One sub, Two Inputs - possible?

balgray

Novice Member
I currently have a BK XXLS400 sub that has been very nicely serving my Yamaha A3050 receiver for a few years. I am wondering whether I can get more use out of my subwoofer by also connecting the sub output of my Sonos Amp to it. The XXLS400 has a high and low input. The low input is split into left and right. The sub’s manual specifies use should use the low/right input (also marked as ‘mono’) when connecting up to a home cinema system which I’ve done. That’s all fine. I could connect the Sonos up to the high input on the sub, which the manual says can be run in parallel with a home cinema system nice and safely over on the low input. But that high input only has a Neutrik interface. That’s potentially fine as the sub comes with that cable, but you are supposed to connect/overlap the other end of the Neutrik cable onto the Speaker outputs of the Sonos amp. I’m sure that would work but as it isn’t using the sub output of the Sonos, I’m concerned it won’t correctly utilise the sub at the crossover point, as effectively it won’t know it is there.

So I’m wondering if I could plug the sub into the unused low/left rca input on the sub. There’s no mention of this in the manual and two messages through to BK have been ignored. I clearly don’t want to overload the sub so maybe?? I need an rca input switcher? Or I just give up as it’s too much of a hassle.

If you’ve followed this, I’d appreciate any thoughts. Cheers.
 

Nico72

Active Member
Your sub has independent crossover, phase and level controls for the low and high level inputs.
If you connect the sub to the Sonos via high level inputs, you set the crossover and level of the sub by ear.
The only caveat is that class D amps may not like the high level connection. I don't know if the Sonos amp is class D or class AB so better check first.
 

ShanePJ

Well-known Member
AVForums Sponsor
As far as I'm aware, Sonos are D class but if you ask BK, they may work the same way as Rel which have a way round that D class amp issue by not connecting the black - cable and only connecting the yellow and red + connections

Can I ask what you are trying to achieve by connecting both? Wouldn't it be better to replace that with a Port if you wish to keep things connected in the Sonos family then you can use both inputs or the BK sub enabling it work via pure direct or processing applied
 

balgray

Novice Member
As far as I'm aware, Sonos are D class but if you ask BK, they may work the same way as Rel which have a way round that D class amp issue by not connecting the black - cable and only connecting the yellow and red + connections

Can I ask what you are trying to achieve by connecting both? Wouldn't it be better to replace that with a Port if you wish to keep things connected in the Sonos family then you can use both inputs or the BK sub enabling it work via pure direct or processing applied
Yes I was thinking along the same lines as I think you are suggesting. If the AV receiver is working nicely with the sub, I could just add a Sonos Port, connect that the receiver, and make it ‘just another input’. My only hesitance is that would make another zone and I’d have to remember to add in that zone to the rest of the room, and set the right inputs on the receiver to get the sub involved.
 

balgray

Novice Member
As far as I'm aware, Sonos are D class but if you ask BK, they may work the same way as Rel which have a way round that D class amp issue by not connecting the black - cable and only connecting the yellow and red + connections

Can I ask what you are trying to achieve by connecting both? Wouldn't it be better to replace that with a Port if you wish to keep things connected in the Sonos family then you can use both inputs or the BK sub enabling it work via pure direct or processing applied
Your sub has independent crossover, phase and level controls for the low and high level inputs.
If you connect the sub to the Sonos via high level inputs, you set the crossover and level of the sub by ear.
The only caveat is that class D amps may not like the high level connection. I don't know if the Sonos amp is class D or class AB so better check first.
I recall seeing something related here in the BK manual stating that they can provide (sell) a different cable for the scenario where you need to connect the high input to a class D amp. I’ll review the manual and verify.
 

balgray

Novice Member
Yes looks there might be an option to use the high input on the sub with a Sonos. Spotted this in the BK manual:

Please Note: It may not be possible or advisable to connect the high level input directly to an amplifier that has a class d digital output. Please check with the supplier of your amplifier that this form of connection is possible.
If you do have a class d amplifier and are unable to use the high level input, then BK have developed a sonicaly transparent isolator that overcomes this problem. Please contact us for further details.”
 

balgray

Novice Member
Looks like the high input is the way to go if I can get one of those isolator things BK mentions. I was concerned initially that not explicitly configuring a sub on the Sonos Amp (ie using the sub output) would somehow lose some functionality or audio quality. However a quick check on the Sonos site it looks like going this route will be better. The BK sub has a variable crossover for the high input whereas the crossover is fixed on the Sonos Amp:

Sonos Amp and Connect:Amp each have an RCA subwoofer output for connecting a third-party subwoofer. The Amp’s subwoofer output has an adjustable 50-110Hz crossover range. The Connect:Amp’s subwoofer output has a crossover of 80Hz and is not adjustable.”
 

TB Rich

Active Member
I rang BK up and spoke to Tom a couple of months back about doing exactly this. AVR in to one of the BK’s low level RCA’s, and Hifi setup (via miniDSP) into the other low level RCA. - Absolutley fine to do he agreed, as long as of course if you’re setting the BK’s low level input to LFE then you need a crossover in place on each of the 2 upstream devices. So in your case as long as the Sonos sub output has a crossover then it’ll be spot on.

Once I finally replace my AVR with one with EQ, I will be doing exactly this. On my BK one RCA direct to AVR which of course has a crossover, and the other RCA to 2ch pre/power setup (which routes via a miniDSP with a crossover set on that).

Problem with taking the 2ch setup into the BK high level input is you can’t perform EQ, and basically no sub in any realistically sized room is going to perform at it’s best without EQ (room modes etc).
 

balgray

Novice Member
Thanks TB Rich, that’s awesome insight. You mentioned room EQ for the sub and after some checks I don’t think my Yamaha a3050 applies EQ for a sub. Still going to check a couple of other resources but it seems a general limitation of my receiver. If so, I was thinking of dropping an Anti-Mode 8033-SII by BK into this setup. This model has two inputs so I should be able to follow the same approach that you’ve outlined I believe, plus also introduce proper EQ for the sub.
 

TB Rich

Active Member
Thanks TB Rich, that’s awesome insight. You mentioned room EQ for the sub and after some checks I don’t think my Yamaha a3050 applies EQ for a sub. Still going to check a couple of other resources but it seems a general limitation of my receiver. If so, I was thinking of dropping an Anti-Mode 8033-SII by BK into this setup. This model has two inputs so I should be able to follow the same approach that you’ve outlined I believe, plus also introduce proper EQ for the sub.
I think from what I have read the older YPAO versions either dont do, or are at best limited, with how effective they are with bass EQ. I think however some Yamaha’s have a 3 band manual PEQ capability so potentially there is that option if your model has that?…but of course requires a mic and REW to work out what you would need to set it all to! And doesn’t of course help with providing EQ on the Sonos output either.

So yeah absolutely, an antimode SII would be a good way to put some automatic EQ in there for both devices.
I’ve never used one but understand its basically largely an automatic miniDSP in effect, and given you have a crossover on both the AVR and Sonos - should fit the bill very well.
I suppose the only thing to consider is if you ever intend to move away from the Sonos for 2ch, and end up with a 2ch amp that simply has pre-outs and not an actual sub out. The Antimode wouldnt work then as it doesn’t Itself have a crossover facility on it (that’s where a miniDSP extra functionality comes in to play)..…mind you antimodes and the like seem always easily sellable, so just cross that bridge if it ever occurs!
 

balgray

Novice Member
Perfect. This suits me nicely. Appreciate the great feedback. Off to buy some new kit which is always fun.
 

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