Q&A # 221 - March 6, 2001

Staff

Q I have my choice of a Panasonic DVD H1000 or Toshiba SD-6200. It will be used with a 65" Toshiba widescreen RPTV (TW65X81) and a nice resolving audio system (Von Schweikert VR5 speakers and Pass Labs amplification). Both video and audio performance are important to me. Which would you choose?

A These two players are very close, but our benchmark results show the Panasonic to have less video ringing. Since you are using the player with a large RPTV, I would probably go with the Panasonic.

Q I purchased the JVC-XV-D723GD as mentioned in your article. I have a Hitachi 61SDX01B rear projection set. This set supports 480p. In the interlace mode, the JVC to Hitachi hand-off worked well. However, in progressive scan mode, I lost video and audio while playing "Terminator II" and "Gladiator". The video and audio were not present for a few seconds and then came back. I tried everything to rectify the problem. I then decided to call both manufacturers and received no help. I returned the JVC DVD player for a refund.  Question: Am I to keep trying progressive scan DVD manufacturers until I find the correct compatibility?

A Since you lost both audio and video, the problem is with the player and those particular discs, not the TV. However, DVD technology is so new, just about any player these days will have a problem with one or two discs out there. Although standards for DVD programming are in place, the manufacturers don't adhere to them all the time. So, no matter which DVD player you eventually settle on, you will probably find a disc somewhere that it won't play. My advice is, rather than looking for that perfect player (which does not exist), just switch to interlaced mode for those odd discs, and let the TV do the line doubling.

Q I purchased a new Sony Wega 36" TV, and it seems that my speakers are not shielded for placement near a TV. Do you know of a product I can use to shield these speakers? They are made in Denmark and I have access to the inside via the speaker hole.

A Use a steel cookie sheet between each speaker and the TV. An alternative would be to get 1/16" steel sheet metal from a hardware store cut to the exact dimension of the side of the speaker facing the TV. Have them sand the edges so you won't cut your fingers. You can't use aluminum. It has to be a magnetic metal like steel. Don't put anything inside the speaker, because if the steel gets too close to the magnet on the driver, it will affect the magnetic field that the voice coil needs to perform correctly.

Q I was listening to a pair of Thiel 3.6 speakers at a local hi-fi store, and I  am set on buying them, but I'm having trouble choosing the right amplifier. I've read that these speakers are very revealing and power hungry. I've narrowed it down to three amps: Parasound HCA-3500, Rotel RB-1090, and Adcom GFA-5802, all under $1900, which is my price range. I will not be able to audition these amps in person and am going on specs and reviews alone. My  question to you is, which amplifier do "you" think would sound the best overall and will get the most from these speakers? What amplifier has the  best quality sound? I will be using the Thiels strictly for music. I listen  to classical, jazz, blues, pop, modern & classic rock, and some hip-hop. I don't play music at "ear-bleeding levels either. I've heard positive and negative things about all three amps. I am leaning towards the Parasound a bit, because it has pure class A output up to 15 watts. Also, should the "input sensitivity" be a big issue, as I will be connecting my CD-players variable outputs directly to the amp?

A All audio amplifiers have at least a little bit of class A, although it might be only a watt or two with mass market products. Parasound and Rotel use bipolar transistors in the output stages, while the Adcom 5802 uses Mosfets. Bipolars tend to have a little more snap and sizzle to them, while Mosfets are a bit more like tubes in sound quality. There is no "best overall" with these three in the $2,000 price category. It is a matter of taste in the type of sound they make. Personally, I (JEJ) would probably go with the Adcom, but that is because I like the sound of Mosfets. If you asked all of my writers, there would probably be a 1/3, 1/3, 1/3 split among the three models for their choices The Thiel 3.6 speakers are low sensitivity (86 dB) and 4 Ohms nominal. So, you are right in choosing amplifiers with 350 watts per channel output into 8 Ohms.

Q I have the Panasonic DVD-RV80 with built in DD and DTS decoders. My receiver is the Aiwa CX-NHMA86 which is "Dolby Digital Ready", but has no optical or coaxial inputs! I have heard that the only way you can get true DTS surround sound is through the optical or coaxial outputs on my DVD player, that the DTS signal cannot pass through the 5.1 analog outs and that my "DTS" encoded movies will automatically instead play "Dolby Digital" 5.1 sound! Is this true or I'm I hearing true DTS surround sound and not DD surround sound?

A The RV-80 has DD and DTS decoding, and both will pass through the digital output jack on the player, but not necessarily through the 5.1 analog output jacks. I could not determine the answer from the Panasonic website. However, many of the new players do send both DD and DTS through the 5.1 analog outs. Your instruction manual should say whether or not this is the case for the RV-80.

Q I have a Yamaha CDC-755 CD player connected to a Yamaha RX-V800 Receiver and I'm wondering what would be the best choice of interconnect?  Obviously, my choices are 1) use standard RCA cable and thereby using the CD player's DAC, or 2) use a digital interconnect (my only choice is optical here) which would use the DAC in the player. My guess is to use the digital cable because the CD player is 5 years old (2 generations ago in Yamaha cycle), and the RX-V800 just came out this year and utilizes a 96/24 DAC. When comparing a Monster Cable RCA cable vs. an Ultralink Toslink cable I'm pretty sure I could detect a little better detail with the digital but I'm not sure if the Ultralink is very good (thereby confounding the comparison). Also, if you do recommend the optical cable are there any brands you would recommend below $50-75?

A We have come to an interesting crossroad. For a long time, all the DACs were 18 or 20 bit, 44.1 kHz. Now that even the mass market receivers have 24/96 DACs, and some have upsampling, it is more and more likely that one will get better results with an older CD player, using the digital output from the player to the new receiver. Especially since you were apparently able to hear a difference, you should use the Toslink optical cable. They all seem to be very similar, and Radio Shack makes a nice one that is less than $50. Get a 6 foot one rather than 3 foot. This makes it much easier to move components in and out of the rack with cables still connected.

Q Has anyone tried hooking up a progressive-scan DVD player to a computer monitor?

A If your computer monitor accepts an RGB input, Extron makes the CVC 200, which can transcode component video to RGBHV on BNC connectors.  Then you need either 5 BNC cables into your monitor, or a 5BNC to VGA connector. Here's a link to information on Extron's CVC 200: http://www.extron.com/product/product.asp?id=cvc200. The Extron box lists for US$895. I saw this for sale at GG Video's Website, http://www.ggvideo.com for US$720.

The Entech CVSI-1 (Component Video System Integrator - 1) also does what your looking for, with output directly to VGA on a DB15 connector. Info for  this product is at: http://www.monstercable.com/product_info/infosheet_entech_component_vid
eosystem.html. The Entech box lists for US$1000 -- and it looks like discounts are hard to  find.

Q I have seen a lot of confusion information on acoustic suspension (sealed) enclosures vs. ported enclosures. Can you clear things up with a summary of advantages and disadvantages?

A Keep in mind that a bottom line is a very simplistic rule that always has exceptions, but generally speaking . . .

A ported speaker will give you either deeper extension, greater efficiency, or a combination of the two as well as greater output capability at slightly above the port tuning frequency. A ported speaker may also "unload" if it receives much content below the tuned frequency. The bass reflex alignment is also more susceptible to differences in Thiel/Small parameters that may differ from unit to unit due to manufacturing differences, or shift due to high output levels temporarily changing the parameters of the driver, so that it is more difficult to yield a flat, accurate response.

A sealed speaker will give you better transient response (slightly tighter bass), may be easier to integrate with a subwoofer, for those who are very critical about the blend between the two, protects itself from content below its own operating range, limiting driver excursion with not only its own suspension, but the air inside the sealed enclosure, and so doesn't suffer from "unloading" that a ported design may, and can't suffer from potential turbulence or pipe resonance problems that a ported design can suffer from.
It is easier to achieve more consistent results between units in terms of low-frequency response, and that response will tend to remain more consistent between different output levels.

� Copyright 2001 Secrets of Home Theater & High Fidelity
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