I'm always a fan of products that can be auditioned at home with a 30 day return policy, especially if they are part of an experiment. Of course, it only matters if the product has an excellent reputation.
ACI is such a company, and their subs...Force XL and Titan...get high marks from users.
Of the subs you mention, only the Velodyne HGS 15 will be of excellent musical quality (around 1% THD). The other two are more for movies, the Earthquake has a passive radiator and is almost certain to have 20% harmonic distortion at the lowest frequencies....although it will probably go very loud at LF.
The only concern I might have with the Velodyne is thermal compression => it uses an elaborate voice coil system to get extreme linear extension....this is fine for an occasional movie earthquake but it might heat up on music with continuous LF demands...(voice coil heat needs nearby mass to dissipate otherwise resistance increases)
Since thermal compression and dynamic behaviour is very speaker/designer dependent...you really should consider a sub from the same people that make your main speakers ( the match at various SPL levels is likely to be much better if you stick to the same manufacturer - it is no good having an amazing sub if your speakers mid range compresses at high volumes levels and vice-versa is ture too - mismatch will just lead to frustration to get it to sound right as you change SPL level).
I auditioned many subs, but only one of the three you mentioned, Sunfire. I ended up with an ACI Titan - the most musical sub of all of the ones I heard. And it has plenty of power. I have mine turned down so low, at times I wonder why I even got one. But when I turn it off it becomes immediately obvious how well it does its job. Superb.
Thanks Tvad: I tried the ACI Titan II LE. And it is high quality and seamless. The only drawback for me was that in my system and room it was too light in the low end.
You might consider the 18" BagEnd. If you really need high SPL, consider stacking a pair of subs. M&K push-pull subs cancel 2nd order harmonic distortion; you might consider them. Look for the largest box you can fit in your room.
Here's a list of M&K's speakers; scroll down to the subs.http://www.mkprofessional.com/grid_speakers.htm
I second the Bag End comment from Bob.
I have tried all the subs you mentioned and of the 3 I would probably go HGS-15 1st, Earthquake 2nd and the Sunfire Sig last.
The Earthquake 15 is an excellent sub though for music as well and hits harder than any of the above mentioned subs. The Velo is more musical though.
The Bag End goes lower than all of them though as confirmed by my Velodyne SMS-1 EQ and is the best music only sub of the bunch.
The Bag End does not hit as hard as the Earthquake though. The bass from the Earthquake can get scary if you want it to and with a EQ like the Velodyne SMS-1 you can tame it for music as well. I have heard 2 other systems with Supernova 15's and no eq. Both sounded very impressive with music so I guess an EQ is not mandatory. Most people think that since it has a passive radiator and can hit crazy levels of 117+ db at 35 hz that it can't sound good for music but that is just not the case.
I hope this helps some.
I would highly recommend the HSU Research VTF-3 HO.
Why not just get the best bass system for music use not a comprimised subwoofer design but a bass horn.Bass horns are at ease at any level you care to listen to.A subwoofer loses detail due to massive driver excursions a bass horn drivers hardly move so detail thats lost to conventional bass systems is reproduced most folks dont know how much detail is in deep bass a bass horn will let you hear this.
A subwoofer loses detail due to massive driver excursions
Depends on the design of the subwoofer. There's probably some truth to the statement when applied to small box subs.
how much detail is in deep bass a bass horn will let you hear this
In terms of power, the horn design is very efficient but you will lose some details from transients and the same can be said for ported designs or passive radiators that boost LF power through resonance. For low cost and high SPL output design you cannot beat a horn.
A subwoofer loses detail due to massive driver excursion
Large excursions in a sealed box are indeed a problem for low cost drivers (small magnets, long voice coils) with correspondingly low levels of linearity (Xmax). The bass output will quickly compress and harmonic distortion will increase dramatically at higher excursions. (although this design may work very well at low SPL levels, more accurate than a resonant design)
Bass horns are exceedingly costly (check out the 'Living Voice' horn sub of old), they are also usually the size of a baby elephant, and don't go down nearly as far enough, 30hz if you are lucky (or unlucky), a friend uses 2 of the smallest REL's (Q50's I beleive) for his med/large(ish)hornloaded speakers to great effect as he only wants to underpin the bass he is already getting anyway (music only system). There are some seriously good musical subs out there for not much wonga. 2 subs are apparently better than one. I personally would love 2 SVS PB12/Ultra/2's!!
That should alter the foundations a tad!!lol
I would look at the Rel subs. I looked at a lot of subs and the Rel out did them all.
if you can find a vintage Janis subwoofer system , It consists of a upward firing (15"?) woofer enclosed in a nicely built and handsome sealed square wood cabinet along with a Janis Interphase 3-A electronic crossover/amplifier. this system retailed for over 2K when introduced.
best musical sub i ever heard, still owen my one (not 4 sale)
re: 21st Century BASS HORN ( http://www.lyngdorf.com/index.php?option=com_content&task=view&id=27&Itemid=55 )
Then there's this:
I've been a dealer for all 3 you mentioned. The Sunfire was my least favorite in my home. (I don't like them myself)The Velo would be my first choice. I use three of them in my own theater to this day, which doubles as my main 2 channel rig. (2 12", and an 18") That being said, for the money, the PSB's are EXTREMELY musical. (also a dealer for them) If I were to start from scratch, I'd be using the PSB's. The only sub I've tried, and may like better, are the JL's. If you have any specific questions, you can email me at zydo1966 at yahoo dot com. I'm not looking for a sale, but, would be glad to help you if I can.
What's your budget and how big is you listening room? How did you come to pick these three subs?