Q&A # 154 - December 29, 1999

Staff

Q I have an AIWA AVX-120 AV receiver, and I just purchased a Magnavox DVD player. I am having a heck of a time trying to get my Mitsubishi HS-U510 to record from the DVD player/AV receiver via the external audio/video inputs. If I try to connect the output of the AV receiver to the VCR, the picture quality is very poor. It won't sync up and the contrast/brightness is bad. It's like the video signal is too low. It is a little better if I go directly from the DVD player to the VCR, but the contrast and brightness vary on the video signal. Again, it appears as if the VCR does not have a very sensitive input. I'm trying to get the specs on the VCR input because the manual does not specify them. The DVD and AV receiver have video output signals of 1 Volt Peak-Peak. Have you ever heard of other people running into this problem?

A You are experiencing the copy protection that is present on all DVDs. Since DVDs are digital, Hollywood is paranoid about making it easy for anyone to copy them because the copies would be perfect when performed in the digital domain (such as DVD to DVD-R, or DVD to digital VCR, or DVD to the Internet). DVD Audio has been put on hold because someone broke the copy protection code. Hollywood is suing 500 websites that distributed the code-breaking software. But, think of it this way: DVD is so good, a taped copy is almost unwatchable by comparison. Also, you can't put the DD or DTS on tape anyway, even if the copy protection were not there. Third, most new movies are only interesting enough to watch once. So, I just rent those and buy my favorite classics when they come out on DVD. Let's say someone does break the DVD copy scheme in the next couple of years, and we all have digital VCRs. The cost of blank media will probably be near the price of a DVD.

Q My friend has Thiel 3.5 speakers. He has one Adcom GFA-555 II driving each speaker. He did this because he wanted to use the full power of each amp for each speaker. He has the amplifiers wired in parallel (both channels amplifying the same signal and the outputs combined and connected to the speaker.) Is this benefiting him in any way? Is the second channel helping or does he have two 200x1 amplifiers instead of two 200x2 amplifiers? I know you can't run the two channels in series, and as far as I know, most home amplifiers are not designed to be bridged. Is there any way do do what he wants? In an unrelated question, do all surround decoders based on the same decoding chip sound basically the same? Or do the additional electronics added by each manufacturer change the sound a bit? I auditioned the Denon 3300 and the Rotel 965. I liked the Rotel much better. I am also interested in a Nakamichi, but am unable to do a direct comparison with the Rotel. Without a good A/B listen, I'm worried that I won't end up with the decoder that I like the best. If the Rotel and the Nak share the same basic electronics (which I have no idea about), I was thinking  that perhaps they would sound similar. Any ideas?

A There are different qualities of DAC chips, even with the same chip manufacturer. A pair of good DAC chips may cost only $35, but that has to be multiplied x 4 by the time you get to the consumer, so that gives $140 just for the DAC. That is why some companies make their own chips, and why different companies use various quality chips. The associated electronics do make a difference too, not only in the circuit design, but the parts. And, of course, the power supply is very important. Since you cannot audition the Nakamichi, and you like the sound of the Rotel, then buy the Rotel. If there is any difference between the Rotel and Nak, it is probably very slight. Also, you might not even like the difference, if it exists. In other words, if the Nakamichi uses better parts and is more expensive, you might still prefer the sound of the Rotel. For the combined channel output, if he means that he connected them by using the + posts of each channel to drive the speakers, then that would probably not cause anything to happen, but it is not effective bridging unless one of the inputs has its signal inverted. Parallel wiring would mean actually wiring the +s and -s of each channel together, and that should NEVER be done.

Q I just had an installer come in and place my speakers and set up the channel volumes using the internal pink noise on my Yamaha DSP-A1. The only thing he didn't set up using test tones was the subwoofer (he did it by ear). Now, I have heard 100 different ways on how a sub should be set up. I read somewhere a long time ago that with the A1, sub volume should be set up by going into the LFE setup menu (#2 on the internal menu) and selecting subwoofer and then setting the crossover point  (70 Hz in my case), and then take the sound coming out and set it up 10 dB louder than the main speakers. I have heard that some people suggest setting up the sub -6 dB with respect to the mains, and I have also heard that it should be set at reference level (equal volume to the mains). So what is the standard way you recommend? What does Dolby Labs recommend for Pro Logic, and Digital soundtracks (should the sub level be different)? What about DTS material (should it be different from Dolby Digital levels)? I also use my sub with my main speakers (Martin Logan ReQuests) on stereo music (rock, r&b only, not classical). Does that affect my setup? 2) Now that I have a home theater system almost up and running, can you recommend some DVDs (DD & DTS) and CDs (stereo & DTS) that would be excellent demo pieces? Is there any way to obtain the DTS Demo DVD that I see being demoed in the stores all the time?

A On the DSP-A1, you can EQ the center channel, but not the LFE. The crossover frequency is not adjustable (unless you have a different DSP-A1 than I have). The default LFE setting for DD is already 10 dB above the mains, while the DTS LFE setting is 0 dB with respect to the mains. You can set the LFE level for DD separate from the DTS LFE setting. Where you set it depends on the quality of your subwoofer and how much you like deep bass. Setting it by ear is fine because you will likely change the setting depending on the movie or music. I use the LFE setting on the receiver to get a generally acceptable level, and then I fine tune the level with the volume control knob on the back of the subwoofer. For demo movie DVDs, I recommend "True Lies" (DD), and "Daylight" (DTS). In "True Lies", use the chapters where Arnie says, "Here is my invitation", and the one where terrorists try to kill him in the bathroom. For "Daylight", use the scene where all the cars are crashing in the Lincoln tunnel. For music, the DTS CD "Holst: the Planets" (Telarc CD-80466) is good, especially the first cut, "Mars, the Bringer of War". The DTS demo disc can probably be had by contacting DTS, if they still have some.

Q My new center channel speaker has the following specs: dimensions: 19.5" x 6.75" x 9.75" (its a big mother), with 2 X 0.5" (14mm) tweeters and 2 x 5.25" (133mm) mid/bass drivers, range 70 - 21 kHz, power: 10 - 200 watts. Is this guy a candidate for "wide" mode? Or would I still be better off directing the bass portion to the mains (40 - 20 kHz)? I don't have a subwoofer yet.

A I would suggest setting the center to Large. Using the Wide mode is a little different. This was a mode that was common in receivers before DD and DTS became available. Just try the various choices out and see what sounds the best.

Q I am in the process of finishing my basement and building a room to hold a home theater system. The problem is that the heating/air conditioning ducts run the length of the room and prevent me from installing a normal 8' ceiling. As I see it, I have two options: 1) boxing in the duct system, which will give me two long narrow areas with 8' ceilings and a lower area in the center of the room with a 6'4" ceiling, or 2) lowering the ceiling for the entire room to 6'4". What impact does the ceiling height have on sound quality and how do I resolve any problems caused by these less than ideal circumstances?

A I would suggest having the center portion at 6'4" and the rest at 8'. You may have to put some acoustical treatments on the ceiling in various places, and perhaps some darker flat paint there as well, to reduce reflections from your TV.

Q What would be the best choice for the shape and size of a home theater room? For example, what about a room that is rectangle in shape, measuring 12 feet wide by 19 feet long by 8 feet high on the main floor of house? An alternative to this is a basement room (much larger room) that measures 37 feet wide at one end and 17 feet wide at other end (due to a separate room at one corner of the basement and stairs to basement) by 22 feet long at one end and again 12 feet long at other end (due to the same separate room) and 7.5 feet high (the room is "L" shaped). The first room is a basic rectangle. The second room contains a bar and a few odd shaped exits and entrances. Can you please comment on room acoustics etc. (commenting on booth problems and benefits of each room, also, given that I can probably put in some kind of acoustical paneling etc. in booth rooms, if needed).

A The first room (12' x 19' x 8') looks like it would be the best due to the ease of maintaining a balance of sound from all sides. You could put a nice 6' screen at the end of the 19' dimension and a projector on the ceiling at the other end.

Q Until recently, I was using a Chiro C800 as an analog preamp. For CD playback, I was using the analog outputs of my Sony DVPS7000 CD player into the C800. I did this rather than using an outboard DAC after hearing review of how great the 7000 was at CD playback (very low jitter, etc.) I have traded up from the C800 to a Proceed AVP. What would you recommend as the best way to link the two: digital or analog? Is it safe to assume the DACs in the AVP are better than those in the 7000?

A I would think the AVP DACs are better than those in the player. However, it will be easy for you to check this out by using both the digital and analog outputs from your player into two different inputs on the AVP. Then just switch back and forth between the two inputs with a good dynamic CD on the player.

Q You recommend 5.1 analog inputs for DVD-Audio. My Yamaha RX-V595 receiver has 6 Channel Analog Inputs for External Decoder. Is that the same thing?

A Yes, it is the same thing. 5.1 is really 6 channels. They call it 5.1 since the 0.1 is a restricted bandwidth channel for subwoofers

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