RM6000 Sub setup

stott281

I just purchased the RM6000 system. I have it set up and it sounds great, especially the sub, it is quite impressive for only an 8" with a 50 watt amp. The advice on not using the sub pre-out jack on my reciever was invaluable. I had it hooked up that way at first and it sounded OK, but then I switched and just used the speaker line-level inputs and it blew me away, what a difference. Anyway, my question is about the phase switch on the back of the sub. What does this actually do, and should I be able to tell a difference when I switch it from 0 to 180? Is placement a factor as to what it sould be switched to? Any help would be appreciated, it sounds awesome now, but you know how it goes, we guys always have to tinker with stuff. Thanks in advance!

mjk91383

welcome to the forum!

joe

stott281

Thanks!!

[Deleted User]

Hello,
Thanks for posting on the Forum, I'm glad you're enjoying your RM6000 system, I agree, it is an excellent sounding system. The adjustment you're referring to deals with the polarity of the sub-woofer with respect to your front satellites. As the woofer cone moves forward it compresses the air molecules producing a wave of high air pressure, the first part of the sound wave. As the woofer cone moves inward, completing it's cycle, it pulls air molecules apart producing low air pressure. So sound is made of high and low air pressure waves traveling through the air, the lower the frequency the greater the distance between these two waves. At the common crossover frequency between the front satellites and the sub-woofer these high and low pressure waves need to reach the listening position synchronously. If the sound waves coming from the sub-woofer reached the listener out-of-phase with the sound waves coming from the front satellites the high and low air pressure would cancel each other out with no audible sound. If your sub-woofer is in the same general area of the listening room then a setting of "0" degrees would be best. If your sub-woofer is very close to your listening position, or further away from your listening position (with respect the distance to the front satellites) then the "180" degree position should be best. It is the path lengths, from the listening position to the sub-woofer and the front satellites that is important. If they appear different, either longer or shorter, then try "180" if they seem similar, then try "0" setting. The very best method would be to have some kind of test tone that is the same as your crossover frequency (150 Hz in the case of the RM6000) and a way of determining sound pressure levels. Then the test tone would be played (there are test CDs with various frequency bands as well as inexpensive test tone generators, the Tenma 72-505 from MCM Electronics 1-800-543-4330 sells for $64.25 is a fine example) and switching back between the two settings, finding the one which gives the strongest output at the crossover frequency.
I hope this is helpful information.
Regards, Ken Swauger

stott281

Thank You!! My sub is behind my entertainment center which sits in a corner. The satellites are on top of the ent. center. I'll experiment and see what sounds best. One more question thouh do you know if polk has any special technology in the sub for this system. I had been looking at similar speaker systems with 100 watt 10" subs and I bought the RM6000 simply on reputation. (I have several friends you have polks and they rave about them.) The sub on this system is amazing, for an 8" or not. I have the volume on the sub set to a little under half and it rumbles my entire house. All I can say is that polk knows what they are doing, and I would be afraid to hear any one of their larger subs.

[Deleted User]

Hello,
Building a good sub-woofer is kind of like building a car that goes fast, carries lots of people and corners like a cat. Hard to do all three at the same time. In sub-woofers the three goals are: goes low in frequency, has fast transient response and plays loudly. Equally difficult to do, most of the time getting two out of three is pretty good. We work hard to strike a balance, building sub-woofers that reproduce low frequencies, have good transient details and play relatively loud. The choice of drivers, the design of the enclosures and the bass amplifiers are all done to cooperate together to enhance each components strong points. The results is bass information that actually sounds like the real thing, music or movies. Enjoy your Polk!
Take care, Ken

stott281

Thanks for the response! I am still amazed it is only an 8" sub every time my wife and I watch a DVD. Even she likes feeling the room rumble when the T-Rex comes on in Jurassic Park.