RM-20 in 7.1 setup

msvara

Hi All, Just became a RM-20 paired with the PSW125 owner and have a question about xover. At which setting should I have my satts set at? Sub? I currently have it set at 80Hz but I know that's too low.

Thanks All

TECHNOKID

msvara wrote: »

Hi All, Just became a RM-20 paired with the PSW125 owner and have a question about xover. At which setting should I have my satts set at? Sub? I currently have it set at 80Hz but I know that's too low.

Thanks All

As per RM20 5 packs specs 80hz is correct for these satellites / bookshelf speakers: http://www.polkaudio.com/homeaudio/specs/recent/rm20pack/

In fact, with my yammy receiver YAPO sets them exactly at that frequency. I figure the sub Xo should be set for 100hz upper for good blending with the sats but will let others provide info on this... Welcome to CP and congrat on your new acquisition

Cheers!
TK

msvara

Thanks Technokid. I noticed that it says -3db at 100Hz. Does that mean that below 100Hz the speakers loose efficiency by -3db each step? I think I'm going to xover at 100Hz.

Also I have an older Cerwin Vega 8" sub AVS-SUB8 that still works so nicely but on higher volumes it flutters so I wanted to keep that sub connected for lower volumes and use my new PSW125 at higher volumes. How should I xover the subs? The AVS xover is turned off right now when I connect the new sub should I xover the new PSW for the really low lows or keep them both turned off? Also I have the Yamaha HTR-5890 AVR and have just one sub output should I Y-split the connection or use the low level outputs from the PSW to the AVS?

Thanks!

BeefJerky

The specs tell you that at 100hz you have already lost 3db in loudness. That also means it's really past its optimal operating range. I personally wouldn't set the receivers crossover any lower than 120hz for both the satellites and the subwoofer. Use the LFE/Sub output from the amp for the subwoofer. When setting the crossover for the sub, turn the knob to the highest setting on the sub itself, then set it to 120hz in the crossover settings on your AVR.

In addition, I really don't think it's a good idea to try to use both subs, especially with them being different models. You're just asking for trouble, as they can actually interfere with each other. This will mean you'll have weird peaks and dips in loudness depending on frequency. To add to that, the lower end of the frequency response between the two will be significantly different. This means for the portion of the frequency range that they overlap, the overall volume will increased, but below that the PSW125 will be having to work harder to keep up. This will only add to the already existing dips in response from using two subs.

As far as using one for the higher sub frequencies and one for the lower sub frequencies, you will not see any benefit to doing that. The frequency response for the PSW125 is rated at 32Hz-225Hz, so its handling up to 120hz is well within it's abilities.

TECHNOKID

This has been discussed way back then on this site and elsewhere:

http://www.polkaudio.com/forums/showthread.php?t=18589

Yes, it goes down or up to the rated frequency response. The -3dB rating is where the frequency starts to roll off.

Translated, in most ideal rooms, the -3db point is where you have useful output. Below that point, your speakers range begins to drop off.

http://www.avsforum.com/avs-vb/showthread.php?t=618137&page=142

so yes you lose some efficiency starting at 100hz and therefore BeefJerky is right and you should set them preferably at the next higher frequency which should be 120hz.

As far as having 2 subs, you’re best to audition how they interact with each other. When it comes to subs, it is not so important that they be of the same brand/model but rather the blending and interaction. The bottom end is usually preferable if it matches. The idea of having 2 subs is not for them to cover different frequencies but instead using them to amplify/accentuate you bass effect in your room. Stacking your subs in a vertical array will focus the low frequencies forward while having the subs set on opposite walls and corners should spread the bass more evenly across the room however, proper placement is crucial and you should take the time to do the crawling method in order to ensure proper placement.

Don't forget bass can also cancel if subs placement is not proper. Your PSW125 is a decent sub and depending on the size of your room it should be more than sufficient to accomplish the task as a standalone. So I agree with BeefJerky that trying to use them both might simply create more headaches and lessen your SQ rather than improve it.