reported
by: Dr. Roland K C Tan
Secretary (Term
1995/96)
On Thursday morning,
March 28, 1996, an audience of 83 audio professionals as well as
recording engineers, including AES members, gathered at The Novotel
Orchid's Aerides Function Room, Singapore. It was a full day seminar on
"Studio Microphones and Response in Acoustic Environments" that stretched
from 10am right up till 5.30pm in the evening. Mr. Benedict Chng,
Marketing Manager of AUVI (S) Pte Ltd, first gave an opening address and
then introduced the speaker, Mr. Juergen Wahl of Neumann, USA.
Wahl, a technical specialist in microphones, is also a member of the
AES and chairman of the Los Angeles Section.
| With the aid of
his interactive multimedia presentation software package, Wahl
had never failed in a single moment to capture his audience's attention
for almost 8 hours! The topics he had covered ranged from studio
microphones to acoustic behaviour in different recording environment.
Wahl stressed the importance of using a good quality microphone by
all pro-recording engineers in order to ensure a high quality output.
This, he highlighted, was equally important to amateur recording
engineers since a higher tolerance level to errors due to poor miking
technique was possible with better quality microphones. |
Juergen giving
a few tips on mic placement, such as recording in rooms with
reverberation using the Allen Sides' Mic Cabinet (1995) software package
on CD-ROM - photograph by Dr. Roland K. C.
Tan. |
Wahl proved his point by
elaborating further on the nature of the directivity patterns emitted from
different musical instruments. The emission patterns were not uniformly
distributed across the whole audible frequency spectrum. Therefore,
determination of the best microphone location during recording had always
been extremely difficult. As such, microphones have been often placed out of
the high frequency range.
|
Interested
audience listens to Juergen Wahl discussing studio microphones and
response in acoustic environment - photograph
by Dr. Roland K. C. Tan. |
Besides a good grasp of its
frequency & dynamic range characteristics of all musical instruments in
order to produce good sound recordings, the ability to choose the right
microphone was equally essential. Wahl reminded the audience that
there was no such thing as a general purpose microphone where one could
simply choose to suit all types of applications. At this point, Wahl
delved a bit deeper into the subject explaining the different types of
microphone technology available. He described the carbon, ribbon, dynamic,
and condenser microphones and then compared its pros and cons. By
understanding the characteristics together with the characteristics of the
sound source, a better decision in terms of choosing the right microphone
for the right job could be achieved.
For example, a condenser
microphone, although highly sensitive, had a wide dynamic range and good
transient response characteristics, was subjected to bad weather and
temperature. At the same time, its performance could deteriorate further due
the presence of smoke particles!
An omni directional pressure
microphone does not remain truly omni with a wide frequency band sound
source due to the size of the diaphragm. On the other hand, there was no
such thing as a microphone that exhibits a completely cardioid pattern
characteristic. Using the white board, Wahl illustrated clearly how
the low and high frequency sound waves travelled on-axis as well as off-axis
towards the diaphragm of a microphone. A small diaphragm pressure microphone
gave a rathergood performance for both high and low frequency sound sources
travelling on-axis towards the diaphragm. However, for sound with wavelength
that was smaller compared to the diameter of the diaphragm (basically the
higher frequency component) and arriving off-axis, the efficiency was
reduced due to cancellation of the pressure at the surface of the
diaphragm. Therefore, the polar response of the microphone was no longer
omni in direction. In fact, it behaved more like a cardioid microphone.
Wahl also gave quite a few
tips on miking techniques such as doing recording in room with
reverberation. This was a trade-off between adopting a close proximity from
the microphone to the sound source to avoid reverberation, or vice-versa, to
include room ambience effect for a more 'artistic' result. The choice
between selecting an omni or cardioid pattern microphone would be immaterial
for rooms without reverberation (eg. an anechoic chamber).
|
Juergen Wahl
(left) with AES Secretary (Term 1995/96), Dr. Roland K.C. Tan together
during lunch break - photograph by Ms.
Cecilia Tay. |
It was important to have
microphones with a wide dynamic range of up to 120 dB. This allowed more
tolerance to human errors during recording, varying environmental
conditions, and more headroom. This was also in anticipation for future
higher resolution digital audio recording standard above 16-bit. Wahl
continued by demonstrating a few recording tips with various microphones
on different musical instruments using the Allen Sides' Mic Cabinet
(1995©) software package on CD-ROM. |
As part of his presentation,
Wahl further aroused his audience's interest by giving a sound
demonstration of a string quartet classical music recording using the
Neumann model CMV3 microphone. That was the first condenser microphone built
in 1927. There were also video clips on stage performance recordings. One of
these was the film reproduction of "The King and I" showing a live recording
of Julie Andrew's singing over a Neumann model U47 vacuum tube
microphone. The day ended with an interesting video documentary of the
history of Neumann from 1928 to 1938 plus some of their earlier products to
their latest model M149 tube dual-diaphragm microphone with switchable polar
patterns.
AES members and the rest of the
audience had certainly gained a lot from this very informative and
enlightening seminar. Wahl had left a deep impression among the
audience with his enthusiasm, passion, and good knowledge in microphones.
Moreover with Wahl's humorous and friendly personality, this event
shall always remain as one of the most enjoyable and interesting audio
events in Singapore.
The Singapore Section would also
like to express their thanks to AUVI (S) Pte Ltd and Sennheiser Electronic
Asia Pte Ltd for sponsoring the event plus the sumptuous buffet lunch and
tea-breaks. |
