Samplers & Sampling

The technology most often used for this is called sampling. Instruments that use sampling technology are called samplers or sample-playback synthesizers.

When you press a key on a sampler (or on a MIDI keyboard attached to a computer in which a software-based sampler is running), the sampler plays a digital recording of an actual sound that was originally produced in the real world. The recording could be, for instance, a single note played on a sax or flute. It sounds exactly like a real instrument because it was the real instrument.

Sampling is also used to play drum loops and for other purposes, but we won’t get into that this month. Also, samplers have many built-in synthesis and sound-shaping functions, such as filters and envelope generators, that we’ll leave for a later installment.

To play a melody using a sampled instrument, all you need to do is play the keys. The sampler does two things, at the very least: It makes the sound louder when you hit the keys harder, and it transposes the digital recording up or down by as many half-steps as necessary so that each key produces a note with the correct tuning.

That description makes the process seem simple. In fact there are some technical details that it’s useful to know if you want to master your sampler. Fortunately, professional sound designers go to great lengths to take care of the details for you. In many cases, all you need to do in order to use a sampler is load the preset containing the sound(s) you want to use.

Most software samplers come with large sound libraries that are ready to use. If you don’t have the sounds you want and can’t afford a professionally produced sound library, another option is to record your own samples. With a computer-based sampler, you may need to record the sounds using a separate program before loading them into the sampler, but most hardware-based samplers have audio inputs on the back panel so you can record new samples directly into the instrument.

If you want to get the most out of your sampler, you’ll need to know about multisampling. You’ll also need to understand the memory requirements of samplers.

Multisampling

Acoustic instruments often sound quite different in one part of their pitch range than in another part. So recording a single sample and then transposing it up and/or down by several octaves in order to play it across a keyboard range tends to produce a very unrealistic sound. The solution is to create a multisampled keyboard layout. The original instrument is recorded playing notes at several (or many) different pitches, and each sample is assigned to a different zone on the keyboard. When you play a key in a different zone, you’ll hear a different sample.

All samplers can play multisampled presets. In most cases, you can simply load and play the preset: You don’t need to load individual samples to create your own multisample. However, you can do so if you need to.

Many instruments also sound different when played loudly than when played softly. In addition to the volume change, there may be changes in tone color. Samplers can reproduce this effect by allowing different samples to be assigned to different key velocities. When you strike a key hard, you’ll trigger one sample. Striking it softly will trigger a different sample.

Memory & Storage

Samples are normally played back from the RAM (random access memory) area of your computer or hardware instrument. When you choose a preset, the samples must be loaded into RAM from long-term storage (usually a hard drive), which can take a few seconds depending on how much data has to be loaded. When you record new samples, you’ll have to store them on the hard drive before switching off the sampler. If you don’t store them, they’ll be lost forever.

With hardware samplers, especially older models, the total amount of RAM is limited, so it’s often necessary to make some musical compromises — whether to load a few long samples or a lot of short ones, for instance. Modern computers tend to have plenty of RAM for even the most demanding sampler.