Amplification of an Acoustic Guitar

November, 2001

Amplification of an Acoustic Guitar

by Richard Gilewitz

Richard Gilewitz When amplifying an acoustic guitar there are a number of variables to consider: the style of pickup being used, microphones, the type of instrument, solo or band setting, string gauges and options, the available sound equipment, player attack, expected crowd capacity, room conditions, and communications with either a house or hired soundman.

Pickups

There are a variety of pickups available, including saddle or 'piezo' pickups (some offering an internal microphone combination) and magnetic soundhole pickups. Some of these pickups are passive and generally require some sort of a pre-amp or 'boost' for the signal, and some pickups are active. You must also educate yourself about when a battery is required, when phantom power can be utilized, and when phantom power can cause problems.

For example, occasionally the active magnetic pickup I have chosen can't utilize phantom power, risking damage to the pickup. Now then, I like to use an external condenser microphone that requires phantom power. I need to circumvent the situation by either switching pickups, switching to a mic that does not require phantom power, or going with a pickup-only sound. On rare occasions for a smaller room, I may try using the mic only- but I have always enjoyed the tones available from a good pickup.

Currently I am using a Sunrise magnetic pickup system, which is passive. I enjoy the option of adjusting the pole pieces for each string for a more controlled and balanced sound. From time to time I also use a Fishman Rare Earth double-coil magnetic pickup, which is an active pickup. Occasionally, I have been asked to demo an acoustic guitar with a built-in saddle pickup and there is often an option 'on board' the guitar for some equalization and volume control. As I have mentioned in guitar and sound seminars I have conducted, the choice of pickup really amounts to a matter of taste and a player's particular style.

Concerning the microphones of choice, one must realize that an external mic can be placed in a variety of positions. Also, when recording in a studio, the selection of mic placement is often different than in a live setting. Sometimes when a good condenser mic is not available at the venue, I will use an internal mic by GHS Strings in combination with the Sunrise. There is an abundance of information on the variety of mics available. Do the research yourself, read the literature, and speak with engineers and soundmen in your quest for the right microphone for you.

Instruments

When amplifying the sound of your guitar, there are options to consider based on the instrument you will be playing. You'll learn to make audio decisions based on personal taste and the particular performance setting. For example, I don't perform in a group setting. However, when I hear a bluegrass guitarist in a band, I enjoy the sparkling tones that shimmer through with the use of a piezo pickup and/or microphone. The rest of the group rounds out the sound with plenty of bottom end and fill. As a listener in this setting, I don't think I would like the sound of a magnetic pickup.
When listening to a classical guitarist, I prefer an unamplified instrument in a nice hall played with good technique, or possibly with a mic added for mild reinforcement. With my 12-string guitar, I prefer mixing the Sunrise with a condenser mic and hope that there is not a problem with too much phase cancellation.

String Gauges/Options

I use GHS Golden Bronze strings and occasionally Phosphor Bronze strings on my guitars. The action is set fairly low on my 6-string guitar so I don't feel as if I'm playing with an emergency break on, and I use a light gauge set (12 16 24 32 42 54).
I pitch the 12-string guitar down two whole steps from standard and often use an open-G tuning which actually drops the low bass down to a Bb (sounds great through a subwoofer!). The action once again is still fairly low and, due to the deeper tuning, I'll use the gauges in pairs: (13/13, 16/16, 24/11, 32/16, 42/22, and wound 56/30 wound). The real key here for me is the 5th string octave as a wound string. As a fingerstyle player, the last thing I want to hear when I come down with my thumb on the 5th string is an unwound amplified string.
I once used GHS White Bronze strings. These create a nice sound since there is some nickel in the string component that responds to a magnetic pickup. Try silk & steel strings, too, and experiment to discover your preferences.

Sound Equipment

This subject can take up to a zillion pages! There are numerous options to choose from and, if you are a touring artist, they will sometimes choose you. More often than not, even if you have particular requests in your contract rider, when you arrive at a venue you must be reasonably diplomatic and utilize whatever the house can provide. The best thing for ease of a sound check and zoning-in on "your" sound is to educate yourself in the operation of as many different models and types of equipment as possible.
Power amps, equalizers, crossovers, subwoofers, a variety of 15" and 12" speakers, horn types, cone types, compressors, special effect units, and mixing consoles should all be a part of your study regimen. You can learn a lot by visiting a local music dealer with a variety of manufacturer's equipment on hand. Speaking with several trained sound and recording engineers to discuss functionality as well as philosophies is a great way to enhance your knowledge of sound. More often than not they'll be willing to educate you, encouraged by your interest. Remember, they are artists too! There are schools of audio engineering, of course, but a tremendous amount of information seems to avail itself to the 'simply curious' individual.

When amplifying an acoustic guitar, be sure to select the right pre-amp or direct in (D.I.) box for use with your particular pickup. Study "gain structure" as much as you can in order to properly use whatever equipment is available to you.

Player Attack

Remember that all too often during a sound check, there is a certain feeling you may succumb to when you say to yourself, "Hey, there is nobody in the room"...and then, when the place fills up, your playing attack completely changes. Be wary of this. If you suddenly play with a totally different fervor during your show and overplay your instrument, you risk greatly affecting the results of all that time you spent in your sound check.

While doing your sound check, keep in mind how you expect to be playing during the show. More importantly- during the show, remember to play the way you did during the sound check. During the sound check, I tend to sit out in the room in front of the speakers so I can hear my house sound, then I move onstage to check the mics. I use very little monitor, if any. I sit far enough away from the speakers and, with the EQ properly set, there is no problem with feedback.

Crowd Capacity/Room Conditions

The capacity of a room can also affect your sound check. This is often a cause of concern and depends on a variety of elements, including your sound equipment and the acoustic qualities of the room. If you are playing in a room which seats 100 and expecting only 25, you must keep that in mind in your sound check. If that same room is sold out, it will also affect your sound. To quote my sound engineer: "Everything affects everything." Some rooms have tile, wood, marble, mirrors, glass, or carpet. Some have high ceilings, metal ceilings; there might be long rooms, wide rooms, and people - sometimes with winter coats!

Each of these factors can influence the final sound achieved during the show. Sound waves get baffled, bounced around, absorbed- you name it! Generally, I have noticed that a good-size crowd in a smaller room will 'soak up' the sound. So, I tend to run my sound check a little hotter with a bit more bottom end and highs because I know that during the show these changes may occur. As an end result for a room, I prefer a sound that is full and balanced, and not just LOUD. Often, a good soundman is present for just one reason- to make adjustments as needed. "Ah, that couple took off their jackets...I had better change THIS!".

Soundman Communication

Upon arriving at a venue, one of three things will occur concerning the sound person: You brought your own soundman, you're going to be doing your own sound, or there is a house soundman. You may also have brought your own equipment or at least some of it - such as D.I. boxes, pre-amps, etc. The objective is to always be professional, maintaining a concept of the sound you prefer and the methods of obtaining that sound, and, most importantly, knowing how to communicate that concept to someone who may never have heard you play.

Unfortunately, the potential for confrontation exists. When either the act has an attitude about the sound they're after and shows disrespect for the soundman's knowledge and abilities, or vice versa, when the soundman disrespects the performers, assuming they don't know what they're talking about- feathers get ruffled. I always treat the soundman with respect and professionalism. If we understand that we are on the same team, the night is ours and not just mine.

More often than not, a good soundman will respond in a similarly respectful manner, especially if you are sincere. You should at least be knowledgeable about your own equipment, its strengths and whatever glitches it may have. You should then examine what the sound company or house equipment entails. Then, let them do their job! Once they have achieved a sound for the room, if you are dissatisfied, offer some suggestions and inform them of your preferences. Similarly, if you have arrived at some unsatisfactory settings by your own devices, invite the house technician's opinion.

Over the last five years, I have had the pleasure of exclusively recording with George Harris at Panda Productions in Clearwater Florida. During the process of recording three separate CD projects, I have always found George to be extremely knowledgeable. He has been kind enough to share his thoughts on this article.

"You could do a little more in the way of describing "phase" cancellation between a microphone, and a pickup. One suggestion is to carry a "phase reverse" mic cable, for situations where the mixer does not have "phase" switches (which actually reverse polarity) . These cables are wired to reverse pins 2 & 3, and may have to be custom-made). I have often found that reversing the polarity (phase) of the microphone yields a more useable blend. As you mentioned, this will take some degree of experimentation. You might also mention the possibility of bringing a reference CD to play for an unknown sound-person. Often this can be a big help in defining terms like "bright", or "full", etc." George Harris, Panda Productions

Once the show starts, the last thing you want to worry about is your sound. Your job at that point is to play and have fun. Oh, and always carry extra strings, batteries, cables, and cough drops!

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