Q&A # 47 - January 20, 1998

Staff

Q I've read the reviews of the Rotel RB-985 and Carver AV-705 amplifiers on your web site and I have auditioned the Rotel. Would you recommend one of these amps over the other? Is it worth the extra $200 for the Carver? What if you could get either for $1000? Which would you choose and why?

A The Carver AV-705 has the ability to play louder without distortion, but that is to be expected since it is rated at 125 watts/ch, while the Rotel is rated at 100 watts/ch. Both are THX certified. We use the AV-705 as one of our reference amps in our home theater lab of the Redwood City office (one of my staff located elsewhere has the RB-985 in a smaller system). For $1,200, the AV-705 is one of the great home theater bargains out there, and if you can get it for $1,000, do it.

Q I just purchased a Sony STR-DE915 which is a Dolby Digital receiver. The unit has an AC-3 RF input for laserdiscs and an optical input for a DVD player. My question comes from the manual for the 915. The following is a note in the manual:

"The receiver is compatible only with digital components using 32, 44.1, or 48-kHz sampling frequencies and not compatible with 96 kHz"

What does this mean to me? I'm going to modify my laserdisc player to AC-3 RF and want to buy a RCA 5200P or any inexpensive DVD player with an optical output. Will the note limit my choices? What does the note mean in plain English?

A It's almost funny how the quality of home electronics is fine, but the documentation continues to be miserable. What that instruction manual is telling you is that the receiver will decode all the digital sources out there except for the new 96 kHz sampling rate DADs (Digital Audio Discs on DVD; the first one was demonstrated at the CES in Las Vegas two weeks ago). The sampling frequencies represent the number of times each second that an audio sample is taken, and stored as a binary digital number. The number is a code for the voltage at a single point on the audio waveform. Various sources have different sampling frequencies, such as 44.1 kHz for standard CDs. Your laserdisc player will work fine, through the RF input on the receiver, and all DVD players will work as well, through the optical digital input jack on the receiver. The nice thing is that DVD players will handle these new DADs, decoding their 96 kHz info, and outputing it through the two channel analog jacks on the DVD player, so you can connect those jacks to the auxiliary inputs on your receiver.

Q My dad was rearranging his video setup. He's using some older, floor standing, unshielded speakers (with 8" woofers). In his proposed setup, he would place the VCRs just above one of the speakers. I suggested that this might be a problem since the magnetic field might damage the recording on the video tape. Does this seem likely? He doesn't live nearby to me, so I'm talking him through stuff over the phone. If there is a problem, would it be immediately evident? Or, mild quality degradation that builds up over time?

How far would he want to place the VCRs away from the woofer (assuming that's the source of the largest magnetic field) to be safe? Would some kind of adhoc shielding help? Perhaps a cookie sheet placed between the speaker and the video tape players? Also, if he places the VCR directly onto one of the speakers, would vibrations cause a problem?

A As long as the VCR has a steel chassis, I doubt that there would be significant interaction between his speaker and the VCR, especially since the larger woofer magnet is toward the bottom of the enclosure (I assume the woofer is on the bottom). Your cookie sheet idea is great, but it would have to be a steel cookie sheet. The shielding must be a metal that can attract a magnet. Aluminum cookie sheets would not work. His speakers must be really BIG if one of them could hold a VCR! My suggestion would be to keep all the components at least 12" away from the speakers. I don't think vibration from the enclosure would be a problem, since the air coming out of the speaker is the main source (supposed to be anyway) of the sound. However, just in case, if he does put the VCR on the speaker, make sure that the speaker is on a rug or other padding to reduce any vibration of the enclosure (something that should be done anyway). Video tapes degrade over time no matter what we do. I am very anxious to have recordable DVD so I can copy my family home video tape albums onto permanent media.

Q Last year I bought on closeout the BOSE 10.2 Series II speakers at what I thought was a good price. Now I am concerned that when I go Dolby Digital (soon), I won't be able to get matching surround speakers. My present receiver is pre Pro Logic so all I have are the BOSE 10.2s. Did I mess up and what would you recommend that I do? Please answer as I'm sure that many others are in a similar position.

A No, you didn't mess up. Speaker models change often. Buying closeout products can be a real bargain. Assuming you want to keep what you have, I would suggest getting a receiver that has DD built-in or has 5.1 input jacks for an outboard DD processor. It should also have pre-out jacks for all channels. Then, connect the pre-out jacks for the rear channels from the new receiver to the auxiliary inputs on your old receiver and the speaker outputs from your old receiver to the Bose speakers. Use the Bose in the rear. This will allow your new receiver to devote its power supply to driving the front left/center/right amplifiers. Set the volume control on the old receiver to a low position (about 9 o'clock) when first turning the system on, and then adjust it from there. When selecting your new speakers for the front left/center/right, take the Bose with you and ask the salesperson to connect them in the showroom so you can compare the sound with whatever you are considering to purchase. Later on, you can add a five channel power amp to drive all the speakers, and retire your old receiver.

Q Regarding your review of the Crystal Vision VPS-1, great article. So in a nut shell, who needs this and who does not need this? I know your article mentions anyone with a 27" or a front projector watching his LD collection. So should I assume the comb filter in the VPS-1 is going to be better than my Toshiba Theater Wide 40" or my Sony KP-41T35 (a 41" RPTV with a nice three line digital comb filter), comb filter's capabilty? Or is the VPS-1 just going to allow some additional tweaking? And would I find it most useful with only analog signal...LD, cable and VHS but not my DVD players (Toshiba 3006 and Sony 3000)? I cannot just go down to my local Hi-end dealer and try it, since they will not be carrying that product.

A I (Stacey Spears) currently use the VPS-1 with the Toshiba Theater Wide TW40F80 TV. This TV has a 3D comb filter, and the VPS-1 gives a noticeable improvement with laserdiscs. However, you should NEVER use the VPS-1 with your DVD player or DSS. Both of these already have the Y & C separated to begin with. LD, VHS, Cable, and CU/K Band Dishes, on the other hand, will all benefit from using the VPS-1.

Q I have a Sony Pro Logic A/V receiver, hi-fi stereo VCR, and a TV with a 5-jack RCA panel. The connections illustrated in the manual for the receiver show an A/V stereo dubbing cable "out" of the VCR to the "video in" on the receiver. An A/V stereo dubbing cable "out" of the receiver back to the "in" on the VCR. Then a video cable from the "monitor out" on the receiver to the "video in" on the TV. I have the left and right "audio out" of the TV connected to the "TV/LD in" on the receiver. Question. What is the advantage or disadvantage of these connections versus just running the A/V stereo dubbing cable "out" of the vcr directly to the A/V "in" on the TV, then the TV audio "out" to the TV/LD "in" on the receiver, thus eliminating the video cable from the receiver "monitor out" to the video "in" on the TV? In other words, why the loop between the the receiver and the VCR? I haven't noticed an audio or picture quality advantage between the two ways of connecting. Is there an advantage as far as recording is concerned?

A Your best bet is to run the video cable straight from the TV to the VCR. Don't bother running any A/V cables from your TV back into your VCR, because you are probably running the Cable TV coax from the wall to your VCR anyway.

The looping is for people with two VCRs or a VCR and LD. That way you can backup your movies onto VHS tape.

Q Our Library here in Hong Kong has a large collection of AV materials, with items from places all over the world. We are aware that DVD products are coded by zones. Do you know if we can order DVD products from places outside Hong Kong and instruct the suppliers to code the products as zone 3 (or multi-zones)? We don't want to limit the choices of our collection.

A You could buy some DVD players from other countries, such as the USA, and then order discs from that country. Your library users could check out the player and the discs to go with it. You would need to make sure that any electrical supply voltage and frequency differences are accounted for. Some discs are zone free, and would play on any DVD player. As far as having the players adjusted for different zones so that you could play discs from the different zones, you would probably have to do that yourself in conjunction with an electronics engineer, since changing them in one country for shipment out of that country might be a violation of regulations set by the manufacturer of the player, and the movie producers. Libraries might be an exception though, so you should contact the player manufacturer or distributor in your area and see if you can get permission for multiple zone purchases.

Q I have been considering a new set of speakers. On my short list are the PSB Gold/is and the B&W 604s. I know there is a price difference, but which speaker do you consider to be the best for overall audio and home theater use. If it's the PSB, is it worth the extra money? If you steer toward the B&Ws, do they produce sufficient low end and high end clarity and performance?
.

A Both speakers are very good. The PSBs will play louder with any given amplifier due to their lower nominal impedance, but they will require a good amplifier for the same reason Also, the PSBs are down only 3 dB at 31 Hz, while the B&Ws are down 6 dB at 30 Hz. Of course, the PSBs are more expensive, and if you are going to use the speakers quite a bit for digital home theater (DD and DTS), you really should have the same speakers in the front left/right as the rear left/right. Tonality-wise, they will be similar, but the PSBs will have greater clarity when you are playing them loud. In either case, however, I would suggest getting a good subwoofer. Although many full range speakers do well in the low frequencies, none can compete with a dedicated, powerful subwoofer in the first octave (20 Hz - 40 Hz).

Q My HT room is 11 ft. x 16 ft. My components consist of the Yamaha RX-V2090, Carver 705THX amp, AC3 DDP-1 Decoder, Sony DVD, Pioneer LD, and the Millennium 2.4.6 DTS decoder.

Here's where the "problem" begins. I purchased the Martin Logan SL3s and the new Cinema Center channel speaker. My surrounds are the big
Definitive Technology dipole speakers. The Martin Logans are incredibly transparent (which is why I like them), but I've noticed in my small
room, the sound seems to get pushed together (possibly because they are dipoles). Furthermore, the panning effects from left to right in
DTS (Jurassic park) aren't very noticeable.

Anyway, I noticed that you did a review of the Newform Research ribbon speakers. I'm specifically interested in the R-8-1-30s as a main
speaker, (they've been hailed as more transparent than the Martin Logan's) with matching NFRs for the center and rear speakers.

Do you feel, based on your listening experience with the NFRs, that they give the same "transparency" as the Martin Logans? Also, how
do you think the NFRs will perform with my system as compared to my Martin Logan/Def. Technology setup?

As you know, I can't go "listen" to the NFRs, but from what I read, they seem to be a top contender for DTS, DD and HT use. What's your
opinion, and again, thank you for the time and thought you put into this subject (my main objective is to have a speaker system that is
transparent, and gives excellent panning effects)?
.

A The "pushed together" sensation you are getting is, indeed, due to the dipolar nature of the Martin Logans, and will be similar to other electrostatic speakers. This effect will be reduced with the Newform Research speakers because the radiating surface of the ribbons is so much smaller than the electrostatic panel. However, the "transparency" will also be reduced. Nothing in life is free. You have to decide what is most inportant to you. Before you get rid of your Martin Logans in favor of something else, however, you should try some room treatments, specifically hanging damping material behind the panels on the wall. You can experiment by using quilted blankets. You can also try moving them closer to the wall, and toeing them in towards the listening position.

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