Utilising two subwoofer inputs simultaneously

[Chaff]

Hi All, I am looking for advice the best way to configure my system than enables use of the subwoofer for both music & film:

Subwoofer: B&W DB4S, that accepts both XLR and RCA inputs.

AV Amplifier: Arcam AVR850 - could connect LFE output to subwoofer via XLR.

Stereo pre-amplifier: Naim NAC 272 - could connect stereo pre-amp output to subwoofer via RCA.

If both the 272 & the AVR are hooked up to the subwoofer, I can see no problem if playing music via the 272 or playing a film with the output coming from the AVR independently. However, I would like to connect up my Naim system to the pre-out L&R channels of the AVR using the AV Bypass feature. Do I need to:

a) Disconnect the AVR LFE channel and set L&R as full range speakers (so the LFE goes via my Naim system to the subwoofer instead)?

b) Disconnect the stereo RCA pre-out between my 272 and the subwoofer so it doesn’t receive an input simultaneously from the 272 and the AVR?

c) Leave both the 272 and AVR connected to the subwoofer but set the low-pass filter at 80hz on the AVR so that the AVR sends anything below that to the subwoofer only?

C would be my preferred option as in theory that means I get to use the subwoofer with both systems but I don’t know if the low-pass filter rolls off gradually thus the subwoofer could still receive the same bass input from two different sources at the same time -not sure if this matters or whether the AVR/Subwoofer can simply compensate for it during calibration. The reason I like this option over A is the subwoofer has input specific settings for XLR and RCA so that would allow it to use a ‘movie’ EQ on the LFE channel from the AVR and a ‘music’ EQ on the RCA input from the 272.

[Chaff]

Subwoofer manual states:

Signal Connections
DB Series subwoofers provide stereo RCA Phono
and stereo balanced XLR inputs. It is possible to
use the Phono and XLR sockets as independently
selectable inputs. This enables your subwoofer to be
integrated with two different audio systems: a home
theatre system and a conventional stereo system
for example. Input selection is managed via the DB
Subwoofers app.

I presume from this I might need to manually switch it from to the other via an app which doesn’t appeal.

Is it possible to do something like disable the pre-out from the 272 when AV Bypass input is selected? (System isn’t set up yet, I’m still wiring in the mains for the home cinema room!).

Nac-N manual says “Preamplifier outputs always reflect the selected input.” I am not really sure what that means.

[Entilzha]

I don’t know your sub, but I have a similar setup using my pair of REL subs.

• Marantz receiver direct to the .1 LFE connectors on the subs.

• Marantz receiver L&R pre-outs into my NAC252 with AV Bypass enabled. The speakers are set to full range in the Marantz setup screens.

• Highlevel connection from speakers to REL.

So it’s fine for music as the .1 LFE output is not used (Marantz not in the picture)

And it’s fine for Cinema in my case. RELs can handle simultaneous low level and high level connections - they call it ‘Theatre Reference’. This is where I am not sure about your sub - it might react differently when there are 2 inputs active simultaneously. A quick email to B&W support might be worthwhile if you don’t get a definitive answer here.