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The Audio Critic

Home Theater BIG Screen, 2000 watts

MP3's v.s CD's, DTS v.s Dolby and other Stuff

Macrovision and how you can avoid it

Read this article for some Sound Advice

Build your own set of biline speakers

Spherex 5.1 (Home Theater in a box) Speaker Review

Proview RX-326 32" LCD HDTV Review

LG LDA-371 DVD Player Review

A Computer for the Living Room, a look at HTPC's

Spyder3TV Review

ATSC: what is it and why should you care

Boxee Box Review


My take on MP3's ''DTS'' and other stuff

Lets start with Mp3's....
Why would anyone want a compressed version of a perfectly good music track?
what was the point?
In the beginning the only place you could play them was on your computer, you could play a CD on your computer anyway, now you can play them on almost anything from DVD players to Car stereo's. I was pondering the same questions as I sat listening to my collection of 200 CD's I had loaded into my ''Jukebox'' (a Sony carousel 200 Disc CD changer) It was simple you put the Cover Jacket from the CD into the spot that the CD was actually in the ''Jukebox'' this way you knew what was where and what songs were available on the CD. I was happy........
Well the 6 second delay between songs was annoying, but I was happy........
It would be nice to only play a certain selection of songs without a 20 minute programming session that you lost when the power failed........
Maybe it wasn't that great, what was the solution?

MP3 to the rescue.
I had heard and listened to various mp3's floating around the internet and was confused by the sometimes great sound quality and sometimes not so good quality, there was a lot of discussion about the inferior quality and it was like listening to a ''FM'' version of the song. I assumed the issue was lack of control from the users preparing the Mp3's, if they used analog versus digital to extract the music that would account for some problems, also what encoder were they using?, what settings? what type of Sound Card were they using?

I decided to purchase a sound card with decent specifications (it even had a digital Spdif out) and encode some music with different settings to determine which sounded better. I ended up using the Fraunhofer MP3 Encoder Pro (which is the version by the inventors of the technology) I used the 128 bit setting and proceeded to encode a file from a digital extraction. I then burnt this version with the unaltered original back to a CD-R this would allow me and others to quickly switch back and forth to note any differences between the tracks.

I used a track with Female vocals and some Piano (these are the hardest for any system to play back correctly) and sat with my ears tuned to find differences. After exhausting my patience switching back and forth I made my conclusions and passed the disk over to some equally critical friends to have a listen. In total about 14 persons reported the same findings (including myself) Track ''B'' sounded well ''larger''. Track ''B'' was the original and ''larger'' was a reference to the overall soundfield generated by the track. If you aren't aware the single most important expression of a speaker is to deliver the recorded soundstage as accurately as possible, if this is being done (with your eyes closed) you should be able to ''see'' where the different artists were standing from the sound ''clues'' in the recording. The Mp3 version just didn't provide enough of these ''clues'' to make that possible therefore sounding ''smaller'' to the listener.

So what the Hell does all that mean to me?
Well it means that if a MP3 is created properly it can sound so close to the original that unless you concentrate on noticing the difference you won't! I did find that most Classical music doesn't convert well, I think it has to do with the quiet passages affecting the noise baseline or something as most I attempted to convert seemed to contain an audible background noise. It may be due to the electrical noise in the computer I'm not sure, so with the exception of Classical Music ''MP3'' is as good as the original for everyone except true ''Audiophiles'' (the ones with $200+ interconnects)

So off I went Converting my CD collection to MP3 and I have never looked back. Now I simply drag whatever I wish to hear into a play list and away I go no irritating 6 second delay between songs no books of covers to flip through, no 20 minute programming sessions and now I can actually see the track names as they play.

'DTS'... V.S. Dolby Digital

'DTS' if you don't already know is an alternative compression scheme highly touted as the end-all be-all ''Dolby Digital'' killer application for the soundtracks on your DVD disks. I have gotten into many arguments about this technology so I'm going to tell you about this little argument that shows the mind is not equal when exposed to the ''Double Blind A-B Test''. So as usual the conversation starts where someone tells me how much better the DVD sounds etc... so here we go

1) DTS is just a different compression algorithm hence the difference should not be as obvious
2) Note most DTS tracks are remixed this means the sounds are readjusted for a smaller room this alone will make a profound change (anyone who has listened to ''THX'' remastered movie can attest to this)
3)But I compared the ''DTS'' track to the ''Dolby Digital'' track.....remember ''DTS'' is remastered, your not comparing apples to apples.
4) If you could compare the same material and only the compression from the different formats was used to create the final output mix you would have a fair comparison.
5) Guess what? I happened to rent a Test DVD with exactly That! (I wish I could remember the name of it.)

So off my Nemesis goes for an objective listen to the evidence, the next day He says the ''DTS'' track sounded better. I asked who was switching between the tracks for him? He answers ''me of course'' so I asked him to try something, have his wife switch back and forth between the tracks and don't let her tell you which is which. The next day looking dejected he says ''you were right I couldn't tell the difference'' So I pushed him a little, as soon as you didn't have the benefit of knowing in your mind which track should sound better you were unable to locate the better sounding track? ''Yea that's about right'' was all he said. This is what usually happens in a ''Double Blind A-B Test'' when the source is unknown and the material does not have the benefit of being labeled almost no one can tell the difference in most audio related tests.

Now I get to vent on some general 'Stuff' but please have a read (lots of Good info!).

1) Most of you probably don't have your speakers set-up to a proper recommended listening environment, do some research and adjust those rears to proper heights etc.. a good resource is www.dolby.com
Here are some quick examples that I've taken from the guide.

2) ''Component Video'' versus ''S-VHS'', we all should know by now Component video is the best choice when hooking up a DVD Player but a properly tuned television with a S-VHS hook-up can look almost as amazing as a Component video set-up! purchase a test DVD with a ''Blue filter'' and a SMTP color bar test. an example of this is ''Digital Video Essentials (2003)'' also ''AVIA Guide to Home Theater (1999)'' and the one I found at my local FutureShop store ''Sound & Vision Home Theater Tune-Up DVD'' You will be amazed at the difference it makes, Trust me on this one.

  Component connection

The Red, Green and Blue color signals are kept independent which helps prevent color separation errors that would occur from typical decoders
S-VHS

The Black levels and color information is kept separate from each other but since the three primary colors are still mixed they can be subject to errors that would occur from typical decoders

3) The single biggest mistake made when purchasing speakers for home theatre is to get a mismatch of makes and models, Always try to get all the same make and model for all 6 speakers, your probably asking about now ''6 speakers? I thought I needed 5 of them?'' I say 6 because the center channel contains most of your movie, it warrants the use of 2 speakers ( yes you can use 2 speakers for the center with any amp, the newer ones explicitly say this and may contain a switch to expressly enable it). Also as the sound stage moves around you when you mix and match your speakers you will have tonality issues with the sound-stage as it moves between the odd speaker models (even 6 cheap speakers are a better than 5 mismatched ones).

4) Adjust your sound levels between the speakers. That dumb pink noise test is there for a good reason, to fully enjoy your surround experience all speakers must be at the same volume in respect to the main listening position. Another problem here is that almost no one has ears good enough to make these adjustments, invest in a ''Sound Level Meter'' it is probably the best expense you can make, it really dials in those volume levels. Almost every home I've been to and checked with my meter has been really off on center channels and rears.Also please Adjust your Sub-level output correctly to your Main speakers (you can find these tests along with the Video tests mentioned in section 2).

 

Sound level Meter

Probably the best expense you can make, it really dials in those volume levels. Almost every home I've been to and checked with my meter has been really off on center channels and rears

Radio Shack's
Digital-Display Sound-Level Meter Catalog #: 33-2055
for $89.99

 

5) Volume! We all like it loud! Especially when an explosion occurs, but keep this in mind when the main characters are speaking, they should not seem any louder than a normal conversation would be if they were actually in your room. Remember the Sound Effect Channels will go up many times in volume as required, also check that you do not have any type of volume compression on such as ''Night'' mode. Way to many ''Demo'' rooms and others showing these systems ignore this Golden rule. Do you really want to ruin your movie with the characters YELLING ALL THE TIME! not only is it annoying but then the ''Effects'' are also to loud.

6) Don't Touch those controls! The production engineer with years of experience (and more controls than you'll ever have) has tuned the mix to sound correct to his ears (with his many years of experience). do you wish to listen to his version or yours! leave all Bass and Treble controls at the ''off'' or ''middle detent'' position. This goes double for Music listening.

7) Cables. I don't care what you've read or heard, all you need is the basic good quality 'Radio Shack' Cables. Please review The Audio Critic for a much more thorough rant than I wish to provide, with good theory!

8) When shopping for speakers and amplifiers ignore all the power ratings, they are a relatively useless measurement that is misinterpreted. You can damage any pair of speakers much quicker with a 10 watt amplifier than you could with a 1,000 watt amplifier.
A Harmon Karden amplifier rated at 35 watts will destroy most amplifiers rated at twice that! The basic test for watts is flawed, they measure the wattage through a static 8 OHM load! No speaker is a static load, as it moves to create music the OHM's will vary from .5 to 16 OHM's, not to mention Back EMF among other things.
''High Current'' designs tend to be rated lower in watts but have tremendous ''Dynamic Headroom'' to make up for it. Also on the same note you need to understand that a 15'' driver requires less power than an 8'' driver to reach a given SPL, this is because of the relationship between decibels and power. For every perceived increase in sound it requires 3 decibels, which in turn requires double the wattage from the previous level to achieve this volume. Take a quick look at the chart below for a comparison of a 15'' and 8'' driver

Chart showing comparison of 15" vs 8" drivers
15'' Driver ''ND15''
8'' Driver ''ND808
98 db = 1 watt
87 db = 1watt
101 db = 2 watts
90 db watts = 2 watts
104 db = 4 watts
93 db = 4 watts
107 db = 8 watts
96 db = 8 watts
110 db = 16 watts
99 db = 16 watts
113 db = 32 watts
102 db = 32 watts
116 db = 64 watts
105 db = 64 watts
120 db = 128 watts
108 db = 128 watts
123 db= 256 watts
111 db = 256 watts
126 db = 512 watts
114 db =512 watts

So The chart in summation says that the 15'' driver will play at 113 db using 32 watts of power while the 8'' driver requires close to 500 watts to reach the same db level!
The same 500 watts with the 15'' driver is over the pain threshold at a whopping 126db!
So why do they put the lowest power amplifier with an 8'' powered Sub-woofer and the most powerful with the 15'' Sub-woofer ?
This also tells us speakers with higher sensitivity will play louder with less power. Just for reference 113 db is like listening to a Table saw while cutting while 125 db is the pain level threshold.

9) most of us will not go deaf from loud music, even those of us with bass emanating 3 miles away from our cars. Here's why, High frequency sounds of 2-4,000 Hz are the most damaging to our ears and hearing. Also all measurements for hearing loss are ''A'' weighted measurements, Bass is not considered damaging to our ears because the sound waves are very large and much slower in frequency, we feel them more than we hear them, have a quick look at the chart below for ''A'' weighted acceptable levels per day as per the 'OSHA' Daily Permissible Noise Level Exposure.

Hours per day
Sound level
8
90db
6
92 db
4
95 db
3
97 db
2
100 db
1.5
102 db
1
105 db
.5
110 db
.25
115 db

Most cars are around 100 db to 105 db which is safe for 1-2 hours of abuse per day!

10) Use your better judgment! Don't believe marketing or some reviewer, question all things Audio/Video related. If you can't see or hear a difference (preferably in a controlled test) then it isn't worth your hard earned dollars!

Hope someone finds my venting useful!
biline

 



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