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December 1994: Volume 3, Number 4


The Annual AES Convention Review

hosted by Stan Lipshitz and John Vanderkooy

Followed by the Christmas Social


AES What's Inside

AES This Month's Meeting Preview

This is your invitation to our Tuesday, December 13, 97th AES CONVENTION REVIEW AND CHRISTMAS SOCIAL, featuring the famed dynamic duo of Drs. Stanley Lipshitz and John Vanderkooy as reviewers, and supporting evidence from other 97th participants, photos and preprints.

Also supplied: ample food, refreshments, loads of car parking space, and unlimited D.I.Y. interaction, (bring a friend) all at the fabled and funky Cherry Beach Sound studio complex, at 16 Munition St.

Take Cherry St. south off the Lakeshore Blvd., (the main Toronto harbor access, just west of where the D.V.P. ends) turn left just after the first Cherry St. bridge, onto Villiers St., then right onto Munition St. Or via Leslie St. south, off the Gardiner Expwy., then west one kilometer on Commissioners St., then north, one block east of Cherry St.

The AES Toronto Section is fortunate to have world-class experts Stanley Lipshitz and John Vanderkooy review advanced audio technologies. John just presented his paper "New Concepts in Pulse-Width Modulation"; it is but the latest in a long series from him, Stan, or both, which advance and optimize the mainstream of audio quantization, dithering, noise shaping, DSP, electro/acoustic measuring technology via MLS, room effects, diffraction effects, psychoacoustics, surround-sound, transducers, to name some.

With this background, most of the 97th technical papers are expertly covered, and a quick explanation of the new technologies will be presented, along with comment on their importance or implications. You'll be encouraged to ask for clarification, as in a professional seminar, which this effectively is. Both Stan and John are very good at explaining difficult concepts... it's been their profession for about 24 years, at the University of Waterloo.

A preview of the technical papers revealed steady progress on various fronts, and one standout new loudspeaker design from Quantum Sound: imagine a 22" long, narrow magnetic motor, differentially driving two 10" by 22" sheets' edges at right angles. The sheets are arranged in a V shape and terminated at their outer edges to a frame of about 16" by 24".

John's PWM paper is also a standout, showing how to configure broadband, high-fidelity, yet cost- effective PWM power amplifiers: a promise unfulfilled for about 30 years. Several combinations of carrier dithering with band-limited noise, precompensation and wideband feedback (as in linear amps) are mathematically and/or experimentally investigated and judged effective.

Stan and John's collaboration dates back to a review of the claims for the Quad 405 amplifier, about 15 years ago, and continues to this day, although the ever-widening audio field of research has forced some individual specialization, particularly in the (somewhat informal) U. of W. Audio Research Group, where Applied Math and Physics students pursue audio-related research under Drs. Lipshitz and Vanderkooy.

The Program for Graduate Work in Physics also demands their attention; it is a shared arrangement between U. of Guelph and U. of W., for physics students and staff. John's PWM paper is one of its outcomes.

At the end of the Review session is an informal question and answer period of indefinite length, due to unfair competition for the audience's attention, via the nostrils. The festivities will start with an offering of scrumptious morsels, wines, beers and soft drinks, leading to lots of real-time Hi Fi 3-D interactivity of the members and guests. No rush, no itinerary, all D.I.Y. Here's your chance to convene a panel of experts, and have an audio trend or problem debated instantly.

If you have any questions regarding the AES, please come and ask. Stan was an AES Governor for years, and President for one year.

by John Fourdraine, Toronto

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AES Editorial

This issue of the Bulletin marks the end of an era, and the beginning of an important milestone which I hope that years from now will seem very trivial, but which is now quite significant.

One should never count their chickens until they hatch, I suppose, but I cannot resist announcing our intention to zoom onto the electronic information super highway beginning with the January issue. And we are not just crossing the road to get to the other side, I may add: we have a useful purpose in mind.

Our first goal is to use a BBS as the means of collecting, editing and proof-reading the information you find in this Bulletin. Hot on the heels of this accomplishment will come the ability of any interested person to download the meeting notice off the BBS, and then, ultimately, the Internet.

The era that is hopefully ending, is that of the days where I receive faxes and documents, some scribbled, some typed, all needing to be transduced into digits by myself or other unfortunate "volunteer" (thanks Anne Reynolds!), and then edited and errantly proof-read, and then sent via painful modem/mongrel com-software to my layout counterpart, Lee White, in Toronto.

We envision a common folder on a BBS, where articles can be uploaded, proof-read, and commented on by interested contributors, a folder that by its nature is available at any weird hour that I might be able to work, and which is as readily accessible by Mr White at a time convenient to him.

Another folder would contain the finished thing, and gone will be the days of waiting for Canada Post to deliver a stale-dated meeting notice. All you will need is a modem (and computer) of some description, and you will be able to access the latest info.

But this is likely just the beginning. Talk to Peter Cook or Glenn Specht about what they think the possibilities are with a computer and a link to the vast electronic web that is the Internet... but we are ahead of ourselves here, at least for the time being.

Or how about finding out just where any given standards committee is at on a given standard that may be of relevance to you. Try to find out about that now, and you will appreciate the almost instant availability of information potential of the Internet.

Details on all of this in the January issue. Stay tuned!

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AES Last Month's Meeting Review


Many highly visible members of Canada's loudspeaker industry were present among an audience of fifty at the Harris Institute for November's meeting to hear Sean Olive and Floyd Toole deliver the results of a new series of experiments in loudspeaker evaluation. Mr. Olive first gave an account of the design and rationale. These tests needed to be run efficiently and produce repeatable results. Subject training was required to enable the correct communication of subjective impressions in an objective way.

A computer-driven test was devised using hard-disk storage for program material, a DSP card, a programmable EQ, power amplifier, and Etymotic ER-4B earphones. Program material consisted of pop, jazz, & classical music, human speech, and pink noise. The task was to determine what equalization had been applied in each of four programs in five experiments. The equalization was either either a 3-dB cut or boost at a variety of centre frequencies and "Q's". Subjects were first given a flat reference and were informed of the results of the tests.

Statistical analysis revealed the single most important factor was the program material used. The wider the bandwidth (as determined by long-term spectral content), the more reliably test subjects could determine applied EQ. Equalization was harder to determine in the closely-spaced mid-band region than at the exteremes and effected by the other EQ's and programs in any given trial. The listener's training enabled them as a grooup to go from a 65% to 80% confidence rating. Sean said there was little doubt the training worked.

In a question period Sean was asked whether the test software would be made generally available and replied that it was mainly to be a shared tool within the Harman group. When asked about broadening the subject base to other nationalities, races, and age groups he said in time these areas would be explored. When asked why there were not as many women in the test population he replied that the listeners were employees of Harman doing the tests on a volunteer basis. Sean also intimated that the women had produced better scores on average than the men.

Floyd Toole then gave his first Toronto section presentation since disappearing south of the border. After a brief description of Harman International, he explained the goals for this co-ordinated listening program to be: competitive product analysis; objective measurement of a subjective phenomenon in order to cut costs and time in product development; and, to produce a better product. The product evaluation broke down into two parts - a blind test and one in which the speakers were visible to the listeners. Speakers for the tests were two high-end Harmon products with a minor difference in their crossover voicing, a competitive high-end name brand speaker of similar type and a relatively inexpensive sub/satellite system. Different listeners were used for the sighted and blind portions. In the blind and sighted listening tests the speaker with the smoothest on/off axis response rated highest, however the sub/sat ratings were adversly effected when visible. Room placement was the third most important factor. A second experiment was performed like the first but using the same listeners. Consistent but different results showed for all speakers. After an initial rating in the sighted tests, a given speaker's ranking di not change much regardless of room position, program material,experience of listener, etc. This led to the conclusion that next to the speaker itself visual identification is the single most important factor. To say the least this is disconcerting upsetting but not entirely unexpected news. Visual sizzle to go with your audio steak.

Mr. Toole was then asked whether this testing approach was viable for pro audio testing. He replied that because of the host of complications in a pro audio system (equalization, room effects) a comparison test would hardly be definitive or controllable. The meeting then broke up in to the usual animated discussions with a new grain of salt to season some opinions and cause to simply shake your head.

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AES Special Features



First of all, I would like to end the furious speculation as to the identity of the teller of last month's inaugural tales. Although Esteemed Editor Earl tried his best to protect my good name, I have decided to spill the beans and admit that yours truly, the Past Chairman, was the perpetrator of those sordid stories. I'm going to give it one more go before opening up the floodgates for the rest of those great yarns that must be floating around out there. If you would like to pass on your favourite audio anecdotes, fax them to me at 416-425-6211 (daytime only) and we can give my stories a rest for a while.

The scene is the original Wayne + Garth rock-on party bar in Scarborough, Ont.; the time is the mid-1970's, New Year's Eve to be exact. Our protagonist has installed a big sound system for a concert by a late '60s American guitar hero, who was one of the discoveries of Woodstock, but, it turned out, had fallen upon hard times.

I suspected something was up when I was asked to provide, not only the PA, stage amps and drums, but also a guitar. To move along the night's festivities, the proprietor of the club had brought in a rent-a-DJ from one of the bigger local services. The sound check and the first set went along almost too well. Imagine my surprise, then, as the second set winds up at about the 20- minute mark when the star, having finished a medley of his hits, loudly announces "Happy New Year!" and disappears... at 10:45 pm.

Oh Dear. Time for Mr. DJ to do his thing while the PA guys tear down... but no. The owner of the DJ service saves money by designing and building all his own electronics, and this phono mixer has definitely gone south for the winter. A call for help yields the fact that many of his other rigs have picked this night to do the same, and we can expect a replacement maybe by 4 AM. All this guy has are vinyl records, and no way my PA has an input with enough gain, EQ and impedance to bring in a turntable.

So there's my crew, huddled behind the mixing board, faced with several hundred screaming, well- lubricated Scarberians and no music EXCEPT... a cassette player and the little box of tapes I drive around with. So we started up the tunes and prayed for closing time... and then we started getting requests. Unfortunately, most of these tapes resembled a collection of Johnny Fever's Faves, and these with-it 70's kids were having a hard time with Buddy Holly and early Grateful Dead.

When, in desperation, I played a bluegrass tune that got them into a John Denver Country Boy mentality, square dancing and hooting, I began to think I might survive the night. Our guitar hero, meanwhile, was last seen at the lobby door of the adjoining motel, mumbling about when the limo was going to show up to take him to his hotel, while his manager was trying to get him to understand that he was sleeping in a motel room just around the back. At least we finally got the guitar back. Our moral for today.. just say no, folks.

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Back in 1948, a newcomer to the Toronto Radio business CHUM Ltd. decided to build its first Live Studios and chose the Mutual St. location where McClear Pathe is now located.

The block of land from Bloor St. to the Waterfront, was owned by the King of England and was first deeded to Samuel P. Jarvis in the 1800's. Samuel P. decided to split it up and sell it off, and this started the first land speculation rush in Toronto. It quickly changed hands two or three times and Thomas McClear, a book-seller, became its owner in 1875. The lane way beside the building, McClear Place, is named after Thomas McClear.

Around the same time as the start up of CHUM, RCA Records started a Recording operation in the Royal York Hotel. With the advent of Television, Radio changed from live broadcast studios to D.J.'s and CHUM no longer needed its studios, whereas RCA was expanding and needed a new home. As a result, in 1954 the Studio changed hands and RCA moved in its 3 input console complete with a "phantom" channel, 5 microphones, and two mono Ampex 300 machines and a Presto lathe.

Over the years, the equipment compliment went from 5 microphones to 150 microphones, mono, stereo, three track, four track, eight track, twelve track, sixteen tracks and finally 24 tracks in 1976. Long forgotten manufacturers such as Presto, Scully, RCA, Ampex and MCI were represented. Another milestone occurred in 1969 when the first large NEVE console (24 inputs/16 buses) was brought to North America and installed at RCA Toronto.

The RCA Studios were sold to McClear Place Studios Ltd. in 1979. McClear Place expanded the studios from 2 to 3 and expanded the mastering department into record, 8 track, cassette and CD premastering for a total of 5 more studios.

In 1990, the company acquired the Pathe film post production studios and renamed itself McClear Pathe. At the same time the mastering department was sold to Lacquer Channel.

Some of the famous names using the studios in the early years included Elizabeth Taylor, Red Skelton, Vincent Price, The Who, BTO, Rosemary Clooney and Mel Torme.

Later on, after reconstruction, people like Gordon Lightfoot, Anne Murray, Ringo Starr, George Carlin, Steve Winwood, Chubby Checker and RUSH have used the facilities.

The studios now boast 56 input, SSL consoles and have the latest 16 track non-linear hard disk recording (tapeless) and editing systems available.

Technology changes, people change and the studios have changed, but they have stayed Toronto's longest running recording studio operation with 46 years of continuous history.

Bob Richards, President

McClear Pathe

a division of The Delarson Group Inc.

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AES What's New

The new office will allow the audio, video and control system design company to provide better service to their Western clients. The company has several Western projects underway, including the Vancouver Civic Theatres, the Vancouver Livent Theatre and Coquitlam Cultural Centre. The new office particulars are:

Fred Gilpin, Engineering Harmonics, 2323 Sentinel Dr, Abottsford, B.C. V2S 5C9

Ph 604/859-8078 Fx 604/859-3068

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Copyright 1994, Audio Engineering Society Toronto Section Bulletin

Articles may be used with the Author's Permission. Contact the Bulletin Editor: earlm@hookup.net

Editor: Earl McCluskie Assistant Editor: Anne Reynolds Layout Editor: Lee White

The Bulletin is prepared in print by Lee White, and on Horizon and the Internet by Earl McCluskie.