Hindsight is a wonderful thing, as we all know. The reason I suggested that THE SORCERER'S APPRENTICE be used in the listening test, was to save Kintek the embarrassment they would surely have suffered had they test been done with the Beethoven 6th symphony, where the steering was just out of control. There was still plenty of time left. Kintek had acknowledged the problem and had asked for more time. Remember, the choice of which processor to use was not mine. I could have kept my mouth shut, but I think that would have been unfair since I knew that the unit was totally unacceptable at that point in time. I also believed that should they fail to cure the problems they were having, they would simply withdraw the unit from the presentation.

This seemed fair to me because the KT-700 was not designed for straight audio processing and they needed time to complete the modifications. When it came time to open the film, the KT-700 was behaving much better. It was decided to use it. But, I was still unsatisfied and would not have used it had it been my decision. I also hated what the surround steering was doing and I made myself clear.

So, yes I did privately regret making the suggestion that saved the KT-700 from certain and early rejection. In hindsight, had I kept quiet I would ultimately have had my preference. If I had it to do again in the same circumstances, I would probably do the same thing and try to be as helpful as possible to the team. It's just the way I work.

So far the customers that install HPS-4000® systems have not elected to use the processors you mentioned. If they had, I would have investigated for them. So, I have not heard those units.

I will say that my complaint with most of the analog processors I have heard, other than Dolby's, is the poor noise reduction decoding. Some of them didn't have adequate equalization.

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First the EQ question: Despite the fact that we don't use much in the way of equalization, what is done requires 1/3 octave adjustments for the screen speakers. No equalization is needed for the surrounds. A 100 HZ low-pass filter is sufficient for the subwoofers.

The acoustic treatment required for the HPS-4000® theatres is an absorptive ceiling and rear wall. In theatres greater than about 37 feet wide, the treatment on the side walls needs to be nothing more than Econopleat with nothing behind it, or its acoustic equivalent. This is to stop high frequency flutter. The relatively hard side walls are good for bass and do not detract from dialog intelligibility due to the vastly superior control we have of the coverage angles from the screen speakers. No absorption is required behind the screen, as there are no meaningful behind-the-screen reflections to absorb. This level of treatment costs about 1/3 rd less per auditorium than what is typically recommended.

We have done historic theatres, that are relatively reverberant by today's standards, with complete success. In fact, some of these installations are among my favorites. Such rooms each have a quality all their own and are very enjoyable for listening to movies. The Tivoli and Arcada theatres outside Chicago come to mind as does the Waikiki #3 in Honolulu. The Carib theatre in Kingston, Jamaica, in its single screen days before a fire, was incredible with big films. The bigger, the better.

Now, I not compairing the two techinally. A properly installed and tuned THX system also sounds great. What I mean is: It seems like if a theater doesn't meet the spec's for an HPS system, you don't get to say HPS approved. If a theater doesn't meet THX spec's, it still might get approved.

Thank you for your comments. Actually, it's zero blown drivers in twenty years. It's something we're pretty proud of.

JFA

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The Tivoli is a theatre about 130 feet long and 86 feet wide. Sometime after the initial installation of the HPS-4000® system in 1982, the old acoustical treatment was removed from the ceiling. This was done because of the condition of the material. The dome is not and has not been a problem. The exposed hard ceiling was detrimental and was the source of acoustic problems until new panels were installed.

Also in 1982, acoustic recommendations were provided by Bolt Beranek and Newman. Among other things, a large heavy curtain was installed across the rear wall, including the rounded corners. This curtain remained until it was replaced with a more decorative treatment during the most recent redecoration and restoration of the theatre which was completed a few years ago. The theatre has in fact undergone a slow but rather complete restoration since I began working there. A freak wind storm once blew away the roof membrane and allowed a massive amount of water into the theatre. This damage has now been repaired. I wish I had a picture of the theatre for you. It looks absolutely beautiful.

I have worked in two large theatres with domes. They can be of benefit for directing sound from live orchestras into the most distant seats. However, these domes did nothing positive or negative for the film sound, as its source was behind the on-stage screen and not in the pit. The pits at these two theatres have the advantage of being out in the auditorium and therefore somewhat underneath the domes.

The Tivoli still hosts live events with live orchestras. Therefore we have left the room more live than most movie theatres. Still, it's a great sounding theatre and the favorite of many. Theatre owners have commented that just the sound coming out of the theatre and into the lobby, is better than the sound in their own theatres.

John F. Allen

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