Originally Posted by alatham
Originally Posted by FMW
I would just go for a low end AV receiver. They're about $200 bucks and a lot more useful than a cheap class D power amp.
Will a cheap receiver run Magnepan's?
First off your question is a bit indistinct, as there are a number of different models of Magnepans, and they are different.
The Magnepan web site is no help, as it repeats the audiophile myth that AVR's can't drive 4 ohm loads. I know its not true because I have one of the cheapest AVRs around, and it drives speakers well that have impedance curves that go down to 3 ohms. I'm also a graduate engineer that has designed, built and tested hundreds of different power amps, ranging from Tripath 10 watt cheapies to the best that Bryston and Crown have.
For example the Magnepan MMG has the following impedance curve:
It's basically a 6 ohm speaker. So, its not even one of those allegedly hard-to-drive 3-4 ohm speakers which are actually pretty common.
Its efficiency is given as Sensitivity: 86dB, 2.83 Volts, 500Hz @1 Meter
This positions it as being 4 dB less efficient than the average 90 dB/W speaker. 10 dB is subjectively "half as loud", so you might say it is halfway in-between being as loud and half as loud as the average speaker. If you have a modern AVR you can adjust the volume in fairly accurate 0.5 dB steps. Crank in a 4 dB change and see what you think. It is audible but its not a deal breaker.
In use (and I have hands-on experience with Magnepans) it's power limitations are set by the fuse, which you are told in the manual (linked above) to never replace with > 4 amp standard (not slow blow) fuse. 4 amps into 6 ohms is just under 100 watts. I've blown these fuses with 200 wpc amps without audibly straining the amps or the speakers, so I suspect that using MMGs with > 200 watt amps might be a waste of amplifier power potential.
I look at it this way. My home system has speakers and a powered subwoofer and the speakers have average efficiency but dip to just over 3 ohms. It gets to reference levels with about 3 dB headroom. I never listen to it that loud. This tells me that I could power MMGs with the same AVR and it would be fine.
Send me 3 and I'll try them out! ;-)Edited by arnyk - 9/17/13 at 6:39am