Volume Control

[laketime]

I am looking at installing some in wall volume controls for a home speaker system. I am noticing two different styles of wall controls. One is a Lutron "transformer free" volume control switch and the other is a Hubbell Netselect volume control switch (looks like it has two small transformers on the switch). There is a big cost difference between the two. What are the advantages or disadvantages of either?

 

[ericsherman37]

I don't have much knowledge in this area at all, but I recently went on a troubleshoot service call for a automotive service shop with a PA system that wasn't working. They had an in-wall volume control device (basically looked like a slider dimmer thingie) and that's what wound up being the problem. It was an impedance matching volume control (with the two coils on it - one for left, one for right stereo). It was one of these, actually, or something similar.

It worked just fine, the only problem was that the little metal "teeth" that the slider contacts to adjust the volume had all started wearing out and breaking off. I replaced the whole device with an identical one and it worked great. This was just a general use PA system and didn't require anything special as far as sound quality. Other than that, I really don't know enough about transformer-free stuff to help you determine which one is better.

 

[hbiss]

The cost difference has only to do with the name and possibly quality, all will provide pretty much the same performance (or lack of). Choose whatever you can get that you feel has the highest quality although all will be made in China.

-Hal

 

[laketime]

Just asking because one I can get on a super blow out sale for $6 and the other is $55.

 

[zbang]

The way you control the volume is to control the power going into the speaker. One way is to use a resistor to disapate some or if, cheap and easy, but wastes power and can mess up the impedance the amplifier sees. The other way is to use a transformer to reduce the voltage presented to the speaker, which being of fixed impedance, will draw less power. The Lutron is probably an L-pad, which is two variable resistors. I can't figure out just what Hubbell is doing, since the NetSelect info was rather sparse.

That said, a transformer-based control is not usually applicable to home systems. I suppose you can't just turn down the amp.

 

[LarryFine]

The transformer-based unit is a (two, for stereo) multi-tapped auto-transformer. It's main advantage is what's called impedance-matching, meaning it presents a constant impedance to the load side, for use in multiple-speaker installations.

They often also have several load-side taps for selecting relative distribution of power, beneficial when using dissimilar speakers on a given channel, and/or in areas of different volumess. The instructions are usually clear on settings.

The variable resistor-based units, sometimes known as L-pads or T-pads. A simple variable-tap unit changes the line-side impedance; adding one (L) or two more (T) has a bit less power loss and better line-side impedance control.

The transformer-based units have a reputation for better fidelity, as well as quietness and the above-mentioned impedance selections. They are power-limited, but, if the power levels are that high, you should be using separate amps.

 

[laketime]

The transformer-based unit is a (two, for stereo) multi-tapped auto-transformer. It's main advantage is what's called impedance-matching, meaning it presents a constant impedance to the load side, for use in multiple-speaker installations.

They often also have several load-side taps for selecting relative distribution of power, beneficial when using dissimilar speakers on a given channel, and/or in areas of different volumess. The instructions are usually clear on settings.

The variable resistor-based units, sometimes known as L-pads or T-pads. A simple variable-tap unit changes the line-side impedance; adding one (L) or two more (T) has a bit less power loss and better line-side impedance control.

The transformer-based units have a reputation for better fidelity, as well as quietness and the above-mentioned impedance selections. They are power-limited, but, if the power levels are that high, you should be using separate amps.

I will just be using them to control stereo speakers in different rooms. Sounds like the transformer ones for $6 is the way to go.