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How do I set the crossover for 2 channel listening on my HT system?

My system consists of a Denon HT receiver powering a pair of B&W 805S speakers (and, unrelated to this question, B&W center channel and surround speakers) with a vintage M&K MX-350 THX subwoofer fed through the receiver’s LFE output via single subwoofer cable. In 2- channel mode the receiver is set for L/R front and subwoofer play only, using the Denon’s “Direct/Stereo” play mode. The signal is fed to the receiver via RCA interconnects from a stand-alone streamer (Bluesound Node 2i) and DAC (Topping D90).

The 805S speakers have an advertised frequency range of 49Hz–22kHz ±3dB. The subwoofer has a variable low pass filter adjustment ranging from 40 to 100Hz. The receiver’s speaker set-up settings allow a crossover setting in steps from 40 to 250Hz. The subwoofer’s phase adjustment has been properly set.

I understand a subwoofer crossover should roughly match a speaker’s low frequency capability, i.e., in my situation the M&K low pass should be set at approximately 49Hz. (I say roughly because the subwoofer crossover frequency is listed at +-6db whereas the speakers is at +-3db). But what effect is the crossover setting on the receiver having and where should it be set for 2-channel listening in my situation? Is the HT receiver’s subwoofer crossover setting controlling the signal to the subwoofer and either cancelling out or somehow multiplying the subwoofer’s independent crossover setting.   

sadbird
oldhvymec
5,101 posts
 

Your head unit is sending a low level signal @ what ever you set it at and normally that roll off is the same as the roll on of the next crossover point. No different than any crossover. IF they lap at the same frequency and have a vey gradual slope there can be all kinds of bloating. 

If you set your sub to a lower point the sub plate (whatever you have) will play lower but your signal is limited by how you're set up. If you would have set the subs in the head unit to "Large Speakers" the subs will be controlled just by the plate.

My subs are set at 4th order 24db but the slope from the mid bass coupler columns is at 48db. A VERY steep slope. Because of that alone there is little bloat and almost no combing or suck-out.

That is what you want to try to do, but remember 50% of great sound is the room, know your room. Ground up approach. Room, Bass, then all the rest, not the other way around. With todays systems you have to work to get bad sound to tell the truth.

Regards

erik_squires
16,056 posts
 

I understand a subwoofer crossover should roughly match a speaker’s low frequency capability,

You want it to blend in with the low pass of the speaker in the room, which could be a lot lower than 49 Hz.  As I've written elsewhere, that's a complicated place and measurement is essential.  In addition, if you can use a high pass filter to reduce the bass to your speakers you will get lower distortion and higher dynamic range, and that means raising up the crossover point to 80 Hz or so. 

audiorusty
270 posts
 

You do not say which Denon receiver you have but I would think that the crossover function in the Denon would contain both low and high filter capabilities so both your mains and sub will be crossing over at the same frequency. The low pass filter on your sub is not needed with type of set-up.

I would set the crossover frequency in the Denon somewhere between 60 and 80 hz and set the low pass filter on the sub at the highest frequency the filter allows.

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