Charles J P

What’s an Ohm?

The ohm is the unit of measure for impedance, or electrical resistance.

What does this have to do with your home theater? It affects how much power your amplifier produces.

Power = voltage^2/resistance. Anything that is fed an electrical signal provides resistance. The higher the number in ohms the higher the resistance. Many loudspeakers are rated at 8 ohms. (This rating is usually listed as “nominal” because resistance is variable-- it changes over the frequency range.)

It is usually not too high resistance that we have to worry about, but too low resistance.

Say you have an amp that will produce 25 watts (power) into 8 ohms. If you show the amplifier a 4 ohm load, you decrease resistance and increase power because any given number will be larger when divided by a smaller number (80/8 is less than 80/4).

As the resistance decreases and power will increase (a theoretically perfect amplifier would double in output) the current will also increase because Ohm’s law states that current = voltage/resistance (power = voltage^2/resistance).

If the amplifier has the capability to produce this much current and dissipate the heat, you will be fine, but if not, you will over heat the amp and may ruin it or at the least trip the protection circuitry. You should always know the limits of your speakers and amplifier to avoid damage.

Home Theater Lounge

Steve Berger

HOOKING UP YOUR DIFFERENT PIECES OF EQUIPMENT

Always read the markings and labels on the jacks. Get a flashlight and mirror (and magnifying glass ?) if necessary to see them. Never try and remember that "the blue one went here and the yellow one went there".An input connected to an input does nothing and an output connected to an output may break it.


START WITH BASIC OPERATION

Start with simple setups and once you've mastered running your systen that way you can add complexity and advanced features. That way if something stops working you have a better chance of troubleshooting the problem.


NEATNESS COUNTS

Route your wires carefully to avoid tangles. Trim wire ends carefully on speaker leads. This will make upgrading or troubleshooting a lot quicker and easier.


POSITIONING

Amps get hot. Don't put the DVD or CD on top of it. The amp may overheat and the optics will have a short lifespan.

Jeffrey Forner

Which Speakers Should I Get?
That question comes up all the time from newbies, and it's an extremely difficult question to answer because there are so many good choices from which to pick. In order to find the speakers that best suit your needs and living conditions, several factors must be taken into consideration:

• What is your overall budget?
  Your budget, above all else, will determine what you can and cannot buy. The higher the budget, the more options you will have. Of course if you spend more money, chances are you'll end up with better sounding speakers.
  
• How big is your room and what aesthetic considerations must be made?
  Many home theater gurus love big, huge speakers, but not everyone can have them or even want them. If you live in a small apartment or the system is going in a tiny bedroom or if you simply do not wish to have huge speakers invading your living space, you certainly don't want anything too big. If these things do not matter to you (or your spouse), than bigger speakers will likely make a bigger impact.
  
• What are your listening habits?
  Do you watch movies all the time? Do you mostly listen to music? What kind of music do you like? Certain speakers are better for certain purposes, and knowing what you will use them for can help us narrow down your choices.
  
• Do you want 5 speakers or just 2?
  If you're interested in a complete film experience, a good surround sound system with 5 speakers (and a subwoofer) is a must. If you only wish to listen to CDs or the radio, two speakers will likely do.

What are some good speaker brands to listen to?
There are many good speaker companies out there. The following is a small sample of some of the brands that have received favorable reviews from audio enthusiasts on the Internet and are worthy of consideration:

• Acoustic Research
• Adire Audio
• B&W
• Boston Acoustics
• Definitive Technologies
• Diva by Swans
• Energy
• Home Theater Direct
• JBL
• Klipsch
• Magnepan
• NHT
• nOrh
• Paradigm
• Polk
• PSB

(I'd like to add more brands to this list that I may have forgotten about. If you know of any others, please let me know and I will add them to the list.)

Keep in mind that you may not like the way all of these speakers sound. Each brand has its own unique characteristics and not everyone agrees on which sounds best. Listen for yourself and decide what you like. It's the best way to pick your speakers. You wouldn't buy a car without test driving it first, would you?


A few words about timbre matching
Another thing to consider--especially if you're buying speakers for a 5.1 surround sound system--is that you'll want to only buy one brand for the whole set. You see, when watching DVDs, often times sounds will pan from one part of the room to another. For instance the sound of a jet flying overhead might begin in front of you in the front left, right, and center channels, but after it passes overhead, it will move to the surround speakers behind you.

If you mixed and matched speakers from various brands (like if you bought JBLs for the front speakers but had nOrhs in the back), the characteristics of the sound may change as the sound pans around the room, since no two brands sound exactly alike.

Fortunately, manufacturers often make various models of speakers with similar components so that they are timbre matched. In other words, the characteristics of the sounds in the different speaker models are the same, even though they may not be the exact same models. For instance, the Home Theater Direct Level III towers are timbre matched with the Level III bookshelves as well as the Level III center channel. So if you wanted, you could mix and match these three speakers together in one home theater system, without worrying about the sound changing as it moves around the room.


What about BOSE? I don't see them on that list. Aren’t they a high-end speaker company?
The Bose brand is an often discussed topic among home theater enthusiasts. In a nutshell, Bose is not a highly respected brand in the world of high-end audio because they do not offer a product that is worthy of the price you pay to get it. For the same amount of money or less, you could buy speakers that sound as good, and in most cases, sound better. To learn more about why we do not recommend Bose, check out this article as well as this FAQ

Again, the best thing you can do when looking for a new set of speakers is to go out and listen to as many different models and brands as possible. The more research you do, the better idea you'll have of what's out there, and the more likely you are to find the speakers that are just right for you.

-J.Fo

Ash Williams

What are some awesome sounding DVDs to test out my system?

There are several, but mine and I'm sure quite a few more HTFer's favorite discs include:

• Saving Private Ryan 5.1 DTS: Simply an outstanding surround mix! Bullets wizzing past from every direction, massive explosions rocking your house, and John Williams' haunting score make this one of THE best.
• Star Wars Episode I: The Phantom Menace 5.1 Dolby Digtal EX: A truly referance soundtrack. It has it all, deep bass, magnificent surround action and a killer score. The pod race brought tears to my eyes.
• The Haunting 5.1 DTS: Personally I have never heard this mix, but I thought I would include it because so many HTFers swear by it.
• Fight Club 5.1 Dolby Digital EX: This mix has it all. Lots of killer deep bass, a lot of surround action and an awesome Dust Brothers score.
• Dances with Wolves 5.1 DTS: I hear this disc is OOP (Out of Print), but I think it can still be had on eBay. Here again, some decent bass, especially in the buffalo hunt scene, and some decent surround action.
• The Matrix 5.1 Dolby Digital: A lot of deep bass and very good surround speaker use. The only bad thing is that it is from Warner Bros., which means you will get a cut bit-rate mix.
• Seven: Platinum Series 6.1 Dolby Digital EX or DTS ES: The opening titles will make you turn your subwoofer down, guranteed! Both mixes have tons of bass and a very good music score.
• Apollo 13 5.1 DTS or Dolby Digital: Be sure to check out the rocket lanch scene, it is incredible. There is quite a bit of surrond action, but the bass is the real eye opener.
• Jurassic Park 5.1 DTS (Re-mix): Ever heard a T-Rex stomp? Well now you've felt it! This disc was re-issued by the studio as the original was lacking bass. Do a search to find out what I mean.

While there are numerous more DVDs with awesome soundtracks, those are some of the best. Essentially, as rule of thumb, if the movie has a lot of action and is a Hollywood blockbuster, then chances are it has a good sound mix.

William_K_F

Don't make this mistake configuring your 16x9 TV for DVD input.

I had my new HD 16x9 Toshiba 34HF81 TV for over a month before I realized that I had the DVD player configured for a non-optimal picture.

Since some DVDs have an anamorphic signal for the widescreen recorded on them, you can get a full 480 lines of data displayed on your 16x9 TV if the DVD and TV are configured properly.

The DVD player should be set for a 16x9 TV, this is sometimes called "wide" mode and means the letterbox picture is stretched to what would fill a 4x3 TV screen, so that you get a full 480 lines of information for display on the TV.

The TV should be set for what my system calls "full" for viewing the DVD. This tells the TV to stretch the picture wider to fill the 16x9 screen, undoing the effect added by the DVD player explained above.

The net effect is a much better looking picture since you now have all 480 lines of data going to the TV rather than having some of those 480 lines wasted on the black bars needed for a 4x3 TV. :b

(Note 16x9 and 4x3 refer to the aspect ratio of the screen described earlier.)

Jeff Kleist

WHY ARE DVDs RELEASED ON TUESDAY?

For several reasons:

1-Most shipping recieving departments (at least where I've worked) work Monday-Friday, because that's when UPN/FedEx runs. This way they have all day Monday to recieve and price the product, and ready it for Tuesday.

2-Sales are slow in the middle of the week, and it gets people into the stores.

Neil Joseph

Subwoofers

A subwoofer is a dedicated speaker used to produce the lower frequencies (deep bass) that we can hear and in some cases, feel. They are essential in a home theatre because the other speakers in the setup seldom produce these low frequencies, which ultimately make the listening experience much closer to the real theatre's audio experience.

There are various ways to connect a subwoofer....

1- The most common way is to connect the receiver's "LFE out" to the subwoofer's "L and R" RCA terminals using a cable that is a single RCA on one end and splits to a dual RCA at the other end. A single RCA cable can also be used with a "Y splitter" that will provide the dual RCA ends for the sub hookup. One note on this: It is better to connect the receiver's LFE out to both of the subwoofers "L and R" inputs. Essentially, this will provide a volume level in the subwoofer twice as much as just connecting to the "L" alone, or the "R" alone. As an LFE sub, the subwoofer will only play "low frequency effects" as was intended by the audio material.

2- Another way to connect the sub is to use traditional speaker wire and to connect from the receiver's "Front Left" and "Front Right" to the subwoofer's "L" and "R" speaker inputs, then connect the front left and front right speakers directly to the subwoofer. Essentially, the subwoofer will always play the low bass information from the front channels as apposed to an LFE sub that plays only "low frequency effects" as intended by the audio material.

3- A third way to connect the sub is to use it as a dedicated surround sub. This is usually done only if used as a second subwoofer. When connected in the following manner, the sub will only play low frequency information from the surround left and surround right channels. The hookup is essentially the same as number 2 above, except the "surround left" and "surround right" are connected from the receiver to the sub's "L" and "R" inputs with traditional speaker wire and then the surround left and surround right speakers are connected to the subwoofer's "L" and "R" outputs.

Click on above image to enter " T H E . H O L O D E C K "
---------------------------------------------------------
The Holodeck. My DIY Screen. DIY Subwoofer: The MaxCaliber
My humble collection of DVD's. HTF Beginner's Primer and FAQ

Kerry Hackney

SPEAKERS: Direct Radiator – The conventional black cone speaker that most everyone recognizes. The two most common varieties are two-way, a woofer and a tweeter, and three way, a woofer a midrange and a tweeter. The other design variation is in the type of enclosure the speaker is placed in and what the effect of that design may be.

SEALED: All speakers are designed with a specific cabinet volume in mind. The volume of air inside a cabinet has a definite effect on the sound of a speaker in the bass to midrange frequencies. Sealed enclosures are just that, an airtight box with speakers mounted in the face. This, in effect, makes an air spring behind the driver that helps control the maximum movement of the bass drivers. This can be visualized by squeezing a balloon. The air inside helps support the motion of your fingers. Sealed boxes were once characterized as the better choice for music reproduction. This was in large part due to the control of the driver that the designs exhibited. This control usually meant that the speaker would have lower distortion. Today there are a couple of other options.

PORTED SPEAKERS: Ported speakers are identified by having an opening or port in the cabinet. This port is a tube normally, that is made to a specific length. The length of the port is used to “tune” the cabinet. Think of blowing over a Coke bottle. The tone you hear is a resonance controlled by the volume of air in the bottle and the length of the neck or port. By calculating the correct length of the port based on the volume of air in the cabinet, the frequency can be changed and designed for maximum benefit. The purpose of the port is to help augment the bass performance of a speaker. By using a port, the design can normally extend lower than the same design and drivers would in a sealed enclosure. Modern ported speakers offer performance that can be just as “musical” as a sealed enclosure. As speaker designers have learned more and more about how the driver and cabinet interact a lot of very good drivers and designs have emerged that take advantage of ported cabinets’ increased frequency range without sacrificing accuracy. The location of the port on the cabinet can come into play if the speaker is to be wall mounted or placed in a bookshelf. The port should not be obstructed or blocked in order to work as designed. This can be a major consideration in rear ported designs.

PASSIVE RADIATORS: PR speakers operate using a device that is in effect a non powered speaker cone. This cone can be vibrated by the air inside the cabinet to again, augment bass response as a port does. However, drivers in ported enclosures can operate in a detrimental way if they are driven below the tuning frequency of the port. PRs maintain the control of the drivers even below tuning. Normally, PR speaker are seen most often in subwoofer applications.

When picking out a speaker, it is most important to listen. Don’t worry about which design the maker has used. What is most important is how it sounds… Listen to music you are familiar with. Don’t try to compare several speakers at the same time. If possible, arrange for a trial period in your home. Make sure that if you listen in the dealer’s location that there are not any other speakers on, particularly subs. I have found on more than one occasion that the audition room had a sub operating at low levels. VERY UNCOOL and even deceptive marketing tactic.

george king

WHEN BUYING EQUIPMENT GO TO A HT OR A/V STORE

Many people think that they will only get a "good" deal if they go to a large mass market retailer. However, cheap prices come at a cost: Limited selection, poorly setup equipment, marginal customer service, and a sales staff that may not be knowledgeable.

However, at a good specialty store, the prices will not be that much higher. One will probably get a wider selection of equipment, good customer service, and generally well setup demo rooms.

Furthermore, many specialty shops have trade-in policies as well as the ability to demo equipment at your home. In addition, with regular patronage, you build a relation with the store which has added benefits over time.

Vince Maskeeper

Bi-wiring & Bi-Amping Speakers


1) True Active Biamping: This is when you have an active crossover unit between your preamp and amplifier which splits the full range signal coming out of the preamp into a Hi and Low freq signal.

These split signals are then fed from the active crossover to 2 seperate amps (or 2 different channels on an amp) and amplified completely seperately. This way your Hi and Low stay completely seperate from the very beginning... they get amplified seperately, and passed down a dedicated speaker cable for each signal...

When these 2 signals are fed into a speaker, they must go into a speaker specially wired to accept 2 discrete signals and route them to the proper drivers in the speaker. These speakers will have no internal crossover circuitry- all signal sent to them must be "pre-filtered"- and the speakers offer direct electical connections to the components inside...

This is true biamping- and it is very rare in Home Theater applications. It is ideal as it keeps the freq discrete starting before amplification - and gives you complete control. You find this type of setup in some movie theaters, some studio monitoring situations and professional PA systems (and many PA systems are actively split 3 way or 4 ways!)


2) Passive Biamping: This is where you don't have an active crossover unit to split the signal and instead you feed identical fullrange signal into two amplifiers (or 2 amp channels).

These full range signals are amplified seperately and then fed each on their own wire into a speaker designed to accept these 2 discrete full range signals.

A passive crossover filter inside the speaker filters out the High signal from the material destined for woofer and filters out the Low signal from the material destined for tweeter.

This crossover circuit inside the speaker is not connected between the HI and LOW- so each band pass is essentially "discrete" after the amplifier: it is just filtered after it is amplified (where as in #1 above it was split before being amplified).

Is also is uncommon in HT- although more common than true biamplification. This requires that you have 2 amps (or amp channels) to drive each speaker- and that the speaker is equipped to be wired this way.

This gives a full amplifier channel dedicated to Hi and one Dedicated to low: giving more power to each driver and usually results in a sonic improvement due to added amplification (and a few other possible factors).


3) Biwiring: This is where it gets sticky.

You run 2 speaker cables from a single amp channel and hook that to 2 inputs on the speaker. If you have special speakers designed to accept this (just like the ones explained in #2 above), The passive crossover filter inside the speaker filters out the High signal from the material destined for woofer and filters out the Low signal from the material destined for woofer.

As above, this circuit is not connected inside the speaker- so each band pass is essentially "discrete" after the amplifier- however since they share a single amp channel-- they are connected at the amplifier.

I am not persoanlly a fan of Biwiring- as I believe it is of no real advantage (however some will certainly argue otherwise- you should seek these opinions out if you're interested in considering this technique).

With Biwiring the advantage of discrete signal chain is theoretcially killed when the speaker wires are connected at the amp channel... You no longer get more power to the drivers, and no longer have discrete signal. Electrically speaking, there is very little difference from this versus just feeding a single fullrange signal to the speaker and letting it split it.

Usually any improvement in sound from BIWIRING seems to be the result of the fact that you're using 2 speaker wires (thus doubling the volume of signal wire).



SO:

True biamping requires a seperates system with an active crossover.

If you wish to experiment with Passive Biamping, or Biwiring- you have to make sure you have "biwire" type speakers which allow you to remove the jumper inside the crossover and run 2 speaker lines to the speaker.

-Vince

Need an introduction to home theater? Check out our FAQ and Primer!!

MarcVH

SO, WHERE DO I PUT ALL THIS EQUIPMENT?

Clearly your fancy new A/V system will have to go somewhere, and if
you're like most new enthusiasts your existing entertainment furniture
isn't up to the task. Good furniture will help make your system easy
to use, protected from harm, and pleasing to look at.

Aesthetics are subjective, but function is not. When considering
entertainment furniture, remember:
[list=1]
[*]Shop for equipment first

If you don't already have the basics of your setup (TV, speakers,
receiver) then you'll want to at least do some shopping for that stuff
first, so you have some idea what you're going to get and what its
requirements are. Even if you don't buy equipment first, you can
usually find spec sheets and manuals on the manufacturer's web pages,
which can tell you things like weights, dimensions and ventilation
requirements.

[*]Your equipment should be stable and well-supported.

Consider that a home theater receiver can weigh over 50 lbs, and a big
TV will weigh well over 100 lbs (and is front-heavy.) You don't want
that kind of weight sitting on something that's going to fall if
somebody bumps into it, or in an earthquake.

Some furniture has rated capacity claims; otherwise you'll have to
look for things like thin shelves made of particle board, long
unsupported spans, flimsy plastic shelf supports, and anything else
that doesn't look strong and durable.

[*]Your equipment should be positioned properly for use.

A TV should be where you find it most natural to look at from your
seating position, not awkwardly high or low. After the TV, consider
center speaker placement. Your center should be aligned with the
center of the TV screen, with the height of the tweeter as close as
possible to the hight of the tweeters in your main speakers. This
usually means it goes right on top of the TV, although underneath it
can be an option as well. If your furniture won't allow either of
these things, that's a problem.

Picture yourself changing a CD; do you have to do anything awkward,
like crouching down or opening a glass door? Can you see the front
displays that you need to? Will your remote control operate your
most-frequently-used components easily, or will something be in the
way?

[*]Your equipment should fit, with room to breathe.

Many home theater components have a standard width (about 17 inches,
some are narrower but very few are wider) and most racks are designed
to accomodate this size. Depth, however, is an area where problems
are common. Equipment depth varies considerably; receivers can be
quite deep, and if the back of your furniture is closed you'll need
another couple of inches for all the conections on the back panel. CD
megachangers are probably the worst offenders -- some are more than
22" deep!

Some home theater equipment uses a lot of power, and thus creates a
lot of heat. Receivers and amplifiers are generally the worst
offenders, though TVs make some as well. It's best to avoid stacking
heat-producing components, and there needs to be ventilation to allow
that heat to dissipate instead of it cooking your expensive
electronics. Usually the ventilation is on the top and back of the
component; the manual will usually recommend minimum clearances.

Equipment has to have cables that connect it together, and if you end
up with a signicant system it's inevitable you'll have a honkin' lot
of cables connecting things together. The plugs for these will take a
couple inches of depth in the back, and the wires themselves will wind
this way and that. No cable should be kinked, and this is
particularly important for optical digital cabling. Some systems
include cable mangement, although this sometimes forces all cables to
run within a single channel -- some people feel it's better to
separate signal cables (interconnects) from power cables (including
speaker cables) to limit interferance.

Because of depth, ventilation and cabling requirements, many prefer
furniture which is "open" (lacks back and side panels) or at least
open in the back. There are disadvantages as well; for exam