Q&A # 44 - December 31, 1997

Staff

Q I really appreciated your candor about advertising dollars and magazine reviews. At last, honesty from an A/V publisher. One other thing annoys me in magazines of all types. They like to say, "The number one whatever in the world" or "The leading authority in whatever". Why do they do that, when obviously there can only be one number one or leader?

A It's marketing bull. When a whatever is truely number one or the leader, they don't have to say it. The readers already know it.

Q The Sony TA-E2000ESD Preamp got very good reviews, but I am not sure what other hardware you need along with this, or is it a stand alone piece of equipment? I also got some information from Sony on their STR-DA90ESG receiver. My quetion is, what is the difference between a preamp and a receiver? The TA-E2000ESD appears to have more bells and whistles, but it does not decode Dolby Digital AC-3. The STR-DA90ESG has "Advanced Digital Cinema Sound" (whatever that is) and it says it has a Digital Dolby Decoder built in.

A A preamplifier has only the circuitry for switching sources (CD, VCR, Tuner, etc.), amplifying voltage from the source (if necessary) to levels that will drive the power amplifiers, controlling the volume, and maintaining a constant output impedance (it's supposed to, anyway) with respect to the power amplifiers. Preamplifiers don't have power amplifiers, and unless they specify processing, they don't have surround sound processing, but would be just two-channel stereo. However, surround sound is so universal, a component labeled as a preamp might have surround sound. You have to just check to see what the specifications are. A preamp/processor has the preamplifier and processing for surround sound, so it will have preamplification for all channels involved. If it has DD (AC-3) processing built-in, it will specify this. If it does not have DD, then it needs a set of 5.1 input jacks for you to add DD processing (an outboard processor or internal upgrade card availability) later. A receiver has preamplifiers (to drive the power amplifiers) and power amplifiers (to drive the speakers) all in one box. However, there are still a few two-channel stereo receivers (they have AM/FM Tuners) out there that are not surround sound receivers, so you need to check for surround sound capability, and if you want DD, it should specify DD built-in, or be "DD Ready", which means it has the 5.1 input jacks. Usually (but not always), receivers have more features than preamp/processors, but, usually, the preamp/processor has higher quality sound (higher quality parts). Marketing terms like "Advanced Digital Cinema Sound" are specific to the manufacturer, and usually mean proprietary sound fields (such as "Enhanced", "Jazz Club", etc.) that can be applied to two-channel stereo, Pro-Logic, DD, and DTS.

Q I recently purchased the DVD "Fleetwood Mac, The Dance" and played it in my Pioneer DVL700 player. The player would start and then stop without displaying any picture or sound. I thought the disc was defective, so I returned it to our local Best Buy store and had it replaced with a brand new disc of the same title. Still my player did the same just like the disc that I returned. In my return to Best Buy I requested that they play the disc on one of their Pioneer DVL700s on display. The disc played normally. If my player is defective, how come I do not have problems with the 37 DVDs in my collection?

A You might have a defective player, but since all your other titles play ok, perhaps they have made some changes to the current run of DVL700s which might fix some problems. Call Pioneer support and explain the difficulty. They might have a fix for you or at least they can take a look at it. If you return the player, also bring the disc with the chapter so they can see the exact problem.

Q I read in an article that DVD is recorded in the progressive scan format. Does this mean that future DVD players will be able to output the signal directly to a data grade projector without using a line doubler? Do the Samsung and the Faroudja player output the signal in RGB format? In these cases, does the use of the line doubler with these players seem irrelevant? Will the picture quality of the progressive scan DVD be equal or better than the component output with line doubler?

A Currently, there are no DVD players that output a progressive signal, but there is talk that Unity Motion will be bringing out one. The signal is recorded in progressive mode, but I am not sure about all the details. I will do some research and post it once I have some info. But as far as the Faroudja and Samsung are concerned, they only output an interlaced signal. And besides that, you should use the component signal rather than the RGB, unless your projector only has RGB inputs. The new consumer TVs that are coming out are not using RGB. They are using component, so if you have a Samsung, you will have to use the S-Video connection.

When it comes to video processors like Line Doublers/Quadruplers or Interpolators, they do all their processing in the component domain. They output RGB as one of the last stages. If you feed one of these units RGB, they will convert it to component to do the work, then convert it back to RGB.

Q I just read a review of the "Sleepless in Seattle" DVD. They liked the soundtrack but had this to say about the AC-3 version: "The Dolby Digital soundtrack is of the two channel variety, so the matrixed track is preferable for this release." This confirms what my DVD player (Sony DVP 7000) displays. The DD soundtrack is 2.0.

Do the two DD tracks contain the matrixed surround sound information? That is, will my surround-sound processor be able to process these two signals into Dolby Pro Logic? It seems I was able to do this with my Meridian 565. It appeared to default to my Pro Logic setting when it only received the two DD channels. Is this the case? Do other surround processors act this way?

A Some movies will have the PCM Dolby Surround recording, while others might have Dolby Digital 2 channel. Depending on how you have your DVD player set up, either the player or processor will decode the Dolby Digital.

With the Meridian, the decoder spits out the DD signal, decodes it, then plays it in either Pro Logic or THX mode. Even though the Meridian does not say it is in DD mode, it still is. It is just decoding the signal, then treating the decoded signal as a two channel mix. If you have the Meridian 518 in the signal path, it will report that signal as DA or data. This is a sign that you are getting the DD bitstream.

Q I recently purchased the "Singing in the Rain" DVD and I was awed by the color fidelity. Even my wife, who thinks the audio difference between my Digital 5.1 system and a T.V. speaker is that "its louder", simply said "wow!" when she saw the video quality of the disc. I have not seen any disc to compare with the intensity of this color. I have seen what I consider to be excellent video transfers, e.g., "Eraser", "The Mask", etc., but this disc struck me, and it's a thirty plus year old movie! My wife thinks it's been "recolorized" but I think not. Why do you think this disc has such rich, spectacular colors?

A "Singing in the Rain" does have some heavily saturated colors. This was how the film was made, although I believe some touch-up was done. Another movie that has similar saturation is "Austin Powers". The opening sequence is amazing, and the bright reds, yellows, and other colors looks fantastic. "The Fifth Element" is one of the best looking DVDs (IMHO). The computer generated city has some heavy saturated colors that look simply incredible.

Q Can you explain what the difference is between 4 ohm speakers and 8 ohm speakers? I have become more interested in home audio, and I hear lots of talk about speaker impedance and how receivers generate power at different ohms. What does all this mean?

A This question points out that I now need to install a search engine specifically for our huge Q&A archive, since we have touched on this subject a few times before. However, we can add something new here. Impedance is different than resistance. If you put an Ohm meter across a set of speaker terminals, with the amplifier disconnected from the speaker, you will often get a reading that is in the range of the specified impedance, e.g., 6 Ohms. But this is a measure of the DC resistance, sometimes called the resistive impedance. When a speaker is rated at 8 Ohms nominal impedance, this means that the total impedance, which includes DC resistance, inductive reactance, and capacitive reactance (the latter two are "reactive impedance" factors, and result when AC, i.e., music, is being conducted), is within a range that depends on the frequency of the AC signal being reproduced, and averages 8 Ohms. At any particular frequency, it might be 5 Ohms, and at another frequency, 11 Ohms. The flow of current is inversely proportional to the impedance, so the higher the impedance, the less current flows. An amplifier generates a voltage across the speaker terminals, and if the impedance is 4 Ohms, more current will flow at that voltage than it would if the speaker were 8 Ohms. The only thing you need to be concerned about is the capability of the amplifier. For mass market receivers, it is better to stick with 8 Ohm speakers, because the power supplies in the receivers are not made to supply the high current demands of 4 Ohm speakers being played loud. For tube amplifiers in particular, higher impedance speakers work better. For high performance solid state amplifiers, 4 Ohm speakers are fine, and in fact, some speakers dip down to 2 Ohms at certain frequencies.

Q I am looking to buy a good pre-pro (Lexicon DC-1 in particular). If I have an average CD player, feed it through and use the DAC in the pre-pro, how would the music sound compared to those high end CD players that have expensive DACs built in? I don't want to spend money on a DAC twice.

A I have used the Lexicon DC-1 fed by a Pioneer Laserdisc player, and I find its (Lexicon) DAC very, very good. Music sounded much more relaxed and especially in the mid-treble where I find cheaper (and usually, but not always, not so good) DACs falter. Bass was also more tuneful and less of a blur.

Having now also used a very decent and inexpensive HDCD DAC, I think you would find that HDCD is even more of an improvement than the DC-1, and I would certainly recommend one (audition first, of course). Why not get the DC-1, which is great for what it does, not limited to its built-in DACs, and get a HDCD-capable DAC even later, if you wish. The one I use is the Musical Fidelity X-DAC which sells for about US$400.

Q I'm a little confused as to what audio quality I should expect from a DVD player with music CDs. The advertising boasts that DVD players also play CDs, but no comparison of sound quality is ever given. I know that the DVD players compensate when playing CDs by changing the laser (Sony), or the laser focus, but what about the differences in the D/As that CD players use vs DVD players? Can you comment?

I'm presently thinking of purchasing the new Marantz CD-67SE because I also use my home theater for music, but is this a redundant purchase if I buy a Sony or Toshiba DVD player?

A None of the current mass market DVD players can do as well with a CD as a dedicated CD player, and this is especially so with the Marantz CD-67SE CD Player, which is reknown for great sound. I definitely would suggest getting the DVD player and a separate CD player.

� Copyright 1997 Secrets of Home Theater & High Fidelity
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