It's a sad fact of life that we all can't have an unlimited home theater (or home, sports car, or vacation) budget. You'll need to determine a realistic budget. One of the spending ratios that can be used is: Video Display – 30% Speakers & Subwoofers – 35% Receiver or preamp / amp combination – 15% Source Components – 10% Interconnects, Wire & Accessories (power conditioner, etc.) - 10%

Home Theater Design - Part 5

Steve Faber | Home Theater Design and Automation

Home Theater Design and Construction - Part 5

It's a sad fact of life that we all can't have an unlimited home theater (or home, sports car, or vacation) budget. You'll need to determine a realistic budget. One of the spending ratios that can be used is: Video Display - 30% Speakers & Subwoofers - 35% Receiver or preamp / amp combination - 15% Source Components - 10% Interconnects, Wire & Accessories (power conditioner, etc.) - 10%

by Steve Faber
 Home Theater Design and Automation

Click here for Part 1
Design Considerations
Click here for Part 2
Construction
Click here for Part 3
Speaker Placement
Click here for Part 4
Room Acoustics and Lighting Design


Finally! It's time to start shopping. Your home theater's really coming together now. All you need to do is put the finishing touches on the room, like paint and trim. That's not so much fun, but buying new home theater gear certainly is! The question is; what to get? Well that depends upon multiple factors, but the three most important are based on your Sources, Performance Requirements and Budget.

Sources

What do you plan on watching and listening to? DVD is a safe bet, but what about a new HD-DVD or Blu-Ray Disc player? Are you using cable or satellite TV, possibly both? Will you incorporate a video game system into your theater? Do you still need a VCR? These are the questions you'll need to answer.

You'll need to be sure your receiver or surround sound processor has enough inputs to accept all your sources. In addition, you should have room for future expansion. Try to look down the road at least a year or two to anticipate your future requirements. There will probably come a time that you'll want to add some additional source components. Keep in mind that HD-DVD & Blu Ray Disc players are just about here and there's a good chance you'll want to get one or both of those soon too. Also, you may want to add a video game console or HTPC.

Make sure the unit you select has plenty of both coaxial and optical digital audio inputs. Three of each is good and more is always better. Most receivers and surround processors on the market today have component video switching, but again make sure there enough to add components. It's much nicer to have three instead of only two. Make sure the component video inputs have sufficient bandwidth to pass all the video signal you're using without attenuating it. You'll want to have twice the bandwidth of the most demanding source you're using. 720P video requires 37MHz so you'll want to be sure your component video inputs have at least 74MHz. 1080P will require you to use a switcher capable of at least 125MHz. Most consumer grade component video switchers will have a problem with that type of bandwidth requirement.

Thankfully, most people will use HDMI for such a bandwidth intensive connection, which brings us to the next type of switching requirement. At the time of this writing, only a few receivers and surround processors feature HDMI switching capability. Some include DVI switching, which can, with adapters, be used to switch HDMI. Obviously the use of adapters is not the optimum solution, it's better to have the real thing. One other note; make sure what ever digital video device you're using is HDCP compliant. This is a necessity to pass the HDCP copy protection signal. Without this, you'll get no video. Most devices are HDCP compliant and will not have a problem. To make matters even more confusing, most consumer video displays available at this time will only accept a 1080p signal through the HDMI inputs, if they'll accept 1080p at all. Oddly enough, there are many 1080p video displays on the market that will not actually accept a 1080p signal. Go figure.

Performance requirements

What type of program material do you like? One of the most common answers custom installer's and retailers hear to this question is "Oh, I like a little bit of everything." While that is probably true, a good way to determine a more useful answer to this question is to ask yourself what your 5 or 6 favorite movies are, what music presets you have set on your car radio (talk and sports channels don't count), and what your favorite CDs or records are. You'll want to select equipment with the most demanding of these in mind.

The next factor in determining the performance requirements is the size of your home theater in cubic feet. The volume contained in the room, combined with the program material will give you an idea of the demands placed upon your system. If you have a large room, over 3,500 cubic feet or so, you're going to need to size your amplifiers, speakers and subwoofers accordingly. You won't get the kind of realism you're looking for in your home theater if you've got a huge room but use a small subwoofer, cube speakers, and underpowered amplifiers.

Specifications are great for comparing products, especially those from the same manufacturer, but should not be used as the sole determining factor. Take output power for example. Remember, a doubling of power will only result in a 3db increase in output. In addition, these specifications are measured in a lab, with the amplifier driving a purely resistive load. Real world speakers have loads that are much more complex and change with frequency. You listen to a speaker, not a resistor, and the amplifier must be able to actually drive one of those too. There are some high quality receivers and integrated amplifiers out there with 50 - 70 watt per channel that sound fantastic, while some lower quality units with 100 watts per channel sound like garbage. All things being equal, more is always better however. In a modest sized room, you can use a receiver or multi-channel amplifier with the aforementioned 50- 70 (good)watts per channel and it will sound great at fairly realistic volume levels.

You'll need to take into account your speakers when selecting your receiver or amplifier. Some speakers are very easy to drive and very efficient at turning watts into sound. Some are not. This is not a reflection on how good they will sound. There is no relation. Some of the best sounding speakers in the world are inefficient and present the amplifier with a terribly difficult load to drive. You can look at the efficiency specification for the speaker to get a rough idea at how much amplifier you'll need to use. This specification is measured in db/watt @ 1meter. Speakers that are greater than 90 db/1 watt should be easily driven to fairly loud levels with a good 70 watt amp.

Setting your surround processor or receiver to "small" for the speaker size settings in the setup menu will remove the bass from the amplifiers and send it out to the subwoofer. This bandwidth limits the amplifiers and will go a very long way to allowing a fairly modestly powered amp to work effectively in your home theater. You can do this even if you've got full range front speakers. A good subwoofer will be much better at reproducing the lowest two octaves that your main speakers anyway.

One more thing. Please, please get a receiver that uses binding posts for the speaker connections, not those cheesy spring clips. You'll have a much better connection to the speaker wire, especially if you're using premium speaker cable (and you should be).

Back to the subwoofer selection. Many of the subwoofers on the market do not really deserve to be labeled as such. A true subwoofer should give respectable response well into the bottom octave (20 - 40Hz). Subwoofers, like other speakers are rated with a frequency response specification that should have a qualifier such as +/- 3db. The lower number on this qualifier, the better. Without such a qualifier, the specification is basically useless. Your subwoofer should go down to at least 35Hz. It doesn't really matter how high it goes, as long as it has accurate frequency response up to the point where it's crossed over to the main speakers. This usually occurs at somewhere between 60-100Hz, depending upon such factors as the lower frequency roll off of your main speakers and the subwoofer's placement.

Manufacturers of high quality (not necessarily expensive) subwoofers will be able to give you a specification for the maximum room volume that a particular subwoofer will be suitable for. I recommend using always using at least two subwoofers. This will give much better, more even bass response throughout the room, by more completely energizing all the room modes. You'll have a huge variety of different designs to choose from. It doesn't really matter which type of subwoofer you choose. There are very successful examples of many different designs. What matters is the performance the sub delivers. As a very general rule, make sure the sub has at least a 10" driver.

There are, however, some very effective designs that use 8" drivers either singly, or in multiples. Most of these use some sort of extra long throw design, coupled with an extremely powerful digital amplifier. Larger subwoofers use this design strategy too. The main advantage of using a smaller, extra long throw driver combined with a very powerful, digital amplifier, is that it allows a much smaller enclosure, while still delivering great bass. This is important to many people who can't or won't use the traditional huge box a traditional subwoofer requires.

Budget

It's a sad fact of life that we all can't have an unlimited home theater (or home, sports car, or vacation) budget. You'll need to determine a realistic budget. If you're working with a custom installer, it will be much easier for them to develop an equipment package that fits your needs if you give them a realistic budget. In many cases, people have nothing to base their budget on. They have no way of knowing how much home theater gear really costs unless they've done some research on the subject. In that case, a trusted custom installer is invaluable.

There have been many formulas floated around throughout the years about what percentage of your budget to allocate to which part of your system. In some cases these have been developed by those with a horse in the race, so can be looked at with a grain of salt. One of the ratios that can be used is: Video Display - 30% Speakers & Subwoofers - 35% Receiver or preamp / amp combination - 15% Source Components - 10% Interconnects, Wire & Accessories (power conditioner, etc.) - 10% This is obviously a very rough guide. In many cases the source components will include a cable box or satellite receiver that is free or leased from the service provider.

This should get you started on some things to look at when selecting your home theater gear. As with so may things, you'll probably have to make compromises for your particular situation. If you can audition your gear, by all means do so, but remember, audio gear will sound different in your room than in the demo room. Get friend's recommendations and read reviews for information as well. Happy shopping!


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