Polk RM6750 Crossover Frequencies

Topflite66

I currently have the Polk RM6750 5.1 Speakers and just purchased a Yamaha RX-V385 receiver. My receiver has several crossover options, from 40 Hz to 200 Hz, and the back of the subwoofer has a dial to adjust from 60 Hz to 160 Hz. I have the speakers connected to the receiver. Does adjusting the dial on the sub do anything? Or should I mainly focus on adjusting the crossover on the receiver? Also any suggestions on setup? TIA

[Deleted User]

What connection method did you use between the receiver and the subwoofer?

Topflite66

I have an RCA cable plugged into the Pre-out on the receiver

Topflite66

Also of note, the receiver has options to adjust for the size of speaker.

[Deleted User]

Thanks for the additional information. In very general terms the satellite speakers, including the center and surround position speakers do best if they receive an unfiltered signal. The reason for this that they all contain a builtin high pass filter eliminating any bass being made. If you send a signal that is also filtered then there is a risk of "double-filtering" and reducing the bass as a result. So, for that reason set the receiver to "large" (which means no filtering) instead of "small".
There might be a potential problem with some receivers in that when the speakers are set to "large" then the receiver won't turn on the sub-out. But, that was what happened with some early surround sound models, but I don't think it will happen with more recent units.
The subwoofer's variable low pass filter should be set to the highest setting, all the way clockwise. Then set the receiver's sub-out filter point fairly high if the front satellites are placed on speaker stands away from a wall or corners. If the satellites are placed on the wall's surface then you can go a bit lower with the sub-out setting. As you know the goal is to get as smooth as possible transition between the satellites and the subwoofer. Since the crossover frequency will be relatively high try and place the subwoofer in the general area of the front speakers to prevent any directionality problems from the subwoofer.
I hope this is helpful information.

Topflite66

KennethSwauger wrote: »

The subwoofer's variable low pass filter should be set to the highest setting, all the way clockwise. Then set the receiver's sub-out filter point fairly high if the front satellites are placed on speaker stands away from a wall or corners. If the satellites are placed on the wall's surface then you can go a bit lower with the sub-out setting. As you know the goal is to get as smooth as possible transition between the satellites and the subwoofer. Since the crossover frequency will be relatively high try and place the subwoofer in the general area of the front speakers to prevent any directionality problems from the subwoofer.
I hope this is helpful information.

So if i understand correctly, you are saying I should set all the satellites to large speaker, the Sub all the way counter clockwise which would be 60 Hz and the receiver to approximately 80 Hz to 120 Hz? I have FR, FL and the two surrounds mounted on the ceiling and the center speaker on on the TV stand in front of the TV. The sub is on the floor to the side of the TV. Probably not the optimum set up for the FR, FL and surrounds but didn't have any speaker stands to mount them on.

[Deleted User]

Set the sub all the way clockwise to the highest setting.

rooftop59

@KennethSwauger I understand your reasoning for running the sats full range, but man those are tiny and can’t handle any bass at all. Are you sure they won’t distort or suffer any damage if he cranks up a movie with them running full range?

To the op, I would compare Ken’s setup with an alternative: Change the speakers to small and cross them over somewhere between 120-150hz, and match the subs crossover In the receivers settings. See which one sounds better with a movie or song you know really well...

Topflite66

KennethSwauger wrote: »

Set the sub all the way clockwise to the highest setting.

Oops. Sorry, not sure why I read counter-clockwise. OK, so Sub at 160 Hz. I did some experimentation last night with changing the satellites from large to small and back. Just to see if there was a noticeable difference. To tell you the truth I didn't really notice any difference. I could tell though the higher crossover settings on the satellites resulted in less Mid and Bass. I am a little disappointed with this receiver, however. I understand it's more of an entry level receiver but it is a Yamaha. My Onkyo that I replaced it with seemed to have a lot better transition and full range with these speakers.

[Deleted User]

There shouldn't be a problem, the speakers contain a high pass filter, preventing them from sending any bass to the drivers. Keep in mind these speakers (or their predecessors) were used for decades before the invention of surround sound receivers with their "smalls" and "larges" with quite hefty power amps. Full range into them and get the sub to play as high as possible to blend, especially if they are on stands instead of hung on a wall. The wall would boost lowest frequencies allowing for a lower setting of the sub.

Topflite66

KennethSwauger wrote: »

Full range into them and get the sub to play as high as possible to blend, especially if they are on stands instead of hung on a wall. The wall would boost lowest frequencies allowing for a lower setting of the sub.

OK, now I get the concept with the sub. That could be why I noticed the big separation between the satellites and the sub, and was thinking it was the receiver. I will have to play around with the frequencies on the receiver again to see if I can hear a more blended transition.

I currently have all the satellites mounted to the ceiling with adjustable mounting brackets and the center in front of the TV. I had considered purchasing some stands. So I gather that if I move them from the ceiling to the stands I might lose some of the lower frequencies in the satellites? Again Thanks in advance.

[Deleted User]

Think of bass sounds coming from a speaker as if it were light coming from a candle. If you place a mirror behind the candle you effectively double the amount of light produced. The same happens with a speaker, if it is placed on a large reflecting surface bass sounds are increased by being reflected. I imagine the same thing happens from ceiling mounted speakers, lowest frequencies are increased.
However, most home theater experts recommend that the front three speakers be placed, as close as possible, to ear level when the viewer is seated. The idea is to have agreement between what is seen as what is heard each reinforcing the other. But I can certainly understand the appeal of having satellite speakers up away from cluttering the room.

Topflite66

Makes sense. Thank you very much for your help.

[Deleted User]

You're welcome.