Best sub for music,

Rel has solid marketing and has defined themselves as a room sub bass systems and talk about "tuning your Rel" - again marketing. I’ve owned a couple and they are good but so is Rythmik and I’m sure many others. JL looks really nice too.

@plaw - same here.

2 x Rythmik (E15HP2), with Wilson Audio speakers.
Those 2 Rythmik’s are about the same price as a single REL S/812.
Just way too many things not to like about REL subs.
Only 63 pages of comments on the AVSForum REL forum since 2008.
For example, SVS (1700+), Rythmik (2400+), PSA (3200+ pages).
Have never read a REL subwoofer recommendation on AVSForum yet (with the exception from within the REL forum itself). Outside that forum, nothing, or very rare.

I have had 4 different subs - and tried about 4 others that were "reviewed" as being the best.  Settled on a Rythmik - love it.  Unfortunately, they are not sold through a dealer network, so the support is not there like a good dealer would offer.  I got the 15" because I wanted something that would extend below my Wilsons.

I have only bought subs in pairs. Having been doing high end audio, I have learn certain abstract generalities that lead me to make choices without knowing facts. I wouldn’t mix. I would buy one and save to buy the second identical.

when I went to buy my first sub, the rule of thumb was, “you only need one, bass isn’t directional”. That didn’t feel right to me. No logic or reason… it’s the little stuff that matters in high end that add up to a really great system. So, I bought a pair. Over the ensuing years I read article after article as it became the common knowledge that in 2 channel 2 subs perform much better than one. And indeed, when you unplugged on e of my subs, the soundstage would diminish substantially. Why, don’t know, but it really made a difference.

This is a great thread! Thanks for the OP and the contributors. Right now I can't spring for a second sub for my main system. But I have one pretty good one in another system that I can add to my main system. Does mixing different sub brands/models introduce more problems than it fixes? My main L/R speakers go authoritatively down to about 40Hz. So I'm just adding the 20-40Hz. Thoughts?

I believe cone material is only one small piece of the puzzle.  Speaker design is as much an art as a science.  My pair of Vandersteen 2Wq subs, now discontinued, have never been anything less than super musical, powerful and of a piece with my mains.  The only hitch is that your mains must be close to flat down to 40Hz.

Another vote for HSU. Don’t like the super slam of HT?
Pull back on the gain. The VTF line of HSU is incredibly versatile.
Amazing performance vs dollar factor.
Best budget “super” sub in the market IMO

I have had two REL 812/s (10 inch) in my system for a year.  I am super happy with them.  They have paired well with my Avantgarde Uno horn speakers (which have their own powered sub woofers). I will be adding another two later this year.

2 HSU Research VTF 2 Mk 5. Driver is 12” front facing. Variable tuning (ported, dual ported or sealed), defeatable crossover, EQ settings to match port configuration and a nicely operating auto on mode that you never notice One wasn’t enough, although they measure down to 16HZ at around 110dB after setup. I will eventually get 2 more for my largish room (24’x 20’). You get a discount if you order 2 at the same time. 

Rel. The T/x series. Various ways to connect, clean and punchy. 

Replaced my S812 REL with 2 Rythmik dual firing subs. Never knew how much my mighty REL were holding back my music until the switch.

Had several over the years (Velodyne, NHT, JL Audio, etc.) and for music REL is out in front by a mile. Their S series and Reference line can’t be touched. 

And come with intercontinental room correction.

I hear the Ohio class subs have great acoustics.

A good sub for music is one that can handle whatever HT throws at it.

If it can't handle cinematic effects it's never going to be able to cope with all types of music.

   A sub's material of construction? While important in the basic sense of what manufacturer wants to use in their products, does not address your question.."Best Sub For Music".
   Don't obsess about materials of construction. Think about how you want music to sound. Sub integration can be a most challenging task and experimentation is most often needed to achieve the results YOU want. Millercarbon made a brief but important statement.
   I have gone thru some length of time to integrate my subs to deliver the sound I prefer. If you're serious about how to really get sub performance to compliment your music I would refer you to this article. It's one of the best I've read on the subject. It's quite lengthy but if you are patient and want to know how subs work read.

http://www.soundoctor.com/whitepapers/subs.htm

The best sub for music isn’t a sub but a bass extension. Genelec W371a with GLM digital management. Bargain at $19K a pair.

https://www.genelec.com/w371a

I do not know where this differentiation between home theater subwoofers and HiFi subwoofers came from. There are good subwoofers and bad subwoofers. Perhaps home theater people tend to buy bad subwoofers. Good subwoofers will do anything. They are even better at doing theater than bad subwoofers. 

Most commercial subwoofers are not even fit for home theater duty. It is very hard to make an enclosure that works at a reasonable price not to mention terrible cross over strategies. Play anything with a lot of bass and put your hand on your subwoofer. That vibration and shaking is distortion. Ideally you should be able to put your hand on it and feel absolutely nothing. I made 200 lb enclosures out of solid surface material and I could still feel some vibration. Next versions will be better.
Stay away from ported subwoofers. Subwoofers have to move a lot of air and it is very hard to avoid port noise. It is better to stick with sealed designs and correct the frequency response with power and room control.
The best subwoofers now use what is called a balanced force design. Two identical drivers are placed at opposite ends of the enclosure and operate in phase so the vibrational forces cancel out.
 Regardless of the size of the room the minimum size is two 12" drivers or four 10" drivers. Bigger and more is always better. The less work any single driver has to do the lower will be the distortion. Making sub bass requires long excursions which take the suspension out of it's linear operating range. Bigger and multiple drivers do not have to move as far. The thought that smaller drivers are "faster" is beyond silly, another example of lay instinct run amok. The sign of a driver not being "fast enough" is it's high frequency response falling off. Any subwoofer driver that can make it to 500 Hz is more than fast enough. I do not know of a subwoofer driver that can't make it to 500 Hz. There are lots of great drivers out there. It is the enclosures that are the main problem followed by poor integration strategies and crossovers. Digital bass management and room control are essential to achieve the best results. 

Don’t overlook Rythmik.  These are very good sounding and well made powered subs for music.
https://www.rythmikaudio.com/F12SE.html

Velodyne servo subwoofer 

Svs has been a front runner lately there 3000 Sb, and 3000 mini 
are very good ,and many awards on the 3000 sb
and very high tech most others subs do not have such as a dual range Pole piece,at low volumes tuneful using the inside ,when music is turned up the whole pole piece is used ,and 50 bit processors very high current mosfets on the outputs and one thing 
most others don’t have a excellent app to control  many functions on demand.

Another vote for Real. Excellent and easy setup. I considered the Hsu. Way too big. T series is good but S series is better

You can get two HSU ULS-15 MK2`s for $1550

OK 
REL it is, Prices,,,let me see ,,,prices all over the place, Which REL,. there are like 20 models
Seas W26 + xovers = $1400. 
So less than 1400 done deal.

Every time I bring up the subject of subwoofer the name REL is the answer. Including my audio dealer who has sold and installed many and of different brands… REL. Best and easiest to install with their setup and outstanding performance.

Always two subs… not one for music.

HSU ULS-15 MkII....Sealed sub, not at all expensive. Get more than 1 

For you Mr Mozartfan, GR OB servo or a low cost DBA. Both are pretty darn easy to set up and they actually work. More the merrier..

REL.  two is better than one.

r e l

The number of subs and their distribution is far more important.