Question about connecting two subwoofers via RCA in stereo.

[VanO]

I’m experimenting with setting up two subwoofers in stereo. I’ve got some different connection options on the way and have a few questions:

If I have source with single RCA outputs for (L) and (R), can I connect one RCA (L) channel via single cable to an active subwoofer’s (L) RCA input only connection, and then the same to another active subwoofer with the (R) channel input only connection?

What affect does it have on the active subwoofers with only one of the RCA inputs connected? Decrease in signal?

Likewise, is there any affect on the source by connecting this way?

Another option I was looking at was just getting a box like this:

https://www.amazon.com/gp/product/B073RCRXPP/

and connecting (L) (L) to one sub and (R) (R) to the other but I’m not sure if a device like this is necessary if I can connect them each with a single cable as described above.

 

[VanO]

I was intrigued to try this out after stumbling across this on the SVS website:

https://www.svsound.com/blogs/subwoofer-setup-and-tuning/75040195-why-go-dual

Stereo Bass for Dedicated 2-Channel Systems
Discerning audiophiles and 2-channel purists know that directional bass cues are important to imaging and preserving the solidity of the soundstage. Using dual subwoofers in a dedicated 2-channel system will preserve stereo bass cues, and prevent the soundstage from collapsing, particularly when small bookshelf monitors with limited bass extension are being used. This makes for a more realistic and convincing audio experiences where you can pinpoint sounds in space and believe you are on stage or in the studio with an artist.

I did a little more digging and found Paul talking about stereo subs also:

 

[DVDdoug]

What affect does it have on the active subwoofers with only one of the RCA inputs connected? Decrease in signal?

You might get half the signal (-6dB) if the signals are actively summed. If they are passively summed there will be no difference. Then you'll get half of that back (+3dB) when you hook-up the second subwoofer.*

If that's a problem you can get a couple of Y-Splitters.



*A voltage factor of 2 is 6dB so that's what you get when you mix/sum two equal signals. And when you double the voltage you also double the current so that's 4 times the wattage. When you double-up on the amplifiers/speakers that's twice the power (wattage) or +3dB.

 

[DVDdoug]

I was intrigued to try this out after stumbling across this on the SVS website:

Well... Bass is supposedly non-directional (you can't tell where it's coming from). And on most recordings it's "centered" (identical in the left & right channels). If you ever subtracted left from right to make a vocal remover, you'll notice the bass is gone, along with any centered vocals (and any other centered instruments).

I assume the bass is centered so the listener can take full advantage of both woofers (and both amplifier channels) since bass is where you need the most power and the most total cone area. (In the vinyl days it also made it easier to cut & play the record.)

 

[VanO]

I’m trying out a Rolls SX95 for a stereo sub interface.
https://www.amazon.com/gp/product/B07KJRYHFH/

This is a coffee table setup for music only. One sub is a 6.5” and is under the table under the mains, the other sub (8” slim) is directly under the couch/listening position and coupled to it. Main speakers are 3’ apart, LP is about 4' away. Subs are centered and about 4’ apart.

It’s set up in close range area in a bigger room and I’m very pleased with the imaging and soundstage. the bass is tight and integrates well with the soundstage and of course you can feel it since the sub is coupled to the couch. I have a few room treatments and I get a very satisfying volume at the LP without shaking the rest of the house.

My next step is to put my mains on a crossover. I’d like to hear how they sound on a cleaner slope and crossover with the subs. I have a Rolls SX45 that will be here Friday.
https://www.amazon.com/gp/product/B00102VWJK/

I’m looking forward to trying it out. I’ll test it with the subs also in stereo and check it out. I may end up going with just it. The SX95 made it real easy to adjust everything in one place especially since the slim sub is very tough to reach the controls in its location: