Two subwoofers for two channel music listening

Bass is STEREO, place front firing subs adjacent to mains, to achieve bass imaging.

It is not just the bass fundamentals, also the overtones that give localization.

The bulk of what you get (except organs/1812) will not be super low bass, A great deal of what you listen to will have low bass, discernable locations. Presumably you mains do not handle low bass as well as you would like.

I have two very powerful 15" in my speakers, you could think of them as subs. They definitely produce stereo bass.

I listen to a lot of Jazz trios, quartets, even bigger groups, with nice imaging of bass players.

IF piano is off center, and IF recorded/mixed properly, low notes are definitely discernable by location.

Yes, organ is Mono, but many other instruments locations are discernable

not complete, but a quickie find showing which (not that many) instruments get way down there into the 'mono bass' range

https://www.researchgate.net/figure/Frequency-ranges-of-several-musical-instruments-30_fig3_22844644...

More than 2 SUBS, SWARMS. Sacrifice Directionality for Extension?

People who want very/extremely lows produced cleanly will use more than 2 subs, sometimes multiple ’Swarms’ which has been discussed here. I’ve never heard that except a swarm of bees chasing me, and that is directional, i.e. run this way.

Swarms, more than 2 subs get super lows, however the results are MONO BASS, even the upper bass will be mono because the fundamentals and overtones emanate from too many locations, and reflect off too many surfaces..

Some use ported mains and/or ported subs. I recommend only front firing ports, again to retain directionality.

I much prefer decently low bass with imaging than a bit more bass.

In my exuberant youth, I, with help from Electro-Voice Engineering department, designed these enclosures with optional ports, to squeak more bass from these 15", which I measurably got.

However, they are rear facing ports. Less pressure in the enclosure, the front 15's go lower. Additional output from the tuned port and rear surface of the woofer, that gets to rear wall/corners. Even more extension, but they muddy the directionality of both the extended bas, also all it's output, fundamentals and overtones muddy everything else.

It's a trade off. I keep the ports closed. Why sacrifice directionality of a lot of low content for most of my music to get more bass infrequently or rarely?.

Martin Logan makes a couple of lines of subwoofers and they recommend the line level option over the high impedance connection where possible, though to be honest, I doubt that you or I  would ever be able to hear the difference.
I'm no audio engineer, but I did stay at a Hollywood Express last night :)

You want your subs to be the deepest, tightest and driest they can be, the last thing you want is an amp driving another amp, that’s just wrong and gives one note bass, that’s why line level drive the best for them.
The last thing you would want is to drive them from say a tube amps etc speaker output.
Probably the only amp driven output that could compete with line level, would come from an amp like a Krells or similar, that have absolutely no ? on bass performance.

Cheers George

I gave you more credit than that, guess I was wrong.

In this scenario, no amp is driving another amp. You are completely off the mark. The only thing that is happening is that the main amp is sending a low level signal to the sub amp. This works beautifully and makes it much easier to make the main speakers and sub(s) coherent.

Oz

It's interesting that the SVS 1000 has both line level and speaker level inputs.  I have the SVS SB 3000 and it only has line level.  But it does have a terrific Bluetooth app to manage volume, xover point, slope remotely. No more continuous getting out of your listening position to tweak the sub controls.  Really comes in handy for music that's recorded a bit this as the Bluetooth app also allows user preset settings.

@ozzy621 - thanks for commenting that the speaker level input doesn't result in an amp driving an amp. Inherently we all should know this can't be as the sound would be horrible. I still don't understand how 'the main amp sends a low level signal to the sub amp' and not full range signal as the main amp speaker terminals are designed to do.
Perhaps someone out there could explain how this main amp speaker output to sub amp speaker input works.