Q&A # 247 - August 11, 2001

Staff

Q With all the recent concern by existing HDTV owners regarding the announcement by Direct TV and Dish Network that they intend to implement DVI, can you please explain how DVI would effect existing HDTV capable projectors such as the Sony VPL-VW10HT?

A We have that projector here in our lab as a reference, and it is going to be bad news. All the existing HDTVs and projectors have analog inputs only. No DVI. So, what will happen is that the HDTV decoders will output DVI HDTV signals (1080i and 720p) for HDTVs with digital inputs and down-converted 480p analog video signals for the rest, including the 10HT and all the other existing projectors and HDTVs. Nice, huh? Although digital TV will eventually give us very good pictures, it is being implemented as a way for the content providers (movie studios) to control copyright, and it totally disregards the consumers' interests and needs. As I mentioned previously, a class action lawsuit against the entertainment industry is already being prepared, I would assume in the billions of dollars. The studios are basically saying that if the broadcasters don't implement it, then they will not provide content.

The movie industry needs to understand something very basic. They are completely expendable. If farmers don't grow food, we starve. If the water companies don't supply us, we die of thirst. If the garbage companies don't pick up, we die of diseases. If the clothing industry stops producing, we freeze to death. But, if the movie industry stops supplying content, what happens to consumers? Nothing. Absolutely nothing. We can get along without their content just fine, thank you. We can also boycott movies from studios that don't supply content to the broadcasters. But what happens to the studios that don't provide content? The cash register stops ringing.

School teachers are paid a pathetic salary to perform what is probably the most important job on the planet: getting our children ready to perpetuate the human species. But, an actor is paid 20 million dollars to act like a moron in front of a camera. Before TV got so hot, studios buried their old movie films underneath the Los Angeles freeway, where they belonged. Now, they want to give the shaft to 99.99% of the consumers to protect themselves against the other 0.01% who might try to copy their garbage and sell it.

I truly enjoy watching movies and listening to music. It is a great pleasure. But, if the content providers are that selfish, they need to learn who gives orders and who takes orders. And, who pays their salaries.

Q Are there any HDTV monitors planned for fall/winter release that will include the DVI/FireWire interface that will come in under $3,000? Alternatively, can you shed any light on the company that guarantees compatibility?

Ultimately, would you suggest just hunkering down and NOT getting anything this year?

Like a lot of others, I am frustrated that HDTV monitor prices are finally falling to approachable $1500-3000, only to find out that they may have limited functionality. The whole situation is ridiculous.

A I am confident that HDTVs with the DVI interface will appear at or near the time that the broadcasters implement the DVI technology, and those should operate just fine with the content. What is upsetting is the fact that the technology is being implemented as a copyright protection policy, not as something to give us a better picture. Hundreds of millions of dollars have been spent by consumers buying into HDTV, and they will all be compromised by DVI.  They will only be able to get 480p when the broadcaster activates that option in specific programs. It won't be an automatic thing. If a content provider (studio) says it is OK for the analog output to contain 1080i or 720p when movie X or program Y is being broadcast, then it will go through as such. But if the studio says such and such a program is to be restricted to 480p at the analog outputs, then consumers with current HDTVs and projectors will only be able to see 480p, even though it is an HDTV program, because we will only be able to use the analog video outputs of the decoders to our TVs.

Q I'm sort of new in the home theater game, and just bought a Denon AVR 1802 to drive my energy eXL15s and Polk SW 250 sub, and have a Sony S560D DVD player. Right now I'm using all RCA cables for each channel between the receiver and DVD player, but both have optical inputs. Would connecting just the optical inputs to each other replace the need for all the RCA cables? And what other components can I connect the receiver to using optical connections?

A Optical (Toslink) cables are for digital audio, so yes, you can connect the digital output from your DVD player to the optical input on your receiver. This will have your receiver decoding Dolby Digital sound as well as regular CD stereo from discs in your DVD player. Right now, that is about the only thing you can connect with Toslink.

Q I am upgrading my home (a.k.a. limited budget) recording studio for surround sound mixing and DVD-Audio recording. The control room is small so I need to use nearfield monitors. I already have a pair of KRK "Rok Its" for the fronts and one DCM CX17 for the center. I need  advice on the rears and LFE. I'm thinking it'd be best to match all the speakers and so am thinking of getting two more matched KRKs for the rears even though for the money I could probably get better non nearfield speakers. Along that vein should I also replace the center with another KRK just to be sure that what I hear is all flat and true? If I can keep the DCM (it's a better sounding speaker) as center, then I will have a bit more to invest in the LFE: a 12" 120 watt instead of a 8" 50  watt sub. Which brings us to question #2: That bigger isn't necessarily better with subs. Smaller = tighter and larger = sloppy . . . is this true? I have  a homemade 18" I planned to use for the much larger theater space (1100 sg. ft) where flat response is not so critical. The large theater is used for large screen projection of 16  mm and video and, its sound is a later project except in choosing a surround  amp now that can do double duty later. A 500 watt amp is more than enough for the small control room and with pre-outs can send the signals to the larger room which will need much bigger amps and speakers. I've been recommended to use a Denon AV 3801 or better, but my budget constraints are causing me to lean towards the Pioneer 810S. What are the major differences? Am I on the right track with all this?

A I would suggest not worrying too much about the nearfield monitors, because so long as you carefully integrate a subwoofer with proper bass management, you can reproduce the full spectrum, while still taking advantage of more optimal placement that small speakers often provide.

I would also suggest matching the front three speakers exactly. From a recreational standpoint, many people are justified in considering a center speaker with similar tonality "good enough," but the truth is that you're not going to match different models, with different drivers, driver layouts, and crossovers, exactly. Frequency response, power response, and phase response simply cannot match between channels from different physical transducers, different layout and baffle geometry, and different crossover points and slopes. Phase shifts at the crossover regions induce group delays. These group delays, in the mid-range/tweeter crossover region, are fairly small in absolute time, and difficult to notice by themselves. However, when the group delays differ substantially on the first arrival from speaker to speaker, they become more audible, as it can cause a certain frequency range of one speaker to arrive out of phase with that same frequency range of another speaker, which can degrade the image.

Many people are satisfied and completely happy with a "matching" center channel that isn't identical, but just know that it's a substantial compromise.

As for your rear speakers, I'd suggest using the same. Full-range speakers all around are a nice idea, but if you don't have the space, those lower frequencies aren't going to maintain whatever directionality they did have anyway, as they'll be pretty much in the same vicinity no matter what you do. I'd stress going with a good subwoofer. 12" sounds good. Remember though, think quality as well as quantity. I'd rather have a quality 8" subwoofer than a cheap, lousy 15" one. However, that's not to say that a 15" subwoofer can't perform just as well in terms of control as an 8" subwoofer. The whole idea of smaller drivers being "faster" bass transducers is a myth, possibly perpetuated by many people's perception that cutting out some of the really low-frequency content makes the sound "tighter." There are sloppy little subwoofers out there, and there are really fine big ones that play tight, deep, and loud.

Denon makes pretty good receivers, so to start out, I'd go for one of their upper middle models, such as the one you mentioned, or perhaps a slightly less expensive model with an outboard power amplifier, which will run you a little more as a whole package, but put you ahead of the game easily in the end.

Assuming you get a powered subwoofer, if you set your bass management properly for the smaller nearfields, you can ease up the requirements on the receiver and perhaps do well even without an outboard amplifier, as it will redirect bass content below 80 Hz (in the case of Denon THX receivers) to the subwoofer, allowing the receiver, and the speakers, to play cleaner, and louder.

Q What is really the correct 7.1 speaker placement as specified by THX (EX)?

A As specified by THX for EX, there should be three across the front, at the same height, preferably at ear level, with two side channels, dipolar, radiating forward and rear mounted a little on the high side, and two "rear" speakers behind the listener, also dipolar in radiation, radiating sound in a manner perpendicular to the "side" speakers, also a little high. Whether this is "correct" depends on whether the soundtrack was mixed for precisely this arrangement, or whether it's simply trying to emulate a commercial cinema. In the case of the latter, it becomes a matter of interpretation and personal preference.

Q Here's what I have:
A pair Altec Lansing 604b' remagnetized and reconed to "E" by Bill Hanuschak, and fitted with Radian Diaphragms, in 7.25 net cu. ft. furniture grade, glued, screwed, braced and properly vented to an f3 of 38 Hz boxes. Connected with 12 gauge multi stranded copper cable (100 ft for 29.95 from Parts Express). The l/f drivers are powered by a high-end Yam RX 770 with damping factor of 240 and incredibly low distortion (not your typical Pacific Rim stuff). The h/f driver/horns each by its own renewed by Gary Kaufman (new high quality 1% pieces parts, matched quad Sovtec EL34's) monoblocked DYNA ST70. All connectors Radio Shack or equal. My neighbors like my stereo:-).

I notice with this configuration that I can make out an acoustic guitar in a mix of fiddle, string bass, mandolin, banjo, dobro (Alison Krauss + Union Station) much more readily than with the Dynas powering the low frequencies and the Yam on the high frequencies. I am bi-amped with a DBX 223 unit, the only way to go with these Altecs and VOTs. My question is: which amplifier(s) are accounting for this increased clarity and definition? I assumed it was the Yam, but now realize that it might be the Dynas' handling of the overtones that account for it. If it is the Yam, then I might lose the Dynas and get a matching second Yam power amp, realizing that this will not please the "tubes for alnico Altecs" gang. If it is the Dynas, I might lose the Yam and use the Dynas in stereo, one for h/f and one for l/f, at 35 w/ch, which is more than enough. Altecs sound great even at 1 watt. At 35, you might hear God.

A The Dynaco ST-70s have been praised for their classic tube sound. High-efficiency speakers allow low-powered tube amps a lot of leeway, so that you might be getting the best out of them without suffering from their drawbacks, similarly by using the Yamaha amp in the low-frequency section, where tube amps generally suffer, not because of the tubes themselves, but because to keep their output impedance low, and maximize power transfer, they usually require output transformers that themselves tend to limit the low-frequency extension, unless those transformers are really good, which means big, and therefore, expensive. Tube amps, for the most part, tend to have a high output impedance, meaning low damping factor, and tend to suffer in bass performance because of that as well. Also, because of the generally higher output impedance, tube amplifiers tend to "compliment" some speakers better than others by altering their frequency response in reaction to the speaker's impedance. Sometimes this works to our benefit, and sometimes not.

In my own experience, I've found that bi-amping with tubes on the top-end, and a solid-state amp on the bottom, might have some interesting and seductive benefits, but in the end I usually revert to either bi-amping with identical amps, or using simply one amp to push the speaker full-range, as using dissimilar amplifiers tends to compromise the blend between the high and low frequency portions of the speaker.

As to your specific situation, I'd say try running the speakers full-range with both sets of amps, separately, and let us know what your
conclusions are.

Q I have read through most all of the Q&A section and have yet to come across this question. I have a small room, in my basement, for my HT (9 x 12), with no place in the room to set a sub. I do have space to cut a hole into a closet next to the room, the opening will only be 15"H x 15"W x 20"D which can be vented from both sides. My question is could something like the Paradigm PDR-10 work well in this situation, and how much will this effect performance?

A You will get considerable bass loading (an increase in the bass) from the wall where the speaker opening is. It might actually improve the performance, in which case you could turn down the subwoofer volume control and take advantage of it. I don't see any particular problem with this, except that you might have a peak somewhere in the low frequencies that you have to tame with EQ.

Q With my new Denon 5800, I have DTS ES 7 channel and DD EX 6 channel sound output options. My questions is what basic type of speaker would be best to use for the rear channel, direct radiating or maybe dipole, tripole? I use dipoles now for the side surrounds.

A It will depend on how close your couch is to the rear speakers, since they have to be behind it. If they are on stands right behind the couch, then probably dipoles facing sideways. If they are on the rear ceiling pointing down at the couch, then perhaps direct radiating or dipolar. Since you already have dipolar on the side, then probably dipolar in the rear too. See one of the above questions and answers on the THX specification for 7.1.

� Copyright 2001 Secrets of Home Theater & High Fidelity
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