Amplify Your Violin: Part 1

I've examined some of the equipment best suited to violin, and many of the issues a performer will have to deal with. Much of the information here will be basic, since the average violin player may not know how electronics are used to amplify sound.
The key to good sound is using appropriate high quality equipment and testing it in performance situations. Links from the products listed here will bring you to the company home page. (Direct links to online product descriptions tend to be changed too often.) The suggestions here are a result of my own research and experimentation.

A system for amplifying a violin includes the following components:
1) transducers: includes microphones, piezoelectric and magnetic pickups
2) signal modifiers: preamps, reverbs and other sound effects processors
3) amplifiers and speakers (PA, "combo" amps or separate components).

Transducers pick up vibrations or sound waves and convert them into an electrical signal. Signal modifiers condition the signal, and add-to or adjust aspects of the amplified sound.

Microphone Information

Microphones (mics) convert the soundwaves produced by the instrument into an electrical signal. They offer the best fidelity and tonal accuracy, capturing the entire complex sound of the violin. Pickups sample vibrations or string movement from wherever they are placed. Mics should be used directly into a PA or a full-spectrum acoustic amplifier. (Outboard mic preamps, the Art MP for instance, can be used to condition the sound and add "warmth" but they are not required.) Microphones suitable for amplifying violins can be found in the $100-$300 range and up. On-stage microphone volume is often limited by audio feedback, which I’ll discuss below. Low frequencies may sound "boomy" through a mic, and tone controls should be adjusted.

The two basic types of microphone are dynamic and condenser. Most dynamic mikes are voiced for solo vocals or another specialty task. Though dynamics have their place, condensers tend to be used for acoustic instruments due to their sensitivity and extended frequency response. Condenser mikes generally require batteries or phantom power (a way of sending current through the cable to power the mic element). They also tend to be more delicate, whereas dynamics can take some abuse. I believe every performing acoustic musician should own a high quality mic, especially if playing on an unfamiliar PA setup.

Recommended Microphones

Condenser Mics

The AKG C-1000s is an excellent live and recording mic for its price (pictured right, ~$200.) It can be powered with batteries. Shure’s condenser mics are also recommended. There are many other suitable microphones under $300 built by ElectroVoice, Sony, AudioTechnica, Sennheiser, CAD and others.

Condenser mics can be miniaturized and designed to clip to the instrument. Most feature adjustable arms to position the mike for the best sound. AudioTechnica's AT-35R or Pro 35X(pictured left~$130) is highly recommended. It and other similar clip-ons require an additional phantom power unit (unless one is available in the amp or PA you are using). Mini mics are also made by Microvox and Miniflex. The Countryman Isomax is a state-of-the-art miniature microphone.

Dynamic Mics

At the low end of the price scale are the Shure SM58 and SM57 , often discounted to about $100 and less. These dynamic mics are widely used, and I would not suggest playing through anything of lower quality. Both feature the same mic element in different configurations. My preference is the SM57, as it is more resistant to feedback. It is often used to mic the sound from an amplifier into a PA system. At a higher price (~$186.00) the Electro-Voice N/D 468 is a highly recommended dynamic mic (pictured right).

Look for sales on microphones at local music stores. It’s also possible to get bargains on discontinued models. Test them against the AKG C-1000s through a music store PA system with another violin player. Bands getting rid of equipment may sell their mics through the local "Want Advertiser" or classified ads. I would buy a used mic if it sounds good through a PA and has no evidence of physical abuse.

Microphone Placement

If you perform with singers, you can control volume by varying your distance to the mic. Bluegrass players are masters of this technique. Proximity of the mic to the violin’s sound holes affects the sound/tone. I’d set the volume so the mic sounds good at ~2 inches from the sound hole or tailpiece. Closer micing will deliver less of the sound of "air" and natural room echo. The echo can be simulated to some degree with an electronic "reverb" effect. A very close mic technique will give a more "electric" tone, and phase cancellation problems can affect the sound. If you need to sing and play into the same mic, I’d recommend a goose-neck mount on a stand. (Singing into a clip-on mic on a violin looks pretty funny.) Wedge your microphone into the holder so it doesn’t slide out and land on your violin.
If you are playing and singing try this trick: Use an SM 57 for the violin and an SM 58 for the vocals (for instance). The 58 will also pick-up the violin for a stereo effect. At the soundboard you can position (or "pan") each sound towards a different side of the stage. This can add to the presence of a violin, but don't pan hard to the right or left.

Microphone Feedback Problems

When the sound from PA speakers or monitors is picked up by the microphone, a "feedback loop" is created. The result is a highly amplified ringing or howling sound at certain frequencies. The body of a violin is very sensitive and can reflect amplified sound into the mic, becoming part of the loop. Usually feedback is just something you adjust for, but there are times it can be a real battle. The architecture of the room can be a factor. I once played in a glassed-in room on the top of a skyscraper. There was only one place on stage I could stand, with the violin pointed at my coat on a rack! In high volume situations, sounds from other amps on stage may cause the violin strings to vibrate. This is a type of feedback, or "sympathetic vibration". Having your violin send out a constant open G note drone can be very annoying. In the worst cases I’ve resorted to muting the strings with my fingers when not playing. Here are some steps you can take to avoid feedback:

1) The main speakers should be closer to the audience than the mics or monitors.
2) Angle the main speakers away from the front of the stage.
3) Make sure no microphones are pointed at any speakers.
4) If you can draw a straight line from a speaker to a wall to a mic, then change the angles.
5) All loudspeakers and speaker monitors should be pointed away from your violin.
6) Mics tend toward low frequency feedback. Reduce the bass on the violin channel.
7) "Directional" mics are better at rejecting feedback than "omni-directional" mics. In addition mics are built (or can be adjusted) to pick up wider or narrower patterns of sound. A "hypercardoid" setting will pick-up sound only near the mic-good for stage use. The wider "cardoid" setting will pick-up room reflections. This is good for recording, but prone to feedback on stage.
8) Overuse of reverb can add to the problem.
9) Using EQ to avoid feedback is discussed in the Electronic Sound Modification section.
10) Covering a soundhole (or both if using a pickup) with leather or tape may help.
11) Reversing the phase may help, if your amp has this capability.
12) Using a closer micing technique may help.
13) Condensers are more sensitive than dynamics. Swap mics if one is feeding back.

During sound checks if feedback seems to be a problem, I explore its cause and nature by trying to induce it. (The acoustic characteristics of full and empty rooms vary though.)

Information on using Microphones

All written material in this document is copyright (C) 2001 by Joel Glassman; all rights reserved.