I need a subwoofer/sub-bass opinion from you

Hello All--

I have a large room (well large to me).  It's 20' long, 15 wide, and 10' tall.  I run either Klipsch Forte IIIs or PSB Imagine T2s through a tube amp.  I have plenty of volume with either loudspeaker.  

What I want to accomplish is to add sub bass.  I did this previously in a smaller room with a Sumiko S5 (I believe it's the same or similar to the REL T5).    When I had the Sumiko dialed in, the system congealed into a wonderful sound.  There was no noticeably appreciable sound coming from the sub.  Instead, it merely filled out the lowest octave and added space, dynamics, and really made the highs seem less harsh.  

The Sumiko S5 does help in this setup but it's just not enough to charge the room or at least add enough.  

I'm thinking REL.  Thoughts? 

PS  When I ran the Sumiko, it sounded clearly better when I ran it off the amp speaker outs than off my Primaluna's dedicated subwoofer out. 
I use 2 RELs bought cheaply from Ebay at different times (200 bucks each..a score!), and they are way more than enough bass for my medium-largish room with Heresy IIIs. Run from the speaker outputs like they should be, using a 12wpc little single ended tube amp...great sounding stuff!
Is your system for Home Theater or music ? If both what % of each.
Are you looking for new or used ? Is there a budget in mind ?
We can give much better recommendations ...if we know those answers.

@grey9hound great points. 

100% 2 channel hifi music. I’d consider used for sure. Budget is flexible. If I was convinced spending above $2500 would be wise I’d do it. Ideally I’d like to not spend more than that or $2k. 
If you are handy with tools I would add an infinite baffle subwoofer.Inexpesive and will work better than any subwoofer that you can buy.
My room is 24 x 25 x8 and with two SVS SB2000 subs there is plenty of very clear and low bass now. They have a home trial offer too which makes them a must evaluation. For me they are keepers.
Rhythmic sealed designs. 
Rythmik, HSU, SVS, and PowerSoundAudio (owner is the V in SVS) all make subwoofers, porter and sealed, that are much better for the money than REL. 
You state you want to add sub bass, yet not a single REL in your budget can do that.
svs 16 Ultra 
or if money is no object 
Marianas from David Gage  at deep sea sound .
I have heard the 24 in my room. Unreal

You can't go wrong with Rythmik, SVS, or Power Sound Audio.  I am happy with the subs I have now (I own subs from all three companies), but if I was looking for a new one I'd take a hard look at SVS' new lineup.  I like the idea of being able to remotely control the sub and adjust it from your listening position.
take a hard look at SVS’ new lineup
Thanks @big_greg, @jbhiller and the rest of you for the dialog. I too am shopping sub configs as upgrade to single REL R-328 in main 2ch hifi room. New SVS SB-3000 looks very promising indeed, given spec and price point - would get dual units if that proves to be the winner.

But I’m kinda anguishing the choices (in a good way):

1. REL S/3 x2 (used, $2500)
2. REL S/3 x1 (used, $1300) + my existing R-328 <= _yes, it can be done: got very helpful & detailed how-to instructions from John Hunter, REL owner & lead designer_
3. SVS SB-3000 x2 (new, $1899)
4. Something comparable from Rythmik?

What do you all think?  Listening area is 2808cf at 18’ x 12’ x 13’h ceiling avg, with one side opening to a 1430cf dining room. The single REL R-328 seems to do fine right now - but I got the upgrade itch, and a hunch that an upgrade will raise the game to whole new level. Main speakers are Nola Boxer v1 on Dynaudio Stand 4.

"Rythmik, HSU, SVS and PowerSoundAudio ... are much better for the money than REL."

@mzkmxcv - why are those brands better for the money than REL?

@big_greg: do you run a 2x sub config for 2ch hifi?  If yes which brand and model?
I run two SVS SB13 Ultra subs for 2 channel listening.  It's overkill, mostly because I don't have enough room to put them in separate locations.  They are stacked on top of each other in between my speakers near a corner.  It would be better to have them in separate spots.  My speakers are Legacy Audio Focus 20/20 (three 12" drivers per speaker).  The subs are dialed down pretty far and blend nicely to provide the lower frequency response that the 20/20s can't reach.  One of these subs would be more than sufficient. 

The SB-3000 specs are close to the SB13 Ultra (a little less power, but 800 watts is more than enough).

The Rythmik F15HP would be better.  I really like Rythmik's subs, very tight and well made.  A bit more money though.  I have two F25's in my home theater setup.  

A great bang for the buck option would be a pair of Power Sound Audio S1510s.  I have an S1500 and it's a nice little sub.  Not as pretty as the SVS subs but it gets the job done.

@@mzkmxcv,  any information on why you (or others) like the other brands over REL?  I'd love to get some intel. 
One of the things that attracted me to my RELs other than the deal I got buying them, is the "high level" input system from the amp, which allows a reproduction of the amp's tone and doesn't require long runs of single ended cable...simple speaker wire does the job. This series of RELs also has adjustability to fine tune the phase, crossover points and level that newer versions may not have in as much detail. Also, although I haven't tried newer versions of RELs, I can say the "Q" series I own sound spectacular within their limits...and those limits (low frequency range and level) are well within what's needed to charge the room with controllable bass for music...I have swapped in my 92 lb studio sub that's flat to 19hz, and found that extra low range didn't improve anything relative to what the RELs are doing with the music I like...plenty of drive and heft with the RELs.
I've done a lot of research on subs.  Hsu Research makes a fantastic product.  Recently, I e-mailed Hsu regarding several technical questions and I received a very thorough and very professional response, as well as a recommendation that I add a high pass filter.  
I highly recommend purchasing Hsu products.  
"I highly recommend purchasing Hsu products"
Have you listened to Hsu products? I haven’t - only my existing single REL R-328, which sounds great for me.

But I’m upgrading - below are the candidates. Pricing is per sub if purchasing dual (SVS will -$100 from the 2x total). REL is not on the list: they’re over-priced compared to these competitors, of which the PSA’s are the priciest.

The HSU and PSA models use paper drivers, not aluminum. Does it matter, objectively? I don’t know.

The Rythmik and HSU models appear to support speaker-level line in. Comparable to REL’s fancy-pants Neutrik connection? Maybe.

sub | $$$ | driver | amp | freq. | size | spkr-level input?
Rythmix F12 | $893 free ship | 12" aluminum | 370w rms class A/B servo | 14-100Hz ±2dB | 15.75x15.75x17, 62lbs | yes
Rythmix F12-300 | $700 free ship | 12" aluminum | 300w rms Hypex servo amp | 14-100Hz ±3dB | 15.75x15.75x17, 57lbs | yes
SVS SB-3000 | $999 free ship | 13" aluminum | 800w rms class D | 18-270Hz ±3dB | 15.6x15.2x17.8 | 54.5lbs | no
HSU ULS-15 MKII | $779 + shipping | 15" paper | 600w rms class D | 20-200Hz, ±1dB | 18x18x18, 65lbs | yes
PSA S1510 | $1,300 | 15" paper | 960w rms class D | 19-200Hz
±3 dB | 17x17.25x18, 63lbs | ???
SVS is having a sale on their SB12-NSD for $399.99

It will soon be 2019 and you're considering flip phone subs.

Subwoofers with room correction that are adjustable from your listening position have become affordable. 

Every subwoofer suggested here can do the job, but how easily and how well they can be integrated to your system and your room is questionable. Compare their setup procedures then look at the procedures here.

Or here.
"... how easily and how well they can be integrated to your system and your room is questionable"
@m-db have you listened to Syzygy subs?

Wrt flip phones the SVS SB-3000 does appear to offer from-your-butt control via Android/iOS app. At a glance the control doesn’t look as refined as Syzygy’s.

Whether those or Velodyne units and their integrated DRC systems perform at or above the levels of comparable "flip phones" should also be questionable. REL, Rythmik, SVS, HSU and PSA all still seem to be in business, developing/improving and supporting their products within constraints of those businesses, and from feedback here and elsewhere seem to have their shares of discerning owners.

Yes I’d prefer to integrate subs into my 2ch rig from the comfort and optimal location of my butt. But I wouldn’t weigh that feature inordinately above overall sonic performance, reliability/service* and fair value. For now I’m fine with some manual monkeying.

* : check recent reviews on Velodyne service and reliability, here: https://tinyurl.com/yasef699

One thing to keep in mind is there are two types of subwoofers. One is made to gel with your system and the other is to go low.

In most rooms once you work with 250hz and below you will have two different sets of pressure zones that react differently depending on your room's material and construction. If you have basic stud and drywall construction with wood floor joist you will get more musical tones to work with. If you have plaster walls or double drywall or quiet rock and a basement, you might end up needing two sub designs.

I have found that almost all newer high end audio main speaker designs end up wanting a sub to complete the range.

Michael Green


wrt 'flip phone' subs, nvm: after a lightening research session this morning, I bought two Syzygy SLF870's.

Will report back with observations & field test results.  In meantime here's a favorable review that helped tip my decision: http://forums.stevehoffman.tv/threads/syzygy-sub-woofers.682718/
REL subs with the wireless transmitter seem to work the same way sort of...and it's all good. REL should make a retro fitted "longbow" gizmo for people like me with older models, but do they? NO THEY DO NOT. I gotta calm down...whew...