When it's time to choose a sampler from the many on the market, it helps to know which features are most significant. Craig Anderton will tell you what you want, what you really really want...
The digital sampler has evolved dramatically in recent years. Borrowing from synthesis, digital recording, computers and digital signal processing, today's sampler is essentially a recording studio in a box.
Synths have even begun to copy samplers, not simply by including sampled sounds, but also by acquiring the ability to load samples and communicate with other devices. Several manufacturers offer sampling add‑ons to synths, while others build onboard ROM sounds (just like a synth!) into samplers. Peavey's DPM series started the trend by adding sample RAM (Random Access Memory) and sample editing to a basic sample‑playback synth, along with an optional rack box for sampling into the instrument; Korg's T‑series synths and Yamaha's SY family included similar features shortly after.
Now synths such as the Korg Trinity offer optional 'flash' RAM for storing samples, the ability to read Akai S1000 samples, a computer interface, ADAT digital interface, and even hard disk recording. So is it a synth, a sampler, or a digital audio workstation? And what about Roland's DJ70 MkII, a version of their flagship S‑series sampler optimised specifically for DJ applications, with automatic looping, load‑while‑playing, and even a scratch dial? The boundaries are indeed blurring.
So let's ditch the definitions, and look at some of the most important features in today's samplers/synthesizers. We'll make sense of the sometimes bewildering options, so you can determine which are most important to your needs. Just remember that most of today's machines are so expandable that if you end up needing a certain feature further down the line, it may be available as an add‑on.
File Compatibility
Early samplers could read only their own proprietary sample file format, but more samplers can now read and translate samples from multiple formats. The most common file translations are for Akai and Roland format (although the newer Akai samplers read Emu EIII format, and Kurzweil reads Ensoniq), which allows access to a huge library of quality sounds. Some samplers can read other formats only from a CD‑ROM connected to the SCSI port (see next section), while others can translate from floppy disks as well.
More and more samplers can read WAV files (Windows' native audio format) or AIFF (Mac format). For example, Kurzweil's K2000‑series samplers (such as the K2500R, shown left) can read Roland, Akai, and Ensoniq EPS/ASR files and keymaps via SCSI, and Ensoniq and Akai floppies. They can also read/write WAV and AIFF files from/to disk or a SCSI device.
More outputs simplifies life in the studio, since you can send different instrument sounds to different outputs for external processing and/or mixing.
One important point: transferring raw audio is no big deal, but translating the associated synth‑like parameters is more difficult — if a sampler processes a sound with resonant filters and you transfer the raw sample to a sampler lacking resonant filters, the final sound will be very different. Translation should convey as much data as possible; for example, Peavey's SP Plus loads complete presets from Akai S1000 CD‑ROMs, including samples, keymaps, and all synthesis parameters (filters, envelopes, and so on).
Many samplers still support the MIDI Sample Dump Standard (SDS) protocol for transferring digital audio via MIDI, but it's a painfully slow process. (SDS dates from when samples were typically a few hundred kilobytes of memory, not several megabytes). SMDI (SCSI Musical Data Interchange) is a newer protocol for transferring samples over SCSI instead of MIDI, and runs about 50 times faster than SDS.
While we're discussing file compatibility, if the sampler in question features a sequencer, it's helpful to be able to import and export Standard MIDI Files. This lets you create and edit your sequence on a computer‑based program rather than using the sampler's limited graphic interface, then load the completed file into the sampler.
SCSI
SCSI (Small Computer System Interface) is a hardware/software protocol for transferring vast amounts of data quickly. If you're serious about sampling, SCSI ports are a must, since they allow you to connect hard drives, CD‑ROMs, optical drives and computers to the sampler. With large hard drives becoming cheaper all the time, SCSI gives access to a lot of sounds for very little outlay. SCSI is also required for using SMDI.
RAM Expansion
Being able to add more memory allows you to load more and/or longer samples. At 5Mb per minute for 44.1kHz mono digital audio, 16Mb will be enough to fly in a 3‑minute vocal, while 128Mb would allow almost 13 minutes of stereo sampling.
Look for the option to resample using the DSP effects.
Most RAM is volatile, meaning that the samples have to be re‑loaded after a power‑down. Some samplers provide for battery‑backed RAM or EEPROMs ('flash' ROM), so that samples are accessible at all times. Battery‑backed and flash RAM tends to be more costly than standard RAM, so the best use of this type of memory would be to keep your 'greatest hits' in battery‑backed RAM, and load other samples into standard RAM. Akai's S3000XL (shown above) and S3200XL both accommodate up to 16Mb of flash ROM.
Polyphony
With more voices, sustaining notes won't cut off when you play new notes, more notes and sounds are available for multitimbral setups, and crossfades between samples are more realistic because voices aren't 'stolen' when you run out of polyphony. At the low end, 16 notes of polyphony is common, but these days 32 to 64 voices is just about standard (and Emu's E4K can be expanded from 64 voices to a whopping 128 voices).
Resonant Filters
Resonant filters are difficult to implement digitally, but many classic analogue synth sounds (essential for today's cutting‑edge dance music) rely on resonance. Most newer samplers include resonant filters; one exception is the Ensoniq ASR family, which trades off resonant filters for 'Transwave' technology. This can create not only resonant filter effects but also pulse‑width modulation, vocalisations, and other swept effects that have more in common with synths than samplers. Also noteworthy in this area are the Emu E4K's Z‑plane filters, which are extremely flexible.
Graphic Interface
Although the graphic interfaces on samplers continue to improve (many have oversized LCDs that let you see the waveform, zoom in on loop points, and so on), nothing beats a good computer‑based editor such as Alchemy or Peak for the Mac, or Sound Forge or SampleVision for the PC. If you're into editing, make sure there's a program available that's compatible with both your sampler and computer. Akai get around the problem of compatible programs by providing the free Mac graphic editing software, MESA (shown above), to registered owners of the S2000, S3000XL and S3200XL.
With large hard drives becoming cheaper all the time, SCSI gives access to a lot of sounds for very little outlay.
Roland go one step further by offering the OP760/1 option board for their S760 sampler, which eliminates the need for a separate computer and editing program. This board features a digital RGB output for connecting to a computer monitor, and both composite video out and S‑video out for connecting to a standard TV. There's also a mouse interface for point‑and‑click editing.
Multiple Outputs
More outputs simplifies life in the studio, since you can send different instrument sounds to different outputs for external processing and/or mixing. The OP760/1 board mentioned above adds two stereo outputs to the S760's four outputs for a total of eight outs, the Emu E4K and Digidesign's SampleCell II come with eight outs, while the Kurzweil K2vx and Peavey SP Plus have four outs. Ensoniq's ASR samplers have only two outs, though an optional output expander can bring the total up to eight. Akai take the same approach with their S2000 (shown on page 124); to keep costs down there are only two outs, but you can acquire eight additional audio outs and S/PDIF I/O fairly inexpensively. Finally, the Akai S3200XL is the heavyweight on outputs, with two on XLR and 10 quarter‑inch unbalanced jack outputs.
Support Software
Check for utility programs that make your job easier. For example, Alesis include Sound Bridge with their synths; this program can transfer sounds from your computer to PCMCIA cards. Stuffing a card into the synth is an incredibly fast way to load new sounds, and avoids the hassles of SCSI and other types of transfers.
CD‑ROMs also come under the heading of support, but just about all samplers these days have substantial, high‑quality libraries available, and file compatibility makes even more options available.
File Management
With all those megabytes of sound available, you can get lost without some way to find and load sounds. Roland offer a Quick Loading feature for marking samples (such as all those used for a particular project) in advance for instant loading later on. Ensoniq have macros for CD‑ROM access, as well as a bank option that assembles the sounds needed to create a bank (including from CD‑ROMs), while Kurzweil's Advanced File Management System can search for any object on any SCSI drive and create macros for loading particular setups. The E4K has both a search utility that works just like the 'find' command in a word processor, and a 'SoundSprint' function for quick auditioning and loading of up to 100 favourite presets.
Hard Disk Recording
So far, HD recording is available with only a few samplers, including the Ensoniq ASR, Akai 3000XL/3200XL, and as an option on the Korg Trinity, but it probably won't be long before we see this facility showing up in more and more samplers. While onboard hard disk recording can't compete with a dedicated computer‑based system, it can be very handy when you want some vocals or guitars to go along with sequenced samples.
DSP
This includes standard (and always welcome) effects such as reverb, EQ and chorus, but many samplers go beyond the norm. The Roland S760 (among others) has a time‑stretch algorithm for changing a sample's length without changing its pitch, as well as a sample rate conversion routine.
Look for the option to resample using the DSP effects. One way to use this would be if you wanted a tough gated reverb sound on the snare, and room reverb on the rest of the kit. You'd simply resample the snare through the gated reverb, then use the onboard reverb on the kit as a whole. In some cases DSP is an add‑on; the reverb card for the Akai S3000XL and S3200XL, for example, is an optional feature.
Sample This!
When you go out to sample a sampler, don't forget such factors as the keyboard feel (or if it's a rack you're looking at, how accessible the editing functions are). And, of course, the sound of the unit is the ultimate clincher — although these days samplers are more alike than dissimilar when it comes to sound quality. One quick check is to take a cymbal and transpose it way down (two octaves or so). The smoother and less grainy it is, the better. Also check the filter sweeps for smoothness, and pay attention to controller options such as LFOs and envelopes, as these are crucial for shaping samples into something more animated.
Digital I/O
It's a digital audio world, and in addition to SCSI many samplers now include built‑in or optional AES/EBU, S/PDIF, or ADAT interfacing. This has several applications: you can send samples from audio CDs directly into a sampler from a CD player with S/PDIF, take tracks recorded on digital tape or hard disk and move them into the sampler (ideal for flying in vocals or adding background voices), and transfer samples between similarly‑equipped samplers.