Q&A # 198 - September 22, 2000

Staff

Q I'm just trying to get something straight about HDCD vs. normal CDs. I do understand the sampling bit depth difference between the two formats, but . . . . Say I have a very good CD player ($1000 range) that's not HDCD compatible, and a relatively good DVD player ($700 range) that's HDCD compatible. Now we all know that if I take a normal CD and do an A/B test with my CD player vs. my DVD player, the CD player should win. If I do the same A/B test with an HDCD, will the HDCD DVD player sound better than the high quality CD player? Doesn't the laser wavelength come into play when playing a HDCD in a DVD?

My equipment:

Sunfire Theater Grand II
Sunfire Tru-Sub MKII
Carver TFM55 (two) for front and rear
Onkyo separate amp for center
DX5500 CD
Toshiba DVD SD 5109
Magnapan 3.5 front, 1.5 rear
JBL ProIII center.

A The problem with a comparison is that there are more variables than just the HDCD. The quality of the rest of the electronics in the players, including the jacks, will affect the sound quality too. Also, a few DVD players have dual lasers, such as the Sony. HDCD is a type of DSP. The algorithm in the chip attempts to recreate the way the sound would have been if it were decoded from 20 bit words instead of what was actually on the CD, namely 16 bit words. When I did a comparison of HDCD recordings vs. non-HDCD, I used a sampler disc that had the same music recorded onto the CD first in standard format and then in HDCD. The difference, to me, was one of loudness. The HDCD tracks had a higher output. This is part of the HDCD technique. I suppose it would lower the noise floor. The sampler disc also had tracks that were recorded in HDCD, but at the same loudness as the standard tracks. I could not hear any difference between those tracks, but some listeners might be able to. My guess is that, if the DVD player does not have dual lasers, you probably would still prefer the sound of the standard CD player over the HDCD-capable DVD player. Note that, although I have no idea of what the HDCD algorithms are (designed by Pacific Microsonics), this is not the only technique for attempting to restore 20 bit sound from 16 bit recordings. The Perpetual Technologies P-A1 does that too, and can "restore" to 24 bit as well, using their own algorithms. Using the P-A1, I was easily able to hear an improvement, regardless of volume settings.

Q I've been considering soundproofing my current home theater room, as it's starting to annoy my neighbor. I understand that an ideal acoustic treatment will use special manufactured absorptive, diffusive, and reflective materials. The problem is that I'm unable to get those products here,
and they are expensive. Is it possible to use substitute products and where should I put those materials in the room in order to achieve the best result?

A If it is your own home, rather than an apartment, you can fill the walls with fiberglass stuffing or even blow in some foam that comes in compressed cans. If you don't want to do that, or you live in an apartment, you can hang heavy blankets on the walls and ceiling (if he is upstairs from you). If he lives downstairs, then cover the floor with a heavy carpet. The idea is to stop the common walls from vibrating.

Q The only room I can use for a home theater has an difficult shape. It is essentially an L with a stair way on one side. The result is that one side of the room has virtually no wall. How can I configure this room? What can I do to reduce any undesirable effects of the room shape? Is this room just hopeless?

A No room is hopeless. All the articles that say speakers should be "x" inches above such and such, and give angles for this and that, are just the recommended ideal situations. How many of us have the ideal situation? Maybe 5%. The rest of us, including me, have to deal with the reality of a home that was not designed with watching and listening to Sylvester Stallone in mind. I would just suggest using some mono-polar speakers rather than dipoles or bipoles. You should be fine regardless. I don't think it will really even be much of a challenge for you to get some great sound in that room. And, if it isn't perfect, so what? You should see my home theater room. There is stuff all over the place, with windows and doors here and there. Not exactly anechoic chamber kind of layout. It's a real room, and that is where people live. The main thing is to get some good equipment. It will more than make up for any imperfections in your room layout.

Q I need your help. I own a B&W CC6 that I'm not fully satisfied with. I find myself asking my wife if she could understand what "he said," when we are watching a movie. I am presently demoing the new B&W CDMC NT which sounds much clearer. Before I make a purchase I would like to listen to some different centers. My question is, what other centers do I compare it to, and what centers do you recommend (under $1000)? I have a Rotel 5-channel amp and preamp.
thanks, .

A The CC6 is a good center speaker, so before you buy something else, make sure your center channel is configured properly, such as having it set to "Large" vs. "Small", volume turned up on the center compared to other channels, etc. If the CDMC NT sounds clearer, it might just be the fact that it is configured properly at the store compared to your home. Bring your CC6 into the store and switch it out with the CDMC NT leaving all settings the same. If it still sounds poorly, then get a new center speaker. Some other very good ones that I really like are the Mirage and the Krix. They have massive construction, which I like, because the center is so important. There are lots of other good center speakers too, but I prefer the ones that are large in size. Of course, you need a big TV to put them on.

Q My name is Dan, and I live in Israel. I need a great subwoofer, and so far, I prefer the Paradigm PW-2220, but I am not sure. I heard some great things about your advice. Do you know of a better sub than the the PW-2220 in this price range? Some people are telling me I need sound absorbers behind the listening position. This is a problem for me, since I am using dipoles in the rear. If I put absorbers there, won't this affect my sound from the rear speakers? Should I switch to monopoles? My room is 3 meters high, 5 meters long, and3 1/2 meters wide. I like the dipoles because they make my room sound larger and give me a 3600 sound field. Now that I am aware of my bad room acoustics, I don't know what to do with my dipoles (the walls are concrete and smooth.

A Well, dipoles make a wonderful home theater speaker, so there is no reason to get rid of them just because your walls are concrete. If you applied room treatment that made the walls completely dead, then sure, the dipoles would be affected a lot. Regardless of the speakers, I don't think you would ever want to make a room completely "dead" acoustically. So, all you need to do is apply room treatment to the extent that it reduces reflections, not completely eliminate them. This can be done with blanket wall hangings that give an artistic look to the room. In other words, the textile hangings would add decor to the looks, but be functional to the audio in reducing sound reflections. Consider the walls as mirrors, and put the hangings in those  spots where you would be able to see the speakers being reflected from your sitting position.

As to subwoofers, the Paradigm is very good, and if you like it, that is the deciding factor. If you are concerned about the choice, then just go and listen to a wide array of subs in your price range. There is quite a bit of difference in the way they sound. Be sure to audition the Velodyne CT-150. At $799, it is one of my favorites. If you don't have a lot of space, take a look at one of the high-power, yet compact, subs, such as Velodyne, Sunfire, and Energy make. They are rather expensive, but they produce tremendous bass from a small package.

Q I have a Denon AV-2500 "AV Surround" receiver and wish to add a DVD player. You may recall that this unit (5-6 years old) had Dolby Pro-logic which required "Dolby Surround" materials to get the best out of it. I cannot afford to upgrade the receiver at this time. Do I need to purchase a DVD player with analog outputs to get the best possible performance?  This unit does take S-Video cables for hookup, or you can use two audio inputs and one video input?

A Yes, you would need the two analog outputs from the DVD player, but they all have them, so you can pick out any player that you want. They all have a digital output jack for connection to your next receiver. Some have 5.1 analog output jacks, but since all new receivers have DD and DTS DACs built-in (see below), you won't need those. However, if you get a DVD player that has DVD-Audio capabilities, it will have the 5.1 analog output jacks, and you will need a receiver with 5.1 analog input jacks regardless of DD and DTS, since DVD-Audio players will do all the digital-to-analog conversion in the player, and will not output the signal through the digital output jack.

Q I am confused about the decoding process in DVD players. I have seen advertisements and reviews in other publications about decoding DD and DTS and having or not having 5.1 analog output jacks. Can you clarify this for us?

A The process of decoding is separate from digital-to-analog conversion (DAC). All the new players decode DD and DTS and will output the digital bitstream to be sent to your receiver. However, only some of them contain the DACs to convert these bitstreams inside the players to 5.1 analog signals, which would be fed to the 5.1 analog input jacks on your receiver. Some publications have been confusing the process of decoding with the process of digital-to-analog conversion.

Q My brother let me borrow his DVD player (Sony 550). He never gave me the manual, so I hooked up the digital optical cable to my Sony ES555 receiver, along with the audio out from the DVD to my receiver (RCA cables).  The problem is when I play "Top Gun" and "Twister" it isn't in Dolby Digital. I had my receiver in the "AFD" mode, which plays back the audio source in the way it was recorded. The "DD" LED did not light up on my receiver. So I gather that it played in Dolby Pro Logic. Is that because I have the RCA audio cables in line? If I take them out, and only use the optical digital cable from the DVD player to receiver will it decode audio? Specifically DD and DTS?

A There are several things to check. One is the player setup menu, to make sure it is outputting the digital bitstream. Some players have a slider switch on the rear panel to set it for analog audio output or digital output. Next, the movie disc will often have a menu selection for audio output, either as two-channel stereo or the 5.1 bitstream. Lastly, receivers default to one type of input if they sense that two are coming in, which is the case in your situation. Make sure it is set to select the digital input when it "sees" both the digital and analog are coming in.

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