Aea R88 User Manual

• STUDIO RIBBON MICS

Audio Engineering

Associates

1029 N. Allen Ave., Pasadena, CA 91104 www.wesdooley.com Phone: [phone] Fax: [phone]

• M/S STEREO

• T ALL ST ANDS

• MIC POSITIONERS

© Sept. 2004

AEA R88 Ribbon Microphone

User’s Manual

The R88 has two figure-8 ribbon microphone transducers angled at 90 degrees to each other. A stereo
microphone configuration is useful for recording situations where it is more convenient to have one microphone
housing for both capsules, such as live concert recordings or drum overheads. The R88 has been optimized to
produce the most natural stereo pickup possible with ribbon transducers. It has a very uniform polar frequency
response, and is therefore relatively free from the “hole in the middle” effect that can occur when recording
Blumlein stereo.

A few things to remember about this microphone:

1) Keep it covered when not in use.

Since the R88 contains powerful magnets, it is possible for tiny pieces of metal to be dra wn into the
ribbon gap. The microphone’ s acoustically transparent cloth surround protects the transducer from this
so-called “tramp iron,” but it is wise to safeguard your investment by keeping the mic cov ered with the
bag supplied when not in use. Avoid leaving the microphone sitting out on a table or workbench. In our
experience this is a likely place where tramp iron may be attracted to the microphone.

2) Store the mic vertically.

Our ribbon transducers are tensioned very lightly, so that coupled air damping provides excellent
transient response. To help ensure a long life and consistent sound keep the microphone stored
vertically whenever possible to prevent “sagging” that may occur during long term horizontal storage.

3) A void phantom power.

Using a correctly wired cable and a decent phantom power supply, there is little
danger of damaging the microphone with phantom power. However since a faulty or miswired cable or
a poorly designed phantom power supply can cause severe damage to the transducer we recommend
avoiding the use of phantom power with your R88 as a general rule.

4) Protect the microphone from wind blasts.

In order to produce the most natural sounding pickup possible, the mic is minimally protected from
wind blasts. Avoid recording horns, drums or anything that might produce large movements of air
within 12 inches of the microphone. A good rule is if you can feel wind on your hand where you would
like to place the mic, don’t put it there! For closer vocal recordings, use a “popper-stopper” type
windscreen to protect the mic from plosive blasts. This mic is designed for indoor recording situations,
although a “big furry windscreen” may be adequate for some outdoor recording situations.

Using the R88

When placing the R88, try to imagine how the position of instruments in front of the microphone will
translate to the stereo image. The “sweet spot” of the R88 is the 90 degree angle found between the
principal axis of each transducer (indicated by channel numbers “1” and “2”). Recording instruments
in this region will ensure the consistency of phase information reaching the microphone. Recording
instruments, or prominent early reflections outside of this region can result in inconsistent phase
information between the channels, which will result an ill-defined and inaccurate stereo image.

In the vertical direction, the best frequency response is obtained within 30 degrees up or down of the
principal pickup axis. When recording an ensemble, try to keep all of the instruments towards the
center of vertical pickup pattern for the most natural sound quality.

The R88’s extended and natural bass response is due to the very low resonance frequency (16 Hz) to
which our ribbons are tuned. However this low resonance frequency also makes the microphone
susceptible to mechanical “rumble” from air conditioning systems, passing trucks, etc. The integrated
shockmount system helps to reduce this noise, but in some cases it may be helpful to use a “low cut”
filter such as those commonly found on quality recording channels to attenuate the very lowest
frequencies, and thereby relieve the strain on amplifiers and speakers that can be caused by subsonic
noise. In most of these cases it is possible to retain the useful bass content of the recording, while
substantially attenuating very low frequency noise.

Like all passive ribbon microphones, the R88 contains minimal internal electronics. This means that
the microphone can operate with very low distortion throughout a huge dynamic range. The SPL
handling of these microphones at 1kHz is greater than 160dB! However the passive design also means
that a large amount of gain is often required at the preamplifier stage. Low preamp noise specs are
desirable, since the preamp will often need to be operated at its highest gain settings. As a starting
point, here are a few specs to look for in a mic preamp to use with your R88:

- Abundant gain (at least 60dB of clean gain, quiet recordings may require up to 70dB)

- Low noise (EIN -127dB or better)

- High input impedance (we suggest at least 1.5 kOhm for good bass performance)

Coincident Stereo Microphone Techniques

The R88 is a coincident stereo microphone system. Coincident microphone techniques use two or
more microphones placed as closely together as possible, but aimed in different directions. Coincident
stereo recording systems have phase coherence between the stereo channels. This means that an
incoming sound wave arrives at roughly the same time to both of the microphone transducers. The R88
may be used with “Blumlein” or “M-S” stereo techniques. There are other stereo recording techniques
generally referred to as spaced stereo techniques, where the microphones used are physically separated
in order to produce timing differences between the microphones.

One advantage of phase coherence is that when listening to a mono sum of the stereo mix, or to a
stereo playback in the “far field,” a phase coherent recording will exhibit much less of the coloration