Electronic Design

Bob's Mailbox

Dear Bob:
I couldn't ignore the letter from S.J. regarding digital projection in cinemas (electronic design, July 24, p. 139). It's true that film can deliver excellent dynamic range and resolution. But, in the real world, this doesn't happen unless the image is static and projected from a single frame of film. Conventional film projection suffers from scratches and dust (especially after multiple showings), as well as from a loss of definition and contrast caused by multiple-generation copying.

Add to this the fact that on successive frames the film may be in different positions in the projector mechanism (in all three axes). So, the apparent high resolution of the film starts to become less relevant. Not only is the film analog, but so is the projection method. In reality we see that grain detail is lost by duplication and then it's blurred in three dimensions—x (weave), y (jitter), and z (focus flutter).

To many people, the digital version is the more watchable with much greater image stability, better coloration, excellent resolution, and zero blemishes. I know that "zero blemishes" is a digital artifact, but it's one that I'm happy to live with. Most people who have seen this technology in action rate it consistently better than the traditional film-based projection.

Recently, I had the good fortune of seeing both film and digital versions of Toy Story 2. I cannot wait for more film producers and cinemas to adopt this technology. I say this both as a film lover and as an engineer who loves things analog, rather than as an employee of any particular company.
Leslie F. Mable
via e-mail

Hello, Leslie. Well, YOU find that digital movies look better, but it seems that not everybody feels the same. Remember when CDs first came out? Many people said that music on CD's was better—just fine. But the people that don't like it, and CAN hear a difference, are very bitter and strong in their condemnation of the drawbacks of CD's for music. THEY have kept their vinyl records (as have I). It looks as though we are in for another (digitized) love-hate experience. Besides, if you see a REAL movie, with some REAL cinematography and not just some digitally generated cartoons, then the ANALOG movie might look a LOT better! Gotta make a reasonable test!—RAP

Hello Bob:
Just read your article on water in the house (electronic design Aug. 7, p. 134). Over here in Europe, we don't see this problem. Why? Because in Europe, the rain gutters have a semicircular profile (like a U). Perhaps someone many years ago already found your problem/solution? The U profile, however, is harder to connect and mount.
Anders Boecher
via e-mail

In the USA, some rain gutters are half-round, but rectangular ones are much more popular DESPITE their drawbacks! —RAP

Dear Bob:
If I may, I'd like to return to the esoteric audio thread that has been a feature of your mailbox. I'm actually reading the June 26 issue right now, but I'm a bit behind with things. I, for one, found that the biggest improvement I ever made to my home-designed and built system was to stop reading the hi-fi magazines. \\[Is that anything like "The Sudden Cessation of Stupidity???" /rap\\]

Most of my system's drawbacks were merely psychosomatic ills which went away when there was no one to point them out, and I saved money too. Twenty three years later, my unassuming power-amplifier design is still giving good service—good enough for me and my family, anyway.

About 15 years ago, I went for a job interview with one of the U.K.'s most highly regarded hi-fi manufacturers. In their listening room, I correctly identified the differences between variously tweaked pieces of equipment. But, I wouldn't have cared which one I used every day. Eventually they decided that because I was a musician, I might be tempted to actually listen to the music being played rather than the equipment itself (SIN! That isn't what we make this stuff for!), and I didn't get the job. \\[THAT is so funny that it's SAD!!! /rap\\]

So, although exotic components can make a difference, it doesn't mean that there's no scientific reason behind it. And it doesn't mean that one is necessarily better than another. The differences in production values and the equipment used to make a particular recording always far outweigh the tiny subtleties which the hi-fi nuts seem to focus on. To echo another correspondent in that issue, don't throw out the baby with the bath water!
Peter Maydew
via e-mail

Thanks for the thoughtful comments and Best Regards! But I bet that you STILL can't hear any difference between different SPEAKER CABLES!—RAP

Note: If you send an e-mail to rap right now, you will only get an Autoreply saying that Bob is hiking somewhere above 17,000 feet. But if you leave your e-mail return address with a request for "minireport," Bob will send you his minireport on his trek, as soon as he gets home. How does it feel, to come down to 13,000 feet after a couple weeks above 14? We shall see! Ten people are on the trek, including five guys returning to Nepal and five newbies; three women and seven men; eight engineers and two sane people.

All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
[email protected]:

Mail Stop D2597A
National Semiconductor
P.O. Box 58090
Santa Clara, CA 95052-8090

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