VTF-3 MK4 Subwoofer

New Q Control and Hybrid Tuning Give Unprecedented Bass Control

With the new VTF-3 MK4, we have added most of the new features from our VTF-15H – hybrid tuning, variable Q, sealed operating modes – making this one of the most flexible subwoofers we have offered to date, catering to virtually any audiophile’s preferences. The VTF-3 MK3 was well known for its sound quality. With the added Q control and sealed mode options, even higher sound quality is now possible. Unlike most of it's competitors, the VTF-3 MK4 comes in an expensive custom satin black paint or real wood veneer.

As with the VTF-3 MK3, the MK4 features heavily flared 4” round ports, which nearly doubles the port size compared to other subwoofers with dual 3" ports or single 4” ports.

Harnessing the unique Variable Tuning Frequency port technology (VTF), each port uses the air generated from the long throw woofer to dramatically boost the deeper frequencies. Both ports are large, with enormous flares to virtually eliminate port noise and distortion. This kind of port design is extremely tricky to engineer, and the VTF-3 MK4 succeeds down to a very deep 16 Hz with one port open (in maximum extension mode).

The reason for variable tuning is that all subwoofer designs, especially consumer-level subwoofers, involve tradeoffs in design. You cannot have a small subwoofer that goes very low, plays very loud and costs very little. Traditionally, the engineer decides what tradeoff he or she thinks is best for the consumer. The consumer has to take it or leave it.

The VTF-3 MK4 changes all that. It allows you, the user, to choose the tradeoff. If you enjoy music that is loud but does not have much deep bass, set the VTF series for maximum output. That way, you get maximum dynamic range with the lowest distortion. If you like music with deep bass, set it for maximum bass extension to reproduce the deep bass accurately. You can even switch between the two modes depending on what you play. That means effectively you get a subwoofer that can play loudly, and can play low, all in one, at a reasonable price!

VTF-3 MK4 Frequency Response Curve - Ported (1 port open, 'EQ1')

Freq Response Curve with 1 Port Open, EQ1

VTF-3 MK4 Frequency Response Curve - Ported (2 ports open, 'EQ2')

Freq Response Curve with 2 Port Open, EQ2


CEA 2010 Measurements (1 Meter, Peak):

VTF-3 MK4 One Port Open:

Tone Burst Center Frequency (Hz) Maximum SPL CEA 2010 Rating
16 108.4  
20 110.2 111.6
25 110.4
31.5 114.3
40 118.2 119.8
50 120.3
63 121.0
80 121.1

VTF-3 MK4 Two Ports Open:

Tone Burst Center Frequency (Hz) Maximum SPL CEA 2010 Rating
20 111.4 115.1
25 116.3
31.5 117.7
40 120.0 121.2
50 121.7
63 121.8
80 121.7


Industry Reviews

"Every once in a while you come across a product that isn't just a good deal, but offers quality so far above and beyond what you'd expect for the price that you find yourself recommending it whenever you get the chance. That's the case with these Hsu Research Hybrid 3 Speakers "

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Charles Starrett, Uncrate, May 2013


"It’s difficult to understand how, after more than 20 years in business, Hsu Research doesn’t own the subwoofer market outright. The level of performance of the VTF-3 MK4 subwoofer is a whole order of magnitude (or two) better than the competition. The ability to produce 16 Hz at realistic levels in large rooms is not something common or even available from most other subwoofers."

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Doug Blackburn, Widescreen Review, March 2012


"The Hsu Research surround system of HB-1 Mk.2, HC-1 Mk.2, and VTF-3 Mk.3 is outstanding by any measure. When you take into account the price, it becomes an astonishing value. The speakers look and sound like nothing I’ve previously encountered in this price bracket. More important, they breathed life into whatever I played through them."

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Jeff Van Dyne, Home Theater Sound, November 2008


"the VTF-3 Mk3 you find a truly top-flight product and an excellent investment for the discerning movie and music lover..." ".. the VTF-3 Mk3’s tendency is to gracefully reach as far down into the infrasonic it can and come back in one piece. Subjectively speaking, the VTF-3 Mk3 consistently surprised anyone who happened to be within earshot at just how much bass emerged from the end table-sized box sitting at or near the front-left corner of my listening space. Overall, two words describe the music and LFE that poured from the VTF-3 Mk3: distinct & articulate"

"The sub did a truly exceptional job, for this price class, of playing back track after track, very, very cleanly.."

"The percussives were clean, distinct (there’s that word again), and downright startling (not many things like the audio track of a combat scene to jack the adrenaline), even when played back at the outer volume limits of the VTF-3 Mk3. Excellent!"

"The HSU Research VTF-3 Mk3 is a well designed product, packing a terrific driver, obviously crafted with an emphasis on the basic features that are important to deliver maximum bang for the buck in a product in its price class."

"Overall, the VTF-3 Mk3 proved it self an excellent example of a well engineered product, purpose built with the intention of wringing every last drop of performance possible from a single 12” driver in a vented cabinet."

"that not only did I like what this sub could do, but was consistently surprised by how well Dr Hsu managed to get this thoroughbred with a 12” driver to perform – and perform on a consistent basis. I’ll close with a strong buy recommendation; buy two if the budget allows for it!"

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Mark Sanfilipo, audioholics.com, October 2007


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"While this combination is relatively new to my reference system, it has been transformative. The combination of isolating and carefully presenting mid-bass frequencies (50-150Hz) through the mid-bass modules, and the superb performance of the VTF-3-Mark III true sub, has re-drawn my system in much larger and more substantial frame. The user ability to tailor these frequencies for room and source material adds a new dimension to the enjoyment of music, most especially that which may have come in a bit thin and threadbare. I don't care what the cognoscenti say about subs and audio, the slightly dry nature of the Hsu units, coupled with their flexibility and musicality add more to the experience of listening to music than you can possibly imagine without hearing them for yourself. At under $2000 for the complete system (two mid-bass modules and a true sub, with turbocharger) it is certainly one of the best values in audio. Add to this their entry-level STF-1 sub ($254), and you can turn a modest integrated amplifier and two-way speaker system into something remarkable. VTF-3-Mark III true-sub, with Turbocharger, $799, MBM-12, Mid-Bass Modules, $499 each"

Dr. Sardonicus, The 4th Annual Positive Feedback Online's Writers' Choice Awards - for 2007, positive-feedback.com


"the powerful bass was nothing less than I expected. And how well the VTF-3 MK3 integrated with the HB-1 satellites without calling attention to itself, was just the icing on the cake"

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Fred Manteghian , Ultimate A/V, March 2007


"At 20 Hz the maximum was extended to 112 dB [with turbo]; a new record in the Ferstler main listening room. It might have been possible to go even louder, but by then assorted artifacts in the area were very close to dancing their various ways to the floor."

"one of the best audio investments you will ever make."

"it would be a very good idea for them to first install a seat belt in their listening chair. Once that is done, and the belt secured, they will experience subjective bass performance equal to or better than what just about any competing subwoofer, no matter what its cost, will be able to do."

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Howard Ferstler, Sensible Sound, Issue 111, Jan/Feb 2007


Customer Testimonials

"Thank You Hsu!!

I recently bought the VTF-3 MK4 after longer than I care to admit trying to convince my better half. All I can say is this: I take a certain satisfaction watching skeptics convert. I can't help but grin watching my wife enjoy music and movies to a much higher level than before.

This subwoofer is in my humble opinion AWESOME!!! It was super easy to set up and integrates to whatever you have like its family. The sound is SUPER clean no matter what volume or set up combo you choose. Also the tones you feel more than hear are clean.....they seem to eminate more than overpower (blast you) but they're definitely there because this sub can rattle your bones if that's your thing......

Thank you for creating this GREAT sub. This added a whole new world of sound and sensation...forgive me if this comes across as maudelin but this for my system was akin to discovering the 4th dimension. The 4th dimension is a happy place!!

So much extension..so much clarity...so affordable.....what else can I say??

I know....Thanks Again!! I couldn't be more satisfied!!"



"Just last week, I read a review where someone compared waiting for their new subwoofer using FEDEX's tracking system to the infamous Santa watch on Christmas Eve. I laughed at the time but then found myself parked at the front door, laptop at the ready......tracking my new VTF3-MK4. Whereas FEDEX's tracking system leaves something to be desired, this system surely does not. I often wonder what life would be like without the internet but fortunately this isn't one of my problems. I had never heard of 'HSU' before this purchase and was well prepared to purchase what I now believe would have been a lesser product but I have learned to research. I scoured pages after pages and this name 'HSU' kept coming up. I kept looking for the proverbial wart but there was none to be found. Couple that with the very personable responses I read from Pete and the good Doctor himself and I was sold! Now to the VTF3-MK4 itself: pictures online do not do it justice. I heard people describe its predecessor as huge but I found myself expecting a rather nondescript box. What I received was something very reminiscent of designs using the 'golden ratio' with very clean lines and a no nonsense approach that I truly appreciate. Even the controls are very 'binary' in nature.

Sound: I still have some experimenting to do but so far I haven't been able to wipe the 'Man Smile' from my face. I'm picturing a Super Bowl ad with men sitting on a couch with Grinch like smiles. At first you think its the beer but then the camera pans to the beer being bounced out of the glass, the dog with the Doritos bag has left the room (with the new cat).

I was blind but now I see: I watched movies I've seen many times prior only to find out, there was something missing before that I wasn't hearing....wasn't feeling (and I'm not just referring to loudness). And then there's the presentation of the meal: when people think of subwoofers, they usually think of that boom, boom, boom! I've learned from this experience, there's more to it than that. Yes, I get the satisfaction from watching 'Hustle & Flow' but I can also enjoy the implosion of Vulcan. And when I'm tired of blowing stuff up, I can sit back and hear/feel musical expressions like never before. I also learned to take seriously 'crossovers'. All the speakers in my 7.1 system (except the center channel) have 8" woofers, the mains have dual 10(s). With this setup I previously ran everything as Large. I now see the errors of my ways since there's no way my speakers could ever handle the frequencies the VTF3-MK4 is interpreting. I now crossover at 80hz and I understand why I'm doing it. Thanks for great experience!"



"It's been roughly 6 months since I took delivery of my VTF-3 MK4, and I must say I'm still absolutely in love with this sub. I've tweaked and fiddled a bit since my initial tuning session with it back in September/October, but my opinion hasn't changed on the settings. EQ1, one port, Q of .3 is the perfect crossroads of frequency response and sound quality for my ears. If I want to tighten things up for whatever reason, plug the port. I really only do this on certain musical recordings, and only for them, and only when I'm feeling seriously anal about it. The difference in transient response is audible, and I'm historically a sealed sub kinda guy, but running with one port never sounds Bad(tm) at all. Movies... never run sealed.

In the over-all scheme with my VSX 1120 and Infinity Interlude 10 L/R and 25 C the MCACC settings have the speakers at "Large" and the Subwoofer at "Plus". The IL10's don't quiiiiite make it down to 50 with authority, but the highpass slope on the subwoofer channel that the receiver provides allows for a nice transition. I know THX specs call for the X-over to be at 80hz, but I really can localize bass pretty low and this setting causes 1. Severe narrowing of the soundfield (staged music or movies) and 2. Too much boom in the 60-80hz range. This second thing is not any fault of the sub, but rather the meager EQ ability on the sub channel of the receiver. It's importance is completely mitigated by point 1 though: I hate the way it sounds when the mains can't do some of their own heavy lifting.

If I had the room to run two of these things wired for mutual stereo and LFE... I totally would. That's not going to happen though.

I know I'm talky as all get-out when I wade into this thread, and today's no exception, but for the review of material played through the sub in the last six months, it's a very short discussion.

This sub plays everything well because it just gets out of the way. This is especially true on EQ1, sealed with Q of .3. Get the levels dialed in and this thing does for the bass material what a solid tweet does for the highs: it doesn't dictate the material, it just puts a shine on it. Bass can indeed be breathy and delicate, even when it's pounding your head into the walls. And this sub does this through all levels of dynamic range, and all without any sign of strain from driver compression, lack of amplification ability, anything. It's just clean. Very, very clean.

When you open up one port, changing nothing else, the character does change as described above, but because of the protective nature of the extremely low port tuning, the lack of strain even down to 12hz in my room is just staggering. If you've not experienced the solid presence of below-20hz material before it may actually startle you at first. I HAVE been around that sort of material for decades in cars, and this still startled me. I've never heard reasonably accessible (from a financial perspective) home subwoofer solution that could do this, and it does it so well that it's just jaw-dropping.

In closing I'll provide a quote from my wife from this past weekend. She'd gotten me the Imax Hubble Telescope bluray for Christmas, but we'd not thrown it in yet until Friday night. There are two shuttle launch sequences in the material. The first one was from years and years ago, and the recording mechanisms used weren't so good. The second one though, was recorded in high-def glory with excellent sound back in 2009.

As a kid she was present for a shuttle launch. When the first one on the bluray played, she commented immediately that "wow... should be more bass than that" and kinda frowned. We both just kind of shrugged and kept watching, changing no levels or settings.

The second one went off later in the material. The whole room sounded like it was going to come apart at the framing and rip itself from the foundation. Once it all subsided, her eyes blinking in amazement, "That... is what it really sounds like."

This sub is just disgustingly good, and you can tune it to sound as beautifully clinical or diviantly quake-ish as you like. And in my house I can do this in ~4000 ft3 at ridiculous reference levels at the seating position with room modes of 120+ db @ 16Hz."

David Henson


"I just wanted to stop by and voice my praises of this sub. It almost brought tears to my eyes when I first set it up. I had it cranked too loud, but just trying it out prior to using audysey to re-setup my system, it sounded amazing! The base was incredibly. After talking much with tech support I have this bad boy dialed in and it is just amazing! If I had a way to move the sub ummediately next to the viewing area I am sure I would be blown away. Where it is now is still amazing.

Thanks HSU Research and your technical support. You have a customer for life."



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Product At a Glance

Amplifier Power (RMS) 1400 W Short Term, 350 W Continuous
Hybrid Tuning 16 Hz Ported, 22 Hz Ported or Sealed
Upper Extension +/- 2 dB to above 200 Hz
Woofer Side Firing 12 Inch
Q Control Range 0.3 - 0.7
Crossover 30 - 90 Hz, Bypassable
Crossover Slope 24 dB/Oct
Phase 0°/180°
Inputs Line Level (2), Speaker Level (2)
Power Outlet Requirement 430 W, 120/240V
Enclosure Dimensions 21 14" H x 17" W x 25" D
Dimensions with Grill, Feet & Amp 22 14" H x 1734" W x 2534" D
Weight 74 lbs
Warranty 7-years on Woofer, 2-years on Electronics
Designed and Engineered in the U.S.A.


Quick Set-Up
Owners Guide

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