Monday, February 23, 2009

Distributed Audio options

Rob Schultz, President of Inspired Electronics, Inc., was recently published in Electronic House magazine's Ask a Pro section. Read the original article here: http://www.electronichouse.com/article/q_how_much_power_do_i_need_for_multiroom_audio or continue reading.

Q. I just moved into a house that is pre-wired for speakers & volume controls in 3 rooms, 2 outdoor porches, a media room and a family room. I will be buying a new receiver and amplifier but don’t know how much power I need or what Ohm speakers/controls I should get. Any budget conscious recommendations or guidance for a 1st time do-it-yourselfer? - John, Dallas TX


Rob Schultz, of Inspired Electronics, Inc. offers up this solution:


The most basic approach is to have a speaker selector and volume control unit at the head end, and split the output from the receiver. This is simple to install, and pretty inexpensive if the house is already wired. The speaker selector must be impedence matching, which means there’s a switch that lets you tell it how many speaker pairs there are. When you select the right number of speakers, the unit adjusts for the impedence of the speakers so you don’t blow the amplifier. The main drawback of this sytem is that you can only control what’s playing and the volume in the main room. So when your favorite song comes on, you have to run to the main room to turn it up!


You can also use a speaker selector in the main room with individual volume controls in each room. Hopefully the pre-wire has service loops to the right volume control locations, and you know where those are! Use impedence matching volume controls in this scenario. Now you can adjust volume in each room, but you still have to go back to the main room to change what’s playing.


For either option, we plan a minimum of 20 watts per zone, and 40 watts for outdoor zones or large rooms, and we spec 8 Ohm speakers. For more zones or when more volume is desired, we use either a high-power stereo receiver with a speaker selector, or a low-power receiver with a distribution amplifier, such as the Niles 1230 (12 x 30 watts) or Niles 1260 (12 x 60 watts).
By splitting your audio signal, you decrease power and volume by as many ways as you have zones. So if you have a 50 watt amplifier split 5 ways, you get only 10 watts per zone - not even enough for background music.


More advanced options allow you to control the equipment from each room, provide metadata feedback on the keypads, and play different sources in different rooms.

If you're interested in having audio throughout your home or business, visit our web site at http://www.inspired-electronics.com, or call Keith at (847) 471-4420.

Monday, February 2, 2009

Architectural speakers

In my last post, I talked about box speakers. These have a well-earned reputation for having the best sound at any given price point.

But architectural speakers (those that are built into the structure, such as in-wall and in-ceiling speakers) have made great strides over the last few years, so that the best architectural speakers are pretty close to box speakers at a similar price point.

The main advantage architectural speaker have over box speakers is that they can blend in with the room, and they don't take up any space. After all, if you bring in an interior designer, or just spend a lot of your own time and energy putting together the perfect room, do you really want to muck it up with speakers? Sure, those boxes may be great in the theater or game room, but what about the living room or dining room, where there aren't a bunch of other electronics in view?

Many people are even willing to give up some of the audio quality benefits of box speakers in order to "get the electronics out of the room." After all, you're not watching movies or concert videos in those rooms, you're really just listening to background music.

Of course, when your favorite song comes on, what do you do? If you're like me (or my wife!), you want to turn it up. And this is where poor speakers really start to show their deficiencies, regardless of whether they're boxes or in-walls.

There are a couple of factors that give box speakers an advantage over architectural speakers. Those factors can be mitigated or even overcome by good speaker design and proper installation.

First, the box is a resonance chamber. The chamber is designed during the speaker design process, and can be changed during early prototype testing to give the speaker the proper tone, timbre, and resonance. With a built-in speaker, the wall becomes the resonance chamber. You may have a big open box, there may be firebreaks in the wall (making a smaller resonance chamber) or there may be insulation in the wall (absorbing some of the sound). For in-ceiling speakers you may even have a huge void (the attic) behind the speaker.

Good installation can help here. First, insist that the installer use a back box that's designed for the speaker. Since the back box is designed before production, you will get many of the same characteristics as a box speaker, and you will avoid most of the problems of architectural speakers. Generally, back boxes are available for in-ceiling speakers and higher-end in-wall speakers. However, the back boxes may not fit well in a standard 2x4 wall, or may be too high for the cavity above the ceiling. In addition, some back boxes are designed as pre-construction boxes, which mean they must be installed before the drywall is put up.

The second advantage box speakers have over architectural speakers is their inherent rigidity. The box is joined on all edges, and is usually made of MDF (Medium Density Fiberboard). This construction is highly resistant to the types of forces that speakers generate when asked to deliver high sound output. Architectural speakers, on the other hand, usually have an ABS plastic or aluminum "spider" - a sort of cage that houses the driver and magnets. Since there are narrow legs separated by relatively wide gaps, the speaker is much more susceptible to those forces, which can flex the entire speaker out of shape, forcing the cone to be out of shape. Of course, this can impair the sound quality at those volume levels.

Again, proper installation is a good first line of defense. These speakers need to be firmly mounted to a well-constructed wall. In doing so, the speakers gain back some of their stiffness. In particular, if you can attach the speakers to 3/4 or 1" drywall which is glued and tightly screwed to good wooden studs, the speaker will have gained considerable stiffness. And a good back-box will also help to stiffen up the speaker - indeed, most better architectural speakers are designed to work best with a back-box. Beyond that, some speakers have specific design characteristics which help with this problem. James Loudspeakers, for example, have an integrated back-box made out of welded aircraft aluminum. These are essentially box speakers that are designed to fit inside the wall. And other speakers have aluminum or more exotic spiders, which further reduce flexing.

For a professional opinion on what speakers will work best in your listening environment, call Inspired Electronics, Inc. at 847.471.4420 for a free in-home consultation, or visit our web site at http://www.inspired-electronics.com/.