SAMPLER BUYER'S GUIDE

October 1999

Published in SOS October 1999
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Reviews : Multitrack Recorder

Time moves quickly in the world of digital recording and since SOS's last sampler roundup in September 1997, a host of new models have been introduced, from 'quick-and-dirty' phrase recorders to top-of-the-range sampling workstations. Derek Johnson & Debbie Poyser steer you through the pre-purchase decisions, and provide a guide to all the currently available models.

Regular readers of SOS's interviews with top artists, producers and engineers can't fail to be aware of the integral part sampling plays in the production of music of all kinds. Indeed, many hi-tech musicians consider a sampler to be an essential part of a well-equipped studio -- the recent SOS Readership Survey (see SOS June 1999) revealed that almost 25 percent of you intended to buy a sampler within the next year. So it's high time we gave you some help choosing the best one for your needs -- which is the aim of this article and the table, giving information on every new sampler available in the UK today and their most important features.

Samplers seem to be falling into just a few categories these days. The first is the serious rackmounting studio unit which has everything required to record any kind of sound source and turn such recordings into a proper instrumental multisample. For example, this kind of sampler would allow you to take many samples of a grand piano (if you had access to one!) at different points in its musical range, manipulate and loop them as desired, then map them across a keyboard for playing just like a piano. This is the kind of sampler you want if you plan to replicate 'real' instruments and/or do a lot of sampling of synthesizers.

The second type, becoming increasingly widespread, is the loop/groove sampler, usually presented in a desktop module format. These have grown up partly in response to the rise in loop-based dance music and are optimised for sampling sections of existing music or rhythm tracks -- whether your own or from one of the many specialist loop-only sample CDs that are currently available -- and allowing you to create a new performance by combining them in new ways. Of course, studio samplers can easily be used for creating loop-based music, and have been used for this almost since they first became available, but the new generation of groove samplers tends to be optimised for the purpose. Indeed, these units are usually pretty much incapable of traditional instrumental multisampling as described in the grand piano example above.

Yet another category that may interest some people is the synth/workstation with a sampling facility built in. These instruments vary wildly in terms of the sophistication of their sampling: the samplers built into Korg's Triton and Yamaha's EX series, for example, are so well specified that they might save owners of these instruments the cost of a separate sampler, but some sampling facilities offer no more than the ability to grab a few phrases for triggering alongside a sequence. Synths offering sampling are covered in the 'Synths With Sampling' box.

Having dealt with the kinds of sampler on the market, let's take a brief look at the areas you should be paying attention to when buying one -- especially if it's your first, or you're new to hi-tech music equipment.

The frequency with which a sampler takes a 'snapshot' of a sound's waveform is referred to as its sample rate. The more snapshots, or samples, it takes, the better is the representation of the sound -- rather like moving pictures, where the more frames per second taken, the better the quality of picture. Currently the most common top rate is 48kHz, which means the sampler takes 48 samples per second and produces very good quality digital audio with a full frequency range; other common rates are 44.1kHz (also high-quality) and half of that rate, 22.05. Low sample rates produce less faithful digital recordings of a sound (high-frequency content in the signal drops off progressively as sample rate reduces) but they have the advantage that less memory is required to store them. Some samplers offer rates as low as 8kHz, which can be acceptable for sampling sound sources with little treble content, such as bass drums, or for creating grungy, low-fi special effects.

A sample's bit depth is an issue that used to be rather more pressing than it is now that high-quality, CD-standard, 16-bit sampling is practically ubiquitous. Returning to the moving picture analogy used above, where sample rate refers to how many 'frames' (samples) are taken per second, bit de

"...many hi-tech musicians consider a sampler to be an essential part of a well-equipped studio -- the recent SOS Readership Survey revealed that almost 25 percent of you intended to buy a sampler within the next year."

pth refers to the amount of detail recorded for each of the frames. Each sample is described by the recording device in terms of digital 'bits', which make up 'words'. The more bits to a word, the more detailed and faithful the reproduction of that sample. Sampling started out with 8-bit words, progressed through 12 to the current standard of 16, and is heading towards 24! For now, though, no current sampler offers more than 16-bit sampling, and since none offers less -- though some groove-type samplers use data compression -- there is no line in the table (see pages 212-3) for this information. It's just worth bearing in mind what bit depth means if you're looking for an older sampler on the second-hand market.

These two are pretty obvious -- you want as much of each as you can get. Perhaps more so than any other instrument, a sampler could provide the sounds for an entire composition all by itself, because a sampler can sound like anything at all. Some people use samplers exclusively and don't even have other sound sources. Ranging from loop-based dance producers to Hollywood soundtrack composers, these people own large-capacity samplers pumped with maximum RAM (see next section) and use them for everything. If that's the way you want to go, you'll need a sampler that provides lots of simultaneous notes and many timbres at the same time. Greater polyphony also means that voice stealing is less of an issue when you're playing held or sustaining notes (such as might occur when playing a sampled solo piano), and that you'll be able to take fuller advantage of your sampler's multitimbrality. The current maximum polyphony on top-of-the-range instruments is 128 notes, while multitimbrality reaches a limit of 32 parts at the moment. Some ranges (Emu and Akai) are very flexible in that lower-priced units can have their polyphony and multitimbrality expanded to the amounts offered by the flagship models, and this expandability potentially gives a sampler a longer life in your studio.

Synths With Sampling     Korg Triton: deluxe £1799 workstation synth, reviewed June 1999, featuring an extremely competent studio sampler that uses the synth's generous touchscreen display to good effect. Spec includes 16Mb of installed RAM (upgradable to 64Mb), 16-bit stereo sampling at a 48kHz sample rate, optional SCSI, effects, and the ability to load WAV and AIFF files and read Akai-format CD-ROMs. Kurzweil: workstation synths from Kurzweil were possibly the first to offer sampling, and have done so for many years. Consequently they have very mature, sophisticated sampling options. The K2000 family's option, for example, offers four sample rates (29.4, 32, 44.1, 48kHz), and has a standard 2Mb of RAM (expandable to 64Mb). SCSI is standard, as are effects, and there's a time-stretching facility and good editing capabilities. Akai, Roland, Ensoniq, WAV, and AIFF files can be read, and digital interfacing is standard. Note that Kurzweil synths have numerous options (of which sampling is one), so they can be bought in a basic form to add to later, or purchased with the buyer's preferred options in place. They're expensive (£2450 for the K2000, up to £4000+ for the K2500X) but are fully professional. Roland EG101: very basic phrase sampling is offered by this largely preset budget hybrid home keyboard/DJ instrument (£599, reviewed February 1999). The highest sample rate is 31.25kHz, at which the longest sample available is 32 seconds mono. A lower rate of 7.81kHz is also offered. Sample editing is rather limited and using the facility to its full has implications for the instrument's overall polyphony, but there is a time-stretch feature. OK for incorporating the odd loop. Yamaha CS6x: a brand-new £1299 instrument that's a progression from the CS1x and CS2x dance-orientated synths. The CS6x is the first in the series to feature sampling (essentially simple phrase sampling only) with an unexpandable 4Mb of onboard sample RAM and a 44.1kHz sample rate. Its 16-bit samples are stored on Smart Media cards, since there's no floppy or hard drive, nor a SCSI option. Also available in the shape of the CS6xR module with the same facilities for £999. Yamaha EX5: Yamaha's £1899 flagship workstation, reviewed May 1998, features a comprehensive sampling facility which appears to be derived from the stand-alone A3000 studio sampler. It comes with just 1Mb of sample RAM, but this is expandable to 65Mb. SCSI, a digital output and Flash memory are options, samples are 16-bit, 44.1kHz, there's a reasonable degree of sample editing provided, and the sampler can read AIFF, WAV and Akai-format samples. Also available as the EX5R module for £1199. Yamaha EX7: This cheaper keyboard workstation (£1399) has a very similar sampling side to the EX5. Yamaha DJX: Like the Roland EG101, above, this is an entry-level combination of home keyboard and fledgling DJ tool, though it has the advantage of a very low price (£269). It holds a maximum of six seconds of mono samples, which can be divided between 12 sample locations, but no one sample can exceed three seconds. It appeared to the SOS reviewer (in September 1998) that samples were retained in memory on power-down, though they can be saved over MIDI if desired. Again, most suitable for working a couple of loops or phrases into a composition

Samplers use onboard RAM (Random Access Memory) to record their samples to, and all come with a certain amount of RAM already installed. They also usually have the capacity to host more RAM; the maximum amount each can hold is shown in the table. Obviously, the more RAM a sampler holds, the more samples you can call on at any one time -- and potentially the longer an individual sample could be. Go for as high a RAM capacity as you can afford if you plan to make a lot of use of your sampler, bearing in mind that a minute of 44.1kHz monophonic digital audio occupies 5Mb of RAM.

RAM is dynamic and loses its contents on power-down, so samples must be saved to an external storage device before you switch off your sampler. Some samplers, however, have a Flash RAM option. Flash RAM is installed in slots inside the computer, just like normal RAM, and can be sampled to or loaded with samples in the same way as normal RAM, but it retains its contents even when power is switched off. It's more expensive than standard RAM and could be treated as a small permanent cache of frequently-used sounds -- like having a built-in sound module.

The next important consideration when choosing a sampler has to be storage. In the early days of 8- and 12-bit samplers, a floppy drive was more than up to the task; a sampler with 750K of RAM will easily save its entire memory to a single double-density floppy disk. But now that samplers are routinely supplied with 2Mb, 8Mb or more, and can be expanded to very high capacities, even a high-density floppy drive is of little use as a storage medium. Thus some current samplers have options to install internal hard drives -- in some cases internal removable media such as Iomega Zip or Jaz drives -- and many also feature a SCSI port (or SCSI option) for connecting an external drive.

Obviously, SCSI allows you to freely choose your storage medium, but it also opens up other creative avenues. It means that the sampler can sometimes be connected directly to a computer, and if the sampler and audio editing software both support sample transfer via SCSI, samples can be freely moved between sampler and audio editor. Many audio editing programs are compatible with this SMDI (SCSI Musical Data Interchange) transfer protocol, and some MIDI + Audio sequencing software even allows an attached sampler to be treated as a virtual drive, with samples movable from the application to the sampler and back again.

A CD-ROM drive can also be attached to a SCSI port, for those who would like to use commercial sample CD-ROMs. Many samplers can access CD-ROMs designed for other samplers, which pro

"...some MIDI + Audio sequencing software even allows an attached sampler to be treated as a virtual drive, with samples movable from the application to the sampler and back again."

vides users with a wider potential selection of CDs, and there is a line in the table to indicate which foreign formats can be read. Cross-sampler compatibility has historically centred on allowing non-Akai machines to read Akai-format sample CDs -- important because Akai samplers have been so popular that huge sound libraries are available for them (where we say a sampler can read Akai samples it generally means S1000 or S3000, but be sure to check if this is important to you). Now that some manufacturers are adopting the computer-based WAV format as their standard, cross-sampler compatibility may become less of an issue, but for the moment if a sampler can read non-native samples that's an advantage. One thing to be aware of, though, is that if you're using sounds intended for an Akai sampler, say, in one from a different manufacturer, not all the sound's parameters may be transferred. If the second machine lacks features that Akai samplers have, the sample transferred to the other machine will reflect this and may sound different.

Aside from SMDI, discussed above, the other sample transfer protocol you might come across is MIDI Sample Dump Standard (SDS), but this is needed less often these days, and is annoyingly slow in any case -- around 50 times slower than SMDI. However, for anyone integrating older (especially Atari ST) software, or synths equipped with sample RAM, into their setups it may be the only transfer method available. Luckily, it's implemented in several current samplers.

The number of audio outputs a sampler offers may be important to you, as multiple outputs can be used to send sounds out of the sampler for treatment via outboard effects and processors, giving much more scope for sonic individuality. This is especially significant if your chosen sampler doesn't have effects as standard. If you can't stretch to a sampler with a lot of individual outs at first, try to choose one that allows more outputs to be added later. Likewise, some samplers allow digital interfacing to be added later, if they don't come with it as standard. A digital output could be plugged straight into a digital desk's digital input (or directly to a DAT or CD-R machine's digital in for mastering, if your entire composition and effects are generated by the sampler), but digital I/O (In/Out) has other implications too. It allows audio to be sampled from a wide range of sources, digitally, with no deterioration (rather than going through the sampler's analogue input); digital I/O is also an alternative for transferring audio to and from a computer equipped with a PCI audio card that has digital connections, if SCSI isn't available on that computer (as with recent Macs and some PCs).

In the early days of sampling, it was enough to be able to record a sound and make it play a tune using an attached keyboard. As samplers have evolved, though, some have sprouted synthesis and sound-shaping facilities that rival synthesizers in their power. If you're interested in serious sound design with your sampler, look for envelope generators, which shape a sound over time; LFOs (low frequency oscillators), which add vibrato and other modulation effects; and resonant filters, which alter a sound's harmonic content and are very useful when recreating analogue synth sounds, and especially for dance music.

Groove-type sampling products typically have fewer of these kind of features: you can expect to find some kind of resonant LPF (low-pass filter), to assist in the creation of typical dance-style sound effects, and

"Having effects inside your sampler is convenient because it means that you don't have to tie up (or even own) external signal processing in order to treat your samples with reverb, delay, chorus, distortion, and a host of other effects..."

perhaps a simple envelope, but not much else.

The more DSP (Digital Signal Processing) functions a sampler offers, the greater will be its scope for manipulating a sample. One of the most important DSP functions is providing processing for effects. Having effects inside your sampler is convenient because it means that you don't have to tie up (or even own) external signal processing in order to treat your samples with reverb, delay, chorus, distortion, and a host of other effects that can transform their sound. Internal effects (which are often of very good quality) also allow an entire composition to be created and polished within one instrument. Some samplers come without internal effects but allow them to be added later, and this is a flexible option if cash is tight to start with.

Other DSP facilities include time-stretching, which changes the length of a sample without changing its pitch, and vice versa. Many people who work with rhythm loops find this facility almost indispensable for matching tempos between loops taken from different sources. Sample-rate conversion may also be offered: this converts a sound sampled at one rate to another rate, and may be useful for reducing the amount of memory samples occupy.

Other features you might find important when shopping for a sampler include:

Direct-to-Disk recording: where a performance is streamed direct to an attached hard disk, and then treated as if it were a single sample. Some people use this facility to save them the expense of a hard disk recorder, putting together entire tracks, including vocals, inside the sampler.

Sequencer: the sequencers available on current samplers range from the very simple (which might just be used to trigger a string of groove samples), to the very comprehensive (which can be used to create sophisticated compositions). Some will load standard MIDI files, which means that you could compose a sequence using the superior facilities of a computer-based program, for example, then load it into the sampler's sequencer for stage use.

Resampling through effects: this facility allows something you've already sampled to be routed through the sampler's effects and sampled again, thus preserving its effect treatment and freeing up the effects again for processing other samples. It's especially useful if the sampler has limited effects power.

Display: some units feature large graphic LCDs that can really make a difference when it comes to sample editing, as they can provide waveform displays to help with looping and so on. A 2-line display offering only lists of numbers will obviously not be as pleasant to work with.

There's never been a wider range of samplers available, to suit all requirements and every pocket. Use this guide as a starting point for your own research, and don't forget to check out the full SOS reviews before you part with any money. Happy sampling!