I have an amplifier question and would like to get some opinions from all the knowledgeable folks on this forum.
The scenario is that I want to use a power amp for my front speakers. I have Niles SPS-4 switch (you can use this to connect up to 4 sets of speakers to a channel). I want to connect front pre-outs on the receiver to run to an amp, then feed this into the Niles switch, then run 4 sets of speakers off the switch. I was thinking of using the NAD C272 or a pair of Outlaw 2200's. Any thoughts?
It depends on the speakers, the volume required and the quality desired. Obviously passing the signal through the Niles will not give the best fidelity as the load impedance of the switch box along with the speakers will loose something in the translation compared to directly wiring a main pair of sepakers to the amplifier. You should have some idea how low the impedance dips on all of the speakers individually. Anything with an impedance that drops much below six Ohms would be a minimally wise choice for the Niles/NAD. You should run the selector box with its protection switch engaged to minimize the possibility of damage to the amplifier. This simply places a fairly large load resistor in line with the amplifier's outputs and isn't much in the way of protection but it is better than nothing - as long as fidelity is not the primary goal. You haven't mentioned volume controls. You would be far better off with an autoformer type impedance matching speaker selector.
Thanks for the reply Jan. As always, you offer top-notch information.
Yes, I am little concerned about the fidelity of this set-up. Obviously if I am spending this amount of coin on an NAD or a set of Outlaws I'm more than a little interested in eeking out every last bit of performance from my system!
All of the speakers I will be running have an impedance of 8 ohms, and I won't be running things at an insane level of volume. I'll have to investigate the autoformer selector nonetheless.
Jan, you mention that "...six Ohms would be a minimally wise choice for the Niles/NAD". If I decide to actually try this out, would the Outlaw gear be a little more forgiving of low impedance loads?
I guess it might be more forgiving. The question is somewhat like asking, "If I want to run something well beyond its capacity, which would blow up the latest?" Check out the impedance matching autoformer boxes and determine what your needs will be as to how much volume from how many speakers playing at any one time. If this is for background music at all times, then you can probably use whichever switchbox you like. Anything more than that and you are asking too much of the amplifier, no matter whose equipment you choose. Autoformers maintain a constant impedance at all points, therefore, the amplifier sees a constant eight Ohms and most amplifiers of any reasonable quality can drive an autoformer load.
Still, placing any switch box between the amp and the main speakers will affect the sound quality slightly. Not much but you might notice the difference if you switch between no box and switch box. Buying the best autoformers allowed by your budget would be the best route here.
And don't get me wrong, the NAD or the Outlaw will drive the basic Niles box within reasonable volumes and the sound quality difference will only be distinguishable should you make the comparison to a straight connection. Most current is drawn from an amplifier when you are playing music with heavy bass, deep bass or large scale dynamics and the current draw obviously increases as you require more power for more volume, it depends a great deal on what your speakers ask of the amplifier. Most "outdoor" or ceiling mount speakers are not terrible loads for this very reason. This is what you should know to make the proper decision.
But the Niles box connects all the speakers in parallel and that essentially halves the impedance of each successive connection. If one pair of speakers dips to six Ohms you should assume that adding another pair would bring the impedance down to three Ohms and adding another pair will lower that to about two Ohms. Another pair will take almost any amplifier well beyond its capacity to safely drive the load. Switch in the "load protection" on the Niles and it places (I think) a twenty Ohm load resistor in series wih the speaker load. That more or less brings the load on the amplifier up to around eight Ohms again but puts quite a bit of a stress load on the amplifier in terms of difficulty in slugging through the resistor and all those speakers. Most well built amps can handle this with minimal "problems", generally running very warm, but will be asked to run against a brick wall of sorts. Think of running your car on the highway with the parking brake on. You can do it but damage will eventually occur if you continue to abuse the system. By comparison autoformers are more like having an extra passenger in the car. Your mileage may vary.