May 1999. Before I begin, let me volunteer that I don't work for nor do I hold any stock in any of the companies whose products I chose and recommend. This is not an advertisement. It's the story of what drifted through my head as I tried to find equipment that offered the best performance I could afford and which also offered the best value. Okay, as I step off the soapbox, let's start with...

The Screen

I'm surprised at how little attention has been given to this vital component. There seems to be endless debate over the merits of one $300 per foot cable as compared to another (more about cables in another chapter), yet the screen ranks second only to the projector as the one component that affects the quality of the image. You must choose wisely.

To get my peripheral vision involved, I tend to sit up front at the motion picture theater. I remember the first time I saw the sequence in The Empire Strikes Back when a rebel patrol is searching for Luke and Han lost on Hoth's desolate ice. Their snow speeders follow the terrain, plunging into valleys and pulling up over ridges. I could feel it in the pit of my stomach. (An even more dramatic example of sensory deception on film is the 360-degree, nine-screen format used at Disney theme parks. When the camera plane banks and the image tilts, there's a tendency to want to fall over. Cool.) I'm sure you've noticed that a large image draws you into the film, involves you emotionally, and makes the experience more complete. So for my home theater, I wanted to push for the largest image possible, just approaching the threshold where distracting video annoyances, like visible scan lines, are about to become visible.

During my visits to the Consumer Electronics Show, I'd seen early efforts by the Japanese video industry to bring analog HDTV to the marketplace. And as I mentioned in the previous chapter, I had seen demonstrations of line doublers and the outstanding Faroudja in particular. From these demos, I learned that a viewing angle as high as 40 degrees looks very good. For comparison with conventional NTSC, 30 degrees is about as high as you can go before line structure becomes annoyingly visible. (For a brief description of how I measure and compare screen widths in Ramers, have a look at part one of A Brief Visit to Region 2.) I felt that HDTV and its 16x9 aspect ratio were inevitable. And I knew from experience that front projection offered higher definition and better contrast ratio than rear projection.

So I quickly narrowed my screen choices to one that would be eight feet wide by four and one-half feet high (16x9 aspect ratio). For that width and a 40-degree or so field-of-view, the viewing distance would be ten to twelve feet. (Unfortunately, to get your peripheral vision really involved takes a field-of-view of at least 60 degrees.) Since my theater would be in a dedicated room, I didn't have to hide the screen when not in use.

This permitted me to focus on a screen (no pun intended) that was highly tensioned and rigidly attached to the wall, ensuring that no resolution-robbing screen movement would occur. Screen gain (most simply thought of as a measurement of how much light is reflected) was not an issue since the room would be windowless and the lighting strictly controlled. This allowed me to select a modest gain of 1.3, which would eliminate any possibility of hot spots (small areas of seemingly higher brightness).

Finally, during a last minute and very helpful chat with the kind folks at Stewart Filmscreen Corporation, I discovered that the reflective materials used to coat various types of screens are designed to have very specific spectral reflectivity (how they reflect back each color of the spectrum). So a screen designed for film projection would have a different spectral reflectivity than a screen designed for video projection. Use the right screen and a video projection of film will look more film-like. So the winner is the Stewart StudioTek 130. I had nearly ordered the wrong screen.

The Projector

The projector is next. As one of the largest investments in my system, I wanted it to last; it must be able to take me to the next stage of video technology, HDTV. At the time I started investigating projectors, hints of high definition horizontal and vertical scan rates for the emerging digital TV standards began to appear. I knew the rates for the Japanese analog system, and the new digital system seemed to be slightly slower. And I was planning to install a line doubler, which also has higher scan rates. (Note that when I started this quest, DVD had yet to be introduced, so no consideration was given to the format. Fortunately, HDTV is more difficult to reproduce, so I lucked out.) High scan rates and bandwidths, the ability to modify the projected aspect ratio to 16x9, and high spatial resolution very quickly eliminated any technology but the good old Cathode Ray Tube (CRT).

A Liquid Crystal Projector - a system in which intense light is cast through a small LCD panel similar to those found in portable computers - simply didn't have the resolution required for HDTV. And LCD projectors suffer from poor contrast ratio since full black on the LCD panel is never completely opaque. Digital Light Processing (DLP) projectors that use a tiny array of micro-mirrors on a Digital Micromirror Device (DMD) have better contrast, but still don't offer HDTV resolution. Early LCD projectors weren't capable of a true 16x9 enhanced video mode either.

This has since changed with the introduction of several models, including the fine Sony VPL-W400Q. (I had the opportunity to A/B test the Sony in my theater; while it's the best looking NTSC LCD projector I've seen, it still can't compete with a good CRT projector.) Not available at the time, even the most recently introduced technology, flat-panel Plasma displays, suffer from the screen-door effect in which you can perceive the presence of individual pixels, and also suffer from lower resolution and lower contrast than CRT, something I observed first hand at Harrods.

A conventional CRT projector designed for the NTSC television system will support a tad under 16,000 horizontal scan lines each second, and a tad under 30 frames per second, divided into two interlaced fields. (Interlacing is when the odd numbered horizontal scan lines are written to the screen first, then the even numbered lines are written to complete the frame. This process is repeated about 30 time each second.) When a line doubler converts interlace to progressive scan (in which all the lines are sequentially written to the screen), it literally doubles the horizontal scan frequency; the frame rate remains the same.

The highest spatial resolution HDTV format currently planned for broadcast writes 1080 interlaced horizontal lines to the screen about 30 times a second (1080I 30), or about 32,400 scan lines per second. The highest temporal resolution HDTV format currently planned for broadcast writes 720 progressive horizontal lines about 60 times each second (720P60), or about 43,200 lines per second. So the projector must keep up with a horizontal sync rate of over 43,200 Hz and a vertical sync rate of 60 Hz. But, sigh, it gets more complicated. The time it takes to move the electron beam (that causes the phosphors to emit light) from the end of one scan line to the beginning of the next is the horizontal retrace time.

The time it takes to move the beam from the bottom of one field or frame to the top of the next field or frame is the vertical retrace time. HDTV requires that these movements take place within very specific maximum times, so the projector has to satisfy those requirements as well. And since HDTV has a higher video bandwidth (how rapidly light intensities change during each horizontal scan), that specification must be satisfied.

Clearly, a data-grade or graphics-grade projector is required. Such projectors are available with both 8-inch and 9-inch tubes. The conventional wisdom is that to reproduce the finest detail 1080I HDTV has to offer, 9-inch CRTs are required to limit the spot size as compared to the image size. Alas, my budget simply couldn't support the larger tubes, so I compromised. My HDTV images will be a little soft.

Now, remember my mentioning the screen's spectral reflectivity? It affects the color. Well, so do the phosphors inside the CRTs. Years ago, my very first projector was the first model produced by Kloss Video. Henry Kloss (the founder of Cambridge SoundWorks, a cofounder of Advent, the K in KLH, and a very early participant at Acoustic Research) loved projection TV; and, he was very particular about color fidelity. To achieve a pleasingly accurate green, he was forced to select a phosphor that decayed more slowly (how quickly a phosphor stops emitting light after the electron beam turns off) than his red and blue phosphors.

As a result, a white object moving against a black background would suffer from a slight comet-like green tail. So now we get into esthetics (and ultimately, your ability to adjust color balance for maximum visual fidelity). Look carefully at your projection candidates. Investigate thoroughly. When I did (and when I looked in my wallet), I decided that the NEC 6PG with the Digital Point Convergence option was my best bet. (Digital Point Convergence divides the screen into many small zones where independent control of the geometry of the three colors is possible - this makes for a more accurate video convergence and a clearer picture.) If I remember correctly, this NEC chassis used by Runco for some of its models. And along with its sister model, the NEC 9PG, may still be available as used and reconditioned.

The Line Doubler

Whew, over 1,600 words and all I've managed to touch upon are screens and projectors. Let me pick up the pace. The line doubler was a no-brainer. From the evidence of my eyes and from the literature, the Faroudja LD-100 was the clear choice. (The obsolete model number reveals the time frame for those of you who are familiar with the product line.) Yves Faroudja's unique (and patented) processes transform video into the most film-like video images I've seen. My guests have commented that the picture quality of line-doubled 16x9 enhanced DVDs on my system look better than projected film at our local multiplex. So despite the sad fact that the Faroudja cost me more than the NEC, it was well worth the investment. I vaguely recall that NEC may have licensed Faroudja technology for its more affordable line doubler. And used Faroudja LD-100s are readily available at a fraction of their new cost. More current models at a higher premium are also available. (Note: a line doubler typically drives a projector with five signals: Red, Green, Blue, Horizontal Sync or Drive, and Vertical Sync or Drive. Some projectors accept such signals. Some expect Sync on Green. Take care that the line doubler and projector are compatible.)

The DVD Player

As for DVD, I can be counted among the early adopters. As soon as DVD players became available in the seven test cities, I rented a Toshiba and some discs. I eagerly connected the player directly to the line doubler, which had been set up with the screen and projector in a temporary room while I was planning the theater. As you'd expect, I was very, very impressed. And I was absolutely delighted that a format whose quality pushed my equipment would be available before HDTV was broadcast. Having previously read reviews describing the Sony DVP-S7000 as a reference quality player, I placed my order that same day. The backordered Sony wouldn't arrive for three months.

The Speakers

For me, the speakers (unquestionably a matter of taste) were an easy choice as well. When I was working my way through engineering undergraduate and graduate schools, I worked one summer for Stewart Hegeman, the man responsible for introducing wideband electronic design to home audio with his Harmon Kardon Citation components (I seem to be giving my age away). He also hand-fabricated some of the finest (and largest) loudspeakers of their day, the Hegeman Pros. That summer, he taught me how to assemble the Pro and how to fine-tune it with instruments and, more importantly, through analytical listening. (Another fringe benefit was his allowing me to fabricate a pair of Pros for home.) To this day, I'm amazed that with the right training, anyone with good hearing can perceive, for example, such subtleties as a 4 kHz peak in a speaker's frequency response. So it didn't take much critical listening to convince me that M&K speakers were most satisfying for me. The question then became which models?

I selected the S-150THX speakers for the left, center, and right channels. Excellent accuracy, low distortion even at high volumes, great balance, very smooth, and they were designed to limit vertical dispersion while maximizing horizontal dispersion (a very important and appropriate THX requirement). Dispersion translation: the sound is projected over a wide horizontal angle to reach each member of the audience with minimal variations in frequency response, even for those viewers seated off-axis. The amount of sound cast down toward the floor and up toward the ceiling is minimized to reduce reflections that would harm dialog intelligibility and clarity.

For the surrounds, I chose the SS-150 Tripoles, timbre matched to the front speakers and definitely not THX approved. At the time, THX had established surround speaker specifications based on Dolby Surround. The goal was a diffuse sound field that would avoid localization of surround effects. THX even went so far as to design and specify a circuit for THX approved Pro-Logic decoders to process the monaural surround signal to "decorrelate" the two back channels for a more diffuse surround sound field. But DVD offers discrete rear channels with Dolby Digital (and later, DTS), so to my taste, localization is preferred. Tripoles cast sound forward, back, and to the side toward the audience. So they provide both localized sound and diffuse sound. (Diffuse sound also helps with the problem of intensity varying with listener distance, but more about that in the next chapter.)

For the subwoofer, I chose the MX-200. Well matched to the rest of the speakers, sufficiently powerful, deep bass extension, and more affordable than M&K's THX approved subwoofers. Very important for my design, there were no backfiring, downward-firing, or side-firing tuned ports or drivers on the three front loudspeakers or subwoofer; all sound emanated from the front of each of those speakers. This was critical for the flush mounting technique I had planned.

The Integrated Components

There are many integrated decoder/amplifiers on the market. And there are quite a few stand-alone decoders, some rather exotic. But film is not high-end audio; esoteric components need not apply. I believe in separating the power amplifiers from the decoder/preamp. It improves reliability (less internal heat), and plays on the strengths of the manufacturers. (Amplifier designers aren't necessarily your best decoder designers and vice-versa.) I wanted a decoder/preamp that would switch S-video sources, accept an optical or coax digital-audio bitstream, and decode the digital audio with high reliability and accuracy. I did not want any room simulations (artificial reverberation to recreate large spaces, like concert halls); they weren't needed and would inflate the cost.

And I wanted to avoid onscreen menus. (I don't want to have my view of a film spoiled by some graphic if I simply choose to increase the volume. Besides, I don't ever remember seeing an onscreen display at my local movie theater.) B&K specializes in signal processing. Their decoders are first rate and straight forward. They include Pro-Logic and Dolby Digital (and DTS for more cost). They are timely and accommodating when it comes to upgrades. I chose the B&K AVP-2030 (which I have since had upgraded to the AVP-3090 by adding DTS decoding capability). Excellent unit, great sound.

Before Bob Carver moved on to start Sunfire, he founded a company that bore his name. He developed and patented several unique circuit topologies while there. His amplifiers consistently drew praise for sound quality and, of course, measured well. I chose the THX approved Carver AV-705x five-channel amplifier. (The M&K subwoofer has an integrated 200-watt amplifier.) With 125 watts per channel, and even more power available for isolated channels with its power steering circuitry, there should be more than enough power to drive the M&Ks to distraction.

Room Acoustics and The Equalizer

Finally, there's the issue of room acoustics as they interact with the loudspeakers. No matter how clever the room designer, no matter how clever the speaker designer, there will be variations in frequency response as room boundaries cause sound reflections to interact. Some parts of the audible spectrum will cancel while other parts will be reinforced. This will add bumps and dips to the in-room frequency response. To minimize these effects, electronic equalizers are placed between the decoder's analog outputs and the amplifier's inputs. To adjust equalizers properly requires a pink noise source, a calibrated microphone, and a third-octave band analyzer (more about those in a coming chapter). But equalizers can cause as many problems as they solve.

The most common equalizer is the graphic type, with banks of fixed-frequency octave-band, third-octave band, or tenth-octave band filters. But here's the rub. All such filters take time to stimulate and take time to calm down. This relates to a filter's Q, which is an indication of narrowness. The narrower a filter is, the higher the Q, and the longer it takes for the output level to build up to the input level. It takes roughly Q cycles. So a 100 Hz burst at the input of a filter with a Q of ten and a gain of one would take about one tenth of a second (10 divided by 100) before the output rises to the level of the input. Similarly, when the 100 Hz signal abruptly stops, it would take about a tenth of a second for the filter's output to decay. This unfortunate characteristic has a tendency to destroy transient response and adversely affects intelligibility. And the filters' center frequencies are never exactly where you need them.

The solution (I should say the best compromise) is a parametric equalizer, a bank of parametric filters. The center frequency, filter width, and gain of a parametric filter are all independently adjustable. So each filter can be adjusted to be the exact compliment of a room problem. And since acoustical problems worth pursuing are spectrally fairly broad, low-Q filters that minimize delay and decay problems (in what is called the time domain) can be used.

Over a decade ago, I designed such an equalizer for a client in Germany (I wish I had saved more parts - the product is not in production). So I naively expected such equalizers to be readily available on the American market. How wrong I was. There are no consumer-grade parametric equalizers available. Only after considerable searching did I find a manufacturer of professional audio equipment that offered such a unit: Symetrix Audio. Their model 551E is monaural, so at least five would be needed. I initially assumed that by manipulating the subwoofer's level and crossover, I'd be able to sufficiently tune that speaker's room response. We'll see.

Coming In Part Two

Next up in Part Two, the room's design. Or, How to Avoid Divorce or Eviction.

(If you have any questions or comments for the author, say hello to Mr. Blandings here.)