The best description I can think of is 'subtle'. You are not going to get the sound of a swept analogue filter from them, but then again, you probably wouldn't want to use such an old-fashioned sound anyway. They do make quite a nice effect, but don't be too impressed by how many filters there are and the degree of control that seems to be available. All I could achieve was, as I said, quite a nice effect. Nothing extraordinary, in fact a lot of the time I was hard-pushed to render any audible effect from them at all. The programmer of the supplied factory sample disks obviously had the same trouble...

'Voice Edit' covers not only the creation of a voice (terminology explained above) but the creation of a Timbre. Only the keyboard split facility affects the Voice as such, everything else affects Timbres directly. Voice Edit at its basic level concerns how the various Timbres are spread across the keyboard. Each Voice may have up to 32 Timbres active, each with its own keyboard slot which may not directly overlap, but it is possible to crossfade between Timbres in adjacent slots over a range of one to nine notes. This is a useful feature for evening up the differences between multiple samples of the same instrument. Other Voice Editing functions are covered in a separate panel.

'Performance Edit' is all about combining a number of Voices. Here, you can layer sounds together or have them appear on different audio outputs. You may be surprised to learn in this day and age that notes are not assigned to Voices automatically by the TX16W. For example, you may have a sequencer playing different Voices on different MIDI channels. But before making any music you have to decide how many notes you want each Voice to be able to play. There is no dynamic voice allocation, whether from the mixed audio outputs or from the eight individual output sockets. The Akai S900 gives you 8-note dynamic allocation from its mono output, and 4-note dynamic allocation from each of its stereo outputs. The Roland S550 (and S330) gives you full dynamic allocation - or manual allocation if you wish.

The TX16W has a number of other interesting functions which are unusual and potentially useful, such as Velocity Curve, which sets the degree of response of the unit to MIDI velocity messages - including the ability to play softer as velocity increases. Also, Velocity Bias allows you to alter MIDI velocity after a note has been played. That's an interesting concept! And it works.

DISKS

It's not usual for the subject of floppy disks to receive its own separate heading, but this time it is deserved. I mentioned earlier that it takes a considerable period of time to load the operating system from disk. It also takes quite a time to load sample disks too. As much as 1 minute 45 seconds for one disk. This is a long time by any standards and the waiting is a source of great frustration.

Another problem, not unique to Yamaha, is the difficulty of loading several Performances from different disks into the memory. Perhaps this has to do with the way samples are identified within the machine? On the Akai S900, each sample is given a name. In fact, it must be given a name because this is the only means of identifying it. With Yamaha's system (and Roland's too), there is a numbered slot in memory for each sample. Sample names are only there for user convenience.

So what does this mean? Well, you might load one Performance from a disk, say, which uses samples placed in slots 1, 2 and 3. If you wanted to load another Performance into the memory simultaneously, from another disk, it might also want to use the samples in slots 1, 2 and 3. There is an obvious incompatibility here, so you would have to load a Performance, load the necessary Voices, and then load samples into the correct locations individually. The S900's system avoids this completely, because samples can go into the internal memory wherever the operating system pleases, a sample's name is its tag. You can load ten or more programs (the equivalent of Yamaha's Performance) from ten different disks, with a minimum of button pushes and no brainwork, as long as the total sample time doesn't go over the limit. It really is a much better way of doing it.

VIEWPOINT

The Yamaha TX16W is something of a puzzle. To me, it is a really great sounding sampler and I certainly wouldn't mind having a machine like this to complement my Akai S900. The problem is that it is not easy to use, and so slow to load disks.

Some people regarded the DX7 as difficult, but it wasn't really. It just had a lot of functions to control, and it controlled them pretty well. In the case of the TX16W, there is perhaps a little more to cope with than in the average sampling module, but not that much. If Yamaha are to help buyers to learn how to use the TX16W quickly, and to explore its full potential, then a better manual is essential.

Price £1999 inc VAT.

Contact Yamaha-Kemble UK, (Contact Details).