Written by Admin in Sound, Whole Home Audio
Aug 29 th, 2011
Impedance matching volume controls are a popular yet special type of stereo volume control used as part of a Whole House Stereo system. This Volume control typically only controls the volume on one pair of speakers in a given room or area of a house.
When the home owner wants to listen to music in an area of the house other than where the main stereo equipment is located usually a 4 conductor (16 or 18 gauge) speaker wire is pulled from the stereo to the Impedance matching volume control. The speakers are wired directly to the volume control and their volume is adjusted independent of other areas in the house.
Difficulty of installation is dependent, in part, to the difficulty related to pulling speaker wiring throughout the home to areas you wish to enjoy stereo. Wiring has to be fished within wall cavities; during construction this is easy as opposed to post construction where many factors limit the running of wires. Exterior walls for example, in post construction, are typically considerably more difficult to run wire than interior walls. However, varying construction techniques can also make fishing interior walls challenging too, blocking inside the wall cavity on taller walls would be an example.
When installing volume controls in various different areas of the home there are a couple factors to consider. One is, its recommended you use the same brand and model of impedance matching volume control throughout the entire project. Two, when selecting which to buy and install give consideration to the wattage rating. More volume controls will generally require a higher watt output amplifier because the wattage is divided amongst the number of volume controls used. 25 watts per volume control would be a good benchmark from which to start. And therefore, if you have 5 volume controls times 25 watts you want to consider an amplifier having 125 watt (or reasonably more) output.
With speakers and volume controls in place its times to talk about the amplifier. With respect to this topic, not all amplifiers are created equal. And, for the purpose of clarification, an amplifier can mean anything such as a stereo receiver, an amplifier only, or a surround sound receiver or combination of. It’s important to note the amplifier should be stable for the use of Impedance Matching Volume controls. Not all amplifiers are stable to support impedance matching volume controls. If you decide to use a non-stable amplifier you will ruin the amplifier, it might work at first but will immediately go into shut down or other protective mode. Some manufacturers like Onkyo, Russound and Audio Source make stable amplifiers, other manufacturers do not. As is the case with Onkyo there are benefits to using this brand but in other situations using a different brand might be more suitable. It’s important to think through your objective and then spec the equipment based on that. When in doubt call the manufacturer and ask to speak with the technical support department before deciding on what equipment to use.
TIP 1 – Make sure the specs on all your equipment match. One spec to match is Ohm’s. Eight Ohm’s is the most common but not in all cases. Check the specs on the volume controls, speakers and amplifier first!
TIP 2 – When you’ve determined the number of volume controls beyond just one inspect the manufacturer’s dip switch configurations that must be set on the volume controls. Sometimes, for odd numbers of volume controls the dip switch settings aren’t clearly explained in the installation instruction yet they are critical to reducing chances of damage to your electronics.
TIP 3 – Understand the Impedance Matching Volume control take up a lot of space inside an electrical back box. Before you proceed with the installation, given your climate location and type of construction, compare the volume control to the back box you’ll be using BEFORE you begin drill, cutting and pulling wires and leave a lot of room.
TIP 4 – A slide switch will tend to wear out versus a knob. More information on whole home audio systems here.
Questions & Answers – Answers to questions we are asked
1. Can I use an impedance matching volume control that has less watts than my amp? Yes but…..if you use a volume control rated at less amps than your amp you run the risk of damaging or ruining some of your electronics. Let’s say your amp is 100 watts but you want to install a volume control rated at 25 watts, if you turn up the volume on your amp it will push more than 25 watts through your impedance matching volume control and that’s where the problems begin. However, if your amp is 100 watts and you install four impedance matching volume controls that are rated at 25 watts each you will be in a more safe position. I am currently running an AudioSource 100Amp to 3 Proficient Audio 25 watts impedance matching volume controls. I keep the volume set to 50% on my Audio Source Amp. This has functioned stable for 5+ years.
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