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Q&A # 224 - March 30, 2001
Staff
Q I have a NEC MT-810 LCD projector and would like to use it in a home theater setup. Connecting my DVD via S-Video has not produced the best results (bad color and motion artifacts). If I use a line doubler like the new Iscan Pro with component video from my DVD, will this give me a better picture? There seems to be some question as to whether a line doubler will make the picture of an LCD projector any better.
A Outboard line doublers, triplers, quadruplers, and scalers are only appropriate for CRT projectors, because the CRTs can show the image at various resolutions. The screens in LCD, D-ILA, and DLP projectors have a set resolution, such as 1024 x 768, and whatever signal you send into them is scaled to that resolution. You are experiencing artifacts through S-Video because the signal is being line doubled (scaled is actually the appropriate term, but line-doubling is the popular one) by the projector, and they are often not up to par. You will be best off by using the component video outputs from your DVD player into the projector, and with the player set to progressive scan if you have it. If it does not have progressive scan, you would probably have the best results by spending money on a player that has progressive scan and component video rather than fiddling around with band-aids of one sort or another. I have been using a Toshiba SD-6200 DVD player with a Sony 10HT LCD projector, and the results are superb. I saw a little improvement going from S-Video to interlaced component video, but a huge improvement going from interlaced component to progressive scan component. The reason for this is that the player converts the signal to progressive in the digital domain, then converts it to analog for output to the projector, and the projector converts it back to digital, since it is a digital display. It scales the image to the LCD panel resolution (in the case of the 10HT, it is 1366 x 768p), so their may be scaling artifacts, but it is not the same thing as converting the image from interlaced to progressive (the proper term is de-interlacing). Color quality is incredible, and edge artifacts are almost non-existent. It almost looks like film.
Q I am experiencing some sound "gaps" while watching DVDs recently. They are inconsistent and occur with a variety of different discs. The other evening the audio just completely cut off about 5 minutes into the film, and after waiting a little while to see if the sound would return on its own (it usually does on it's own), I shut the whole system down for 5-10 minutes. After powering everything back on and restarting the DVD, it played without incident for its entire length. I have a slightly unusual setup, with a Technics surround processor SH-AC500D, a Toshiba SD-1200 DVD player, a Proceed HPA2 amp for the front speakers, Adcom 5503 for the remaining surrounds, and a Levinson 380S preamp as a pass-through. I do not involve the system when playing VHS movies or while watching regular TV, but have not experienced any audio problems when using the Proceed and Levinson for stereo listening. Can I assume the problem lies with the DVD player, and if not, is there an easy way to isolate the cause before I bring anything in for service?
A I assume you are experiencing this with the digital output from the DVD player into the processor, in other words, using the Technics' DD decoder. Some DVDs are still causing problems, but if it is happening with a lot of discs, and it does not always happen with the same disc, it may be a defect in the Technics decoder. Try using the stereo analog output from the DVD player. If there are still problems, then it is the player. Also, make sure your digital cable from the player to the Technics processor has a good connection. A poor connection (perhaps the cable itself is defective) could cause audio dropouts.
Q Two weeks ago I had the misfortune of having my house hit by lighting and I loss both of my older Mitsubishi televisions. When I placed a claim with my insurance company, under my replacement warranty, they offered me a Zenith Console B25A76R (value $629) for my 25" Mitsubishi Console CK-2575R (retail $800) and a Sony 20" KV-20M42 (value $330) for my 20" Mitsubishi 20SX13 (retail $450).
This offer seems a little less than fair. I have always been under the impression that Mitsubishi was one of the best televisions on the market, perhaps close to Sony in craftsmanship quality, but better in picture and certainly much better in craftsmanship and picture than a Zenith.
In your opinion what would be today's equal to a Mitsubishi direct TV? The position I have taken with the insurance company is that Sony's Wega table top series would be "like quality and craftsmanship", and they should throw in a nice entertainment stand to cover me for the console portion of the Mitsubishi. But they have balked at it, and I'm in the process of fighting it. I am not looking to "stick it to the insurance company", I am just looking for a fair comparison. I would appreciate your opinion on what model TVs would be equal in "like quality and craftsmanship" to the Mitsubishi.
A There are a couple of reasons they are offering you something different than you requested. One is that they probably have a deal with some of the manufacturers to supply replacement TVs at a discount. Secondly, since your TVs were not new, the insurance company was not obligated to replace them with a TV at their original cost. My suggestion is to take the replacement in money and then go buy what you want.
Q I plan to buy a Sony DVP-S9000ES, a Dish Network HDTV Sat receiver (model 6000), a Yamaha RX-V3000 (or RX-V1000) and a Sony 65XBR10W RPTV. For some reason there is only one HD component input (or RGB/HV) on the
XBR. I plan to use the RX-V3000 to switch the two HD sources. Using the macro capabilities of the Yamaha remote, I guess I could automate power up sequence. The component output signal bandwidth on the Yamaha is from DC-30MHz, -3dB. Is 30Mhz enough for all HDTV resolutions? I have heard that DC-75Mhz is required to handle the full HD signal spectrum, is it true?
A The sampling rate of HDTV is ~75 MHz. This gives you a max bandwidth of 37.5 MHz. It's best to have 5x the bandwidth to ensure no degradation happens, which means you really want a flat response to 187.5 MHz. None of the set top boxes are flat even to 37.5 MHz.
Q I was just curious if you had the chance to actually review the Denon DVD-2800 player yet. I'm highly curious about this model, as I currently have the Pioneer DV-37. After reading your article about progressive scan units (Yeah, I know you warned me about reading further and not liking my player), I of course noticed all the problems with it. Granted I wanted the Camelot Roundtable afterwards, but not being able to float the $3500 price tag, I ordered the Sony-9000es. I got the chance to view my two players side by side, and the Sony does handle all the problems you talked about much better than the Pioneer.
Then I found out about the Denon player. It uses the same de-interlacer as the Camelot, and only costs $800. What a bargain I say to myself. It meets all the specs of the Sony, and has a virtually flawless de-interlacer. The only problem though, is that I can't find out if the player has the chroma upsampling error or not. Talking to Denon is a joke, and anyone who sells it, of course they want to sell it, and more likely than not, don't know what the heck I'm talking about. The other problem is that the first batch of 2800s that came out were defective. They had a faulty power supply on them that caused wave patterns in progressive mode, and also the EPROM on the unit was programmed incorrectly. These units were supposedly recalled, and good units have been shipping out. Yet I still can't find out about the upsampling bug.
You can see my dilemma, as obviously I don't want to waste my money on a $1,500 Sony, and the Denon could be a better unit for half the price.
A Denon apparently has fixed the problems on the 2800 that Stacey told them about, but not in a totally complete way. The upsampling error is still there, but vastly reduced. We don't have our test unit in hand yet, but have spoken to some people who do have the corrected player. The good news is that Denon supposedly will send a DVD that has the correct software on it, and all you do is put the DVD in the player, and it automatically reprograms the EPROM. For $799, the 2800 may very well be the player to buy, but also, the Toshiba SD-6200 seems to not have very much upsampling problem when used in the progressive component mode either. It is about the same price as the 2800.
Q I have Sony EP-9ES processor and Panasonic EN-300 DVD player. I'm thinking of upgrading them and considering a Yamaha RX-V1 and DVD player which has DTS output. I'm very confused whether it's a good time to upgrade to a DD-EX and DTS-ES, as I am worried a new surround format might come in the near future. Should I stick to my existing gear or upgrade them? I use multi brand speakers for front (Infinity Kappa 7), center (Paradigm Studio CC), and surround (B&W Solid). What speaker should I buy for the rear ES? The Solid model has been discontinued, and should I stick to one brand of speakers all around? I have a car subwoofer (JL Audio W-0). Can I use it as a home theater subwoofer as it is rated 8 Ohm? If yes, should I use a crossover or just connect directly to my processor sub output? I'm planning on running it with a Rotel power RB-971.
A There are already a few new formats to look for in a receiver, namely Pro Logic II, DTS Neo:6, and DTS Discrete 6.1. The receivers coming out during the next few months, such as Onkyo offers, will have these formats. I would suggest waiting until late Summer or Fall to see which ones have which formats. It would appear that having a port on the receiver for installing software upgrades will be more and more important.
Q How important is bi-amping? When you bi-amp a set of speakers, do you just split the channel's pre-out to two different power amplifiers, then feed the two amp channels to the speaker (jumpers are off of course) and then let the speaker's internal crossovers take care of it? Or are you supposed to do something to the pre-out signal before it gets to the amp?
Would it work to say take a set of studio monitors and bi-amp them using an Outlaw Audio 1050 (6x 65 watts) for the upper set of binding posts and an OutLaw Audio 750 (5x 165 watts) amp for the bottom set of binding posts?
A Bi-amping can be an extremely good thing, when it is part of the speaker's design. By that I mean, in the case of "active" (self amplified) speakers, the crossover(s) are implemented at the line level BEFORE the amplifiers. When this is done, each amp only gets the signal the driver is destined to produce, yielding all sorts of benefits. You get more efficient use of power, can more easily tailor the response of the drivers, and will have more consistent results not only between models, but between output levels, as the impedance of the drivers changes in relation to power dissipation, and the effects of the passive crossover depend on the impedance of the drivers. If you're designing from the ground up with any amount of expertise in both loudspeakers and electronics, it makes more sense to go active. Unfortunately, the high-end market is resistant to active designs, as most audiophiles like expensive outboard amplifiers. Interestingly, an active design requires less robust amplifiers to do the same job, and when the person designing the speakers designs the amplifiers as well, the amplifiers can be built to task, as opposed to overbuilt to be ready for a wide variety of loads. So long as you're talking the higher price range of loudspeakers, a completely integrated active approach equates to more performance for less money, assuming that the designers know what they're doing.
Does that mean that an active speaker (with dedicated amplifiers for each range, and the crossovers in the line level) will be better than another passive speaker? No. In fact, if you arbitrarily rip out a passive crossover from a carefully engineered loudspeaker and throw in some generic electronic crossover to go active, chances are that you'll be worse off all the way around, as the crossover not only addresses dividing frequencies between drivers, but also correcting for the inherent response of the driver as well, both in the crossover range, and outside of it.
What you're describing is known as "passive-bi-amping," which can be a waste of resources. What you're doing is simply running both amplifiers full-range, and then letting each side of the crossover filter out the output which the designated driver array doesn't want. That means you're pushing just as much voltage out of each amplifier as if they were driving the whole loudspeaker by themselves. There is a benefit to each respective amp, in that the respective crossover segment will raise the impedance above or below (whichever) the crossover frequency as a side-effect of the filter, and, that as a result, with musical content on both sides of the crossover, each amplifier will have to provide less current. However, since the voltage requirements are not eased, this means that so long as a single-amp wasn't seriously running short of current in the first place, using two amps in a passive bi-amped arrangement will NOT substantially improve dynamic range. Plus, if the content is dominantly on one side of the crossover point, that amplifier could still fall short in current delivery. If the problem was a lack of current, get an amplifier with more current instead of using two weaklings to hold each other up.
I used to have some Onkyo M-504s that worked nicely with passive bi-amping, driving some Infinitys. Driving a relatively easy load, they were pretty good. My Infinitys weren't such. On a single amp, the system squealed and waffled. With two of them bi-amped, it was pretty respectable, and a great improvement, which at the time sold me on the whole passive-bi-amping thing. I later threw in a single amp with more muscle, and the speakers just sang, coincidentally, in my opinion, outperforming many active systems at normal listening levels.
Q I am under the impression that, if not done correctly, the sound from the sub and the speaker that the crossover splits between will have holes or increases in the sound level, depending on how close to in phase or out of phase the sound waves are. Is this correct?
A The phase relationship between two waveforms is represented by how the high-pressure sections of the wave match up with the low-pressure sections. If the phase relationship is 00, or 3600, the high pressure and low-pressure sections match up spot on, and the amplitude of the waveform is doubled, in terms of pressure, and the actual output is quadrupled in terms of power. At 1800, the pressure relationships are opposite and they cancel. At 900, it's in between, and the combined response is 3 dB higher, or double in terms of power.
� Copyright 2001 Secrets of Home Theater & High Fidelity
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