Q&A # 216 - January 30, 2001

Staff

Q I have a Sony 930 AV Receiver and Pioneer 717 DVD player. For video connection until recently I used Composite Video connections between DVD-Receiver and Receiver-TV Recently, I bought a S-Video cable and used it between DVD - Receiver for better quality. My TV set does not have an S-Video input. The result is I have no picture on the TV. Any ideas?

A In general, receivers do not convert composite video to S-Video for composite video inputs to the receiver, nor do they convert S-Video inputs to composite video. So, if you connect the composite video output from your receiver to your TV, only the composite video inputs to the receiver will be sent there, such as your VCR, assuming it is composite. In order for your DVD's S-Video to be sent to the TV, you have to use the S-Video out from the receiver to the TV. Since you don't have an S-Video input on your TV, you can't do this. For the time being, you will have to continue using your composite video out of the DVD player to the receiver, and receiver to the TV. When you get a new TV, make sure it has an S-Video input, and perhaps component video inputs too. Probably by next year, most DVD players will have component video outputs.

Q I have a Sony Wega 36XBR400, and it has a startlingly clear picture on anamorphic DVDs. However, I feel that I am not taking advantage of the progressive scan capabilities of my Sony ES9000 DVD player with such a small display as the Wega provides. What I really want is a true 16X9 monitor. My budget and situation will allow me to purchase a Mitsubishi 55 inch HDTV Rear Projection TV that is true 16 x 9 (WS55857). Do you think that I will be satisfied with the Mitsubishi after having viewed the Sony? I occasionally watch standard broadcast material, but not often. I really want the Home Theater experience that I feel a much larger screen will provide, but not at the expense of drastically reduced image quality.

A There will definitely be an improvement in the overall image, because of the progressive signal. As to sharpness, it probably will be at least as good as the Wega because the HDTV has smaller phosphors which should translate to a sharper picture. However, you should try letting the player do the line doubling, compared to letting the HDTV do this. It is likely that the player will do the better job since it is performed in the digital domain.

Q I am currently using a JVC RX 888 VBK for my receiver, B&W CDM 7NTs for my mains, a B&W CDM center, and some old Infinity RS 625s for the rears. I am thinking of upgrading the receiver to a Denon 3801. While saving up for an outboard five-channel amplifier, I was going to use the JVC to power the center and rears. Does this make sense? Or should I power the center with the Denon and just use the JVC for the rears? Also, I am kind of confused about the connections. How exactly do I run the output from the Denon to the JVC?

A In order to use both receivers, run the pre-outs for the center and rears (or just the rears if you want) of the Denon, to any set of line-level inputs on the JVC, such as the CD inputs. If the Denon is more powerful, just use the JVC for the rears. Start out with the volume control on the JVC down most of the way, and then use the JVC volume to balance the center and rears with the mains.

Q I have recently completed almost all the necessary items for my home theater system. My final purchase will be the cables for the DVD player. I am looking for the highest quality sound attainable. My questions is which DVD outputs are best to use for picture and sound? I have optical, digital coax, component, and S-Video. I have been told the best to use is the optical to the receiver and component to the television. Is this true?

A There should be no difference between the optical and coax as long as you use a good 75 Ohm impedance coax cable. But, to reduce the potential of ground loop hum, the optical connection is a good choice. On the other hand, if you run coax analog cables from the DVD player to the receiver as well as the optical, then the ground loop can occur through the analog cables. Theoretically, component video should be the best choice, but we are finding that it does not always work that way, depending on how the manufacturer has constructed the player. Some of our tests indicate the S-Video is better for specific players, but the use of progressive video is an important factor.

Q 1) I'm trying to set up a home theater for my dad. He has a Sony DVP S530D DVD player, a Mitsubishi VS-50705 TV, and a Pioneer VSX-D409 receiver with built-in 5.1 decoding. I can't seem to get this thrown-together system to work smoothly. My first problem is that I can't get the TV's built-in speaker to work as a dedicated center speaker. When playing DVDs, it acts as a center speaker, but I have to adjust two different volumes (master volume for L/R/Rears/Sub and TV volume for Center) so the dialogue is often unbalanced. Do you know if it's possible to somehow "lock in" the center channel at the desired volume, and then adjust all 5.1 channels through the receiver's master volume? I would think there would be some type of "bypass" as a TV function, so that the speakers could be controlled by an external amp.

2) Is it true, as I've read, that I may use standard yellow video interconnects as a digital coaxial connection? I'd rather not buy a "digital interconnect" and instead use the video interconnect I have lying around.

A (1) If you want to use the TV's own amp and speakers for the center, you should connect the center pre-out from the Pioneer to the audio input jacks on the TV that are part of the same input as the video jack you are using on the TV as well. Then, you use the channel balancing feature on the Pioneer to balance the sound in the front mains to the center by setting the volume control on the TV to about mid-level and adjusting the center volume on the Pioneer. If the volume on the TV is not changing with the volume control on the Pioneer, then you might not be using the correct pre-out jacks on the Pioneer. If, for example, you used the rec-out jacks by mistake, this could cause a problem. However, use of the TV's own speakers will likely make for a poor movement of sound across the front, as the TV's speakers are likely to be very dissimilar to your other speakers. I would suggest buying a center channel speaker of the same brand and line as the other speakers.

(2) Use of a coax cable that is intended for analog use may or may not work for the digital connection, depending on its impedance. Digital cables should be 75 Ohms. Often, analog cables are much lower than this, and it will result in harsh audio. So, just try it out and see if you are happy with the sound. Otherwise, get a digital cable for connecting the DVD player to the receiver. You can also get a Toslink optical cable, which eliminates the impedance problem. A good Toslink cable is not very expensive ($40) and can be found at Radio Shack. Of course, this assumes your DVD player has a Toslink output, which most do seem to have these days. DD/DTS receivers all seem to have at least one Toslink digital input now as well.

Q How does the benefit that a power line conditioner offers differ from what you'd get with an uninterruptible power supply (UPS) designed for a computer server? I'm not talking about just a power strip or even a surge suppressor, but a full battery backup unit that provides consistent output by absorbing positive spikes and providing power from the battery for negative spikes. If I can't afford $3,000 for the recently reviewed Furman unit, would a computer UPS be preferable to plugging my equipment straight into the wall?

A The problem with UPS is that they don't really output a sine wave. As we have shown in a previous article, the output of a UPS is almost square, meaning that it has harmonics. However, it is not necessary to spend $3,000 for AC line conditioning. Even the Furman does not make the output a smooth sine wave. The PS Audio units allow you to output various combinations of frequencies besides just the 60 Hz. Something like the Rotel RLC-900 for $200 works nicely. I use it in my home theater.

Q Is it necessary to amplify all 5 channels in a 5.1 Dolby Digital home theater with equal power? If the rear speakers are not full range and you set bass management to cross over at 120 Hz or higher, can a lower power amplifier be used to drive the rears without negative results?

A This all depends on the type of movies you watch and how loud you like to crank things up. With DD and DTS, as well as DVD-A, all the channels are full range, including the center and rears. This means deep bass in all channels. As long as you have at least 100 watts in the rear, then I suppose it would be alright to have, say 200 watts to the front left/right and center. Crossing over your rear speakers at 120 Hz would certainly reduce the need for power back there, but it would seriously deteriorate your soundstage because everything above 50 Hz is localizable, and that is the negative result you are asking about. But, even with 100 watts to each rear speaker and crossing over at 120 Hz, there could be some mid-range and high frequencies that have demanding transients which require more than 100 watts. All of our home theaters are compromises between what we really want to get out of them, what we can afford to buy, and how much room we have to put it all. You just have to decide what you are willing to give up and what you are not willing to give up to achieve the desired result. But you don't have to buy it all at once, you know. You can get the nice stuff one piece at a time, such as a good receiver and DVD player, with just one pair of great front left/right speakers. Watch the DVDs in two-channel for a while until you can afford rear speakers, then the center channel speaker, then a good subwoofer, then a three-channel outboard power amplifier, then a two-channel power amplifier for the rears. If it takes a couple of years to build it all, so what? I prefer this approach rather than getting a less than adequate set of five speakers that I would have to replace later with the ones I really want.

Q I recently read about "tactile sound", which is supposed to produce low frequency, high powered waves - that the entire body feels. I understand that this type of unit is supposed to be hooked up in addition to a subwoofer. There are several charts on hooking this type of unit under wooden floors. I have a stone tiled floor, so will the unit be as effective? How do I hook it up (in parallel with my subwoofer)? Can I buy the unit already encased in a box?

A The most efficient way to install shakers, such as the ButtKicker and Clark Synthesis is to put them into the chair or couch rather than under the floor, because even if you have a wooden floor and enough room underneath the floor to mount it, you are trying to shake the entire house. You can also put it into a platform on which your chair sits. Some people use the shakers without the subwoofer in situations where someone is asleep upstairs, or someone in an adjacent apartment does not like listening to your subwoofer. There is some evidence appearing that suggests vasodilatation occurs with certain low frequencies, which means increased blood flow. This might have application in certain diseases, perhaps with a program of low frequency stimulation on a CD. So, there is your excuse to get one. I hope this medical research turns out to be substantiated.

� Copyright 2001 Secrets of Home Theater & High Fidelity
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