by Jeff Fisher
There are many types of speaker cable on the market. Most are not suitable for whole house audio applications. We sell speaker cable designed specifically for in-wall wiring.
Select Speaker Impedance and Maximum Acceptable Loss, then look up maximum cable run distance.
When speaker cable is installed inside the walls, it is important to use cable that is rated for in-wall use. This is often referred to as premise wiring rated. Most speaker cables sold for consumer use are not rated for premise wiring. There are two strong reasons for insisting on premise rated wiring. First, it complies with the National Electric Code. Second, it assures you the materials and the design of the cable meet well established standards for fire safety.
Because the impedance of loudspeakers is quite low, (usually 4 or 8 ohms) the resistance of the cable feeding the speakers becomes quite relevant in determining how much power actually reaches the speaker. As an example, a hundred foot run of 16 AWG cable will have a round trip resistance of 0.8 ohms. If this is used to feed a 4 ohm speaker, approximately 17 percent of the power will be lost to the cable, and 83 percent will reach the speaker.
Larger wire will reduce the power loss.
From a practical standpoint, the wire sizes normally used for whole house audio speaker wiring are either 16 AWG or 14 AWG. These sizes provide a good compromise between line loss, cost, and ease of installation. Most of the equipment available for whole house audio systems have connection devices designed for these wire sizes. Going to a non-standard wire size can immensely increase the difficulty of installation.
Power Loss Budget Table
The following speaker wire power loss budget table provides a guideline for selecting the right size speaker wire.
Speaker Wire Power Loss Budget Table
|Speaker Ohms||db Loss||Power Loss||16 AWG Run|
|14 AWG Run|
A 3db loss may seem like a lot, but since the ear has tremendous dynamic range, you probably won't notice that size loss and with the power of the amplifiers typically used, it is easy to overcome a 3db loss. There is another effect that you should consider. Some high end amplifiers have special speaker compensation circuits. Over the full range of frequencies handled by a speaker, it will perform better at some frequencies than others. Some high end amplifiers sense the response characteristics of the speaker and automatically compensate for non-linear responses. This is sometimes called servoing. When the resistance of the speaker wire is a significant part of the speaker impedance seen by the amplifier, it can impact the effectiveness of an amplifiers compensation capabilities. For most amplifiers intended for whole house use, this is of little relevance.</p>
Speaker Cable Comparisons
Two speaker cables we recommend are the Monster Cable in-wall cable and new speaker cable from Belden in their New Generation series.
|Speaker Cable Comparisons|
|Monster Cable||S162 (16AWG, 2 Conductor)||Rated UL CL3 for premise wiring. Very fine strands (14AWG consists of 100 strands). Quite flexible. White outer jacket. East to strip and install. Monster Cable is a highly respected manufacturer of premium audio cables.|
|S164 (16AWG, 4 Conductor)|
|S142 (14AWG, 2 Conductor)|
|S144 (14AWG, 4 Conductor)|
|Belden||5102UE (14AWG, 4Cond)||Rated UL Type CL3R for premise and riser wiring. Fine strands (14 AWG consists of 27 strands.) Easier to connect to terminals than Monster Cable because of larger strands. Grey outer jacket. This New Generation Speaker Cable by Belden is new on the market. Belden is a highly respected manufacturer of general use and specialty wires.|
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