Q&A # 104 - February 22, 1999

Staff

Q I'd like to make a comment with regard to the current DD/DTS 5.1 channel setups. Manufacturers are now including DD and DTS in processors and receivers, as well as 5.1 channel inputs. Do they really think there is any chance of a third compression scheme? I hope not because even just two choices has caused enough headaches. I know that 6.1 channel DD might be a future upgrade, but what good will 5.1 channel inputs be at that point? What I would like to see, however, is for the manufacturers to go with a 7.1 or 10.1 (or more!!) channel input scheme. This would accommodate an upgrade to the SDDS 7.1 channel setup or would actually be "future-proof", in that the additional inputs would, at worst-case, be downmixed into the current 5.1 DD or DTS, and best-case a software/hardware upgrade would allow the full potential of all the channels.

I love the additional front effects channels provided by Yamaha on my 2092 (and the 2095 and DSP-A1) and the extra rear channels on the Lexicon DC-1. In my mind the ultimate setup would include:

Left Main+LFE , Left Effect, Center+LFE, Right Effect, Right Main+LFE
Left Side, Me, Right Side
Left Rear+LFE, Middle Rear+LFE, Right Rear+LFE

Maybe I should get that DC-1 too! For large rooms (especially long ones) like mine, this setup would be better than an SDDS cinema, which is the best I've heard yet. What do you think?

A I agree with you about the format changes that are going on. We barely have 5.1, and already there is 6.1 coming this May with the new Star Wars movie. Fortunately, 6.1 is easy to adapt, since it has a center rear channel that is matrixed with the rear left/right, so we can just use an old Pro Logic receiver to extract it (connect the rear left/right analog outputs to a stereo analog input on the old receiver, and the center channel speaker output to the center rear speaker). The front effects channels of the Yamaha and the extra rear channels of the Lexicon are not in the original mix as you know. They are computer generated.

I see the evolution of discrete digital surround sound moving towards 9.1 channels. The table below indicates the layout. The additions would be the right and left center, the rear center, the ceiling (for airplane fly overs), and a tactile transducer in the floor or couch. The tactile transducer would replace the .1 LFE channel which has not turned out to be used very much anyway, and could consist of frequencies of about 25 Hz and lower, down to perhaps 5 Hz. Mono or stereo subwoofer outputs on current receivers are fine for the low frequencies below 50 Hz, and that signal could just be extracted from the low frequencies that are already in the other channels. If you wanted to connect a subwoofer to each channel, pre-outs would allow that, along with connections for outboard power amplifiers. The signal would be digital most of the way, with the DVD player sending the 9.1 bitstream to the preamplifier/processor, where it is decoded, DSP added, volume adjusted, and then sent out as a digital bitstream to the various amplifiers around the room, using an IEEE1394 digital cable, and each amplifier being a "device" in a daisy-chain. The amplifier would have a built-in decoder that selects its specific channel information and sends it to the power amplifier and speaker. I also think it will be important to incorporate digital EQ which will allow us to fine tune each channel, since with speakers in so many different places, tonal balance is unlikely without EQ.

Left Front	Center Front	Right Front
Left Center	Ceiling Consumer Couch	Right Center
Left Rear	Center Rear	Right Rear

Q My receiver does not have a low level output, so I'm going to use the high-level connections (the speaker outputs). Now, my understanding is that I simply connect the receiver high-level outputs to the sub and then use the outputs from the sub to drive my front speakers. Assuming that is correct, if the receiver is rated at 100w/ch and the sub is rated at 85w, how much power gets to the front speakers? Is the sub simply pulling the low frequency stuff out and passing the rest straight through?

A When you use the speaker outputs from a receiver to drive the subwoofer, the subwoofer passes a low voltage replica of the signal through a crossover (variable frequency low-pass, selected by the consumer), and sends the low voltage low-frequency-only signal to the subwoofer's power amplifier. The power from the receiver has the low frequencies removed by a second crossover (usually at a fixed frequency), and the remaining power (high-pass) is sent to your satellite speakers. You don't really even have to use the speaker-level outputs from your subwoofer, but rather, you can simply connect your receiver's speaker outputs to the speakers, and a second set of speaker cables to the speaker-level inputs on the subwoofer (sending full spectrum sound to your speakers, and letting the subwoofer's crossover send low frequencies to its built-in power amplifier). This is not the same thing as connecting two speakers in parallel, because the speaker-level inputs on the subwoofer don't go directly to the driver. They go to an active crossover and then to the built-in amplifier input.

Q I have a 40" Mitsubishi model 40507 TV that I have adjusted with the Video Essentials DVD. Although the picture has improved quite a bit, I'm still not satisfied and contemplating having the set calibrated by an ISF techician. My question is what more would be done by the ISF people than what I did? And is it worth the $200 or so to have it done?

A An ISF technician can go into the back of the TV and make electronic adjustments not available to consumers. For example, on my TV, I can't turn the brightness down low enough for my own preferences, and an ISF technician could adjust it internally so I would have the range that I want from the user interface. Most of what we want can be achieved with the VE DVD, but if the factory settings are way off, the ISF technician can make them right.

Q I was recently told by a salesperson that although Dolby Digital and DTS send full range signals to the surround channels, they are still mainly used for subtle effects and therefore it is overkill to have the same speakers for the surrounds as the fronts. Especially when using a sub which will take care of the low frequencies anyway. I have a Dolby Digital Built In and DTS Built In receiver but have not purchased a DVD player yet (most places are sold out of them lately) so I can't listen to DVDs to find out for myself. I am currently looking at surround speakers. While bookshelf speakers would be easier to fit into the room (not to mention cheaper), I can put floorstanding speakers in the space I have. Is it true that Dolby Digital and DTS use the surround channels mainly for subtle effects and that the signal to the surrounds is much less than the signal sent to the mains?

If I were to purchase floorstanding surround speakers which were say 3 feet high, would placing them 3 to 4 feet behind my couch (which is more than 3 feet high in the back) be OK? I don't have enough space to place them to the sides of the couch. Should I put them on stands so that at least the tweeter is above the back of the couch? Or angle them up towards the ceiling? All the placement articles I've seen focus on small Pro Logic surround speakers as opposed to the larger full range speakers recomended for Dolby Digital.

A When Pro Logic was the thing, small rear surround speakers were fine because the frequency range was also small. There wasn't any deep bass or high frequencies. It was really just for ambience and subtle effects. Dolby Digital and DTS use full spectrum sound, and even though the surrounds still are used mainly for effects, it is their frequency range that dictates using the same speakers as in front. Because the effects are full spectrum, you get the best tonality balance by having the same speakers. With DD and DTS music, I have found that the rear channels get much more signal than they do with movies. So, having the same full range speakers in the rear has made a big difference with these recordings. For example, there is a new DTS audio CD of Holst' "The Planets". There are instruments coming from all channels, and because I have the same floorstanding speakers in the rear as in the front, the balance is excellent. A choir introduction to Tschaikovsky's "1812 Overture" on DTS DVD audio is also much better with the same speakers all the way around because the voices in the front have the same tonality as the voices in the rear. Digital surround has changed everything. Obviously you are concerned enough about this to write to us, so get the floorstanding speakers for the rear as you are doing for the front. You will be glad you did. Rather than angle them towards the ceiling, just get some basic floor stands that will raise the speakers about a foot so that the tweeter just peeks over the couch. You can test the correct height by putting them temporarily on some books or other supports and playing some music. You don't need a DVD player to try some DTS music. There are plenty of DTS CDs available now, and they will play on your CD player as long as you have a digital output jack to connect to a digital input jack on your receiver. (Of course, your receiver must have a DTS decoder inside, or you must have an outboard DTS decoder connected to the receiver. The reader who asked this question has DTS decoding built-in.)

Q Compared to mass market CD changers, single disc player companies like Marantz seem to get favorable reviews for their products. Are their any changers out there whose performance is comparable to the higher end single disc players/transports built by companies like Theta?

A Theoretically, there is no reason that a changer mechanism would cause the sound to deteriorate. The changer just moves discs around in a circle, and once the new disc is in place, the transport operates like it would in a single disc player. The problem is the marketing image that a CD changer creates. It has been associated with mass market for so long, the high performance consumer does not want to be caught dead with one. So, the high performance manufacturers don't build them. One product I am keeping my eye on is the new Denon DCM-5000 which is a jukebox changer that stores 100 CDs for immediate playing. It is $1,800 and looks to be a fine component. Other than that possibility, I can't think of any potentially high performance multi-disc CD players out there.

Q In your experience or best estimation, what percentage of loudspeaker companies actually manufacture their own drivers? I've seen ads for companies that say "Powered by ScanSpeak" or the like, and I know that there are several companies (including ScanSpeak) that offer high-quality drivers to the public. Could I buy, for example, the drivers for a Wilson Audio Grand Slamm and build it at home (Wilson Audio's website says they buy their drivers) given that my construction skills are up to the task? How good is the quality of the "DIY drivers" compared to what commercial companies use? Are we just paying lots of money for the R&D that goes
into good cabinet and crossover design?

A Very few speaker companies manufacture their drivers from scratch in their own factories. It is not cost effective. (Most do not build their own enclosures either.) Probably every one of the high performance speaker manufacturers have the drivers made to their own specifications though, even if it just means they have a standard model changed slightly. The drivers that are in the catalogs are designed for general use. It's the same for the crossover parts as well as the parts inside amplifiers. The resistors, capacitors, inductors, and transistors are made by someone other than the company that sells the speakers and amplifiers, but some of the parts may be customized, particularly capacitors from what I can tell. Although you might be able to purchase the same general drivers that a high performance speaker manufacturer uses, it is unlikely you would have the same exact design as the ones they end up with, since they probably have been modified somewhere along the assembly line.

Q I know you think that DVD players don't play CDs well. That is debatable. But you also suggest getting a dedicated CD player while saying it willl be obsolete in the near future. Do you mean that you will be able to use it for your old CDs? For the new DVD playing everything format it will be useless, correct? Also, one last time. If you had a choice between a $400 CD player or a $400 DVD player to use for CDs which would you choose?

A Current CD players will be obsolete within two years due to Pioneer's 24/192 format and Sony/Philips SACD format. Both will be music formats on DVD discs rather than CDs because of the space required for all those bits, although the discs will play on regular CD players too since they will have an additional layer with regular 16/44.1 PCM. However, for the large CD library I have now, I would still get the $400 CD player rather than a DVD player that plays both, since the current DVD players will not play the 24/192 or SACD. Those formats will need a new player (OH NOOOOOOOO!). What I use now is a standard CD player for CDs and a DVD player for DVDs. If I had to choose one or the other and could not have both, then obviously I would get a DVD player since I like movies and CDs. Yamaha is rumored to have a player in the works that will play all formats, including 24/192 and SACD, so we will wait and see how it handles the old CDs. So far, I have not seen a DVD player that really does a good job with CDs, but I am always willing to modify my opinion based on a new product. I would love to have a player that does it all, and does it well. I just haven't found one yet. It would be against our policy to recommend a product to our readers that is not good enough for us. If we recommend it, then we would be happy to have it in our own homes too. That is the way we do things.

Q It seems strange to me that few use (or are even aware of) the amazing quality of audio-only recording on Hi-Fi VHS. What else will give 20 Hz - 20 kHz frequency response and 80 dB of dynamic range on a 6 hour tape that costs less than two bucks? Granted the sound is a bit compressed if the VCR lacks a manual input level control, but the quality as compared to even the best high-end Type 4 cassette tape is phenomenal. The only real flaws to the format are the real scarcity of portable equipment, and long cueing up times. Despite this, however, it would seem to be an almost ideal consumer recording format. Why didn't Hi-Fi VHS ever take off for home recording?

A I think it was a combination of things that just caused some bad luck for the format. One is that the digital nature of CDs, along with the emergence of Digital Audio Tape (DAT), turned consumers off to the nature of analog recording, no matter how good it was. Secondly, the lack of portable recorders causes a problem for location recording. Third, the large size of the cassettes is very inconvenient. Imagine trying to use a VHS cassette on an airplane, even if portable recorder/players were small. Imagine trying to negotiate one into a player in a car. This is all especially prominent when compared to the very small size of DAT. On the other hand, DAT and MD have not exactly been market busters either. The problem there, in my opinion, was not so much that we hate compression (which we do), but that the media is so expensive. If blank DAT tapes or MD discs had been $1.99 at the Price Club, I think they would have been a tremendous success.

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