Q & A

Q&A # 289 - May 16, 2002

Staff

Q I enjoyed your recent Secrets review of the SVS CS-Ultra. What I found most valuable (and interesting) are the various measurements that you took and reported. (I'm actually the owner of an SVS CS-Plus, so I figure there's some relationship between your measurements and my sub. :-)

Anyhow, I did want to point out what I think may have been flaws in a couple of your measurements. In particular, the measurements you took at an 8" distance from the sub's driver. For the reasons you gave (minimizing the effect of the room), the 8" distance makes perfect sense. However, for the lower part of the frequency range (below 30 Hz, perhaps?) the sound emanates from the ports, not the driver. At least I think so. This means that when measuring the lowest frequencies, your microphone was no longer 8" from the principal source of the sound, but rather more like 40 or so inches.

My concern is that the steep roll-off you saw starting at about 30 Hz in your 8" FR measurement (the red line on your chart) can largely be attributed to the ports-to-microphone distance. Similarly, your 20 Hz THD measurement may have the same problem. It's hard to know, though. It might be interesting to see what you'd measure at 8" from the ports.

In any case, I don't think any of the above affects the overall gist of your review, and it did sound like you're trying to develop some fairly precise and reproducible measurement techniques, so perhaps you'll find my observations useful.

A Actually, I did measure the frequency response 8" from the ports, and the graphs are shown below. They were about the same as those measured with the microphone 8" from the driver at the bottom, with a slightly different MLS picture due to port turbulence, and perhaps a few dB better response overall. I felt we had enough graph clutter in the article, so I did not publish them there. There may have been some absorption from the rug on the floor near the driver, and the ports are almost at the center of the room height. The ports are huge and there is so much air coming from both the driver and the ports, I suspect I would have to put the microphone right in the face of the driver or inside the port to separate the two in the graphs. Remember also that the MLS technique is very, very conservative. It imposes restrictions of anechoic chambers which reflect nothing, so it probably detracts from the live-room performance, which subwoofers typically get an improvement from. Subwoofer "X" was terrible by comparison, and the same price essentially. It is a very popular subwoofer, and I decided not to say what brand because it was not under official review. The bottom line is how it sounds and punches in a real room, and the SVS is one of the best subs I have ever listened to.

Q I am in the market for a sub and the SVS is one that I am considering. However, I had read where some people found SVSs not as good with music and preferred for instance the HSU VTF-3 or VMPS subs. Have you any experience with these other subs or how they would stack up musically to the CS Ultra?

A It depends on what kind of bass you prefer. For really low frequencies, say 20 Hz, you feel them but don't hear them, other than the studs in the wall creaking in time to the signal. Some people prefer more THD than the SVS has, because it adds a sense of hearing the 20 Hz. What you are actually hearing, of course, are the harmonics at 40 Hz, 60 Hz, 80 Hz, etc. With a high THD, such as Subwoofer "X" has at high output, the effect is not pleasant, but if the THD is lower, say at 10%, it might be enjoyable, depending on the effect you like. The SVS is very clean, even at high output, and in my opinion, this is the best kind of sound to have for movies or for music because it represents the source rather than artifacts.

Q My system consists of:

1. Denon AV 10 SE surround amplifier with Denon POA T10 power amplifier for front L & R speakers.

2. Sonus Faber Grand Piano Home.

3. Concertino surrounds.

4. REL subwoofer Q100E.

5. Monitor Audio centre.

Which one (1) of the following would make the most significant upgrade for 2 channel listening of mainly acoustic music i.e. vocals, violin, cello and chamber music, total of some 1,000 so-called recommended audiophile CDs:

1. Perpetual Technologies P 1A/3A DAC & upsampler.

2. Musical Fidelity A3-24 DAC & upsampler.

3. Adcom GFP 750 preamplifier.

4. Sonic Frontiers Line 1 preamplifier.

5. Audio Research SP15 preamplifier.

6. Anthem AV 10 & PV-7 processor and power amplifier to replace existing Denon system.

Here in Singapore hi-fi dealers generally would pull a long face if you audition and not buy, so I can't really make an A to B comparison. My room size does not allow for a second audio only system. I'm an audiophile on a tight budget. Grateful for your advice.

A You have such a nice system, it is hard to say what you could do to improve it, but I would say either the Sonic Frontiers Line 1 or Audio Research SP15 preamps, since they are tubed, and would be quite different from your Denon. In particular, if you purchase the SF Line 1, be sure to get the SE upgrades, which include New Old Stock (NOS) Siemens ECC88 tubes. NOS Telefunken ECC83s (12AX7s) are legendary, and Siemens ECC88s are thought of highly as well. The Audio Research SP15 is now the SP16, unless you can get the older model in Singapore.

Q I have been thinking about buying a 7.1 receiver (Denon). Does a DVD player send all of the information to the receiver if it is playing a 7.1 movie? I have never understood how all of this works. Or does the DVD player need to have 7.1 outputs to feed into the receiver? If there are no external devices that send 7.1 info to the receiver, why are receivers built with all of these decoding formats? The same thing applies to a VCR. You play a 5.1 movie. Does the VCR send all of the information to the receiver so that it can play the movie as 5.1 or 7.1? How does the receiver decode 7.1 or 5.1 if the DVD player is not the same?

A When you see a receiver described as "7.1", it's referring to the number of speaker outputs, not the number of discreet channels in the soundtrack. There are various processes to create extra channels from a 5.1 signal. In the case of formats like THX Surround EX, the extrapolated channels are part of the soundtrack while other processes simply synthesize extra channels.

For VCRs, the soundtrack on the tape is stereo (two-channel). Your receiver decodes it into 4 channels using Dolby Pro Logic, but it is not discrete 5.1 like DD and DTS.

A decoded Pro Logic soundtrack should not be referred to as 5.1. It is two channels with two cardinal axis channels derived. Some people refer to it as 4.0, but that is misleading as there is such a thing as discrete 4.0 Dolby Digital, found on several DVDs.

Even though THX Surround EX delivers 6.1 output channels, its not really 6.1. It's 5.1 plus an extracted channel. Same for DTS ES. Only DTS ES Discrete is true 6.1, but it is unsupported by the cinema industry and thus far has simply been a novelty on a couple of DVDs.

Originally the X.X moniker referred to the discrete input channels at a time when a single format, like AC-3, could accommodate many permutations of discrete channels. Anybody with a head on their shoulders continues to do so. But marketing people started using it to refer to the number of speaker outputs a receiver has. I think it was wrong of them to do so as it confuses the consumer, and we as a press entity do not condone it, always promoting the correct context of the X.X term.

Here are some examples of how to properly label a soundtrack:

Stereo
Dolby Stereo (or Pro Logic) Encoded
Dolby Digital Mono
Dolby Digital 2.0
Dolby Digital 2.0 Dolby Stereo (or Pro Logic) Encoded
Dolby Digital 4.0
Dolby Digital 5.1
Dolby Digital 5.1 THX Surround EX Encoded
DTS 5.1
DTS 5.1 ES
DTS 6.1 ES Discrete
(Note that DTS refers to DTS ES as "6.1")

Here are some proper ways to refer to receivers and surround sound decoders:

Pro Logic
Dolby Digital
THX Surround EX
DTS
DTS ES
DTS ES Discrete

Saying that a receiver is "7.1" means nothing! Tell me what processing it includes. That would communicate something meaningful. There is one true discrete 7.1 format, and it is called SDDS (Sony Dynamic Digital Sound). It is a glorious, cinema-only format, calling to mind the grandeur of the 70mm era, but alas Sony seems to be loosing interest in marketing and promoting it.

Q If I listen to a CD through a DVD player, should I switch the audio on the DVD player to PCM or just leave it in the Bitstream position? Also, would it be better to use the the digital output of the CD player so that the Pre/Pro can do the D/A conversion or use the analog outputs? (My CD player is the Denon DCM-460 and the Pre/Pro is the Denon 4802 receiver used as a preamp with a Bryston 9B).

A This menu is for configuring the player's digital output according to what your processor has. Use PCM if your receiver does not have DACs that can handle 24/96 or does not have a DD or DTS decoder. All modern receivers have DACs that can at least handle a 16/44.1 digital input. When you set the DVD player's digital output to PCM, the signal is down-converted to a lower rate so that your receiver's DACs won't be damaged. If the signal is 4.0 or greater for DD and DTS, it is down-converted to a left/right two-channel track. If you have one of the new receivers that has 24/96 or 24/192 DACs, as well as DD and DTS decoding, then use the Bitstream setting in the DVD player setup menu, rather than the PCM setting.

As to whether to send the DVD output to your receiver in analog or digital form, you can test them both ways by connecting a digital cable and analog cables to two different sets of inputs and just switching back and forth while the music is playing. As long as you have a good digital cable (75 Ohm coax or Toslink), I suspect you will get better results by using the digital output from your DVD player, because there is no signal loss, compared to analog cables that do suffer loss. This is especially so in your case, with two Denons that may very well be using the same DACs.

Q What do you guys think of the Aragon Soundstage Processor?

A We are waiting for our review unit now.

Q There was a subwoofer review http://www.hometheaterhifi.com/volume_8_4/subwoofers-12-2001.html that had a conflicting Conclusion. In the article, Brian Weatherhead comments very highly on the Klipsch RSW and the Velodyne being a great match for music lovers. However in the conclusion it states "If clarity and musical performance were you main goal, it would be hard to pick from the Klipsch RSW and Velodyne." Did he mean 'hard Not to pick'. Meaning he would pick either the Klipsch RSW or the Velodyne for music lovers?

A He meant that it would be difficult to decide between the two.

Q I need a TV, DVD player, and sound system and all I have is $2000 to $2500 to spend. I need help because after days of searching the internet comparing, I am confused and do not want to walk into a store with cash and get talked into something I do not need. I live in the Toronto region and so far I have not met a salesperson I trust. Do you have any suggestions on what I can do with so little?

A I would suggest going to CostCo (or Canada's equivalent), and getting a 32" NTSC TV that has an S-Video input. They are about $500 in the USA. For your DVD player, get a Panasonic RP-56 at less than $150. Then, get a small receiver that has pre-outs for all channels so you can get a more powerful outboard power amp later on. Something like the Denon AVR-2802 ($799) or Onkyo TX-SR700. With the remaining funds, get something like the Velodyne Classic Home Theater speaker package. If you shop around, you should be able to get all of these items at less than MSRP.

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