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District of Columbia - September 1, 2009

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Summary

Meeting summary for 1 Sep 09 — Rick Chinn at DC AES

On 2 September 2009, Rick Chinn, Vice Chairman of the Pacific Northwest Section of AES presented a talk entitled "Live Sound for Jazz (and other acoustic music)". Approximately 50 AES-DC members and guests met in the boardroom of National Public Radio headquarters. The meeting was chaired by David Weinberg, AES-DC section chair, who welcomed everyone and took a few moments before introducing the speaker for the purpose of matching up any available positions in the audio field with people seeking positions. Section executive committee member Jim Mastracco introduced our featured speaker.

Rick Chinn is a consultant in audio systems design and troubleshooting, sound design, live sound mixing, recording, technical writing, and web design. His presentation emphasized the different techniques he employs when approaching the problem of amplifying acoustic instruments as opposed to the usual methods developed during the early days of rock and roll (beginning with the Beatles and still employed today).

Rick began by asking: What is an acoustic instrument and why might it need reinforcement?
He defined an acoustic instrument as one that doesn't need power to be played. If the balances among instruments are satisfactory and the audience space is not too large, there should be no need for amplification. Examples are a jazz combo in a club venue or a string quartet in a small auditorium. The factors that might force the need for amplification include 1) the venue is too large or dry and those seated at a distance have trouble hearing, 2) the instruments in the group are not balanced with each other, 3) there is a soloist such as a singer who needs reinforcement relative to the rest of the group, and 4) there is a need for equalization of the instrument(s) or voice.

Addressing this latter need, equalization, involves first the choice of microphone. Various mikes have their own EQ characteristics (coloration): proximity effect and presence peak, plus off-axis frequency response. These are often useful characteristics: 1) from an artistic viewpoint as a soloist moves in close, and 2) as a way of providing "presence" to the sound. Rick presented a number of measured frequency responses of several microphones at various distances. It was interesting to note that the proximity effect is measurable not just inches from the microphone, but also up to 4 feet. The amount of proximity effect varies among the various microphones, and only experience can enable on first try the optimum choice for a given soloist without experimentation. Presence peaks also vary in terms of shape, prominence and position in the spectrum. Rick noted that sometimes an omnidirectional microphone, lacking proximity effect, is the best choice; the advantages include constant frequency response with distance and low handling and breath noise.

Rick presented several examples of microphone choices for various instruments, illustrating some choices with recorded audio examples. He suggested some approaches to miking "problem" instruments such as acoustic bass, drums, and piano. For bass he often uses an Electro-Voice "variable D" directional microphone such as the EV RE-20, which has zero proximity effect. For drums, his main microphone or mike pair is overhead, and there might be no additional microphones needed (Sometimes a bass drum microphone is added). For piano he suggested two possibilities: a microphone pair "looking" into the box at the reflective lid, and removing the lid if the reflection is found to be coloring the sound. Audio examples of successful reinforcements of drums and piano were presented.

On the subject of mixing, Rick sets levels first, then adjusts EQ as needed (not by talking, but by using the instrument or known music as the source). All tweaks are made before the performance so there is little need to change the settings during the show.

Rick next addressed the subject of stage monitors, suggesting that the best monitor might be "no monitor". Well known are the problems of feedback, sound leakage into the microphones, and their audibility in the audience space. He recommends a steep high-pass filter (not a slider adjustment on the graphic equalizer which only puts a dip in the response). A good monitor is one that sounds good when the monitor system is set to flat.

Rick introduced the concept of "reverse mixing". When someone can't be heard in a mix, the natural inclination is to turn up that instrument. Often a better strategy is to determine who is doing the covering up, and turn them down. This approach avoids the tendency for the mix to get ever louder as adjustments are made.

To finish the presentation he described some unusual past gigs. Of particular interest was a setup in surround using four microphones in quad surrounding the performers in an abandoned concrete cistern (the "stage") with a reverberation time (RT60) of about 40 seconds. The corresponding speakers were set up in a large quad arrangement on a hilltop whereby the audience was completely inside the quad. Needless to say, special slow music was composed for the occasion.

A lengthly and lively question and answer period followed, as well as later conversations; the topics included instrument pickups, recommended wireless microphones, PZM microphone mods, the "loud drummer" problem, microphone setup for big bands, and how to protect one's hearing. Asked if Rick is working on a book, the answer was "no time for that".
Fred Geil, Secretary DC AES

Additional Information

* Live Sound for Jazz (MP3 Audio - 43.6 MB - Length: 1:35:08)

* Dan Harpole Cistern Explanatory Text (Text File - 1 KB - 1 page)

* Dan Harpole Cistern Audio File (MP3 Audio - 775 KB - Length: 1:06)

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