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Q&A # 184 - June 23, 2000

Staff

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Q I have been gearing up for an RX-V1 purchase to replace my DSP-A1, but fear maybe I am making a mistake since it is a pseudo-EX processor. Unfortunately, I have already purchased a rear center channel for the additional rear surround channel of Yamaha's Matrix 6.1. However, I erroneously thought that 6.1 THX also required  a single center channel for the additional rear surround channel. As it turns out, it calls for 2 mono diffuse surrounds in the rear. By the way, are these two mono surrounds bandwidth limited like old DPL? Maybe this could make me feel better about already committing to Yamaha's EX system by purchasing a single rear center channel since the Yamaha rear center is full bandwidth! Also, the Denon 5800 (specs published yesterday on-line) boasts being the first true 6.1 discrete decoder. I know Yamaha advertises their system as Matrix 6.1. Can you clarify the two naming systems? How can you have a discrete 6.1 system when the decoder must derive the rear surrounds from the 2 channel rear signal?

A The paint is not even dry with surround EX (rear center channel matrixed with the two digital rear channels), and now more formats are being introduced. I am wondering when consumers are going to be fed up with having to buy yet another receiver. Fortunately, it looks like some of the high performance receivers have the capability of downloading software upgrades that will allow decoding of new formats. The new Denon AVR-5800 has the matrix 6.1 built-in, and also the new DTS discrete 6.1 decoding built-in. As you know, during the past year, 6.1 EX came out, and this produces a sixth channel in the rear center. This rear channel is information that has been encoded into the rear left/right channels of digital surround (5.1) signals. Dolby came out with it first, then DTS followed. You can use an old Pro Logic receiver to decode this information by running the pre-outs from the rear left/right of your 5.1 receiver into it, and taking the front left/right pre-outs of the Pro Logic receiver to drive power amplifiers for the final rear left/right, and the center pre-out of the Pro Logic receiver to drive the rear center (EX). With 6.1 discrete (DTS calls it DTS-ES Discrete 6.1), that sixth channel (rear center) is not matrixed. It is a discrete digital channel like the other channels. It cannot be decoded with Pro Logic. DTS can have more than 5.1 discrete channels, but Dolby Digital cannot. That is why Dolby came out with the matrixed rear center channel. There are other new formats now too, such as DTS Neo:6 which offers 6.1-like decoding from 2-channel stereo. Dolby has Pro Logic II for improved decoding of 2-channel stereo, making it more like 5.1 than older Pro Logic could. Lastly, Dolby has Dolby E which can have up to 8 channels. We will be reviewing the Yamaha RX-V1 shortly, and a review of the new Onkyo TX-DS989 is coming soon too. We hope to get the Denon AVR-5800 when it is released in August, 2000.

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Q I am thinking of buying a large screen TV, probably in the 52" range. What is the recommended viewing distance for a TV that size?

A The recommended viewing distance is about 2 to 3 times the size of the TV, so about 8 1/2 feet to 13 feet for a 52" TV. Of course, that is the calculation to start from. In practice, it is a matter of what is comfortable, and whether or not you are watching a widescreen movie. I tend to sit closer when it is a 2.35:1 aspect ratio movie than when it is 16:9 or 4:3.

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Q I'm planning on buying a home theater system, and I need your help. We have limited choices here in the Philippines so I willl just mention products that are available. For now, I've decided on getting an Onkyo 575 Surround Receiver. I'm still shopping for the speakers. Initially, I looked at the Acoustimass 10, but through reading, I am looking for other brands. I just tested the PSB Alpha speakers and they sounded good and just right for my budget (<$1000). My problem is I'm not sure if the ratings for the receiver are okay for these speakers. From the specs, there are some mismatches like the 4 Ohm impedance of the subwoofer as opposed to the 6 Ohm minimum impedance for the receiver. Also the input rating for the speakers is 10 - 80 watts, while the receiver has a rating of 75 watts rms at 8 Ohms. Are these speakers okay to use on the receiver that I mentioned? If not, can you recommend something else?

A The PSB Alphas are excellent choices for receivers, as they have a good quality sound, are 6 - 8 Ohms, have high sensitivity, and best of all, are inexpensive. The 4 Ohm subwoofer impedance is not relevant to your receiver since the subwoofer has its own amplifier. You use the subwoofer output jack (RCA) on your receiver to drive the subwoofer.

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Q I am interested in the NAD T760 receiver. I currently have a Denon AVR2700 and M&K LCR55 speakers and a V75MKII subwoofer. I would like to add DTS and minimal functions, which the NAD has. Available shelf space is why I don't buy a separate decoder for the Denon. It states on NAD's website that the T760 is 60W x5 continuous and 40 amp peak current. Will the NAD be about the same as the Denon in terms of sound quality, and how will it fair with the 4 Ohm M&Ks?

A The Denon and NAD amplifiers would compare favorably, but the amplifier will not do well with the 4 Ohm M&K speakers. Mass market amplifiers don't have the power supply to drive 4 Ohm loads. It will be better to wait until you can afford to get an outboard power amplifier that is rated into 4 Ohms, to go with your receiver.

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Q I have a Yamaha DSP-A1 and have a chance to pick up a Rotel RB-985 five-channel THX amplifier. I was wondering if this is an upgrade, downgrade, or not worth the effort? I know that outboard amplifiers are usually considered better but in this case it seems the power ratings are the same?

A The 985 will definitely be an upgrade. Although the DSP-A1 is a high performance product, it just cannot compete with the large power supplies that are in outboard amplifiers. The power ratings may be the same, but the 985 will be able to sustain output during high impact movie action scenes. If you can get it at a good price, do it.

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Q I recently obtained a used VandenHul speaker cable from my friend. looking at the cable and the brochure, I cannot find any indication at all stating which side of the cable is to be connected to the positive and negative end of the amplifier and speaker. All I can see is that one side of the cable to be in a rounded sleeve while the other is squarish. My friend says either one can be used for the positive and negative. Are there cables made this way with both sides being able to be used as either "+" or "-"? Could you please advise!?

A In general, speaker cables can be connected with either conductor to the + and the other to the -. Just be sure to connect both speakers and amplifier posts the same way on both sides (right and left channels). With interconnects (cables with RCA plugs for connecting your CD player to your receiver), the hot (+) conductor is usually in the center, and is surrounded by the ground (-) conductor. If you buy them already terminated (with the plugs on them), you can't connect them incorrectly. Speaker cables may have spade lugs or banana plugs as termination, and it really does not make a difference which you use for the + and which for the -, although they are usually marked just for convenience.

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Q I am thinking about adding a 5-channel amp to my system. I have a Yamaha DSP-A1 and Definitive 2002tl fronts and Definitive BPXs in the rear. What would you recommend for the minimum wattage of an outboard 5-channel amp in order for the sound improvement to be more then just subtle? I'm also confused about what happens to the built-in subwoofer performance when you add more power to the system. I'm thinking that it will remain the same. Is this true?

A I would suggest getting 200 watts per channel in your outboard amplifier. Because the DSP-A1 has good amplifiers, you can get away with just buying a three-channel outboard amplifier, such as Adcom. Use the three-channel amp for the front left/center/right. Since the built-in subwoofer is self powered, you are correct that its performance will not change with the added outboard amplifier that powers the other drivers in the speaker enclosure.

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Q I am planning on upgrading my system and would like your professional opinion. My current speaker system consists of a pair of Definitive Technology BP2000s, a Definitive Technology C/L/R 1000 center, and a pair of Definitive Technology BP1 surrounds. My components consist of a Yamaha RX-V890 receiver, a Yamaha CDC555 multi-disc player, and a Sony VCR. I'm considering a couple of systems. (A) a Yamaha RX-V1 as a processor and to drive my center and surrounds, while using a Sunfire Signature two channel amp (600x2) to drive my mains. Or (B) a Parasound AVC2500 pre-amp/processor with a Parasound 2205A (220x5) amp. Music is more important to me than H/T. It will probably be about 70% music 30% H/T. Both systems are around the same price range. What would be the main difference musically and for H/T? Are there better choices in this price range? I will also be upgrading my multi-disc player, adding a DVD player, and high quality cables. What products do you think will compliment either system? I have not purchased any A/V equipment for about six years, so I want this next purchase to be right. Any advice you can give will help me out a great deal.

A Your planned choices are all good, but there are currently a bunch of new formats in the wind, including DTS-ES Discrete 6.1, DTS Neo:6, and Dolby Pro Logic II. What I would suggest is waiting until we have had the chance to look at the new crop of receivers and processors to determine which ones will be able to download the software to handle these formats as they become available. They (receivers and processors with capability for downloading the software upgrades) should be on the market this summer and fall.


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