A Primer for Home Theater Newcomers (1 Viewer)

[Brian Fellmeth]

What does a BFD do and do I need one?

BFD stands for Behringer Feedback Destroyer.

One of the goals in setting up your audio system is a relatively flat frequency response. This means that all frequencies in the audio spectrum are neither enhanced nor attenuated by your system. Thus, what strikes your ears is exactly what the musician or sound engineer mastered into the source.

Designing the electronic components to have a flat frequency response is relatively easy, and virtually all currently available electronic components do not introduce significant varations.

Speakers, on the other hand, are tougher to achieve flat response, and the manufacturers go to great lengths to get within a few dB of perfectly flat in an anechoic environment (which basically means that aside from the interactions you'll find in the room- the speaker is "flat").

Unfortunately, when a speaker is placed in a real room, the room becomes part of the sound generating system, and the manufacturer’s best efforts are undone. The problem is by far at its worst in the deep bass area- frequencies below 150 Hz. It is not uncommon at all for a room to boost frequency X by 15 dB and reduce frequency Y 15 dB even though the sub is putting out exactly the same overall sound pressure level (SPL).

The effect on what you hear is that the deep bass becomes boomy and dominated by the boosted frequencies. The problem is most apparent with bassy music where some notes will jump out of the music and other recede into the background as if the bass player was playing some notes very hard and barely hitting others.

There are two methods of attacking this problem : room treatments and equalization. Room treatments involve installing sound absorbing panels and boxes in strategic locations such as corners and along long uninterrupted walls- trying to get the room to behave more like the ideal echo free chamber that the manufacturer used to design the speaker. This is expensive, time consuming and has a horrid SAF (Spouse Approval Factor). The alternative is equalization, and this is where the BFD comes in.

The Behringer Feedback Destroyer (BFD) is a $140 piece of pro audio gear that was designed and marketed for an entirely different purpose from improving the bass response of home theaters. The BFD is supposed to be used to monitor the amplified signals in live music performances (mostly microphone channels) and snuff out feedback by blocking (or filtering) the specific frequency that is generating the feedback.



As a secondary, almost throwaway feature, the Behringer engineers decided to allow the user to control the 24 available EQ filters by specifying a filter frequency, the degree of boost or attenuation at that frequency, and the degree to which neighboring frequencies are affected (or the “bandwidth” of the filter). By applying combinations of these bell shaped filters to the signal sent to the subwoofer amp, it is possible to very precisely shape the frequency response curve-- effectively counteracting the peaks and valleys introduced by the room.

Understand the the BFD is not really a unique item in that it is an equalizer. There are several thousand EQ products on the market, and any one of them - in theory- could be used to tame peaks and valleys in the subwoofer signal. However, what the BFD does offer that is lacking in any unit even remotely in this price range is a great number of filter points and full frequency control. Where other Eqs may only have 2-3 filters positioned to control bass frequencies (and others which are assigned to midrange and treble)-- the BFD can use all 24 filters in the "bass" range- making it specifically well suited to use with subwoofer- offering ultimate level of control.

So, the BFD is used to equalize the signal sent to the sub in such a way that is a reverse of what the room is doing to mangle the response curve. The frequencies that the room makes too loud are quieted down, and those that the room sucks out are boosted. The only equipment required to program the BFD filters are a radioshack SPL meter and a CD with low frequency test tones. There are several expert BFD gurus at HTF that are very generous with offering assistance via the board. The archives are loaded with threads where most of the common problems are discussed.

There is also a comprehensive tutorial published by Sonnie Parker here :

Link Removed

So, if your bass is boomy and uneven, this $140 upgrade may have much more impact than a $1000 sub upgrade. Room effects do not discriminate. A top of the line SVS, Rel or Velodyne is just as susceptible as a Bose bass module.

 

[Brian Fellmeth]

Should I consider a Do It Yourself (DIY) speaker or subwoofer project?


Most of the HT and Audio discussion boards have areas where members discuss their DIY speaker projects. If your reading this note, you may be wondering: is it really possible and practical for an individual to make a speaker in their garage with performance equivalent to commercial products?

The answer is absolutely yes.

In fact, it is easily possible to build units that outperform everything available in a mass retailer such as Best Buy or Circuit City--even get "high end" performance for a fraction of what compariable speaker would cost at a retail “high end” shop.

Starting with no experience at all in any aspect of speaker building, I have successfully completed three speaker pairs (cost about $500 each) all of which sound (to me) significantly better than the expensive, highly regarded B&W nautilus units at my local audiophile boutique. There is access to the very same world class drivers found in $10,000 plus speakers such as Wilson. Before proceeding, it is necessary to define three levels of DIY speaker construction.

Level 1- Vender supplies all parts including a completed cabinet and sometimes a completed crossover. You just put it together.

Level 2- Follow an established “recipe” but construct the cabinet and crossover yourself.

Level 3- Start from scratch with a driver set and design the cabinet and crossover yourself.

Level 1 projects only take 1-3 hours and require no special tools or skills. The problem with these is that the selection is not too vast and the savings are pretty minimal. The role of these is as a first “get your feet wet” project to see if the process is appealing without risking getting in over your head. My first project was one of these, a MTM center channel from Madisound with nice Vifa drivers. When this thoroughly trounced the Klipsch I had been using, I was hooked on DIY and ready to move on to level 2.

Level 3 projects require a MAJOR commitment of time, study and equipment. Although the appeal of creating a novel and unique instrument that has never before existed is great, do not consider attempting this without at least one successfully completed level 2 project.

Level 2 projects are the sweet spot for amateurs. There are hundreds of tested, proven designs to choose from where the difficult crossover and cabinet tweaking has already been done.


There three advantages to DIY : Bang for buck, pride of accomplishment and control of the result.

Of these, the first is by far the least important. If your sole motivation is to save money, forget it; unless you put no value on your time at all, then money savings alone is inadequate compensation for the effort. You must relish the process.

The last advantage is the most important. YOU get to decide where to make the compromises, and every speaker project involves trade offs and compromises. For example, a commercial manufacturer has to worry about shipping weight limiting the wall thickness and bracing. You can choose to make your cabinet as dead (and heavy) as you like, and dead cabinets sound great. You can choose any color or wood species to match décor. If you want them biampable, no problem. Gloss or satin finish, your call. Need the port in the front, put it there. You can distribute your budget towards the drivers, crossover components, damping materials, binding posts, special veneer- whatever is most important to you.

The following check list that will help decide whether speaker DIY is for you :

·I own or have access to a router and table saw
·I have woodworking and/or finishing skills
·I know how to solder
·I like to make things
·I want to learn woodworking
·I have free time for a new hobby

You should be able to answer "YES" to at least three of these points if you want to move forward into DIY building.

Another important point- free help is just a few mouse clicks away. Speaker builders are generous people who like to help. The "DIY and Advanced Projects" section right here on the HTF is a great place to start. Some other places to get help :

http://www.madisound.com/cgi-bin/discuss.cgi
http://www.diyaudio.com/
http://www.pesupport.com/cgi-bin/config.pl

HTF moderator Patrick Sun has a nice site which outlines his personal DIY projects and offers tons of tips and several dozen photographs of projects in progress:
http://www.io.com/~patman/diy.html

And one final link- to a large list of other speaker DIY links. This should get you going:

http://home.iprimus.com.au/gradds/DIY1.html

Good luck!

 

[Vince Maskeeper]

Why do CDs recorded recently sound louder than older recordings?


Here's a basic explanation that usually works well with "non technical" people:

CD is a digital medium, which means it has a very specific maximum level. The loudest amount of sound you can put on a cd is called "0". Since 0 is the max, all other sound works backwards from that point and is expressed as a negative number (-10, -20, etc). All cds have this maximum-- think of it as a global speed limit.

So, if all CDs have the exact same maximum level, why do some cds (specifically "modern" recordings) sound so much "louder" than other recordings. If the CD format has a global "speed limit"- it seems logical that one disc shouldn't be able to sound louder than another.

Most people assume older recording sound softer because they do not exploit the full level of CD- they are simply recorded quieter- and never achieve a sound level that reaches the maximum level. That isn't usually the case.

What is the case involves the reduction of dynamics. Newer recordings have much reduced dynamic range which results in the illusion of "loudness". By removing the dynamic range of a given sound using tools like compression and limiting, more of that sound can be crammed closer to the maximum level-- which causes the listener to perceive it as "louder". To say it another way: without a wide difference between loud and soft-- everything is simply perceived as "loud".


Here's an analogy that often helps folks to picture it:

Say you were bouncing on a trampoline. Above your head, there is a ceiling made of brick. You begin bouncing, and you find yourself bumping your head slightly on the brick ceiling. However, you really want to bounce higher...

So you start bouncing higher, and as you get up to the ceiling, you tuck your head a little, to prevent it from hitting the ceiling. And you want to bounce even higher...

So you start bouncing even higher, and now you have to tuck your head and shoulders a little, to prevent them from hitting the ceiling. You bounce higher. Now you tuck your whole upper body to prevent from hitting the ceiling.

Now think about what has just happened. Have you really bounced "higher"? No, not really- because the brick ceiling was always the limit of how high you could go. However- by ducking parts of your body out of the way, you created the illusion that you jumped higher, because more of your body was at the max point at any given time.

So, modern recording use tons of compression and limiting to basically "tuck the head and shoulders of the music" so that they can cram more up to the very tip top-- and it seems "louder" as a result.



For a visual example, here is a visual representation of the Creedence Clearwater Revival song Fortunate Son, recorded circa 1969:

[c] [/c]
Notice that the peaks of the song reach the maximum level- but the average level of the material (the thick dense part in the graph) is pretty low- like -6 or so.

Here is a visual representation of the Watchmen song Stereo, recorded circa 1996:

[c] [/c]
Notice that the peaks of this song also reach the SAME maximum level- but the average level of the material under the peaks is pretty giant-- the distance that the peaks are above the body of the sound has been reduced!

The dynamics of the song have been squashed- creating a "loud" mix that sounds "better" in your car or on the radio. You can see the material has just be smashed into a big block of sound.

The problem is that this reduction in dynamics is not a win-win situation. This reduction will often result in ear fatigue on the part of the listener- and will often have negative effects on the perceived quality of the music. By removing dynamics- one of the main elements of music expression is removed- and often results in a more sterile sounding finished product.

by Vince Maskeeper

 

[Neil Joseph]

4x3 vs 16x9 - Which type of setup do I select?

As far as deciding whether or not to go 4x3 or 16x9 and wanting the biggest display possible, I think a lot of it has to do with what you watch most (4x3 or 16x9) and the quality of the 4x3 and 16x9 signals.

Most often, 16x9 material offers the better picture quality, DVD, HDTV etc and most often, 4x3 offers the lower picture quality, TV.

So the question is, should you opt for a 4x3 screen which will give you a bigger 4x3 image and a smaller 16x9 image with black bars on the top and bottom or should you opt for a 16x9 screen with a bigger 16x9 image but a smaller 4x3 image with black bars by the sides.

I chose a 16x9 setup because since the 16x9 material I watch is of a better quality than the 4x3 material, I wanted the 16x9 image to be as big as possible rather than having a larger (blown up) 4x3 image of a lesser quality.

If you're on a budget, you may be inclined to buy a 4:3 set as long as the difference in price with 16:9 sets is not insignificant. If a 16:9 you fancy is just a bit too expensive for you, you could lookup the price of a 4:3 having exactly the same width as the one you've chosen. Perhaps the price difference is not enough to switch, perhaps it is.
The (16x9) image on that set could be almost the same quality as one on the 16:9 set, provided that the 4:3 allows for a 16:9 squeeze (most modern TV-sets do). You will only "buy" black upper and lower bars in that case - but for a negative amount of money!

The squeezed image has exactly the same physical size as the one you would have had otherwise, but on some machines it may have spurious scanlines above or below the image, so some people construct a black 16x9 mask that can be affixed to the TV set with velcro. The result is really amazing, BTW.

Here are (in short) the pros and cons of the different choices:

On a 4:3 set
- 4x3 images will be reproduced without any problem, 16x9 images could be reproduced rather faithfully if a 16x9 squeeze is available
- 16x9 images (or wider) will be physically smaller than 4x3 images
- if a 16:9 squeeze is not (practically) available, enhanced-for-widescreen images will not be reproduced with full resolution, in fact all 16x9 or wider images will have less resolution
- so-called "full-screen" video versions (VHS & DVD) will have at least 25% of the movie chopped off for the same price as the whole widescreen version; the part you get is reproduced with a higher resolution though (which may or may not really be available on the source!)
- there's probably no HDTV support - and it makes no sense either.

On a 16:9 set
- 16x9 images will be reproduced without any problem; 4x3 images can be reproduced faithfully as well
- 4x3 images will be smaller than widescreen images, the set will display black or (on some) gray bars at the sides.
- images that are even wider than 16x9 still show empty bars at the top and bottom
- there's a setting - generally automatic - that takes full advantage of enhanced-for-widescreen resolution increase
- there are probably more functions than on a 4:3 set, especially all sorts of stretch and deform functions to make the image fill the screen (at a loss of either a part of it or of its physical accuracy)
- HDTV support may be present.

 

[Adam Lenhardt]

What is Region Coding?
Region Coding is a part of the DVD standard which allows the publishers of movies on the format to restrict playback of any disc to the geographic region in which is released. The regions are as follows:Region 1 -United States, CanadaRegion 2 -Europe, Japan, South Africa, Middle East, GreenlandRegion 3 -Asia (except for India and China)Region 4 -Australia, New Zealand, South America, Central America, MexicoRegion 5 -Eastern Europe, Russia, India, AfricaRegion 6 -
ChinaAll players sold should be coded to the region in which they are purchased. If a publisher doesn't wish to limit the region playback, they can encode it as a Region 0 disc, which would be playable on any DVD player. Also, DVDs can be encoded for multiple regions... ie. a DVD encoded Region 2 and Region 4 would be playable on a player coded for either region.

Why does Region Coding exist?
Studios don't release movies everywhere in the world at the same time. In some instances, the staggering of the release dates is so extreme that a movie will be out on DVD in one Region before it hits theaters in another. Since people in the other region could skip the theatrical release altogether and enjoy the DVD in the comfort of their own home, this puts studio profits in extreme jeopordy, or at least that's how they feel.

What can I do about it?
There are players out there that can play DVDs from any region. As a matter of fact, the astronauts use such a DVD player. Some are made that way and others have been modified to be that way. It is possible to modify a DVD player to be region free but depending on the player you may risk damaging the player and you will unquestionably be voiding your warrenty on it. It is not recommended to do so, and neither this site nor the manufacturer of the player will be responsible for the result. Most players sold in the UK have been modified, but unless you have tested with DVDs from multiple regions, assume that your DVD player is NOT region-free.

Is there a catch?
Yes. Recently, Hollywood studios have implemented a new technology called RCE (Region Coding Enhancement). This provides further protection against code-free players. Thus far, I know of only Region 1 releases which have featured this technology. It will block some (but not all) Code-Free players from playing discs with the technology. It isn't known which titles feature RCE until they are released, and it's hard to tell which players will be affected by it.

Is there anything else I should know when buying DVDs from other regions?
Yes... not all TVs work the same way. There are three basic formats: NTSC, PAL, and SECAM. You can read about the former two here if you haven't already. The third is the same as PAL, expect for the manner in which it manages color.

 

[MikeH1]

The truth about Nuance Speakers

A salesman said they are the #1 selling speaker in Canada. Is this true?

Probably not but a lot of people do buy them. Nuance audio is a Canadian speaker company based in Markham Ontario that is sold throughout the country in various shopping malls and stores. In any given store that sells these you may be looking for a specific product (like a DVD player) but the salesperson will want to show you these "amazing new speakers". So off you go to the demo room.

I heard them and they sounded quite good, especially that spatial 3D sound

So what was it they played for you? The man chopping the wood? The song Vogue by Madonna? Perhaps it was the hula girls? Maybe the Roger Waters tune? All these tracks have one thing in common which is Q sound. They do have some great imaging like the salesperson claims but its only because of Q sound encoded discs. To put it simply, Q sound makes the audio seem like it comes from the sides and behind you when in fact no speakers are there. Remember- its not the speakers that do this. Any speaker will have this effect (to a degree) as long as you play a Q sound encoded disc.

But the speakers are so big and loud, they have to be good!

Yeah them towers are quite impresive. Big bad-boy in your face sound. But there's a reason behind this, they do it to appeal to the 18-35 demographic. Big 12" subs, lots of drivers and 6 feet tall. Everything a testosterone ridden 20 year old needs. As for the actual sound of them...well I have done my own listening tests and I can honestly say they fall way short of what is considered good sound.

How come when I told the salesperson I wasn't interested he said he would slash the price by 50%

Because he can afford too. He could probably afford to slash it another 50% on top of that and still make a good doller. These things are ridicuously overpriced to begin with. When he slashes the price he's fooling you into thinking your getting a bargain. Its a great selling tactic that unfortunatly works.

But they have a 10 year warranty!

Yes they do. Most speaker companies have 5 year warranties so a 10 year warranty seems like they must have faith in their product. The truth is that the drivers (woofers and tweeters) are very cheap and inexpensive for the company to replace. Without going into great detail the woofers are paper with a laminate of sorts on the surface to give them a more expensive polypropelene look. Paper drivers, for the most part, are a thing of the past as new and better materials become available.

I checked out their website but couldn't find any pictures or specifications

Nuance belives we should all "trust our ears and to not be fooled by flashy specifications" and that specs are not needed. Well then I guess its a crap-shoot as to whether your amplifer at home will properly drive them to a real world listening level. This spec called sensitivity makes all the world of a difference of how loud a speaker will go and yet they don't supply it. Wow, a company marketing their product on their website and there is not even one picture of it. Very strange.

Now I'm starting to wonder about Nuance...is there anything else I should know?

Glad you asked. For one, they do not advertise. Also, Nuance does not allow any professional reviews of their products. They have even threatened to sue Andrew Marshall, publisher/editor of the Canadian magazine Audio Ideas Guide if he borrowed or bought a pair to do this. And if that isn't enough, journalists (like Andrew Marshall) are not allowed to go into the Nuance closed door demos at such events as the Canadian Hi-Fi Show and Montreal Festival du Son.

In short, these speakers are not a good value. They will sound louder and better than many speakers that grace many Canadian livingroom's. But those speakers are a few hundred dollers, not thousands like a full set of Nuance. And for thousands, you can buy a much better sounding quality speaker that doesn't employ shady tactics. Quite frankly, Nuance Audio is a disgrace to Canada's reputation in the audio world for we manufacture some world class speakers.

If anymore information is required you can click

here

heres a link to Nuance's website.

http://www.nuanceaudio.com

 

[Cees Alons]

The Dreaded Chroma Bug


The so-called Chroma Bug actually consists of two problems, one of which is a real bug - in some DVD players. Both problems are related to the use of 4.2.0 colour decoding in interlaced video signals, although the bug is only obvious in static parts of progressive images.

What you may see is this: distinctly coloured objects (against a differently coloured background) have scan-lines directly above and below their edges where the colour of the object is still present in places where it shouldn't. It's very difficult to see on smaller screens (27" or smaller), but easily spotted on the larger ones, especially large projection screens. Also, slightly differently coloured horizontal stripes may be visible inside coloured objects (in fact: colour lines are "switched", more or less).

You may never have noticed it yet.


(1) The real Chroma Bug is caused by DVD-players in which the colour-decoding part of the MPEG-decoder makes no difference between interlaced frames and non-interlaced frames. They should be using a different decoding algorithm for each, but instead use the interlaced technique for both (sort of laziness of the developing engineer). Thus, the problem is visible in progressive (= non-interlaced) frames, but in fact only in static parts of the image (moving parts have "busy" edges anyway, so the human eye won't notice it). The interlaced frames are decoded properly in these DVD-players.

Most newer DVD-players have it right, now, so the chance of seeing this problem gets less and less (there's a difficult technical complication caused by some encoders that set the progressive-frame-flag in an odd manner - but it goes too far to go into that here, and it can be solved by the decoding algorithm anyway).


(2) The other Chroma Problem is more severe in nature, although slightly less visible. It's inherent to the MPEG 4.2.0 encoding of colour fields and the interlaced decoding technique. A 4.2.0 encoding means less resolution in the chroma signal than in the luminance signal. That's not too bad: the human eye itself uses a different resolution there (the rods-and-cones thing).
But as a result, the colour image, when properly (sic!) decoded in the "even" frame (reconstructed to full resolution, so to say), still cannot be the same as the image of the "odd" frame. Thus odd and even lines may have differently coloured edges along (again: static) objects, which will be visible to the human eye on large projections. This is not a bug in either the encoder or the decoder (as the above mentioned problem is), but nevertheless: it can be solved by special circuitry, especially inside the de-interlacer.

Again, it goes too far to discuss this in detail here, but be assured that the Faroudja deinterlacer, to mention one brand, solves the problem rather well.

 

[Brian L]

Universal and Hi-Rez (DVD-A and SACD) Player FAQ

The purpose of this FAQ is to address many of the common questions that occur with regard to proper operation and connection of universal (SACD,DVD-A, DVD-V, CD) and hi-rez (DVD-V and SACD or DVD-A) players. With every new uni or hi-rez player, there is a new group of users that seem to be facing the same problems, and asking the same questions, over and over again. Hopefully, this will shorten the learning curve, and speed up the process of enjoying, to its full potential, hi-rez music.

To start with, here is a quick checklist for multi channel, hi-resolution playback that should get you up and running in a minimum amount of time. If these steps fail to produce the required result (Glorious Hi-Rez Sound!) review the questions in the remainder of the FAQ. The checklist assumes that you will be using the common set-up of 5 small speakers and a subwoofer.

1. Connect the 5.1 channel analog outputs from your player to the 5.1 analog inputs of your receiver or pre/pro. The 5.1 connections are required for hi-rez, multi channel sound.

2. Go into the set-up of your player, and make the following selections (if present):

a.) Enable the player for 5.1 analog output. Many players default to 2 channel.
b.) Enable the player to select the multi-channel layer of SACD discs.
c.) Enable the player to select the DVD-A layer of DVD-A/DVD-V discs.
d.) In the “speaker settings” section of the player set-up, choose “Small” for all main speakers, and Subwoofer On.
e.) Set the speaker distances to match your actual set-up.
f.) Exit your players set-up menu, making sure to save your settings.

3. Select the 5.1 input of your receiver or pre/pro.

4. Insert the hi-rez disc of your choice. Push “play”, sit back, and ENJOY!

Q1. I am connected to my receiver or pre/pro via my coax or optical output, but I am not getting any sound from my DVD-A or SACD tracks. Why?

A1. The standard coax or optical outputs and inputs do NOT support hi-rez audio. To get the full benefit of DVD-A or SACD, you MUST use an analog connection; either 2 channel or 5.1, depending on your speaker configuration.

The digital connection can still be left in place to allow for DD, DTS, or PCM decoding in the receiver or pre/pro. For a variety of reasons, this may be superior to using the decoding in the player; you should try both.

Note that there are some higher end components that do support a hi-rez digital connection (typically IEEE 1394 Firewire or a variation of Firewire) between player and receiver or pre/pro. We will discuss those in question 10.

It is also possible that a given player may down-rez DVD-A hi-rez data to a lower resolution sampling rate and bit depth. While this may produce sound from the standard digital connection, it would not produce true, hi-resolution playback.

Q2. If I have the 5.1 and optical connections, do I also need to connect the analog stereo L/R pair?

A2. You don’t have to, but you may want to. Making the stereo connection will allow you to use Pro Logic, DTS, or other matrix decoding on two channel sources. Since you will not be able to send two channel hi-rez material through the digital connection, and Pro Logic and DTS are not normally available via the 5.1 inputs, the stereo pair will be the only way to invoke these surround modes on two channel sources.

Q3. I connected my player to my receiver or pre/pro via the 5.1 analog connections, but I am only getting sound out of the L/R channels.

A3. Assuming that you have correctly selected the 5.1 inputs of your receiver or pre/pro, there are two other likely causes. First, most players require that you enable them for 5.1 playback; but many default to 2CH playback. You will need to go into the players menu to enable this. Second is the possibility that the disc in question is only 2 channel, or that you have selected the 2 channel mix of a disc that also has a MC mix. A visit to the player’s or discs’s menu will be in order.

Most SACD discs require that you choose the mix in the player’s menu; you can not normally do it from the remote’s “audio” button, and SACD discs have no menu’s. The choices are Redbook (for hybrids), 2CH hi-rez, and MC hi-rez.

Most DVD-A’s do allow you to make this choice either from the disc menu, or from the player’s remote “audio” button.

Q4. What if I do not have 5.1 inputs on my receiver or pre/pro?

A4. In this case, you can connect to your receiver via a 2CH stereo pair, AND via a digital connection. For both DVD-A and SACD, you will be able to play back 2CH software at full resolution via the analog connection. Note that ALL SACD discs will have a hi-rez , 2 channel track.

For MC playback of DVD-A software, you may find that the disc has a Dolby Digital or DTS MC track. This will play back properly through the digital connection to your receiver or pre/pro. While you will not be enjoying the full benefit of hi-rez playback, many DTS and DD tracks can sound quite good.

Q5. I am connected properly, but I am not hearing much sound from the center channel. Why?

A5. There are no real standards in terms of how a given disc is mixed. Some discs are actually in 4.0 (no center or sub channel), and some, while using a center, have it mixed very low compared to the other channels. The important point is that unless you have made a set-up or calibration error, the fact that the center channel appears low is likely due to the choices made when the mix was created; nothing is wrong.

Q6. I can calibrate my main speakers for equal sound levels, but the subwoofer channel is very low. Why?

A6. This can get very complicated, and delves into issues of bass management that are beyond the scope of this FAQ, but there is usually an easy answer. Many universal and hi-rez players seem to have very low gain on the subwoofer/.1 channel. The reasons for this are not 100% understood, and there are some users of newer equipment that are not seeing the problem, but if you do see the issue, the solution is to increase the sub/.1 channel level trim using either the player’s channel trims, the receiver or pre/pro channel trims, or the subwoofer amps gain control.

Be assured that, even if you see this problem when calibrating with test tones and an SPL meter, there is no bass that is actually missing; its just very low. When the channel gain is adjusted to provide equal levels, you will have no problem shaking the room.

As a side note, some receivers (Denon’s in particular) have a switchable sub channel boost (0, +5, +10 or +15 dB) on the 5.1 input that addresses this issue. Also, the author has seen this problem when using an older receiver, but after a recent receiver upgrade no longer has any issues with low sub/.1 channel levels. Users of Outlaw 950 pre/pros also report no problems getting channel levels balanced. The reasons for this are not understood, but it has been speculated that newer products may have a non-switchable boost already built in.

Suffice to say, if you don’t have the problem, great, but if you do, you will need to dial in some gain in the sub/.1 channel to set things right.

Q7. I am trying to play a DVD-A track, but my player’s DTS or Dolby Digital light is illuminated. Why?

A7. The DTS and/or DD tracks are on the DVD-V layer of a DVD-A disc. You will need to go into the players set-up menu and tell it to choose the DVD-A layer when playing DVD-A/DVD-V discs. This will not affect normal playback of DVD-V discs.

Q8. In my players set-up, I have to choose the speaker size. My choices are ‘large” or “small”. My speakers are average size. How do I set this?

A8. This question relates to bass management, which determines how low bass is reproduced in your system. While there is no “one size fits all” answer to this question, if you have a common arrangement of 5 speakers and a subwoofer, you normally will get the best results be setting all speakers to small, and the sub to on. Even with largish tower speakers, you are normally better off to set them to small, and have all bass below a certain frequency (not normally adjustable in the player, but commonly around 80hz to 120hz) sent to the sub.

Please note that while this question could probably justify its own FAQ, a setting of all small/sub on will be a reasonable choice for most users. If you do have speakers that can genuinely reproduce low bass (response down to below 30 hz or so) then feel free to experiment.

Lastly, the speaker size settings in the player only deal with the analog outputs. Bass management of the digital output signals are handled in the receiver or pre/pro.

Q9. My player has speaker size settings, but with DVD-A or SACD titles, I am not hearing any output from the sub. Why?

A9. Not all players do bass management for all formats, and even when they do, some do it better than others. Again, this is a topic that could justify its own FAQ. Cataloging how each player behaves is beyond the scope of this FAQ, however your best source of information on this topic are the player specific threads in the Audio/Video Sources section of the Home Theater Forum, as well as test reports in the major A/V publications. Should you find that your player does in fact have incomplete or inaccurate bass management, there are outboard solutions, such as the Outlaw ICBM that can address these problems. Some pre/pros (the Outlaw 950 and its clones) also have rudimentary bass management on their 5.1 channel inputs.

In cases where bass management is done externally, best results are usually obtained by setting the player's speaker settings to all large/sub on.

Q10. Is there any hope of a purely digital connection for hi-rez audio?

A10. Yes, in fact there are player/receiver combinations available today from Denon and Pioneer (pricey to be sure) as well as separate player/processor pairings from Meridian, among others. While these are not priced for the masses, they do represent a trend that will eventually work its way down to the more popularly priced equipment. In fact, Pioneer has announced a lower priced receiver that supports the iLINK open standard that is present on their 47ai universal player. The new Denon 5900 is also said to allow its digital out to be set for proprietary or open standard functionality. The advantages, besides reducing the number of cables, are that things like time alignment and bass management, can be handed in the receiver or pre/pro, and hopefully, be done properly.

 

[Vince Maskeeper]

People often ask what a calibration DVD is, whether they need it and which kind they should buy. I thought I would take a crack at offering a basic piece of information on these discs both in concept and in specifics:


AN INTRODUCTION TO TEST & CALIBRATION DVDS
aka "Why the hell do I need one of these things?"

As Jay mentioned in his excellent post here-- a major part of enjoyment of the Home Theater hobby comes from accurate reproduction of the intended look, sound and feel of a film. Respect for film and moviemaking as an ART is taken seriously around here, and thus respect for the INTENT of the artist is a closely protected concept.

When films are conceptualized and shot, a good deal of time and energy goes into color palette choices, lighting, production design and film stock -- all decisions, it is hoped, that help to subtly (and sometimes not so subtly) influence the viewer's mood: enhancing the emotional impact of the scene.

When film is processed and printed, again, much care is taken to ensure the intended color scheme and look are maintained to express the visual message of the person(s) creating the imagery and the overall visual style.

When a soundtrack is mixed and finalized, great care is taken with relative levels of music and effects- of the impact of bass and LFE, and with the volume and presence of surround information.

Finally in the DVD stage, the film masters are once again scrutinized to ensure that the intended color and look of the film is maintained-- sound masters are checked to ensure the proper levels and audio information is conveyed. Technicians and artisans work for hours on specially calibrated display and sound devices to tweak nearly every subtle hue, shade and frequency-- to present the most accurate and proper reproduction of the original artistic vision.

When that disc gets to your home- it is only natural to want to continue this chain of correct reproduction. Without doing so, all the previous work and effort that went into maintaining the specific look and sound of the film would be wasted.

By calibrating your system to the same standard the creators and technicians used, you ensure that the intended presentation is maintained in your home. You can see what they saw, exactly as they intended you to see it!

There are VERY talented people working on many of these films, and the fruit of their labor is often impressive-- and even more so when viewed, heard and EXPERIENCED as close to the original intent as possible.

It is with this goal in mind that we seek to conform our home equipment to the identical standards (or as close as budget allows) as were used in the creation of the material in the first place. We WANT to see what they saw-- To do so, we need some sort of calibration tool...



THE TOOLS WE HAVE AT OUR DISPOSAL
aka "All I want for Christmas is a color comparator!"

There are really two levels of "calibration" that exist:
1) "User" calibration, using basic user menus and picture/sound adjustments (Brightness, Contrast, Sharpness, Speaker Level, etc) to conform to standards using test patterns and basic measuring devices and filters.
2) "Professional" calibration, using service menus and physical adjustment/repair of the internal workings of the display device to conform to standards using advanced test patterns, expensive professional equipment and a professional eye.

The various calibration and test DVDs on the market operate, for the most part, at level one: User calibration. While all of them have test patterns that would be useful in attempting a professional calibration- all the "on screen guides" and instructions contained on these DVDs stick with using the user level controls and menus.

They use various test patterns, along with some colored filters and some fun instructions that allow you to make adjustments to your set's controls to get your test material to display properly.

Higher-end "professional" calibration is also an option (and an excellent investment!)

Organizations such as the Imaging Science Foundation (ISF) train technicians to calibrate and service display devices to ensure visual accuracy. Some of the better calibrators actually tour the US and beyond doing full calibration and setup.

This service runs into the hundreds of dollars, and while being well worth the money, getting your set in the "ballpark" is often as easy as buying a calibration DVD and sitting down with it for the evening. Nothing substitutes for a professional calibration (just do some searching here for testimonials)-- but a calibration DVD is a GIANT step forward in presenting and maintaining a proper system. Even after professional calibration, a test DVD is an essential element of keeping your display looking its best.



THE APPEAL OF THESE DVDs BEYOND SIMPLE CALIBRATION
aka "Don't answer yet, just see what else you get in this spectacular offer..."

One of the bigger complaints I see on these boards by new people looking for a calibration DVD is the cost. I can't count the number of posts I've seen that say "I don't wanna pay $50 for something I will use once."

First and foremost it's silly to think you will use this disc only once. I own three different discs and all of them get a spin a couple times a year at my place- not to mention the half dozen pals I help out with basic calibration. These discs will be used every time you change equipment (and if you are into this hobby, the upgrade bug will bite as often as the spouse and wallet allow), every time you unplug or move your equipment, and probably a few hours before you have guests over- just to make sure your stuff is operating at peak!

And a very important additional element to note, beyond calibration and test patterns... these DVDs really do offer an excellent overview of video and audio technology, terminology and pitfalls.

My first big "learning" moment in the hobby of home theater was when I rented VIDEO ESSENTIALS from a local video store and sat down with it for the afternoon.

The information contained on the original Video Essentials (which I will refer to from this point onward as "VE") walked me through how a display device works, how light level and color in the room affected my perception of the display, how signal was carried, etc. It covered basic wiring, concepts on how surround formats worked, and even went through an introduction of why calibration and accuracy was important-- giving examples and visual aids-- all before we got to even the first test pattern setup.

I learned more about home theater in that one afternoon than I knew to that point, and I can't say I ever learned more in a single day since...

So, aside from test patterns and the raw utilitarian value of these discs, it is important to take into consideration the added value and importance of these discs as learning tools. If you're interested in home theater, these discs will supply some excellent background info- and you'll soon be the "expert" among your friends.

If I had a nickel for all the people who complained about the cost of Avia or VE, only to come back and proclaim that it was the best investment they made in their Home Theater-- well, I would have enough nickels to buy a ccalibration disc for each and every one of you! Trust me, it's the best $50 you'll spend on your home theater.



THE DIFFERENT DISCS AND THEIR ATTRIBUTES
aka "I'm sold, which one do I buy??"

The big three are Digital Video Essentials, Avia, and Sound & Vision Tune Up -- I'm going to stick with these three.


Digital Video Essentials

Digital Video Essentials (DVE) is the recently released sequel to Video Essentials, which originally appeared on Laserdisc many years ago. VE was the standard for Laserdisc calibration, and VE continued to be the popular solution for DVD for the first few years of the format. It wasn't until the birth of Avia that VE got its first real competition.

Video Essentials and the new DVE are the product of JOE KANE, one of the main guys behind the Imaging Science Foundation (ISF, the guys I mentioned above that certify TV calibration technicians).

DVE PROS: DVE’s strongest point is the sheer amount of material and test patterns it offers. DVE is designed to guide the novice through basic tests as well as to supply professional level test patterns and added refrence-quality film and video clips. DVE is the most recent calibration disc on the market, so it has the most modern mastering and authoring (without getting too technical, it was created in high definition component digital, and ported to standard definition NTSC or PAL for the DVD releases). It's the most up-to-date in terms of test patterns, information and authoring technology.

Bottom line, it is the latest and greatest, the heavy hitter in the tradition of the most popular calibration disc ever released. It's got the pedigree and the chops to back it up...

DVE CONS: Like its predecessor, DVE has been criticized for being difficult to navigate. DVE (like VE) was obviously designed with the more "technical" user in mind and includes a wide variet of test patterns. As a result, the navigation and simplicity suffers.

I have also read that the sub calibration tones on this disc are incorrect, or at the very least are 2db different in level from the previous VE release. I not familiar with why it happened- but anecdotal evidence states that the tones on DVE are 2db louder, resulting in a lower level when you calibrate. A quick solution would be to simply calibrate to 2db higher readout on your sound pressure meter.

Information on this possible error available here on this forum in the DVE discussion thread.

With its numerous testing capabilities, DVE feels more techy, which some users might find a turn off (I'm a nerd, so I like techy).

Release date: September 2003
List price: $24.99

Reviews:
http://www.dvdfile.com/software/revi...sentials.html
http://www.dvd.reviewer.co.uk/review...=3605&User=203
http://shop.store.yahoo.com/dvdinter...iesdvdtar.html


AVIA

Produced by Ovation software and written by Sound & Vision Magazine's technical editor, David Ranada-- it offers some very good explanations of HT concepts and expansive tests. Ovation's main test designer Dr. Guy Kuo is a respected member of this forum, and a regular contributor to the discussions in our hardware section (both on the topic of Avia and others).

Here is a post from Dr. Kuo outlining the tests on Avia.

AVIA PROS: Avia is the middle ground of these three calibration discs- not including as many test patterns as DVE, but is easier to navigate and understand. Its strength is in its ease of use and excellent narration. Avia does a very nice job of presenting an "infomercial" style overview of HT technology and methodology.

I took this disc to the in-laws years ago to set up their home theater. They both (in their 50's with no real techno passion) enjoyed sitting and watching the explanation of audio and video concepts. They both said it explained the audio and video components far better than their instruction manuals.

Avia also has some interesting test patterns not featured on other discs and Avia test patterns are easy to find in the menu system. Overall it represents the middle ground between user friendliness and power.

AVIA CONS: Avia is the oldest of the group mentioned here (not including the original Video Essentials of course). As a result, it lacks any DTS audio test (although one could argue its necessity) or any information on 6.1 audio.

Avia also has a subwoofer calibration issue - without getting into too much technical detail- the main test pattern for subwoofer calibration actually puts the test signal in the main channels, and must be rerouted by bass management in your receiver. If you use your speakers set to "large", this test will not work for subwoofer level in your system. There is also a weird sub test that is incorrect (although most people don't use it anyway)-- I have authored and posted alternate test signals for anyone interested, just search on posts from me and LFE TEST TONE.

Avia has released and updated version known as AVIA PRO- but it is LITERALLY a professional package, consisting of seven discs and costing four hundred dollars. As of now, the only consumer update to Avia is the S&V disc (discussed below), which is abbreviated in comparison to the original Avia.

Release date: June 1999
List price: $49.99

Reviews:
http://www.hometheaterhifi.com/volume_6_2/aviadvd.html
http://dvd.reviewindex.com/reviews/630551982X.html


Sound & Vision Home Theater Tune-Up

The Sound & Vision disc is made by Ovation, the people who brought us Avia. Targeted at the HT beginner, S&V was designed to be sold to the budget-conscious dabbler looking to run basic system tests without investing in a full $40-50 disc. Very simple, many of the tests of Avia are removed, easy navigation, simple instructions- but lacking in more advanced tests and calibration tools.

It's important to note that S&V came out well after Avia, and has newer tests Avia does not offer such as 6.1 related tests.

It is cheaper, it is less in depth, and it is easy to navigate. It does have some basic information about HT methodology, like Avia it is well written and easy to understand!

S&V PROS: S&V is cheaper and easier to navigate. Some higher-end and redundant tests of Avia have been removed in favor of simplified navigation and basic tests targeted at the average user. It really is the opposite of DVE in terms of scope and audience- and as a result ends up with a much more "average user" feel than DVE offers.

It's made by the same people who did Avia, so it is well laid out and well explained-- and the tests are accurate.

S&V CONS: Like most things, when you add user friendliness, you sacrifice power. S&V is very simple, has only the basic video and audio tests and only limited HT discussion and information. It really should be seen as Avia-Lite (slightly updated due to more recent release of course).

Release date: January 2002
List price: $19.99

Reviews:
http://www.dvdtalk.com/reviews/read.php?ID=3354
http://dvd.reviewindex.com/reviews/B0000CGECF.html




A WORD ABOUT THX OPTIMIZER AND INTERNAL TONES
aka "A note to cheapskates who want to get off without buying a calibration disc..."


With the release of Star Wars Episode One on DVD, THX began including an "optimizer" program with THX certified DVDs. The basic optimizer tests were supposed to serve as a calibration tool with basic audio and video test patterns for speaker level, phase, and picture settings like brightness.

Unfortunately, these tests have proved to be inconsistent and criticized by everyone from the average HT dabbler to professional technicians. There are large differences from optimizer to optimizer (the one on Ep1 vs. the one on Ep2 for example) causing some debate to be made that each test is catered specifically for the disc it is placed on-- however the reality is a set of baseline standards are necessary for accuracy- and no one wants to have to recalibrate for each disc.

In the end, the THX optimizer serves as a good starting point, and for those people who would never buy a calibration disc (and will never discover this forum)- it's a passable substitute-- if nothing else it makes them understand that there are guidelines and target ideals for equipment settings. If you're serious about getting the most performance out of your home theater system, you should look beyond optimizer.

If you're looking for evidence pointing to the use of Avia or DVE over Optimizer, just look at THX's own site, where they give information on optimizer, followed immediately by links directly to Avia and DVE.


As far as internal tones are concerned: most receivers have their own internal test tone generator which you can use to set speaker level. Most people, unfortunately, attempt to set the level by ear- instead of using a sound pressure level (SPL) meter. This will not result in accurate calibration... it is important to note, whether you use a calibration disc or the internal tone, a measuring device like a SPL meter is a MUST!

There are two schools of thought when it comes to using the internal tones versus disc tones:
1) The internal tones are preferred. This comes from some rather important people, like the folks at Dolby Labs.
2) The tones generated by a good test disc are preferred. This is a more popular opinion around here, and one I subscribe to.

In my estimation, the DVD player will be the source for the actual movie playback, so eliminating it from the calibration chain (by using receiver tones) seems incorrect. Any variations introduced by the player will not be reflected in using the internal tones-- so it seems better to use the entire intended playback chain when calibrating.

I’m not sure why Dolby Labs prefers internal tones, but one could theorize that the chips that produce these tones are based on their specifications, and thus they would side with the internal tones...

In the end, there is absolutely no substitute for one of these discs and a SPL meter. Your system will provide the best possible ACCURATE representation of the material...

See also:
Home Theater Means Accuracy & Calibration! by Jay Mitchosky
A Quick Overview of Home Theater Calibration by Vince Maskeeper