Subwoofer recommendation and wisdom

First, I recommend watching Nemo Propaganda's most recent posting on YouTube on the Rel s/550.  He has reviewed more subs than anyone (his statement, not mine), and places everything into perspective.

Secondly, I had one shot to buy a sub (WAF), and I didn't have the luxury of playing around with different brands...I went straight for a Rel S510.  That one sub completely transformed my system in ways I never thought possible.  Expensive, absolutely, but zero complaints about the sound quality nor integration within my system, which was seamless.

After 4 years of using that one sub, I decided to add a second Rel S/510.  I can tell you first hand, the one sub provided 80% of what two subs can provide.  But,  having 2 subs truly completed the soundstage and enhanced the realism by quite a bit.  So, yes,  2 subs are better than one but not for overall output,  but rather on completing the soundstage and making the sound more homogeneous and realistic.  It's still amazing how well one sub did though...I didn't even notice the gaps in the soundstage until I added the second sub.

Lastly, if you're going to get one sub AND if it's going to be a Rel, get the absolute best you can afford within the Rel Serie S line... you'll thank me later.

Good luck. 

It depends on the speaker design.

You can’t expect much in the ways of midrange improvement when you’re dovetailing a sub in, i.e. when you’re not cutting off the lower octave from a bass-mid driver in a 2 way, for example.

But, if you use a active crossover/bass management or the likes of it to cut the lower octave out of a bass-mid driver on the mains, it cuts out a lot of driver motion (cutting out 1 octave will reduce driver motion by 4 times). A very common thing, for example, is cutting out a driver that extends down to 40hz with 80hz cutoff.  Naturally, a driver that didn’t have to multitask with the lower octaves with a lot of driver motion will do better with the upper octaves. This part of the discussion is not exactly rocket science...

(However, psychoacoustics, perception of soundstage changes, tonal balance changes, etc can be a strange thing. Michael Borresen tried to articulate it in some video....look it up or whatever)

Nevertheless, subwoofers are primarily for the ROOM. They are active room treatment devices that can kill a lot of room modes. It is hard to describe to a dude what that exactly sounds like...when all he’s ever heard in his life is peaks/nulls and painful lower octave energy distribution.

I also have some diaphragmatic absorption that works down to 40, 30 hz or so....But, guess, what? They weigh 250lbs each and can consume significant square footage in a room... not meant for old guys sitting in closet sized rooms... It is a whole lot easier to do that better even with...tiny microsubs like the kef kc62, upto the subwoofer’s operating range. The reason why dual subs are encouraged with crossovers of upto 90hz...or quad subs upto 110, 120ish hz. You can’t localize sht with multiple subs, if integrated correctly...and killed all the modes up to that crossover point.

2 is a good number for a noob, in general.

Nope. The sub’s job is not to complement the midrange. 

@stuartbmw3 

I would also consider a pair if it really made a difference for me in my room

Music is stereo, not mono. If you're new to subs, get a couple $500 subs and connect them in stereo near the speakers, especially if your speakers only go to 50Hz and you have to use a higher crossover that can be localized. You don't want bass that should be coming from the right speaker come from a sub behind you.

However, with tower speakers down to 30-40Hz, you have the advantage to have your cake and eat it too; you get stereo bass from the speakers down to 40Hz and you can place subs elsewhere for more coverage. You can also operate the subs in either mono or stereo since bass is harder to localized below 40Hz.

If you want more slam, which is above 50Hz, you will have to raise the crossover. With towers, you can keep the crossover low and still get slam. Anything below 30-40Hz is smooth and warmth, not slam.

Generally the crossover on the sub should be sufficient to minimize any overlap with the speaker. If you want more slam from the sub, use a higher crossover. But you then need a preamp with digital EQ to knock down the overlap with the speakers.

You might want to read this

https://www.acousticsciences.com/wp-content/uploads/2024/11/Soundoctor-Barry-Ober-sub-integration.pdf

And this

https://www.harman.com/documents/multsubs_0.pdf

No doubt - 2 subs.  I like the starke recommendation.  Also would recommend Rythmik servo subs - especially if you like tight - not boomy - bass.