Q&A # 133 - August 19, 1999

Staff

Q I have a set of Wharfedale 100W (8 Ohm) speakers which I have connected to my old hi-fi system. I'm replacing the hi-fi and I notice that most hi-fi systems nowadays use 4 Ohm speakers with much lower power output (many work on 20 Watts). Will I be doing harm to my hi-fi or Wharfedale speakers using them on a system designed for 4 Ohm 20W speakers?

A No, you won't be doing the amplifier or speakers any harm, and in fact, 8 Ohm speakers will be less stressful on the amplifier. The only difference you might notice is that, if the amplifier is rated at 20 watts/ch into 4 Ohms, it will mean that it has a lower output at 8 Ohms, probably around 12 watts or so. I assume you are referring to a very small system, since they are the ones with such low output even at 4 Ohms.

Q I am thinking of purchasing the Sony SDP-E800 Dolby Digital decoder. Does this unit also decode Dolby Pro Logic through the analog inputs? If yes, then how does it output them through the 6 channel analog outputs? Do only 4 channels out of the 6 get the signal? What about hooking up a CD player for stereo output?

A Some decoders with analog inputs will pass through the analog signal when analog signals are sent through it. This is for when you have a source that outputs analog signals as well as digital ones. However, outboard decoders usually are only meant for one type of decoding, such as DD or DTS. The Pro Logic decoding has to be performed by the circuitry in your receiver. In the case of the CD player, this is where you would use the analog pass through of the DD decoder. A better way, however, would just be to connect the analog stereo outputs of the CD player directly to the two-channel analog inputs on the receiver.

Q My TV has only one S-Video input, but I have two devices that provide S-Video output. Is there the equivalent of a Y-adapter or a switch box that would allow me to keep both S-Video cables attached to the TV? The devices are never used simultaneously.

A There are lots of S-Video switchers available now. Here is one link, but there are plenty to choose from: http://www.multidyne.com/vas1000w.htm. Use several search engines to look for S-Video Switchers, or Audio Video Switchers, since each search engine is indexed differently.

Q I am a relative newcomer to home theater and audio equipment. On some of the specs for the receivers, I have come across a term called rear channel stereo (e.g., Sony). Some call theirs 5 channel stereo (e.g., Onkyo). Do these terms refer to the same thing? What exactly do these terms mean? Do they mean that the stereo sound is output equally to all five channels?

A There are a couple of possibilities. One is that Dolby Digital (DD) and DTS have stereo in the rear as well as the front, so it may be within that context that you are seeing the reference. A second possibility is that there may be some DSP (Digital Signal Processing) in a particular receiver that takes the Pro Logic signal and creates stereo in the rear rather than having the standard mono in the rear between the two rear speakers.

Q I was wondering if I could upgrade my RCA connectors to balanced XLRs. Is this technically possible? The equipment in question is: Preamp - NAD 917, Amp - NAD 912, DVD - Pioneer 414.

A Yes, it can be done with RCA-Unbalanced - to - XLR-Balanced adapters. Balanced Audio Technology sells them for $50 per set. However, this is only an issue if you have severe hum problems created by long interconnects. It won't improve the sound quality, other than this. If you don't have hum problems caused by the interconnects, you could actually end up with worse sound, since your components are not balanced, and you would be inserting additional circuits in the signal path.

Q I want to purchase a DVD player under $500. What kind should I buy and what kind of options should I look for?

A There are so many DVD players now in that price range, it would be very difficult to make a recommendation. I would suggest getting one that outputs DTS (they all output DD). Looking at last year's models will usually net you an excellent price ($300).

Q I have a NAD 705 receiver that I like to use to listen to music. I am interested in purchasing the Yamaha RX-V2095 receiver for home theater use but still want to use the preamp section of my NAD for music. What I am thinking about doing is getting an input selector such as made by Niles. I could run the pre-outs on my NAD and the front left and right channel pre-outs on the Yamaha to the input selector and from the selector to the front left and right amplifier input on the 2095. Would I be losing noticeable sound quality if I were to use this sort of setup or is there a better way to do this? And if this would be a good setup, what would be the best brand of input selector to purchase? I only know of Niles.

A Niles makes good equipment, and here is another link: http://www.linkelectronics.com/products/800switcher/index.html. Again, just use a couple of search engines to get lots of choices. However, I don't think you would obtain a better sound by using the method you outlined. Any preference you have for the NAD preamp sound would probably be lost in all the switching and jack connections that would be required. To check this out, try connecting the output from your NAD to the main-ins on the Yamaha and go back and forth between using the NAD and the Yamaha as a preamp by moving the cables by hand. Consider that the sound will be somewhat worse when you use the switcher and additional cables.

Q I have heard different stories about which component you should turn on first, the processor or power amplifier. Can you help me out? Is it good to have the power amplifier on always?

A I always turn on the CD player or DVD player first, then the receiver. Or for a separates package, the CD player first, then the preamplifier, then the power amplifier. I turn the power amplifier off first, then the preamplifier, then the CD player. I never leave tube equipment on when I am not listening to it, but this means I have to turn it on for a half hour or so before I do any critical listening. Solid state power amplifiers can be left on continually without any problem, but some of them use a lot of power at idle, so they get hot and make the wheel in the electric meter run quite a bit ($$$).

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