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Issue 53 | Aug. 06
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Ian ColquhounWe've been busy this month with the installation and testing of a new 96-foot-tall steel measuring tower. This tower allows for the most accurate possible testing of subwoofers, since their soundwaves are too long for even the largest anechoic chamber.

 

by Alan Lofft (bio)

Five Steps to Integrating A/V Installations

It's a given that good loudspeakers require cabinets or enclosures to do what they do best—imitating the sound of real musical instruments and human voices whether on CDs or in movie soundtracks. Loudspeakers have to move lots of air molecules in order to produce sound, so the rules of physics demand that speakers have appropriate enclosures in order to produce powerful deep bass and clean undistorted sound. But it's those same cabinets or “boxes” that become the bane of spouses and interior designers who are trying to achieve a certain “look” to a particular room.
Featured Question
Sherwood High Current Amplifier

High Current Amplifiers

Q. I have a question regarding the amperage demands of multi-driver speakers -- more specifically, the M60ti's, which I've owned and loved for almost two years now. Do they require a "high current" amplifier? My NAD has definitely been up to the task of driving the M60's thus far. -- Jon

A. I'm delighted you like your M60s. They are nominally an 8-ohm speaker, so they don't require as much current (amperes) as a 4-ohm speaker like the M80s would demand.

Amplifier "power" as we think of it in watts, is a function determined by your amplifier's output voltage (voltage is analogous to the "push" of water pressure) and the resistance (impedance) of the speaker to the flow of electrons from your amplifier. The more drivers you install in parallel in a speaker, the lower the resistance, so more current (measured in amperes) flows, hence the term high current. It seems almost counter-intuitive that more current would flow when more drivers are connected in parallel, as in the M80, which has six drivers parallel-connected. One might conclude that with all those extra voice coils full of fine wire in a multi-driver speaker, the electrical signal would meet more resistance, not less. But in fact, the opposite is true.

The best way to explain this is to continue the water analogy. Connecting more drivers in parallel is like connecting three or four garden hoses to one faucet. The pressure (voltage) drops, because the added hoses act as a lower resistance (impedance) to the flow of water. So when you design a six-driver speaker like the M80s, the impedance drops to 4 ohms, which means more current will flow through the output transistors.

Most Class A/B solid-state analog amplifiers (by far the most common type) produce up to twice as much power into 4-ohm loads as they do into 8 ohms, because there is less resistance to the flow of current from a 4-ohm speaker. But when more current flows through (read the rest Alan's answer here)

The first impulse is to try and hide speakers, or instead choose tiny inconspicuous cubes or orbs that house small little drivers (drivers are the cones and domes that move air to create sound waves). The impulse to hide speakers is generally one you should avoid. Sound quality will suffer drastically if you try and bury good speakers inside something else---special cubbyholes in custom cabinetry or the like. Speakers need to be open to the air they have to move in quantity, and they can't do that concealed in an armoire or from behind a fancy latticework wooden grille.

Nor are the unobtrusive little cubes a solution. The weak little drivers may work in a small den, but they can't begin to generate the big, compelling sounds of a full orchestra, band or movie soundtrack with anything approaching real fidelity.

So, how to solve this dilemma?

Here are five ways to get around this problem and keep all parties satisfied.

Consider a hybrid in-wall speaker with a finished real wood veneer trim that will complement rather than sully the furnishings and décor.

In-Wall/On-Wall Epic Master Home Theater
In-Wall/On Wall - Epic Master
While we don't suggest you get speakers that are concealed within the wall or ceiling, there is a real alternative that combines excellent sound quality with an attractive appearance: a hybrid in-wall speaker with an exterior finished frame and the bulk of the speaker enclosure inside the wall. It's precisely designed to duplicate the sound quality you'd get from a comparable bookshelf speaker. You will have to choose carefully where to install a hybrid in-wall, because holes will need to be cut into the wall. But once installed, the wiring can be routed inside the wall to the AV receiver, resulting in an almost invisible installation that sounds excellent.

Consider custom-finished beautiful real-wood veneered speaker enclosures.

If floorstanding speakers are recommended or required for bigger spaces and great rooms, go for custom-matched real woods that blend with and enhance the décor. You can order samples ahead of time and match the finish of the speakers to the decorator's or your partner's requirements.

For dual-purpose rooms, get an electric projection screen that's hidden behind a valance and descends when you want to watch a DVD or TV show in surround.

Depending on your lifestyle, space and budget, you may want to have your home theater be part of a central family room or living room, rather than having a dedicated theater room. It's not that difficult to accomplish. Quiet, smoothly descending electric screens with remote controls can be installed behind a valance finished to match the surrounding wall or woodwork. When you're in the mood for a DVD, a touch of a button lets the screen descend for viewing and retract out of sight at the movie's end. Modern DLP (digital light processing) or LCD High-Definition video projectors are so compact that they can be unobtrusively installed on the ceiling with the supply cables run inside the ceiling. Control of the projector is enabled with a remote that bounces off the screen surface.

If you prefer a flat panel display, companies like Ethan Allen now have customized cabinetry equipped with a motorized lift mechanism that hides the television when it isn't in use.

Use the subwoofer as a nicely finished end table or support for a lamp or plant.

VaSSallo Series EP500
EP500 Cherry Natural - VaSSallo Series

Subwoofers—the big boxes required for ultra-deep bass—don't have to be ugly. You can order one in a highly attractive real-wood finish and locate it at one end of a couch as an end table to support a lamp or plant. The versatility of surround sound acoustics allows for the subwoofer to be placed almost anywhere in a room because we don't hear “direction” from low bass energy. So the subwoofer does not have to be at the front of the room near your front speakers, screen and video display. As often as not, it may in fact perform better at the side or the back of the room or, in some rooms, off in a corner.

Unlike good speakers, the electronics, DVD players and amplifiers can be hidden away in attractive custom cabinetry, a refurbished closet or a special niche in the wall.

The house wiring that powers your lights and appliances is hidden inside the walls of your home. In the same way, the versatility of modern electronics and cables lets you do that for the AV receiver, DVD player, and amplifiers that you'll need to power the speakers. You can house the electronics in custom cabinetry or a redesigned closet, so long as you add an accessory “muffin” cooling fan to ensure proper air flow. If you don't wish to display separate power amplifiers for larger systems, they can be put out of sight in a cooler basement room with the audio-video processor/controller upstairs in the viewing area.

There are lots of creative ways to incorporate a home theater into your home. Have a beautiful installation in your home? Please send pictures to amie@axiomaudio.com.

Questions about this article or anything related? E-mail us at newsletter@axiomaudio.com

 


Loudspeaker Auditioning-- A Delicate Balance

Getting loudspeaker tone quality exactly right is really a matter of balance. Even slight variations in the relative contribution of bass, midrange and treble tones may dramatically alter our impressions of a loudspeaker. If there is too much bass output relative to the midrange, the mids and highs may seem less intense, even sounding a bit muted or distant.

Conversely, if a speaker has little or no bass output, its midrange becomes more noticeable and we might describe its sound as "forward" or "middy" or "too bright" because the midrange and treble seem more prominent. Keep this idea of balance in mind when you audition speakers. "Well-balanced" is one of the highest compliments you can bestow on a speaker, because it says that the loudspeaker reproduces deep bass, midrange and treble frequencies equally well, without embellishment or attenuation.

In the old days, balancing a loudspeaker was called "voicing," and it was viewed as a kind of black art. The term was borrowed from the practice of organ builders, who "voice" a pipe organ after all the pipes are installed in a church, adjusting each pipe's relative balance or contribution so that one frequency doesn't sound louder or softer than another. Musical instrument design also involves achieving good balance between the low, middle and highest frequencies. Whether it's a guitar or a trombone, a musician doesn't want some tones to stand out over others within the instrument's range.

Epic Grand Master - In-Wall Home Theater in Black Oak
Epic Grand Master - In-Wall Home Theater in Black Oak.
Even the Altec-Lansing slogan "Voice of the Theatre," which Altec-Lansing used for its big movie theater speakers, carried with it the idea that speech clarity was of paramount importance -and of course that still holds true in your own home theater as it does in large cinemas. If you can't hear the dialog, you can't follow the movie's plot and appreciate the characters' interactions. Dialog clarity in a loudspeaker is largely a product of smooth, even midrange frequency response. If a speaker's midrange output is depressed or recessed, you'll have more trouble comprehending speech, and singer's voices may seem more distant.

Remember RCA's famous trademark of Nipper, the black and white terrier, listening to "His Master's Voice" through the big horn of an old phonograph conveyed the idea that the fidelity of RCA phonographs was so good that Nipper could recognize the voice of his master? Since dogs can't talk, we'll have to take that on faith. While I have my doubts that Nipper could distinguish vocal nuances through the low fidelity and scratchy disc noise of RCA's early disc recordings, it's still an important illustration of how much trust we place in accurate sound reproduction of possibly nature's greatest instrument-the male and female singing voice. If a loudspeaker gets it right, most other instruments will sound accurate as well, because much of the harmonic content of musical instruments resides in the midrange.

But if a loudspeaker buries the vocal, makes it muddy or distant or sharp or strident, we tend not to forgive it, because our hearing is acutely sensitive to midrange sounds. It's partly survival-we need to understand speech to communicate with each other. Of course deep bass and the nuances of an instruments' high frequencies are also important, but when you audition a loudspeaker's tonal balance, concentrate on the midrange sounds. Are singers' voices smooth and clear and natural sounding? Do trumpets, saxophones, and trombones seem smooth and undistorted? Are strings-violins, cellos, double basses-free of strident or harsh accents?

Great sounding speakers should define the term "high fidelity" by achieving a kind of musical truth through keeping all sounds in correct relative balance, exactly as they were recorded. - A.L.

 

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