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E-Mu Emax SE HD

Sampling Keyboard

Article from Music Technology, June 1988

E-mu enhance their popular Emax sampler with a built-in 20 Meg hard disk and two new methods of sound synthesis. But how successful is the sampler-as-synthesiser? Bob O'Donnell takes it to the max.

As samplers move forever onwards and upwards, the options open to sampler manufacturers are few: supersede or update.

COMPETITION IN THE sampling world is becoming very fierce. This is true generally, but right now the recent arrival of the much talked-about EPS and Yamaha's long-anticipated TX16W has added volatile fuel to the fire. Manufacturers are being forced to come up with more functions and better features to make sure that their sampler is the one that people want to see and hear. The great thing about this competition, of course, is that we're all benefiting from it (if they could only get those prices down a little further...).

The E-mu Emax SE is one of the more recent entries into the fray. It has the disadvantage of a hefty price tag but the advantage of being directly related to a successful existing instrument. In fact, the Emax SE is simply an updated Emax; existing Emax owners can add the Synthesis Enhanced capabilities of the SE machines for a nominal charge.

New Features

ALONG WITH THE introduction of the Emax came the promise that even further enhancements and updates were to be added in due course. The first of these takes the form of an internal 20Meg hard disk option (HD) which can be retrofitted to existing Emaxes or bought as a standard feature on new instruments. It adds considerably to the price of the instrument, but if you use it in performance or need quick access to lots of sounds, it's well worth considering. And once you get used to working with a hard disk, you'll never want to give it up. The internal disk can hold the equivalent of 36 floppies in separate banks, and load time from it is a mere three-and-a-half seconds. It comes loaded with 30 banks of sounds (actually 33 if you get the SE HD) from the E-mu library.

Backup, Restore, Formatting and Scanning functions have also been added specifically for the hard disk, so that you can prevent (or at least try to avoid) catastrophic losses. I can't vouch for its reliability - manufacturers get a bit upset when we try the drop test approach to reviews - but E-mu claim that it's shock-mounted and should be able to stand all but the most inconsiderate roadies.

The second, most recent enhancement to the Emax is a major system software upgrade which adds a number of new features, including two new methods of sound generation. The upgrade comes in the form of three disks for existing Emax owners: one containing the new operating system; a preset with 30 different D50-like sampled attack sounds and 95 different factory Spectrums for use in the synthesis mode; and two example disks with sounds created by Spectrum Interpolation Digital Synthesis and Transform Multiplication. If you're buying a new instrument, the new operating system can be considered a built-in function, like the hard disk. Appropriately equipped Emaxes are referred to as Synthesis Enhanced (SE), highlighting the fact that synthesis features are the main portions of the upgrade. But there are other features deserving of a mention.

You can now load entire banks of sounds from the hard disk with a MIDI program change. The process still takes a few seconds but it will remotely initiate the load. Also, the Preset Definition Module now includes a Stack Presets function which allows you to layer up to four consecutively numbered presets for those all-important layered sounds. Depending on whether or not each of the presets uses Dual mode or not, you'll either have monophony or dual-note polyphony with the stacked sound.

A transparent change made to the operating system of the Emax with the new software is that it adds a CD-ROM interface capability. In conjunction with this, the American company Optical Media International recently announced a CD-ROM disk made specifically for the Emax which stores the equivalent of 505 floppies (distributed in the UK by The London Synthesiser Company).

The biggest changes, however, appear in the Digital Processing Module, where a number of different digital signal processing (DSP) functions have been added. Four of the functions allow you to alter existing samples in the digital domain, and the last two are the new methods of sound creation. First, the Gain/Attenuation feature adjusts the level of a sample over a range of +/-40dB. By cranking the level up you can produce some really ugly, distorted sounds - which have a beauty all of their own - or by making smaller adjustments you an match the levels between samples and perform other "domestic" chores. The Reverse Sound function does exactly what it says: it permanently and unalterably swaps the numbers in a sample. The Emax needs a bit of free RAM to perform this, and all the following operations, so you need to make sure that you leave some space with which to work. Otherwise you'll start running into the very tiring "Not Enough Sample Memory!" message. It's not fun.

The Change Sample Rate function is a very handy tool for converting samples received using the MIDI Sample Dump Standard into a format which the Emax can use directly. In other words, you could take a sound sampled on an Akai S900 at a sample rate of 40kHz and convert it into the Emax' standard rate of 27.778kHz. The process involves setting the original sampling rate of the sound, setting the desired new rate, and then letting the Emax resample the data. You can also use it to take sounds originally sampled and stored in the Emax and convert them to a lower sampling rate to save memory space.

"Transform Multiplication: Most of the sounds on the E-mu disk are unique timbres that I can't imagine being produced by any conventional synth or sampler."

The Change Pitch feature lets you digitally alter the pitch of a sample over a range of +/-35 semitones, 99 cents. If you need to fix the pitch of a slightly - or grossly - out-of-tune sample, or if you want to use the same sample at a different pitch, this function can prove very useful. I should point out that both the Change Sample Rate and Change Pitch functions can take several minutes of processing time - which the Emax will warn you about - so don't plan on using these in a tight situation.

New Sounds

THE TRANSFORM MULTIPLICATION feature is the first of two new sound generation methods offered by the SE upgrade. Both methods give the Emax synthesiser-like capabilities, but they still actually produce samples and must be treated accordingly. In other words, you still have to deal with synthesising sounds for different sections of the keyboard and mapping presets to their proper location. You can generally get away with fewer samples across the keyboard than you normally would be able to - two or three should be fine - but, unlike a synthesiser, you still have to worry about the problems of pitch-shifting when you transpose the samples a long way from their original pitch.

Transform Multiplication produces its sounds by taking two samples - the current sample and another one of your choice, and combining them in such a way that all frequencies shared by the two sounds are kept and accentuated and all other frequencies are removed. The results are often more wild than either of the original sounds might suggest. E-mu provide a disk full of excellent examples to give you an idea of the things you can do with this feature. Most of the sounds on the disk are unique timbres that I can't imagine being produced by any conventional synth or sampler.

According to the manual, Transform Multiplication can be used to experiment with room impulse responses - a rather esoteric application if I've ever heard one - but I think you'll have more fun just playing with it. Be prepared to be extremely patient, however, because as nice as this feature is and as interesting as the resulting sounds may be, they take a long time to produce. One experiment I tried took 41 minutes and the result was a useless din. Another point to be aware of is that you can only use very short samples when using the TM function, and consequently only produce short samples with it - looping the result is almost mandatory. The maximum combined limit of the two samples can only be 32K, which works out to a little bit under 1.2 seconds at the 27.778kHz rate. The sampled attack waveforms which come with the new development disk turn out to be excellent fodder for experiments...

Spectrum Interpolation Digital Synthesis is certainly a mouthful, but what E-mu have basically added to the Emax with the Spectrum Synth feature is a slight variation on true additive synthesis. You have access to 24 sine wave "oscillators" which can each be controlled by independent, 24-stage frequency and amplitude envelopes, or "contours". You an also set the pitch of the sound's fundamental and the pitch ratio for each of the remaining harmonics.

Enticing as that much control and flexibility sounds, producing sounds by individually defining each of the available parameters can get very boring, very quickly. E-mu obviously realised this, and came up with a number of short cuts to the process. The two basic concepts they've come up with are Spectrums and Time Slices. Spectrums are simply the static amplitude and frequency ratios of all 24 harmonics at a given point in time. In other words, they describe a single cycle waveform. E-mu supply 95 of these, but you can create as many of your own as you want. Time Slices are simply Spectrums placed at a particular point in time. Each SE sound consists of 24 Time Slices equally spaced out across the length of the sample time you're working with, and each of these Time Slices holds its own Spectrum.

The Interpolation part of the name comes from the fact that you can define the Spectrum at certain Time Slice locations and then let the Emax figure out what the Spectrums should look (and sound) like at the other Time slice points. In other words, you could put a sine wave Spectrum at Time Slice 1 and a more colourful brass-like Spectrum at Time Slice 24, then select the Interpolate Function from the 10-option Spectrum Synth menu and the Emax will do all the dirty work of filling in the other 22 Time Slices for you.

"Synthesis: Smooth synthesis interpolates from Time Slice to Time Slice producing gradual timbre changes; the stepped function jumps abruptly from one Time Slice to the next."

The actual operation of the Spectrum Synth is straightforward. After you've created an empty voice to work with you can either place an existing Spectrum at a certain Time Slice location, draw a new Spectrum or Time Slice, or edit an existing one. Drawing is achieved by moving the data slider up and down as the cursor moves across the LCD - the Emax gives a count-off and then starts to move the cursor automatically after you select the Draw function. Similarly, editing is done by stepping through the various harmonics with the cursor controls and making adjustments with the data slider. You can also do the same for individual harmonics' frequency and amplitude contours, but in that case you'll draw out the levels at the 24 different Time Slice locations. In other words, it's like working along the y-axis as opposed to the x-axis.

The process of creating Spectrums, Time Slices and contours works pretty well but it is slowed down by the Emax' aggravating habit of returning to a main menu after it's performed a function. For example, after you've drawn a Time Slice, you get the option of editing or copying it, but you can't start drawing another one without having to leave the menu, select a new Time Slice location and then start again. Why? Thankfully, choosing the fundamental pitch and ratios for each of the harmonics - which can range from 1.00 to 40.99 in increments of one hundredth can be accomplished in one menu access.

Once you've created a set of parameters that you like, you can save them in one of three backup banks and then load them back into the active voice at any time. You can also erase any Spectrums, Time Slices or contours that you've created.

The final option in the menu is the Synthesise function, which takes the parameters you've created and crunches them into a sample which the Emax can play back. You can choose from two types of synthesis: smooth or stepped. The smooth synthesis function will interpolate from Time Slice to Time Slice to produce gradual timbre changes, while the stepped function will jump abruptly from one Time Slice to the next, for PPG-like sounds. The amount of time it takes depends on the complexity of the Time Slices and the length of the voice you're working with, but to give you an idea, you can synthesise a fairly simple one-second sample in just under a minute.

Like any synthesis method, the quality of the sounds you can create with the Spectrum Synth ranges from awful to very usable. Again, the sample disk provided with the update gives a good indication of the types of sounds you an create. Theoretically, of course, you should be able to create or recreate any sound with additive synthesis, but practically, most of the sounds you'll hear emanating from this section of the Emax have a bright, metallic edge to them.


E-MU HAVE DONE an excellent job of continuing to support the Emax. Both the HD and SE options offer some powerful features not available in any other sampler in its price class. Certainly other manufacturers have hard disk options, but none offer the power and convenience of an internal hard disk. Likewise, some samplers have basic wave-drawing functions, but none have the sophistication of the Emax' Spectrum Synthesis, let alone Transform Multiplication and the other DSP functions.

Problems do exist with the SE upgrade - some of the time requirements to perform certain functions border on the absurd - but I think it is more appropriate to applaud E-mu for their efforts to get as much out of the limited processing power of the Emax as they could, than to chastise them for making us be patient. This is particularly true considering the low price of the upgrade. Any viable attempts to incorporate new methods of sound generation should be welcomed with open arms.

Prices SE upgrade for existing owners £199; Emax SE £2399 or £2249 for rack version; Emax SE HD £3149 or £2999 for rack version. All prices include VAT.

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The Dolby System

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Programmer's Protocol

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

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Music Technology - Jun 1988

Gear in this article:

Sampler > Emu Systems > Emax SE HD

Gear Tags:

12-Bit Sampler

Review by Bob O'Donnell

Previous article in this issue:

> The Dolby System

Next article in this issue:

> Programmer's Protocol

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