It's my first topic here, so greetings to everybody.
I've just bought a new A/V amp, a Yamaha RX-V540RDS. It comes with a relatively poor set of speakers, NS-P240. I have 2 B&W DM305 (from my previous stereo system) which I use for the L/R front channels. The 2 B&W's (front L/R) are 8 ohm, and the 3 Yamaha's (front center, rear L/R) are 6 ohm. There a swith on my amp to select impedance. From the manual :
Switch..................Speaker....................Impedance level position -------------------------------------------------------------------------------- --------------- Left....................Main.......................If you use one/two set(s) of main speakers, the impedance of ...................................................each speaker must be 4 ohm/8 ohm or higher.
........................Center,....................The impedance of each speaker must be 6 ohm or higher. ........................Rear Center, ........................Rear -------------------------------------------------------------------------------- --------------- Right...................Main ......................If you use one/two set(s) of main speakers, the impedance of ...................................................each speaker must be 8 ohm/16 ohm or higher.
........................Center,....................The impedance of each speaker must be 8 ohm or higher. ........................Rear Center, ........................Rear
So I swithed it to the left.
Because I'm not very satisfied with my center speaker (which sound really bad compared to the B&W's), I ordered an LCR3 B&W center (8 ohm) which I'll get this week.
Now there are my questions (sorry for this long story) : - Do I get the best of my amp by letting the switch to the left ? Will the sound be better or louder (or the both) by switching to the right ? - If I switch it to the right, all my speakers must be 8 ohm, but the 2 rear one's are 6 ohm. Won't I stress my amp ? I have 2 spare speakers (the ones I replaced with the DM305's), if I cable them in series with the 2 others, I'll get 2 12 ohm speakers for the rear. With this configuration, I think I can put the swith to the right.
You will achieve less THD and increased response and sensitivity form the amp by leaving it in the 8 ohm mode. (to the right).
The downside is that you will be overdriving your amp by running 3 6 ohm speakers on it... Depending on how long and how loud you play your amp this will shorten its life.
One option is to replace your cent/surround with 8 ohm speakers.
There are some impedance matching volume controls and speaker selector boxes on the market, where you could power the 6 ohm speakers through them and still show an 8 ohm load to the amp, but in the long run i think you would just do better to change out the speakers as you can.
Thanks for your advices Michael. So i'll try to set my amp to 8 ohm. The center speaker won't be a problem anymore since I'll get the B&W this week (which is 8 ohm). For the surround, is my idea to couple in series my 4 6 ohm yamaha speakers into 2 "virtual" 12 ohm speakers good ? With this configuration, I could switch my amp safely to 8 ohm.
Your going to have a hard time balancing the sound if you run 2 pairs of speakers in series, but it will work.
You might want to consider a cheap pair of hold me over surrounds... or if you could swing 50 bucks I saw a set of Athena SR 5's on Ebay, buy me now price 49.99.
I bought a full system for my Niece for Christmas and was really impressed with the sound produced by the Athenas for the price.
I've installed the LCR3 yesterday. For the surround, I've tried 2 x 2 little Yamaha in series. I've switched the amp to 8 ohm. So, I'm quite satisfied with my HT ('quite' because my previous system (stereo) was a Denon, and the sound was really pure and present). Later, I guess I will buy some good surround speakers.