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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
audiorusty
267 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.

sadbird OP
22 posts
 

Thanks to all. To oldhvymec4: The front speakers are indeed set to Large in the speaker set up of the Denon AVR-2807. I thus understand the crossover setting on the Denon is irrelevant and the low pass filter setting in the M&K will control. On the other hand audiorusty appears to say the low pass filter on the M&K is irrelevant-- yet it is suggested I set the low pass on the M&K to its highest available, which in this case is 100Hz.  These seem contradictory.

Eric_squires: The 49Hz figure cited is the manufacturers spec for the 805S. I haven't any instrumentation to determine precisely. As indicated that figure is ±3dB and the M&K rating is ±6dB so there is a fractional difference where the blended frequency should be which I also cannot calculate and thus have used the speakers 49Hz as a "compromize". 

 

 

bjp9738's avatar
bjp9738
64 posts
 

Thanks to all. To oldhvymec4: The front speakers are indeed set to Large in the speaker set up of the Denon AVR-2807. I thus understand the crossover setting on the Denon is irrelevant and the low pass filter setting in the M&K will control. On the other hand audiorusty appears to say the low pass filter on the M&K is irrelevant-- yet it is suggested I set the low pass on the M&K to its highest available, which in this case is 100Hz. These seem contradictory.

The large/small setting in the Denon will control whether or not any bass is routed out the subwoofer output. The crossover setting in the Denon is irrelevant for the FL/FR speakers set to Large, but still relevant for any other speaker set to Small -- center, surrounds, etc.  Note that crossover settings do not apply to the LFE channel as that typically covers a frequency range of 3Hz to 120Hz based on the source mix.  Since you are using bass management in the Denon, you should set the low pass on the M&K to the highest setting, essentially disabling it. You don’t want to use both.

russ69's avatar
russ69
3,360 posts
 

I like simple. Set your 805s to large and just adjust the sub until it sounds right. It would be tricky if your loudspeakers were full range but they cut off pretty high. 

sadbird OP
22 posts
 

To bjp9738: Thank you for the clarification that the Denon crossover settings fo not apply to the LFE channel. I was concerned I was mutiplying or contradicting the settings if both the Denon's and M&K's were in play.

Based on what you said, if I am only listening to 2-channel stereo (thus only employing the FL/FR speakers and subwoofer and not the remaining surround sound speakers) there  apparently is no base management being used in the Denon. Under this circumstance I assume I should NOT set the low pass on the M&K to its highest setting but instead find an appropriate setting sounding best with the front speakers. Do I have this right?

(Also presumably when reverting to HT and using all speakers your advice to set the M&K high would then apply.)

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