Q&A # 215 - January 28, 2001

Staff

Q I have two infinity il40 floor-standing speakers as my front two speakers, an infinity 36c speaker as a center and two old infinity bookshelf speakers as my surrounds. I also have a Klipsch KSW12 as my subwoofer (downfiring). My question is how should I place my speakers in my living room? I have a carpeted floor and a 42 inch projection TV. Do I need to get some kind of spikes, speaker stands, or shelves in order to maximize my speakers' potential?

A The purpose of spikes is to decouple the speakers from the floor (some magazines mistakenly referred to it as coupling some time back). Although spikes do work, they will make holes in hardwood floors, so if you have nice flooring under your carpet, don't use the spikes. Secondly, a carpet does a relatively nice job of decoupling anyway, so just placing the speakers on the carpet without any spikes or other devices underneath may work just fine. You can experiment by rapping on the enclosures while they sit on the carpet, and then putting some padding underneath and rapping again. If resonance decreases with the padding, then you should go to a hardware store and get some pads to put under the speakers permanently. If the resonance does not decrease, then the rugs are sufficient for decoupling. As to your rear bookshelf speakers, putting them on a shelf can result in bass loading and other artifacts, so put them on stands that will result in the tweeters being about ear height when you are sitting in your listening position. You don't have to spend a lot of money on stands. There are plenty of them in the less-than-$100/pair range that will work nicely.

Q Is there equipment out there for building a multi-zone home theater?

A Sure. It's called multiple receivers or surround processor/power amp combinations with the audio/video from the sources split every which way.

For splitting analog audio, a simple Y connector will do. If you've got to do it more than a couple times, you can get a buffered distribution amplifier such as a Xantech AV 61, which will take a composite video feed, along with a pair of analog outputs, and split it 6 ways without any impedance matching problems. If you're looking to do S-Video and analog audio through a Matrix switcher, look into the Autopatch "Half-Y" series of matrix switchers. You can also simply divide the S-Video into two RCA plugs, and use the Xantech AV61's twice, although the Autopatch products have a really easy RS-232 interface if you're going to be using a control system.

For component video or RGB, look into Extron products, or Altinex. I'm not all that up to speed on model numbers, but I've seen switchers from these two companies that will do both component and RGB.

Digital Audio, at least on the coaxial side, can be distributed by the above mentioned Xantech AV-61's composite video amp. It handles the bandwidth and signal levels fine. I tried it with an older Meridian DVD player and the 565 surround processor, and it doesn't seem to have problems with either Dolby-Digital or PCM.

If you're only distributing PCM, Nirvis makes a product which will allow, I believe, eight inputs (Toslink or coaxial S/PDIF) and as many as 16 outputs (switching as 8), although I've never tried to get it to pass a Dolby-Digital bit stream.

So, yes, it can be done, and I'm sure that somebody has a multi-zone home theater. But in my experience, it rarely is done, because although many theaters may share the same sources, such as a stack of 400 disc CD changers which store the user's entire library, most people find it easier to just have separate systems with separate sources for things like DSS receivers, VHS recorders, video hard disc recorders, etc., and carry the DVD or VHS tape to where they're going to watch it. That way, what one theater is doing doesn't infringe on what the other theater's doing. However, with so many multi-disc DVD players coming out, that may be a future trend, but I haven't seen a turn-key solution in a single box for it yet.

Q I'm using a Sony receiver (STRDE-505) to run my Paradigm M3, CC-350 center channel, and a pair of Bose Accoustimas 5s at the back. What kind of power amp do I need to match this kind of old receiver? I'm thinking of buying a Rotel, so how do I connect it to get more power? Or is it better to buy a new receiver like the Yamaha RX-V1000?

A As long as your old receiver has pre-outs for whatever channels you want to add a power amp to, any power amp, including the Rotel, will work. However, the record loop will not do the job because it (rec-out jack) is not affected by the volume control. You could use an external volume control in between the rec-out jacks and the power amplifier, but that is not cost effective. It would be better, in this case, just to get a new receiver like the RX-V1000. There are a few power amplifiers that have little volume control pots on each channel, and that would work with the rec-out jacks until you get your new receiver, which would also benefit from the outboard power amp.

Q I am most impressed by your recent DVD benchmark articles. I was curious to know if you had received any feedback from the manufacturers about your results?

A Yes, some of the manufacturers are incorporating improvements to their models based on our tests. The reason for this is that we performed tests that even some of the companies who designed the players never did, let alone other magazines. Benchmark-2 is being organized now, and we are lining up products for testing. For Benchmark-1, we had to beg for players. This time, we will have to limit the entries, because we have had so much interest from manufacturers who want to be included.

Q This is a question based on an article you wrote in 1998, titled "Product Review - Yamaha RX-V592 Surround Sound Receiver - August, 1998"

In that article you indicate it is a workable solution to connect a DVD player with built in DVD Dolby Digital decoder directly to a Yamaha RX 592 via its 6 RCA Pre-In jacks (Including subwoofer). From this, can I take it to mean that if the DVD player has the DD decoder built into the player, I can connect it to my Yamaha RX 592 receiver via the 6 analogue inputs (for audio) even if I don't have the coax or optical input on my receiver?

While your article seems straightforward and clear, the reason why I want to verify this is, the Yamaha RX 592 receiver does not have the optical or coax connector, nor does the manual say it is "Dolby Digital Ready", and my dealer said it won't work. The receiver does have the 6 discrete input channels which the manual says can be used to connect to an external decoder (which I assume can also mean the one inside the DVD player). A dealer who is selling me a Panasonic RV80 DVD player says I won't be able to get 5.1 sound since I don't have the digital inputs on my receiver. However, I'm sure it should work fine (even if it means more cables) and get the full 5.1 sound (and video). The DVD player does have the multiple output jacks.

I'm assuming that if this does indeed work, I need to also connect the video to either the receiver (which is connected to the TV) or connect the DVD player directly to the TV via S-Video.

Are you aware of any disadvantages to doing it this way? It might be preferable to have a receiver with digital inputs, but I would prefer not to have to buy a new receiver. Also, will I get DTS capabilities if the DVD player has a built in DTS decoder?

A Yes, it will work fine. In fact, that is exactly what the 5.1 analog output jacks on the player are for (connecting to the 5.1 inputs on your receiver). However, although all new players will output DD and DTS bitstreams, DTS output through the 5.1 analog jacks is just starting to be a feature. You will have to check that particular player's capability in this regard. But, certainly you will have DD in the 5.1 analog output jacks.

Q My AVR (as well as most others I'm sure) allows you to set the subwoofer's crossover frequency for Dolby Digital and DTS surround modes. Yet it's my understanding that these digital surround modes have the subwoofer's signal encoded on its own separate channel. If the subwoofer signal has already been derived, how can the receiver modify its crossover frequency?

A Bass management on processors and receivers is getting better, but unfortunately, it still lacks what it really needs, namely an adjustable low pass frequency for all the channels. The subwoofer crossover frequency you are referring to is pre-determined at about 90 Hz. Although THX requires that the processor not have the option of lowering the crossover frequency to other settings in order to be THX certified, even the non-THX processors have not really developed bass management the way they should. It all involves politics I suppose, with THX, Dolby, and DTS involved. What we really need is the ability to set the crossover frequency in all channels to between 40 Hz and 120 Hz, with 5 Hz increments (or better). That way, you could have your front floor-standing speakers crossed over at 40 Hz, the center channel at 60 Hz, and the rears at 80 Hz if you wanted. With any of these crossover settings, including the one that is in your current receiver, what happens is that the low frequencies from the channels you specify as "Small" are routed to the subwoofer channel (LFE channel) output. Regardless of these settings however, the LFE channel may or may not contain low frequency information of its own from the DVD. It is not affected by the crossover settings except if you specify that you don't have a subwoofer and want all low frequency information directed to your large front floor-standing speakers. Usually, the bass information in the LFE channel contains bass that is duplicated in other channels. But, sometimes, there is not anything in the LFE channel, and this has caused concern by some consumers. Check out an article on bass management, written by John Kotches, to be published in Secrets this coming week.

Q This is a general inquiry based on some of your other responses concerning mimicking the rear EX matrix with an old Pro Logic receiver. I have an old Pioneer VSX-453 which is rated at 60 watts into L/R and just 40 watts into the center. However, this receiver only has rudimentary analog inputs such as CD, Laser Disc, VCR, and Tape Loop. So for example, if I had an AV receiver with pre-outs for all channels (such as the NAD series) how would I hook this up?

A You would take the rear left/right pre-outs from your new receiver and connect them to any of the input sets on your old Pioneer, such as the CD input. Then, the front left/right speaker outputs of the Pioneer would feed the rear left/right speakers of your home theater, and the center speaker output of the Pioneer would feed the center EX speaker in the rear of your theater. There might be a little bit lost to the Pioneer decoding something that goes to its rear surround, but unlikely, since it has to be identical material in both channels that is 180⁰ out of phase.

Q Any thoughts on the NHT 1.5 speakers?

A NHT makes fine products. As to this specific model, its weaknesses would be not having a lot of deep bass due to its relatively small woofer in an acoustic suspension enclosure (but the bass that it does have would be nice and tight), and secondly, the sensitivity is relatively low (85 dB). The solutions to these weaknesses would be adding a good subwoofer, and using a powerful amplifier, such as 150 watts per channel, rms, into 8 Ohms. Depending on whether you are using these for two-channel music listening, or home theater, the subwoofer could be a small one (10")  in the former case, or an 18" in the latter case. The important thing would be to find a sub that takes care of the lowest octave, 20 Hz - 40 Hz, because the NHTs roll off in the 50s.

� Copyright 2001 Secrets of Home Theater & High Fidelity
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