I would NEVER purchase another HSU product. After about three months of moderate listening in a stereo setup the sub just quit. I checked the fuse and it was not blown. Turns out the amp was toast. I contacted HSU Research and the tech casually requested that I remove the amp board and ship to them. Of course I had to pay for the shipping back to CA. Why should I pay for shipping their defective amp after a new purchase? They need to do a better job at quality control. They did send a replacement amp board in a reasonable time frame and I had to install the board myself. The sub functioning as it should but compared to my 1990 Velodyne it is boomy with no real bass extension. Not recommended!
I just received the STF-2 . I was not prepared for the sound this unit produces. Watching Transformers in BlueRay shook the walls, floor and couch and I was only on level 2. Be prepared to rock your house with this unit.
I've been at the two-channel audio hobby now for over twenty years, and have had a number of high-end systems. That includes some expensive subs as well. My present system is more modest, and I review this sub in that context. I am a firm believer in dual subs (if you're doing subs), and bought two STF-2 subs to upgrade from a pair of Cambridge Soundworks BassCube 10s.
The Cambridge subs took about an hour to set up. After that, no room nodes, no "hearing the sub," nothing but good bass, well integrated with my Tyler Taylo reference monitors. They worked well with five different amps I had. Weren't the deepest or the best textured, but their errors were basically those of omission only.
The Hsus were impossible to integrate, either singly or in a pair. I tried for three weeks to find any spot, any setting, any cable that would make them integrate, all to no avail. My suspicion is that these subs would be very nice for HT, but they are, in my view, NOT musical subs, and have no place in a quality music system.
They made "low sounds." In fact, they tended to over-emphasize the 40-80hz range. Because they do not have an adjustable phase, I was limited in what I could do for integrating these things.
The bass was substantial, prodigious, and tuneful. However, it did not match the bass from the mains in any respect, using either sub-outs from the amp or line level feeds. It was simply bass "doing its own thing." The notes were not continuations of instruments - rather, they were simply "deep tones."
I contacted Dr. Hsu, and he emailed me with some ideas to assist me in integrating these subs, which I appreciated. However, his suggestions didn't work.
I then decided to return them. With shipping both ways, I was out about $200 for this experiment. Okay, that's how it goes sometimes. I understood the deal going in, so that was okay.
However, after not receiving my money back, I contacted Dr. Hsu and was told that it was the busy Christmas season and he'd get to my return when he could. I really didn't appreciate that response, and told him so. He then proceeded to tell me how he'd taken his time to assist me, and asked me, "how many other presidents of companies would do that?" I was stunned by this response. In twenty years of this hobby, I've dealt with at least a dozen "presidents of companies," including the president of the company whose speakers I presently own, and the president of the company whose amp I own. I really did not appreciate the attitude that an Audio God had deigned to assist a customer out of his own benificence. The up-end audio market is filled with qualified engineers like Dr. Hsu following their passion and trying to make a living - including responding to customer inquiries and taking out the trash.
I would also point out that Dr. Hsu states in his literature that if you own dual subs, they should be placed next to each other. I actually tried that, with disastrous results. I would additionally point out that there is no other sub manufacturer or audio critic I know of who takes this "position on position" of dual subs. There are a number of technical articles available on the net concerning this issue, and they invariably choose one of two set-ups: 1. Both on the front wall, with each one outside the plane of the main speakers or 2. immediately behind or adjacent to each main speaker. The idea is to get stereo bass, which is impossible to do with Dr. Hsu's recommmendation. Doug Blackburn has written about this in the SoundStage archives, and there is an excellent article on the 6 Moons site at www.6moons.com/audioreviews/vb...
I am therefore left with three reasons I did not enjoy my "Hsu experience." First and foremost, I think if you are interested in music reproduction with anything approaching accuracy, you can do better...and you can do better for the money. Second, I'm not at all sure Dr. Hsu is correct in his sub theories, if his placement recommendations are so different from the mainstream for stereo subs. Third, although I appreciated his support, I actually (I know this may be hard to believe) EXPECT support on a purchase at retail price from the manufacturer. His response to my request for a return of my money was less than stellar, in my view.
I went on to buy a used Alon Thunderbolt sub with an adjustable phase, which took about 20 minutes to integrate. I was biding my time for the second one, which I got about a week ago. I did have to fiddle for another half hour or so to get them right. Are they perfectly right? No - I'll continue to refine them over time. Are they listenable? Yes. Were the Hsus listenable? No. So, I've used subs both substantially cheaper and substantially more expensive than the Hsus in my music room, without major difficulties of any kind.
Under all of these circumstances, I cannot recommend either this particular sub, or the line itself. I did not appreciate begging for my return or being treated as if I should have been honored to receive some set up assistance from Dr. Hsu - who basically runs the place himself. As I mentioned to him, if he hired additional customer support staff, he would never have had to take his valuable time to assist me.
My rating pertains to music only; these may be perfectly fine for HT, which I didn't try.
This subwoofer does not disappoint. I use this purely for music, and it blends wonderfully, much easier and more naturally than my AR-30 -- regardless of whether the volume is subtle or cranked. It can hit the deepest "natural" piano and bass notes (non-synthesized) with absolute purity, there is no "boominess" whatsoever.
My first mistake was purchasing a sub without checking reviews. I purchased a Velodyne DPS10 for $500 and found it to be very boomy, and not very musical. I think it would be superb in a home theater system, but for music, it lacks. I took it back, looked at online reviews and found the Hsu STF-2 for a hundred dollars less. As people have stated, it works wonderfully in a 2 channel audio system. It disappears in the room, blends with the primary speakers excellently, is not boomy, just well defined. I keep the volume at around the 10 o'clock position most of the time. The crossover is variable down to 30 Hz, which is where I put mine, so my Meadowlarks can play to their fullest. I listen to smooth jazz, blues, a little rock, and the Hsu is magic with them all. Very musical!
Used with Phase Linear 700 II amp, Classe Audio DR-5 preamp, Linn LP-12 turntable, Jolida JD-100 tube CD player, Meadowlark Audio Osprey speakers.