Subwoofer high pass setting for N805

[DarrenR]

Hi
Just purchased a pair of N805 to replace my CDM NT7. I'm planning on using my subwoofer to help the N805 with the lower bass. What setting do other N805 oweners use for the high pass filter setting? I'm currently using the 50 Hz setting (the lower -3db frequency response for the 805's), does anyone use something different from this?

[greggz]

The N805 is a ported speaker. All bass below the tuned frequency of the port is out of phase with the woofer. The N805's port is tuned to 42Hz.

Most subwoofers have a -12dB slope. In my opinion, the best way to augment the bass of the N805's it to start with the sub out of phase with the N805's and the high-level crossover set at -12dB from the port frequency. Then start experimenting.

I'm using a REL Strata III with my N805s. I have the sub set out of phase with the N805's and the high-level crossover set at either 31Hz or 33Hz (can't remember off the top of my head). The gain (volume) on the sub is somewhere around 11 (as in 11 on the face of a clock, not "our's go to 11" from Spinal Tap )

Here are a couple of charts of the N805 from Stereophile's Oct 1999 issue to use for reference:


B&W Nautilus 805 tweeter, woofer and port responses plotted.



B&W Nautilus 805 anechoic response as complex sum of tweeter, woofer and port.

[Aussie Geoff]

Darren,

The Answer GreggZ gave is correct if you are running the subwoofer in parallel with the B&W 805s and want the sub to blend in with the 805s using the natural cutoff slope of the 805s (ie in a pure Analog system). Essentially a full range signal is sent to the 805s and the sub and the sub is set to cut off high frequencies to parallel (roughly) the rate at which the 805 stops playing them at adequate levels...

If (however) you are using a processor to digitally process the sound and split the sub and the speakers (e.g SMALL setting) - then there is a different (potentially better) option - which is to cut-over at 80 Hz with the sub in phase... This has the benefit of:
1) Reducing the stress on the 805s by not trying to play low bass
2) Keeping the 805s out of the "out of phase" range - so that the bass can be in phase with the rest of the music

You may want to try both and see which works best for you with your sub in your room...

Geoff

[DarrenR]

Thanks Greg & Geoff
I took your advice & did a bit of experimenting last night, & indeed the lower cross-over setting on the sub blended more seamlessly with the N805s than at the 50 Hz setting I was using previously.
In answer to your second point Geoff, I have a slightly complex hi-fi/home theatre system consisting of a surround processor (Rotel RSP 1066), 5 channel amp (Rotel RMB 985 Mk2) and a Classe CAP-150 integrated. I use the the CAP-150 for (i) running my main speakers when watching home threatre (by hitting a pre-amp bypass switch on the amp), & (ii) use for stereo, by bypassing the Rotels althogether. I have taken this approach as (to my ears at least) I thought to the processor put a slight veil over stereo music...but that is another topic. Anyway, I will have a play tonight to determine any differences between the Rotel with bass mgt applied, & the Classe integrated using analogue outputs.

Cheers
Darren

[caleb]

Sub with 805's

This is my first posting so you are my "guinea pig"

I use 805's for the surround and rear of my 7.1 setup.
For each of the 805's I use a REL quake to augment the bass running from the speaker connector to the "high level" input.

I find it works a treat if you keep the cross over to the 80-5 at 50Hz.

I found it makes a tremendous difference.

Let me have your thoughts.