Whole Home Audio: Impedence Matching Volume control w/powered subwoofer - AVS Forum
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Old 11-08-2012, 09:44 PM - Thread Starter
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Hypothetical Question: I was planning on running a whole home amp to multiple zones in my home, with the caveat that in specific zones I would place powered subwoofers with speaker level inputs. I would wire them in parallel with that zones speakers as the input the the sub amplifier is high impedance such that it would not significantly affect the load presented to the whole home amplifier. In my haste, I assumed the volume of the said subwoofer would also scale with the position of the volume knob in that zone. However, I think that operation may depend on how the volume control actually works. Does it simily add incremental amounts of impedence into the line to attenuate the current through the speakers? Or is there a transformer game being played here? If is simply adds impedence that will do nothing for controlling the volume of the subwoofer as the voltage present at the subwoofer high level will not change. If the voltage is controlled by a transformer then by placing the subwoofer high level inputs downstream from the volume control, I imagine it would work as intended. Can someone help in my dilema?

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Theeld
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Old 11-08-2012, 10:40 PM
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Volume controls are potentiometers - adding the sub should work fine...

Jeff

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Old 11-09-2012, 06:41 AM - Thread Starter
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Quote:
Originally Posted by jautor View Post

Volume controls are potentiometers - adding the sub should work fine...
Jeff

If that is the case, I actually believe it may not work as you stated? The voltage difference across the subwoofers speaker level inputs will not vary with the position of the volume control, as it is set on the "whole home amplifier" gain, not at the volume control. If the volume control is truely a potentiometer, it varies the load on the whole home amp such to control current through the speaker, but the voltage "difference" signal at the subwoofers terminals will not be attenuated, by adding or removing impedence from the circuit, such that you would likely have a variable audio level of the speaker, but not the powered subwoofer, that output would likely be constant.
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Old 11-09-2012, 07:52 AM
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"Voltage divider"... It will raise/lower the volume of the subwoofer like any other attached speaker.

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