The violin has been called the marvel of the woodcarver’s art. It’s a relatively small instrument—a mere fourteen inches long—constructed of spruce and maple with an ebony fingerboard. Yet for more than four centuries, the violin has captivated listeners worldwide with its soaring tone and ability to evoke emotion. Everyone knows what a violin looks like, but exactly how its astonishing tone is produced remains acoustically inexplicable.

Even with today’s technology, we cannot produce an instrument whose tonal qualities truly rival those of the great master builders like Stradivari and Giuseppe Guarneri del Gesù. In much the same way, a superb solo violin sample might be considered the touchstone of the sound designer’s art. Indeed, a sonically compelling set of samples of any of the solo strings—from violin and viola to cello and double bass—often seems beyond the grasp of even the most dedicated sound designers.

In this article, we’ll take an up-close look at string instruments to see exactly why they are so difficult to sample. We’ll then discuss ways to work around these problems to ensure that your string samples are the best they can possibly be. For the most part, a solo violin will serve as the primary example, though the techniques we’ll be examining will work just as well for any instrument in the string family. Mind you, this article won’t deal with string ensembles—that was covered in "All Together Now" in the June 1998 EM. Be prepared: hard work lies ahead, but so does a great finished string sample!

BOWING TECHNIQUES
Unless you are intimately familiar with string performance techniques, I suggest you find a few choice recordings of some exceptional violin performances. A particularly fine example is the 1980 Philips recording of Bach’s Sonatas and Partitas for Solo Violin as performed by Gidon Kremer, though there are hundreds of wonderful recordings out on CD now.

Regardless of what recording you listen to, you will be astounded by the range, dynamics, and expressiveness of the violin. You’ll hear slurred notes, hammered notes, flying staccatos, ricochet bowings, glissandi, double stops, and more. Essentially, the immense variety of timbre and effects that a violin produces occurs through a combination of bow speed and the interruption of that speed by the pressure of the right index finger on the stick. The distance of the bow from the bridge is also a significant factor. It sounds simple, but adequately performing such techniques demands an amazing amount of finesse and dexterity on the part of the performer, not to mention the ability to accurately finger the notes with the left hand—all at the same time!

While you don’t need to be an expert on classical bowing technique, it is important to be aware of the many ways a violin can be bowed and how each one affects the instrument’s sound. Most of the sampled solo strings in CD-ROM collections are limited to legato bowing, though some may include one or two other performing styles. If more than one performing style is provided, they must be well matched. Otherwise, when you Velocity switch between samples, it’s quite apparent that an entirely different set of sounds is being heard, thus screaming at the listener: "This is a sampled string part!"

In the sidebar "Standard Bowing Terms," you’ll find definitions of a few principal bowings that you should be aware of. Although these definitions are not strict interpretations of playing style, they should be adequate for the needs of the sound designer. (Classically trained violinists in the crowd, please don’t write us nasty letters!) There are many variations on these techniques, and a skilled performer should be able to effortlessly move from one to another.

Ultimately—and I cannot stress this enough—your finished samples will depend upon the skills of your player and, more importantly, upon his or her cooperation and desire to do the job right. Don’t even bother with a performer whose heart isn’t in the project.

QUALITY CONTROL
Besides working with a skilled player, if you want a really great sample set, you also need to be working with a better-than-average instrument. A well-crafted instrument will produce a more consistent tone, which is important because we will be grabbing only a limited number of representative samples. We must timbre-match our violin sound across the sampler’s keyboard, so we want to start with an instrument that has a consistent sound.

The instrument’s acoustics are another important factor to consider. Every violin (and every other acoustic instrument, for that matter) radiates its fundamental tone and each set of harmonics from different areas of the body. A lovingly crafted violin is going to have a very nice balance between fundamental notes and overtones, as well as a wood body resonance somewhere between 500 and 600 Hz. While the fundamental is radiated more or less spherically, at frequencies above 2,500 Hz, sound radiation is quite sensitive to direction. If the harmonics are well tuned (as they will be in a well-made violin), you stand a very good chance of placing your mics in one of the instrument’s sweet spots.

On the other hand, a lesser-quality instrument might produce a set of harmonics that are not perfectly in tune with the fundamental. If you place your mics in a position that is in-line with one or more of these strong overtones, your samples will end up having a thin, raspy quality. Those of us whose ears have not been trained to pick out these subtle tonal qualities will not recognize them until it’s too late, and we may inadvertently place our microphones directly in their paths. What’s more, imagine an out-of-tune harmonic that is now transposed up one or two semitones—the sampling world’s equivalent of fingernails on a blackboard.

Almost every mediocre violin sample I have heard suffers from the same problem: placing the mics too close to the instrument. This typically results in a sample with too much of a particular overtone and an unnatural amount of body resonance. At first, this may seem to give your recording a nice "woody" tone; however, it’s going to sound strange when you start to transpose your samples up a semitone or two.

Even more disturbing is the fact that close-miking overemphasizes the scrape of the bow on the strings. I’ve heard samples where the bow scrape is actually as loud as the note being played. While the scrape is an integral part of the sound of any bowed string instrument—and part of what separates a sampled violin from a synthesized one—it’s unnatural for this to be such a dominant part of the sound. (Refer back to the sound of the violin on that CD I suggested you purchase.) Add to that the same problem we had with the violin body’s resonant peak: a loud bow scrape transposed up and down a semitone or more will not sound natural. However, when our finished violin samples are played over accompaniment, the transposition of a small (and even moderate) amount of bow noise will be quite acceptable.

Unless you’re working in a soundproofed studio, you’ll also have to factor in the relative noise level of your recording environment. If you’re working in a concert hall, it would seem logical that you’d want to have your mics near the best seats in the house: front row center, or about twenty feet from the stage. However, in most instances, that placement is just not practical because all but the very best concert halls have some amount of ambient noise (air conditioning vents, traffic, outside noise, etc.), and in all probability, the mics will need to be moved in. Ambient noise can also a major problem when you’re recording at home.

So what can you do? If you place the mics too close, the violin won’t sound natural when it’s transposed, and if the mics are too far away, you run the risk of capturing some unwanted room noise. My advice is to simply trust your ears. Walk around as your soloist is playing and listen to the various characteristics of the sound. When you have found a spot that pleases your ears, put the mics there, which should be somewhere in the area illustrated in Figure 1b. Then listen through a pair of headphones in mono to make absolutely sure no phase cancellation is occurring.

Of course, it also goes without saying that you need a pair of exceptional mics to capture the sound of such a fine instrument. I always depend on my AKG 414s, but plenty of great mics are available these days that won’t set you back a year’s salary (and naturally, quite a few that will). Most importantly, remember to do your recording in stereo, even if you don’t think you’ll be using stereo samples.

BEGINNING THE SESSION
Depending upon the attitude of the player, the session itself can be either a relaxing part of the project or a sure-fire migraine starter. If you have your performer’s complete cooperation, congratulations! Start by having them play a brief piece that they’re comfortable with, so you can get an idea of their playing style (three or four minutes is plenty). This is also a good opportunity for you to check your mic placement and the overall quality of the recording.