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Pre-meeting "Dutch Treat" dinner, 6:00 pm at On the Rocks Restaurant, 169 Front Street East (near S.W. corner of Sherbourne & Front)
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Ferrofluids are becoming more and more an integral part of speaker design. Incorporated into the voice coil gap, ferrofluids provide a range of benefits including heat transfer, damping, centering, lubrication and sealing.
The early use of ferrofluids was primarily in hi-fi systems, and was further restricted to modifying only tweeter response. Today, however, ferrofluids are used in more demanding applications such as pro-sound and automotive systems, and include performance enhancements for full ranges, midranges, woofers, and compression drivers. New ferrofluids were developed with wide temperature capabilities, low evaporation rates and a unique combination of magnetization and vicosity values to meet requirements of new markets.
The subject of this presentation is to elaborate on advancements made in audio grade ferrofluids. Some experimental test data will be presented on the performance of these new fluids in various drivers.
The presentation will be given by Barry D Moskowitz. Mr Moskowitz is the Vice President and General Manager of the Fluids Technology Division. He has previously been the Marketing Manager for the ferrofluids product area and Product Manager for Ferrofluidics Corporations' viscous inertia damper product line. He has had responsibility for several other areas within Ferrofluidics Corporation as well. His experience also includes leading a small electronic company which manufactured status displays and interconect verifiers for printed circuit boards. In addition, he has a B.S. in Biomedical Engineering from Boston University and M.B.A from New Hampshire College.
AES
EXECUTIVE COMMITTEE NOMINATIONS:
Currently, the Chairman also stores and sets up the P.A. system for each meeting.
The Vice-Chairman of the Section is more than a stand-in for the Chairman in case of absence: he or she must become familiar with the responsibilities of the Chair, as traditionally in our section, the Vice-Chair normally becomes the Chair in the following year. He also assists other members of the Executive Committee if they are temporarily overloaded.
The Vice-Chairman also is responsible for the coffee machine at each meeting.
The Secretary actually does very little typing, if any at all. This person's primary responsibility has been to prepare and organize the mailing of the section notices (we use a mailing service!). He or she also looks after any official correspondence on behalf of the Section, and any other paperwork required for running the Section.
The Secretary also makes certain that an overhead projector is available if needed.
The Treasurer prepares a fiscal year budget in accordance to the requirements determined by the Executive, and maintains the financial accounts of the Section, including issuing cheques for Section expenses.
The Treasurer has in the past brought the donuts to each meeting, although the current Treasurer edits this newsletter, and has been happily relieved of the donut duty.
The Toronto Section has two additional Executive positions which serve an important function as the section continues to grow.
The Membership Secretary maintains an accurate membership database of Section members, and ensures that AES New York is kept informed of any changes. Since the creation of this position two years ago, we now feel that our database accurately reflects our membership... something we could not have been confident about previously.
The Public Relations Secretary position is currently being developed. This job will entail keeping national audio and music media informed of AES Section events which may be of interest to them.
Just as important as the defined positions are the Committee Members. While each formal position ensures that the Section can function in a co-ordinated manner, it is the combined contributions of each member of the committee that makes each meeting possible. Committee Members usually fill the Executive positions as they become vacant.
The Toronto Section of the Audio Engineering Society has in recent years become increasingly active, with more and more involvement from a committed and enthusiastic committee.
In September of 1991, it hosted the AES conference Overview II. Prior to that, it has hosted an AES digital symposium and Overview I.
Meeting events have included tours of audio production facilities in the Toronto area, including the CBC Broadcast Centre during its initial construction phases, the Skydome, numerous recording studios and radio stations.
Guest speakers have given presentations on topics ranging from loudspeaker technologies, digital audio implementations through to noteworthy product introductions.
AnnouncementsThe AES Educational Foundation, created to encourage talented students to enter the various fields of audio engineering, each year awards grants for graduate university studies. The winners are selected on the basis of demonstrated past interest.
Six grants to new recipients have been awarded this year: Scott Bittle, MSEE program, California State University in Chico; Dominique Cheenne, Ph. D. program in Auditorium Acoustics, University of Nebraska; Richard Humphries, graduate program in Audio Technology, American University; Glenn Josefiak, graduate music engineering program, University of Miami; Janusz Stanislaw Masztalerz, candidate for diploma in Sonology, Royal Conservatory in the Netherland; John McLean White III, working towards Ph. D. in Digital Audio Signal Processing.
The AES Eductional Foundation was created to provide a viable means of encouraging talented students to enter the various fields of audio engineering.
Grants for graduate university studies are awarded annually.
New members, especially executive, are always welcome! We are always looking for new faces, and for new ideas.
If you are interested, contact our chairman Dan Mombourquette, at (519) 748-2780, or send us a MiniDisc, announcing your intentions!
According to Chris Plunkett at AES New York, your AES membership dues must now be paid either with a cheque drawn on a U.S. account, or with a major credit card (VISA, MasterCard or American Express).
At this time, we understand that AES is not accepting any money orders or cheques drawn on non-U.S. accounts.
The date and venue for the 1993 95th Convention have been set. They are Thursday through Sunday, October 7-10, 1993 at the Javits Convention Centre in New York. In the past, the fall New York convention has been held at the Hilton. The new facility is necessary for increased space requirements, and to accomodate new dates.
"We simply outgrew the Hilton," said Leonard Feldman, 95th Convention Chairman. "Also, we wanted dates that would include a weekend, meaning lower overall and move-in/move-out cost for exhibitors, which the Hilton could not provide. Lastly, we wanted attendees to have a weekend stay to benefit from reduced air fares."
Henry Zmijak is the newest member of the AES Toronto Section.
Henry is Head of Sound for the Canadian touring production of Andrew Lloyd Weber's Phantom of the Opera. A graduate of the Music Industry Arts program at Fanshawe College in London, Ontario, Henry has worked as Sound Man for many theatre productions including Weber's Cats.
If you have a tendency (ahem!) to overdrive your home, studio or PA loudspeaker system, and perhaps even have destroyed some drivers, crossovers or amplifiers, you probably wish that there was a way to protect your system from your over-indulgences!
Many speaker protection devices introduce some characteristic of their own to the signal path, or are ineffective, or activate too easily, even when the signal present can do no harm.
Most speakers can handle short powerful transient bursts (within reason!) but have trouble when the durations of these bursts exceed their thermal capabilities. A speaker protection device should allow the shorter transients, but control those of longer duration.
We feel that the ideal place for a speaker protection unit is between the preamplifier and the amplifier. Acting as a soft-knee power limiter, the device is wired to monitor the output of the amplifier with a threshold set so that at a user-defined power threshold, it begins to attenuate the signal going into the amplifier.
To accurately calculate and adjust the power threshold, you need to know the impedance and maximum real-life power limit for your speaker load.
Since the insertion loss resulting from such a device is before the amplifier, there is no effect on the amplifier's damping factor. And since control is achieved through the use of optical isolators, any possibility of destructive feedback is eliminated.
The effect on the signal as you increase the preamplifier gain past the protection threshold will sound like a very transparent power limiting.
This is, of course, no longer a true representation of the input signal, but neither will it destroy the speakers!
In Cambridge, Earl McCluskie and in Toronto, Denis Tremblay
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Copyright 1993, Audio Engineering Society Toronto
Section BulletinArticles may be used with the Author's Permission. Contact the Bulletin Editor: earlm@hookup.net
Editor: Earl McCluskie
The Bulletin is prepared in print and on Horizons and the Internet by Earl McCluskie.
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