What is it actually?
Shoulder rests are designed to comfort the violin holding and playing. Its a particular equipment placed under the violin in order to elevate the violin to the level of the chin, reducing this way the gab between the chin rest and the jaw.That facilitates the the head (by resting on chin-rest) to take a role in holding the violin in straight position and releases the left hand. Shoulder rest are particularly useful for techniques like vibrato or position changing. They are not however a must. The use of shoulder rests will depend on the physiology of the body of the violinist his technical habits and abilities and sound expectations.
Strategies for the best shoulder rest adjustment.
The way each violinist holds the violin should be very individual and in accordance to his body physiology. The shoulder rest (if used) should facilitate the posture. There are many different options out there, and it is very important to find the combination of shoulder rest and chinrest that is most suited to your body in order to maintain the appropriate posture for you.
Here are some brief, generally agreed upon guidelines for posture. First, think of sitting or standing tall. This natural stance should be maintained when you hold the violin. The end of the violin should rest on the collarbone, and the scroll should be level with the body of the instrument. Keep the head in a neutral position, turned slightly to the left. The head should not tilt or strain to reach the violin. The jaw simply rests on the chinrest. There should be no tension involved in holding the violin between the collarbone and jawbone, solely the weight of the head. A proper shoulder rest will make this possible.
Pads and sponges
For young children holding violins of smaller size I usually suggest homemade violin pads (see the picture on the right
You can also get sponges and have almost the same result as the violin pads.
Alternatively for smaller you can buy shoulder Rests that feed the size of the violin and the length of the child’s neck. I usually suggest the cheaper choices where you can experiment a bit with minor economic consequences. (Note : I usually discourage parents from buying the wolf shoulder rests as they never adjust properly to the measurements of the violin and the child).
More rigid shoulder rests that clamp onto the underside of the violin are usually good for anyone with an average to long length neck. They come in all heights and many are adjustable. Some of the more common shoulder rests are the Kun, Mach One, and Wolf. Others include Bon Musica, Everest, Comford, Resonans, and Viva la Musica.
Another option is to play without a shoulder rest or sponge. This is most common among people with shorter necks. Some people use a cloth over the end of the instrument. Most importantly, the violin needs to feel comfortable and stable where it sits.
Where to get them from?
Very often the shoulder rests are included in the package of a new violin. Otherwise wise you can find some models in almost all local shops violin makers (there you can also make a customized one). You can buy them also online in music stores like paganino.de.