4ohm question [Archive] - Audio & Video Forums


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12-13-2007, 11:55 AM
I just recieved the Denon 3808 receiver which comes set at 8ohms and am connecting Vienna Acoustics towers which are at 4 ohms. I believe I am able to change the settings on the receiver to 4 ohms, is this correct? And if I do this what wattage would I be pushing to the towers? The denon specs state that it is 130 watts per channel at 8 ohms

12-15-2007, 09:05 PM
I would leave the impedance switch on Dennon at 8 ohm for maximum performance.

Since 4 ohm speaker loads demand more current from amplifier than 8 ohm loads, the manufactures provide an 4/8 ohm impedance switch to protect the receiver over loading from lower impedance speakers. At 4 ohm impedance setting, the rail voltage on receiverís speaker output is lowered as to limit the current draw for 4 ohm speakers.

At 8 ohm setting, full voltage is applied to receiver speakers output. So at this setting, your receiver can deliver more power. But be careful when receiver impedance is set to 8 ohm and you are using 4 ohm speakers, not to over drive the amplifier.

12-15-2007, 09:53 PM
AND even with the switch set to 4 ohms I'd still keep an eye on my receiver for a few days ,
just to be sure its not running TOO hot, (it'll run a little hot)
The power output will be a bit higher under 4 ohms, but it wont matter how much, you can only play them SO loud...
should be in the owners manuel what the watts rating is at four ohms:1:

12-19-2007, 03:57 PM
You should be fine with a 3000 series Denon receiver with a 4 ohm load especially if your speakers are fairly efficient. Where you run into problems is with cheap power supplies and inefficient speakers like my Magnepan's with a S/N of 85dB.

Just make sure your amp is not getting too hot if you set the receiver to 8ohms.