Would I hear an improvement?
 

Aside from the entertaining discussion in another thread about deep-bass recordings, I have a basic question about upgrading

I have a VTF-3 Mk 4, purchased in 2014. If I were to replace it with a VTF-15 Mk 2, what differences would I expect to hear? Would it reach any deeper? The specs suggest it wouldn't. Would it have any audible advantage over what i have? If I were to replace the one VTF-3 Mk 4 with TWO VTF-15 Mk 2, would there be any improvement in audible LF extension? I'm somewhat limited in where I would put the second subwoofer. I'm thinking of trying behind my primary seating location.

How large is your room? Cubic Footage wise, so LxWxH?

My understanding is that the VTF-15H Mk2 should play louder and lower with less distortion than the VTF-3 Mk4. While the tuning frequencies are similar, you'll get more SPL across the board with a VTF-15H mk2. If your listening level doesn't change, then the primary difference is the VTF-15H mk2 would play at lower distortion since it would need to "work" much less to provide the same SPL.

2 VTF-15H mk2 would have dramatically lower distortion than a single subwoofer, since each one would need to work about 1/4 as hard to reach the same SPL. The pair would also have up to 6dB more headroom (if placed appropriately and delays are matched properly). The VTF-15H mk2 also has a port area advantage, so they can play louder with less port noise.

FWIW, I've got a pair of TN1220HO subs (each fed by a HSU 500W amp), and a pair of VTF-15H mk2 subs in my 2350cu ft theater room... By pretty much any sane definition, I'm into overkill territory.

Is a VTF-15H mk2 an upgrade over a VTF-3 mk4? Absolutely. Is it going to "wow" you? Perhaps not, unless you are really pushing the output capability of the mk4. What I think you will notice, however, is that the VTF-15H mk2 is an incredibly good sounding subwoofer that is as at home playing the deepest pipe organ notes at high level as it is at producing fast double-bass drum notes on death metal, to shaking the room with a T-Rex step in a movie.

My HSU subs have always played the neat trick of being completely unobtrusive until called upon to wreak havoc, disappearing into the music and only calling attention when it is appropriate.

Room is about 3,960 cu ft, 22 x 18 x 10 ft. I've also been looking at non-Hsu subwoofers (not SVS).

In that room size, I think a VTF-15H Mk2 would be a definite improvement, and twins would be pretty awesome.

I've spent some time over in AVSForum, and I saw a number of posts from Mr. Sorny.

My main interest, the reason I'm thinking about another sub(s) is LF extension. It's very hard to compare advertised LF extension specs for subs of equivalent driver size (say, 15") and design (ported vs sealed). You see something like "16 Hz +- 2 db" vs "14 Hz +- 3 db." Sure, 14 Hz is lower than 16 Hz, but does this mean they are actually about the same at 16 Hz, and that they are actually about the same at 14 Hz, since the drop-off tolerance is greater for one than the other?

Now, I'm aware that notated classical music rarely, if ever, drops below 16 Hz (the 32' pipe). Playing the Saen-Saens and The Planets with my VTF-3 Mk 4 gives me a good shake. But I've read that the "Irene" scene in "Blackhawk Down" and the simulated T-Rex footfalls in "The Great Fantasy Adventure Album" (Telarc) have signal below 10 Hz. I'd like to hear it. But I don't think any 15" sub can do it.

Were I to decide for twin VTF-15 Mk 2 subs, I would wait until a relaxation of Covid restrictions, since I can drive to Hsu Research HQ to avoid shipping costs.

You don't hear it, you feel it.
 

When you get in the lower frequencies (below 15-20) it becomes more of a "feeling" than a hearing thing. I have been running two VTF-15H MK2's for over 5 years and am still blown away at the power and accuracy. None of the other smaller subs I have owned have produced the sub 10hz frequencies like these do. My room is 2900 cf BUT is a loft that dumps the sound into a 6400 great room and beyond into the rest of the house. I do plan to wall off the loft soon and can't wait to hear the difference in a "sealed" room.

Two of these would be the perfect fit for your room size. I'm not sure you will find the same ability to port tune and Q adjust your subs with other brands. I do like to tinker so have made further adjustments with a miniDSP unit.

Thank you, Mr. Acepaul.

Have you tried any of the recordings I've cited or the "Irene" scene in Blackhawk Down with the twin VTF-15H Mk2? What have you tried that goes below 10 Hz?

The price of the VTF-15H Mk2 increased $40 overnight from Jan 22 to Jan 23. Not a good sign. Also, this model is seven years old. There'll probably be a Mk3 one of these days, and I wouldn't want to get stuck with an obsolete model.

The Irene scene has an 8 Hz note. Getting audible response at 8 Hz requires large ported subs. Note that I said requires multiple subs, and ported. There are some excellent low tunes subs. I like HSU. That is what I own. Look at AVS Forum for information about low tuned subs. I also like Rythmik and Power Sound Audio (PSA) for low tuned subs.

I really like the Rythmik FV25 HP, and the PSA TV1812. Excellent response at 10 HZ and even better response at 12.5 HZ. Take a look at Data-bass.com for the subs that have excellent response at 10 Hz. Getting single digit response is costly. But if you want the bottom octave, its going to cost you.

Best Regards

A week ago at this time, I was ready to order 2 ea VTF-15 Mk2, but with two stipulations: (1) that Hsu Research actually have the product in stock, and (2) that they allow me pick them up personally at Hsu HQ. I asked Hsu Research. The answer to both questions was negative.

Therefore, I ordered 2 ea TV1512 subs from Power Sound Audio. They should be here tomorrow (Feb 12). I don't think these will go low enough to let me hear the "Irene" scene adequately (the specs say no), but I don't think there's anything I can afford and have space for in my listening room that will provide "Irene." I'll have to live with that.

I've already found a taker for my Hsu VTF-3 Mk4. I am leaving the Hsu Research family. I may check back into this forum on occasion, but not as part of the Hsu Research family.

Please let us know how things go with your new subs and how they compare with your old setup. It's really too bad you could not get the MK2's as they really would have blown you away. In answer to your previous question, the MK2 comes with a demo disc that contains some of the lowest recorded sounds you will ever hear (pipe organ). When I first listened to that I knew there would be no buyer's remorse. Still feel the same after over five years.

My previous sub was a Hsu VTF-3 Mk 4. I have the demo disc that came with it. The VTF-3 Mk 4 gave me a good 16 Hz. But the new subwoofers are superior in every respect. They have bigger drivers (15-inch vs 12-inch), go deeper and play louder. But there are two of them, so of course they're better. Power Sound Audio's owner, Tom Vodhanel, was ultra-responsive to all of my questions before I ordered them. Shipping was "free," but I know the shipping is worked into the cost of the product. PSA subs are mostly made in USA. The drivers are made in Italy, but the cabinets and amplifiers are made in Ohio. While Hsu Research is waiting for ships in L.A./Long Beach Harbor to be unloaded, Tom is shipping subwoofers as fast as he can make them.

When I asked Hsu Research about the VTF-15 Mk 2, I was told that, not only was it not in stock and would not be in stock for many weeks (this was early Feb 2021), but they would not let me pick them up at their loading dock in Anaheim. No way am I going to pay $366 to ship two subwoofers 100 miles. That was really the decisive factor in my abandonment of Hsu Research.

Edited to add: My comparison is a bit of apples-and-oranges, i.e. not quite the same thing. The PSA TV1512 does not allow variable tuning. There's one open port. That's it. The VTF-15 Mk 2 provides a choice between max extension and max output.