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Quick Guide To Samplers

Once a rock star's luxury, now an essential instrument in every professional and home studio. We explore and explain the core features of the sampler...

Cast your mind back to 1979 and the early '80s and you may recall that the instrument of desire at that time was the sampler. The Fairlight and the Digital Synclavier, costing more than most of us expected to make in a lifetime, made us drool as they demonstrated the power of sampling technology.

Throughout the 80s samplers became more affordable (although many still cost a year's wages) and then, as the 90s progressed and finally turned into the new century, software samplers began to appear offering more power and versatility than their hardware forefathers and at much lower prices, too.

But whether a sampler is hardware- or software-based, they all have a common set of functions and features for arranging and manipulating the raw sample material.

Rates for the job

Tech terms ADC Analogue-to-digital converter, the gizmo that samples audio and converts it into digital data. DAC Digital-to-analogue converter. Bit Short for Binary digIT, a number which can only have one of two values - 0 or 1 - and which is used by computers at their lowest level of operation. Pitchshifting Changing the pitch of a sample by playing it back faster (to raise pitch) or slower (to lower it). Timbre Posh word for tone. Key mapping A general term for the assignment of samples to keys. It covers key splitting, layering and multisampling. Analogue-to-digital converter, the gizmo that samples audio and converts it into digital data.

 If you're not using off-the-shelf samples, the first step is to record or sample some material. For a more detailed discussion of digital sampling see our Quick Guide To Digital Audio but briefly, there two main sampling considerations - sample rate and sample resolution. The sample rate is how many times the source material is read or sampled per second. The higher the rate, the more accurate the sample. Audio CDs use a sample rate of 44.1kHz. Many samplers offer rates up to 96kHz and some even go as high as 192kHz.

The sample resolution is the measuring scale used to store the sample readings. It's measured in bits and early samplers had a resolution of 8- or 12-bits. You can calculate the resolution by raising 2 to the power of the number of bits. So, an 8-bit system is 256 (2^8) and a 12-bit system is 4096 (2^12). Each sample in an 8-bit system, for example, must take a value from 0 to 255.

Home on the range

Given the vast dynamic range of natural sounds you can see that 256 values is not going to be terribly accurate. 4096 is better but the 65536 values of 16 bits is better still and this is the resolution used by CDs. Many samplers now offer 24-bit resolution which comes as close to capturing all the nuances of natural sound as you can get. Until they move to 32-bit sampling, that is...

So why not simply record at the highest possible sample rate and resolution? One day we will, but the higher the rate and resolution the more processing power and storage space is required so at the moment we balance what we would like against what we have and what we can afford.

Sample this

Not everyone has access to a symphony orchestra, exotic percussion and the Vienna Boy's Choir from which to create their own samples so it's good to know that dozens of sample producers do and there are thousands of pre-recorded samples you can load into your sampler. Unfortunately, there's no single standard sample format and samples come in several guises. Most sample producers tend to produce samples in Wave (for the PC) and AIFF (for the Mac) formats and these are as close to a standard as we have at the moment.

Most of the other formats were developed for specific samplers and you might want to consider how important it is for your sampler to be able to read them. In the heyday of the hardware sampler, the Akai sample format was de rigour to read. The Sound Designer II (SDII) format used by Digidesign software is still popular on the Mac, and many collections were created for the SampleCell sampler, originally designed for the Mac but later ported to the PC. Creative Lab's SoundFont (.sf2) format is popular with hundreds of thousands of SoundBlaster sound card users and is also commonly supported by samplers.

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