Home Entertainment Blog Archive
Brought to you by your friendly, opinionated, Home Entertainment and Technology writer, Stephen DawsonHere I report, discuss, whinge or argue on matters related to high fidelity, home entertainment equipment and the discs and signals that feed them. Since this Blog is hand-coded (I like TextPad), there are no comments facilities. But feel free to email me at scdawson [at] hifi-writer.com. I will try to respond, either personally or by posting here emails I consider of interest. I shall assume that emails sent to me here can be freely posted by me unless you state otherwise.
This archive is for an uncertain period commencing Thursday, 4 September 2003
A superficial reading of the specifications of a CD-ROM drive can generate a fearsome number. The now standard 52x read speed suggests a disc running at 24,000 rpm, with a linear velocity at its edge of over 150m/s (that is, nearly half the speed of sound!)
In this Australian HI-FI article I discuss the likelihood of this causing damage. If you don't want to read it, the short answer is 'not likely'. The reason is all to do with the difference between CLV and CAV.
Calling Virginia! -
Tuesday, 23 September 2003,
10:25 pm
The statistics on hifi-writer.com show that the highest volume of visitors, by region, come from North America (not surprisingly, closely followed by Oceania, which is where I am). And for the past couple of weeks the biggest number of visits have come from the Commonwealth of Virginia in the United States. So far this week (ie. since Sunday), they have accounted for one third of North American visitors (55). Who are you? Is Virginia a hotbed of home entertainment freaks? Did you somehow discover that my eldest daughter's name is Viriginia? Write to me, please, at scdawson at hifi-writer.com. I'm fascinated.
The DVD User Group has come to arrangment with Sound and Image magazine to reproduce some of the magazine's hardware reviews on-line. My review of the Denon DVD-2900 DVD player is now there (you need to become a member -- it's free -- then hover over 'News' and click on 'Hardware review').
The damping factor of amplifiers is a measure that has fallen out of favour in recent years. Many brands don't specify it any longer. I had long considered it an important specification, since a low damping factor can lead to frequency response anomalies and poor control over the bass driver in a speaker. But, like an idiot, I failed to take into account that the effective damping factor of an amplifier and speaker system is based on the internal impedance of the amplifier (I knew this), the resistance of the speaker cables (I knew this as well) plus the resistance of the speaker voice coils. It was this last that I had overlooked.
No excuse: the whole thing is explained in an ancient (1967) paper written by George L. Augspurger from James B. Lansing Sound Inc. Read the whole thing.
Some experimental types have been working out the effect of infrasonic sound on people's emotional states. The recipe: take a seven metre long pipe, stick a 'long throw' bass driver (woofer) therein a third of the way down, then drive it with a 17 hertz signal. Insert into live performances from time to time, then have the audience complete a questionnaire. Compare their feelings about the music when the infrasonic sound was on with their feelings when it was off. Apparently it had some effect.
I am interested in their infrasonic production apparatus. Not very much information is provided. Presumably the pipe is tuned to resonate at 17 hertz, and I imagine it would be designed to reduce harmonics to the minimum possible. The problem with producing pure bass is the harmonic distortion that is almost always generated. Let us say that the second harmonic is at, say, five per cent of the fundamental frequency (measure some subwoofers and you'll find that this isn't an unusual number!) That equates to 26 decibels quieter. But the sensitivity of the human ear drops off very sharply in the extreme bass regions. The Fletcher Munson curves (which attempt to equate the sensitivity of the human ear across the frequency spectrum) suggest a fall-off in sensitivity of as much as twelve decibels per octave in the bass (ie. between 40 and 80 hertz) and this drop-off likely becomes steeper the further into bass one descends. So high levels of distortion can result in audibility of an 'infrasonic' tone.
Thanks to my brother Mark for the heads-up. Go visit his Website Images of Canberra to see a stack of wonderful photos of Canberra and environs.
The CRT projector lives -
Sunday, 21 September 2003,
9:57 am
Yesterday I finished a review of the Barco Cine 7 LT projector, which should appear in a couple of weeks in the 'Livewire' section of The Age newspaper. I had thought that CRT projectors were big, heavy and expensive. The Cine 7 LT is indeed big and heavy, but sells for around the price of the less expensive Mustang-based DLP projectors.
The picture gives a hint as to why they are big and heavy. Three CRT tubes and a huge amount of electronics.
So why did I have it opened up and guts displayed to the world? Well many of the setup features (including such tricky matters as convergence, which can be performed automatically) are accessed through regular setup menus. But the projector's location isn't. To set the picture the right way around for ceiling or table-top use, or for front or rear projection, you have to open up that big electronics chassis, pull up to six signal feeds from the board, and re-plug them in the other way around. Fun, eh?
If you want a list of all Australian radio or TV stations, including their frequencies and power outputs, these are available on the Australian Broadcasting Authority Website. In particular, for radio go here, and for TV go here.
Perhaps it was a mistake, but today I turned down doing a radio interview. Seems someone over in Western Australia had published an article on this most exciting topic: cleaning your hi fi. I had to ask for clarification from the Australian Broadcasting Corporation person who was trying to arrange the interview for some local 'drive time' show: do you really mean cleaning, like scrubbing, a stereo? Yes, with Windex and alcohol, I was told.
A million thoughts: first, I almost never clean my gear. Just the odd-dust off when it looks to be getting so thick that heat dissipation is being restricted. Second, every second manual I read has dire warnings about using benzene and so forth on the equipment. I thought I ought to mention that, then realised I don't really know what benzene is. Then I thought, what if I say to use Windex and it discolours someone's super-expensive piano-gloss speaker finish?
So, no. Want to talk about the kinds of equipment to buy on a budget? Need expert advice on connecting up and configuring a stereo or home theatre system? Like to hear the pros and cons of DLP vs LCD projectors? Then I'm your man. But cleaning the damned stuff? No way!
So says high-end cable maker AudioQuest (go here, enter the site, choose 'Cable Theory' and then page through to '2/10' -- oh I hate sites that rely on Flash Media for their entire content, rather than easily linkable HTML). 'Necessarily' is a weasel word. The fact is that an S-Video output implemented (on a DVD player) with no more than basic engineering competence will always outperform a composite video output. Some very well-engineered composite video processing circuits on display devices can do remarkably good jobs, producing quite watchable results, but they do this by dint of correcting and covering up the basic flaws in a composite video signal. See here to read how all this works.
Naturally, AudioQuest also offers power cables. The need for these is justified by the following:
The Challenge: The cable carrying AC power from a wall outlet adds distortion, and even the most sophisticated power supplies and filters cannot completely eliminate these upstream irregularities.Every word of this is true. But that does not make it at all meaningful. The amount of distortion added by a few metres of power cable is immeasurably tiny, most likely even if you generated a pure 50 or 60 hertz supply with which to test it.
Of course, your wall outlet does not deliver a pure sine wave. Mine delivers power from a cable that connects my office to the house switchbox, through which it runs through a circuit breaker, which in turn is fed (via a supply fuse) from a wire hanging in the air to a power pole, which is in turn bolted to an exposed cable made of anything other than long-grain copper. This cable is also attached to thousands of electrical devices in other houses. It runs after a few kilometres to an 11,000 volt to 240 volt stepdown transformer (which, incidentally, is wired in delta configuration on the high tension side and star configuration on the 240 volts side).
That 11,000 volt line runs, after a few more kilometres of exposed wires, to a largish electrical distribution plant, where it is fed from another transformer which steps the supply down 330,000 volts. That is fed, in turn, by more than a hundred kilometres of cables hanging from large metal pylons to a hydro-electric dam which provides the bulk of the power. But at various points the grid to which all this is attached and with which it is synchronised is attached to other power sources: coal fired generators, gas fired generators, probably even some windmills out there somewhere.
And that's only the 'active' cable. The 'neutral' cable is directly shared with three times as homes as the active cable because by using three-phase power, all the 'neutral' signals tend to more-or-less cancel out.
Somehow our 'sophisticated power supplies and filters' manage to cope with all this crap feeding into the power line, yet AudioQuest has the gall to suggest that reducing the immeasurably small amount of distortion created by a metre of cable between the wall socket and my amplifier will make some kind of audible difference. Yeah, sure. And all for just $US149.95 (one metre NRG-2 three core cable).
UPDATE (Thursday, 18 September 2003, 2:40 pm): The author of Number Watch emails:
What you say is true, but I think that you are too generous to them. They seem confused between distortion and interference, among a lot of other things. The term distortion cannot really be applied to AC power. A switching power supply works on square waves. The output of a full wave rectifier has an infinite-spectrum harmonic content, which is adequately dealt with by the tank capacitor and filter. Other sources of harmonic distortion are negligible in comparison.
A few more tens of hours, and a few more entries in the Dictionary of Home Entertainment. There are now 311 entries there, but I must confess that 77 of them offer little more in the way of explanation than 'coming soon'. Still, I have finally been able to rid myself of my scrappy notes, and can work on filling in those missing definitions.
Those interested might like to look at my new, somewhat contrarian, entries on jitter and HDCD CDs.
Numbers Watch, which should be on the required reading list of anyone interested in the statistics constantly flung out by the media, draws attention to 'a speaker cable with an integrated battery' that apparently costs 'just over ten thousand dollars' (US, I assume). Unfortunately the explanatory link to which it pointed is now dead. But the other link points to a high-end cable maker, AudioQuest. A word of warning on the AudioQuest site: it's all flash (that is, Flash Media), rather than good old HTML.
Now as it happens, I reviewed a couple of AudioQuest cables back in 1997, around the time I started all this hi fi reviewing stuff. They were the last cables on which I ever wrote reviews. At least one of the magazines I write for simply refuses to touch the stuff because of the controversy that is always generated. I can understand this. As a result of this 1997 review I was, or so I heard on the grapevine, black banned by the Australian distributor of AudioQuest products for a couple of years from reviewing the various products it distributed.
And here are the concluding paragraphs of the review that provoked this alleged reaction:
Okay, I confess to being somewhat of a sceptic in regard to high quality interconnect cables. But still it is my job to listen and report. Here is what I heard.Personally, I think I was being rather kind. These days, with several more years of experience, and many examples of having myself exposed my own inadvertant self-deception, I have come to the conclusion that the differences I heard really were 'all in my mind'.But firstly, some qualifications. AudioQuest claims that it takes time for the conductor/insulator interface to stabilise and recommends two weeks of running in. What with the first set of review samples being lost in transit and then me having to perform surgery on my preamplifier, I had about eighteen hours to use the cables before my review deadline. I left both sets of cables running for twelve hours with two CD players on repeat before trying to do any serious listening. I only hope that the Quartz was not unduly biased by its unrelieved exposure to Tchaikovsky's 1st and Rachmaninov's 3rd Piano Concertos, nor the Turquoise by carrying two Schubert Piano Sonatas without respite.
Another qualification is that I felt unable to perform the direct A-B testing I routinely do. This would have involved wiring up a fairly complicated switchbox which, given the necessarily subtle -- if any -- sonic differences for which I was listening, would have invalidated my results. So I had to listen sequentially: play some music several times, swap cables and play it again several times. Repeat the process over and over for different kinds of music.
Having disclosed my bias and given myself sufficient grounds for equivocation, what did I find?
My feeling is that on some kinds of music -- especially very complex sound using a full frequency range (such as Rush's Test for Echo), both the Turquoise and the Quartz gave a slightly more dynamic, punchier result. On small orchestral works, both cables again seemed to smooth the flow of music, to quieten and sweeten the violins. I thought I noticed a little more definition of a left of centre guitar in the Eagles' Hotel California.
These results were obtained comparing the cables with a stock standard one metre RCA to RCA cable of the type given away with equipment. This cable was several years old. The differences were extremely subtle and I am by no means certain that they exist. These impressions could simply have been all in my mind. Between the Turquoise to the Quartz I could detect no difference.
So there you have it. I fear I've done nothing to resolve the cable controversy -- neither in my mind nor in yours. It makes sense to use good quality componentry at every step of the audio reproduction process. Whether these cables are overkill is a matter for each listener to decide by auditioning.
But I can positively say that if you are looking for cables in the respective price ranges of the AudioQuest Turquoise [$AUS139 for the pair of half metre cables] and Quartz [$329] audio interconnects, you will be hard put to find finer examples of materials and construction. They are, simply, beautifully made and gorgeous to look at.
Having said that, if you have those thin black cables connecting your bits of equipment, throw them away. What you should look for with interconnect cables are rather thicker ones that use real wound shielding (to ensure decent rejection of electrical fields in the vicinity) and, preferably, gold-plated plugs on the ends. The gold has no magical qualities, but its established physical qualities are that it is far less subject to corrosion than most metals. So once you plug your equipment in, your connections should remain trouble free for years.
If you frequently change your connections for whatever reason, you're better off without gold because the mere act of plugging and unplugging generally cleans the connections and gold, being a very soft metal, wears away rather quickly.
But such cables are available for around $AUS20. There is no need to spend hundreds of dollars.
UPDATE (Sunday, 14 September 2003, 10:47 am): The author of Number Watch confirms that he was indeed talking about an AudioQuest product, known as the 'Cheetah'. I leave it to the reader to consider the homonymic implications. I see that you can buy these interconnect cables, complete with their '12V Dielectric-Bias System (DBS) pack', for just $US900.
Pioneer Australia is flying me down to Melbourne tomorrow for the release of its new product line up. The company is strong in Plasma displays and DVD players, although its budget DVD Audio/SACD DV-655A is a disappointment (no real setup for DVD Audio or SACD).
I keep hoping that the next generation will deal with this problem.
Well, I remain on my so-far fruitless search for a DVD Audio disc with useful audio test signals. I had my hopes up for the
AIX 8200 Start Here disc, which I just bought today from
Rockian Trading for a reasonable $25. Rockian kindly throw in AIX's first DVD Audio sampler as well.
Unfortunately the test tone don't help me out. The reason? They're all DVD Video test tones, not DVD Audio. This means that they are useful for aligning your surround decoder for playing back movies and music DVDs, but not for DVD Audio! You see, most DVD Audio players either do not perform speaker time alignment, or bass management, or both for the DVD Audio material. Their manuals tend not be explicit about this. Some just don't mention it at all, while others mention it briefly in the notes somewhere within the manual. The only way you can be certain that your DVD Audio player does all this properly is to read one of the few carefully conducted reviews (most reviews don't actually touch on this subject at all!), or to test it yourself.
It is because of these omissions in most DVD Audio players that many DVD Audio discs actually sound better playing back the Dolby Digital version of the material than they do the surround MLP version, at least in the great majority of real-world home surround systems.
Checking out these decoding capabilities with actual music recordings is a slow process, requiring me to find visually identifiable markers on recordings of the various channels' analogue outputs. Looks like I'm going to have to keep on doing it this way for a while longer.
On the brighter side, the AIX disc has lots of music sampler tracks. The stereo ones, on a quick first listen, sound eerily like actually having the instruments in the room.
Things go in circles. InstaPundit comments on Lileks' comments on Sony, and adds some observations of his own on Canon video cameras. As it happens, video cameras are not my strong point. I've only reviewed a couple over the years so I don't really feel competent to remark upon them.
The Bleat is a regular stopping point for me. As a professional writer myself, it brings me back to earth to read James Lileks, a writer who is, oh, at least three orders of magnitude better. Fortunately he doesn't write primarily about my area. Whew! Still, sometimes he notices home entertainment equipment and this time Sony cops it.
I am bemused by his Sony 'amplifier [which] has -- groan -- proprietary plugs for the speaker connections.' I don't think we have one of those here in Australia. Thank goodness. He is also 'surprised that Sony movies don't require the installation of a third eyeball, or perhaps a cochlear implant to pick up certain wavelengths of sound.' Hmmm. How about SDDS? Are any Australian theatres outfitted for this?
Well, last month this Web site scored a total of just under 4,400 visits, with 6,200 page views. The visits were up by 100% over the previous month and page views by around 50%.
The most popular content pages (ie. not counting the entry points and links pages) were this Blog (686, or 997 if you count the most popular archived page); the page on copy protected CDs (497), a short piece on Dolby Digital and DTS (427), the long-standing piece on video connection standards (370), a somewhat newer piece on progressive scan (357), a discussion of Superbit DVDs (219) and an explanation of anamorphic DVDs (133).
Early figures for this month indicate the Dictionary of Home Entertainment has made its way onto the top-ten list. I've added a few more entries, and a couple of photos to illustrate things. Still lots more to do though.