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HSU Research VTF-3 MK5 HP

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HSU Research VTF-3 MK5 HP

By Jim Wilson (theJman)

The subject of this review is the HSU Research VTF-3 MK5 HP, a 15" bass reflex subwoofer with dual front-firing ports and variable tuning. It measures 24"x17.25"x21.5" (HWD) and weighs 83 pounds, certainly not out of line for a ported subwoofer with a 15" driver. The listed frequency response is 18Hz-200Hz with one port open, 22Hz-200Hz when both ports are closed. Those ranges are specified by HSU as being within +/-2dB (4dB spread), which is tighter than the typical response window of +/-3dB (6dB spread). The BASH amplifier outputs 600 watts RMS, with a class leading 2000 watts short term peak.

HSU Research is an Internet Direct (ID) company, meaning they sell their products directly to the consumer. The VTF-3 MK5 HP retails for $799, with an additional $89 for shipping in the lower 48 states. That means folks in the continental US will pay a total of $888. There is a 7 year warranty on the woofer, while the electronics are warranted for 2 years. Most ID companies have a 30 day in-home trial and HSU is no different; audition the VTF-3 MK5 HP for up to a month in your theater without risk.

After unpacking literally dozens of subwoofers I can sense, right from the start, which units the manufacturer truly cares about and which are nothing more than a mass-produced sideline. With the VTF-3 MK5 HP it was obvious from the get-go, and it fell squarely into the 'cares about' category.

The unit only came single boxed, which sort of runs counter to what I just said in the previous paragraph, but the cardboard used was very thick and sturdy so I gave HSU a mulligan there. The flaps were not only taped shut but they were also sealed with 2" brass staples, the type you're likely to find on the packaging of a heavy appliance (think refrigerator). The outside of the box was adorned with all manner of graphics, logos, information, warnings, etc. It wasn't nondescript packaging, that's for sure.

Once you open the top flap there's a sheet of paper containing very clear and concise unpacking instruction. Somebody even took the time to make sure the pictographs accurately reflect the packing used; they weren't simply generic images, but instead looked just like the actual material. I don't really need unpacking instructions but others might, so it's nice to see HSU not only included them but took the time to do it properly.

Cradling the entire top and bottom of the VTF-3 MK5 HP were custom molded 1" medium density foam sheets. Protecting all 4 sides from impact were 1" sheets of hard styrofoam, so in essence the entire subwoofer was encased in protection of some sort. Along each vertical corner of the box was a thick cardboard sleeve designed to avert anything from crushing the corners. There was even a 'foot' of sorts on the very end, there specifically to prevent anything from moving around during shipping.

Once you finally liberate the subwoofer from all the protective packaging you still aren't done. First you have to remove the plastic bag it's encased in, and then you need to take off the foam sheet wrapped around all the painted surfaces. I've worked up a sweat by this point, so thankfully that's the end of the journey. I'm not looking forward to packing this one back up at the end of the review, that's for sure.

"classy" was the first word that popped into my head when I finally got the HSU VTF-3 MK5 HP unpacked. The tall, slender profile and gently rounded edges give this subwoofer a refined appearance. A flawless satin black paint covered everything, applied beautifully and smooth as glass. The paint did give off a chemical-like smell though, one that lingered for the better part of a week before it completely disappeared. The cabinet itself is constructed from 1" MDF, while the driver is held in place by a 1.75" section of the same material. The entire interior is cover with dual 1" sheets of an acrylic foam. Underneath you'll find considerable 2.5"x.75" round rubber feet. Size-wise it's about as small as a bass reflex subwoofer with a 15" driver and dual ports could possibly be. Thankfully the smallish enclosure did not cause an output or performance penalty.

The grill exhibits the same attention to detail as the cabinet does. It's built using a 1" MDF frame that's not only polished smooth but painted as well. It looks and feels substantial. The fabric is very transparent and was attached perfectly. It's held in place with metal pins and rubber cups, unlike the more conventional plastic/plastic combination most other companies use. It was very secure when on and came off with little effort, not an easy thing to design. There's also a very tasteful HSU logo centered at the bottom.

It's obvious somebody spent a lot of time on the documentation because it proved to be excellent. Even a complete novice will find everything he/she could possible want, from setup to fine tuning. There's actually two pieces of documentation; the first is a dual sided laminated sheet with an explanation of the amplifier controls on one side and a quick setup guide on the other. If you've ever hooked up a subwoofer in your life the amp section is all you'll need to fully understand every single connector, dial and switch. No lie, it's that good. The quick setup guide is about as basic as you'll find though, but for the experienced person it will probably suffice.

The owners manual is a thing of beauty, and is among the best I've seen from any manufacturer. Want tips on placement? Check. How about a detailed explanation of hookups, crossover settings, phase, variable port tuning, the Q Control? HSU covers all of those. There are in-depth sections dedicated to fine tuning, equalizing and troubleshooting as well. Even the translation is spot on - something all too often overlooked - so there's no need to decipher what you're reading. The font is clear and legible too. This manual is a template for other companies to follow. The amplifier and its controls takes a bit to explain though, so grab a beverage and let's dive in...

One thing uncommon with this amp is where you set the gain (volume) knob. Generally speaking what I've seen is the 12:00 or 1:00 position is ideal, but not in this case. HSU specifies in their manual to set it at the 9:00 position which made me think "yea right, that's too low". Turns out they were right; after running my receivers auto-EQ with the sub set at 9:00 I only had to bump it up to 10:00 in order to get all the bass I needed. Unfortunately the volume knob only has indicated settings for Min and Max, with slashes for everything in between. I don't understand why companies do that; is it really so hard to use the numbers 1-10 instead? Another gripe would be that the low level inputs are only RCA, there's no XLR (my receiver has XLR out for the subwoofer, so I had to use an adapter). The phase adjustment is a two position toggle switch and not the more common variable type, so you can only choose 0 or 180 degrees. Since I'm complaining about things, how come the Crossover Defeat toggle switch has settings marked Out and In? That's not really intuitive, at least not for me anyway. How about making it say On/Off or Enabled/Disabled instead? That would be more instinctual. The crossover dial itself does clearly indicate 30Hz-90Hz, in 10Hz increments, but this particular unit only went to 80Hz - the dial would not go to 90Hz. As far as complaints go that's pretty much all I have - the rest of this review is almost all positive.

The VTF portion of this subwoofers name stands for Variable Tuning Frequency, and to support that HSU includes two other settings on the amp; an Operating Mode toggle switch and the Q Control dial. The former works in conjunction with the dual ports, while the latter is more for personal preference. Let's begin with the Operating Mode switch.

Unlike traditional subwoofers - which have one or two ports of equal size - HSU uses two different sizes, 3"x15" and 4"x18" (diameter x length). The Operating Mode switch works in parallel with those ports, providing 5 different tuning options. By plugging both, neither or just the 3" port you can adjust the characteristics to your particular situation or tastes. Want the sound/performance of a sealed subwoofer? Plug both ports and flip the switch to EQ 1 (Max Extension) or EQ 2 (Max Headroom). Prefer the benefits of bass reflex instead? That's easy; plug the 3" port and flip the switch to EQ 1 (Max Extension) or EQ 2 (Max Headroom). Want the most output possible? No problem; leave both ports open and set the Operating Mode to EQ2. With the last configuration be sure to use EQ2 though. Failure to do so may result in driver damage, which probably would not be covered under the warranty. HSU does include plugs for both ports which are made from a very dense foam, so once you wrestle them into place they aren't likely to come free no matter how hard you push it.

The Q Control dial is intended to adjust the sound depending upon your specific preferences. Want the most output? Set it for 0.3. Want a 'thicker' presentation? Set it for 0.7 then. I went for 0.5 more often than not, which seemed to be a nice balance between a rich sound and total output. The dial indicates the 0.3, 0.5 and 0.7 positions quite clearly. For some reason HSU put two slashes between each of those settings, even though realistically there is only one option to choose (0.4 and 0.6, respectively).

For the 2 channel folks there are high level inputs, so if your receiver/amp does not have bass management you can use the controls on the VTF-3 MK5 HP's amp to handle those chores. That's a nice touch. There's also a toggle switch for power, with settings for on/off/auto. Auto was a little finicky for me, but still usable. The amp can be set for 110 or 240 volt input so HSU did not forget about folks who live outside the United States, although the included power cord was US-centric.

The driver in the VTF-3 MK5 HP is certainly up to the task. It has a very generous high density foam surround attached to a fiberglass reinforced paper cone with an inverted polymer dustcap, all of which is nestled in a stout 12 spoke metal basket fastened to the cabinet with machine screws and T nuts. The ventilated voice coil is motivated by dual 1" magnets and uses multiple shorting rings to lower inductance and distortion. This driver appears to be the exact same one used in HSU's flagship subwoofer, the VTF-15H MK2. If so, it certainly has pedigree.

My living room is 13x17x8 (1768 ft^3), so it's not terribly large. The main seating position is approximately 11 feet from the subwoofer. All testing was done after the unit had been broken in for at least 20 hours.

If I was forced to use one word to describe the HSU VTF-3 MK5 HP it would probably be "composed". It never seemed perturbed or ruffled by anything I threw at it. Perhaps what I enjoyed most about this HSU subwoofer is it didn't draw attention to itself, instead going about its business without making a spectacle. Formidable, yet not offensive. Dr. Poh Hsu has a reputation for such things, and with the VTF-3 MK5 HP it turned out to be a well deserved one. Frankly, what it did do was just as important as what it didn't do. Nothing exaggerated or overdone, everything in proportion and under control. Basically, my kind of subwoofer.

HSU includes the BAS Test CD (Boston Audio Society) with every one of their subwoofers. Contained on the disk are various orchestral passages, pink noise, warble tones and frequency sweeps, content intended to push your subwoofer. Certain portions proved quite taxing, but as you probably already surmised the VTF-3 MK5 HP had no real problems with any of the material. This disc is a nice add-in for people who like to test and tinker.

During my movie tests the HSU VTF-3 MK5 HP remained steadfast, refusing to lose its poise regardless of the content being played. Whether it was asked to provide deep bass, intricate detail or some combination of both, it was up to the task. It basically laughed at my attempts to trip it up.

War Of The Worlds (blu-ray)
I decided to break out an old favorite, a movie that to this day - 10 years after its release - is still a standard for subwoofer testing. There probably isn't anyone reading this who hasn't seen the movie at least once, so it seems pointless to go over the plot. Let's just jump into it then, shall we?

Generally I will use a few different scenes - a gauntlet of sorts - and for this evaluation it was no different. The first of those is scene 4 (Lightning Strikes) because it has quick, sharp hits courtesy of the lightning bolts. What amazed me the most was the subtlety, the way each strike increased in intensity without any indication the VTF-3 MK5 HP was nearing its limit. Each of them got successively louder and stronger.

Of course scene 5 (The Pod Emerges) is what this movie is most famous for, so how could I ignore that one? As the machine extricates itself from the underground lair the subterranean rumbles from the street collapsing were forceful. The onslaught was very evident, yet not droning or the least bit objectionable. During the ensuing maelstrom there's a crackling sound that's more of an undertone, something sharp but not necessarily all that deep. Those sounds add to the sense of mayhem though and the HSU did not disappoint, producing them as cleanly as the really deep content.

The bridge destruction as Ray (Tom Cruise) and his family are trying to flee is still one of the highest output scenes ever recorded, so if you want to force a subwoofer outside its comfort zone this is a good one to use. It didn't seem to faze the HSU though; even at an elevated volume level everything remained under control. As a gasoline tanker truck is catapulted off the overhead bridge and into Ray's neighborhood it exploded with force and sent ripples through my living room, yet there was nary a complaint from the VTF-3 MK5 HP.

Avatar (blu-ray)
Six years after its initial theatrical release, Avatar is still a treat for the eyes and ears. This was a ground-breaking movie, combining stunning animation with a formidable soundtrack. James Cameron at his best, and a staple for people looking to test their audio system. For this evaluation I focused on two scenes in particular, 22 (Assault On Home Tree) and 30 (Battle For Pandora).

Scene 22 opens with Colonel Quaritch and his military forces departing their base in helicopters and warships heading toward Home Tree, the Na'vi peoples revered gathering spot. The Colonels plan is to bring down the 100+ story tree because it happens to sit on a rich vein of a very precious metal, and he's been paid to clear the way for its mining. As the attack forces lift off from the tarmac the VTF-3 MK5 HP rumbled to life, producing deeper and louder bass as more aircraft took to the skies. If you've ever experienced a real-life aerial armada take flight you know each craft has an unmistakable sound signature, and the HSU went about producing each of these fictional ones in a similar manner. Obviously not with the impact of the real thing, but with sufficient depth and distinction to make it quite enjoyable.

Upon arriving at Home Tree the strike force hovers in position, poised to begin their assault. At first they fire smoke bombs, then incendiaries and finally missiles. The VTF-3 MK5 HP made short work of this part, producing each different weapon with excellent detail. Everything blended perfectly, yet each element was clearly differentiated from the others.

By the time Quaritch's forces have expended all their munitions the massive roots of Home Tree have pretty much been obliterated. The HSU produced a huge groan as the roots finally succumb, buckling when the tree begins to list. There's no stopping the inevitable once the weight of this enormous tree shifts. Gigantic branches rain down on the Na'vi people below, and each time one broke free from Home Tree or hit the ground the VTF-3 MK5 HP complied by letting you know in no uncertain terms. Eventually the tree crashes to earth with a resounding thud, something that prompted this subwoofer to send a wave of bass through my floor.

While the collapse of Home Tree is often used to test a subwoofers mettle, I actually like scene 30 better (Battle For Pandora). The reason being the former is about deep and punishing bass - a valid test, for sure, but somewhat one dimensional - while the latter has many and varied elements which, when combined, tend to trip up a subwoofer that isn't articulate. No such problem here.

As Colonel Quaritch's helicopter crew lands in the forest the tranquility is shattered. The contrast between stillness and the booming rotor blades is stark, just as it should have been. Once on the ground the helo's open their pod doors and out jump several 25 foot tall mechanized robots operated by soldiers. Every step they took produced a thump from the subwoofer, clearly indicating their presence and enormity.

The Na'vi aren't taking this invasion lying down though. They mount a fierce counter attack and come storming back atop their 6 legged horse-like beasts. As a phalanx of them descend upon the invading troops I could feel the collective hooves pounding the ground, establishing a legitimate sense of impending doom. Ultimately a head-to-head showdown results between the Na'vi and the invading forces, yet in spite of the chaos the VTF-3 MK5 HP went about its business unperturbed. Every gunshot blasted away with authority, every explosion ripped through my room. Very enjoyable indeed.

Collateral (blu-ray)
Before anyone points it out to me, yes I (now) know this review includes two Tom Cruise movies. That was not by design. True, he has acted in a number of blockbusters with extraordinary soundtracks - so it's not uncommon for a reviewer to include one of them - but this bit of symmetry was not something I planned for.

One evening I had a few hours available to compile movie notes, or so I thought anyway. I got through WOTW but then 'life' happened and I ended up being sidetracked by other things. Before I knew it my free time was gone, so I packed it in for the night. It wasn't until almost a week later that I had another block of time long enough to focus on my evaluation, so I grabbed a few more movies and continued. Trouble is, I had pushed WOTW to the back of my memory when I dropped Collateral into the draw of my OPPO. Weeks later, as I started to convert my notes into this review, it finally dawned on me what happened in one of those slap-palm-against-forehead moments. My rational for including Collateral was partially due to the fact that the Club Fever scene has both music and potent gunshots. For me the logic still rang true (more about why the music part is applicable below), so I decided to just forge ahead and write the review with the notes I had.

I started out with scene 7 where Max (Jamie Foxx) the cab driver is trapped in an alley, handcuffed to his steering wheel while Vincent (Tom Cruise) has gone off to locate another of his targets. This part is used mostly to gauge transient response because it only contains a few gunshots and not much else in the deep bass region. For me the test is in how it renders those shots. Once Vincent finishes his business inside he confronts a pair of street thugs who try to steal his briefcase in an alley. The close proximity of buildings make the sound reverberate so it's a shot/echo sequence a total of 6 times, 5 of which are in rapid succession. Those 5 are where I concentrated most of my attention, and the VTF-3 MK HP didn't let me down; each shot rang out with authority but didn't step on the ensuing echo by continuing to linger afterward.

From there I jumped to scene 16, Club Fever. Vincent is walking through a packed dance floor, stalking yet another of the people he's been hired to assassinate. Typical electronic club music pounds away in the background as he inches ever closer to the victim. The HSU held its own and gave a sense of what one might experience from such a situation, albeit without quite the overall impact (something no single 15" subwoofer would ever be able to accomplish, no matter how powerful it may be). The thump and rumble I was getting was realistic enough to draw me into the scene though, so all was good.

Liking what I heard thus far I turned up the volume to just below painful, yet in spite of that the dynamics remained true. Louder sounds and lower ones stayed in proportion, providing the correct sense of size in spite of the elevated sound level. When the inevitable shooting starts Vincent's pistol produces the loudest kick of all the firearms, only outgunned - pun intended - by the lone shotgun blast from one of the victims bodyguards. Everything was just as it should be. What surprised me the most though was how restrained the presentation was. What I heard was a very solid rendition, but it never came across as over the top and exaggerated. Powerful, yet not pretentious.

After all the testing had concluded I checked the amp to see how it had fared, and it was generating some heat. Not "don't touch me!" hot, but there was an indication it had been given a bit of a workout. It didn't take long before the heat fins cooled down appreciably.

Conventional wisdom suggests a 15" bass reflex subwoofer would be geared more toward orotund sound, primarily home theater applications at the expense of music performance. But is that always the case? With the HSU VTF-3 MK5 HP it certainly wasn't. Quite the opposite, actually; while fully competent at all things HT it was music I used this subwoofer for more than anything else. Surprised? I certainly was, but I grew to embrace the dichotomy nonetheless. The HSU VTF-3 MK5 HP possess an abundance of finesse and poise. More than once I sat for hours playing all manner of music genres, and I thoroughly enjoyed every minute of it. With as fanatical as I am about music reproduction that's really saying something. And I had it setup for the deepest possible bass, which is not the most accurate setting, yet it was still enjoyable. The HSU VTF-3 MK5 HP may be a mouthful to say, but it's a delight to hear in person.

It's Love, Kings X (CD)
Kings X, who on earth is that? A progressive rock/funk band that never hit it off with the mainstream public, that's who. The band primarily consisted of three extremely talented musicians who remained on the fringe of success their entire career unfortunately (which has encompassed almost 40 years, yet they're still going strong). For the most part the Kings X lineup has been a left handed bass player named Doug Pinnick, along with guitarist Ty Tabor and drummer Jerry Gaskill. Their modus operandi has always been to be different. Until recently I had never seen this band perform live but thankfully I was able to rectify that in 2014. Spirited performance too, with a lot of rabid fans in the audience.

It's Love was one of two Kings X songs that got significant radio air time in the early 1990's, with the other being Black Flag. Beyond that, no one has ever heard of this band it seems. It's Love is from their third album titled Faith Hope Love, which almost sounds like the mantra from a self-help group or something. This tune doesn't have a tremendous amount of bottom end in the final mix; like most Kings X songs it predominantly features the drums in the rhythm section. However, even though the bass guitar plays 2nd fiddle the VTF-3 MK5 HP produced a crisp and well rounded version of this song. Very tight and precise, never falling apart even when the volume was turned up to ridiculous levels ("falling apart", oddly a perfect segue for the next song).

Fall To Pieces, Velvet Revolver (CD)
Velvet Revolver was formed from the ashes of two bands, Guns-n-Roses and Stone Temple Pilots. Both of those groups helped define their respective genres of music and influence countless other bands even to this day. The initial version of Revolver consisted of Slash (guitar), Duff McKagan (bass) and Matt Sorum (drums) from Guns-n-Roses. Throw in Scott Weiland (vocals) from STP and Dave Kushner (guitar) of Wasted Youth and you end up with Velvet Revolver.

Fall To Pieces is from their debut album Contraband. Released around 2004 it proved to be their most successful offering, spawning not only Fall To Pieces but another favorite of mine titled Slither. Both tunes made the top 10 on virtually every rock oriented radio station. One of the hurdles VR faced was they weren't able to record or tour for more than a few hours at a time because Scott Weiland was in a court ordered halfway house due to his many drug-related convictions. He was only allowed to leave the facilities for 3 hours per day, so the band was forced to work around his schedule.

I really like this song, but I don't feel the same about the mix. To me it seems like the recording was intended for a car radio and not a quality home audio system. The sound is rather bland, with little in the way of dynamics. That's precisely why I chose it though - I wanted to see what the VTF-3 MK5 HP could do with lousy material. A good song, but a bad recording. While it wasn't quite able to turn lemons into lemonade, it was capable of transforming marginal source material into something that sounded good. I heard an abundance of detail and texture, even though it was working with a handicap.

Texas Flood, Stevie Ray Vaughan (CD)
The majority of this review was written in June of 2015, a time when the state of Texas was getting hammered by once-in-a-century rain storms. Some of the downpours were measured in inches per hour, what you might expect in a Brazilian rain forest instead of the central part of the US. Unfortunately Texas can not handle anything like that, so there was quite a bit of damage from the prodigious rain storms. While I'm certainly not making light of what happened, somehow the Stevie Ray Vaughan (SRV) song Texas Flood came to mind for this review. That was partially why I chose it. Ironically, the other part was I missed one of Stevie's last concerts for the exact same reason; an intense rainstorm.

In August of 1990 myself and a few friends had tickets to see SRV play an outdoor concert. The day of the show the heavens opened up, dumping a staggering amount of rain on New Jersey. It stopped about 2 hours before the show was scheduled to begin but by then the damage was done; the venue was an absolute mud pit, roads were closed, traffic was a complete nightmare. It was chaos everywhere. Not knowing if I could even make it through all the carnage to see the show I told my buddies "enjoy yourself, I'll catch him the next time he comes around". Fateful words, as it turned out, because less than 3 weeks later Stevie Ray Vaughan died in a plane crash. Twenty five years have passed since that fateful day, yet I still kick myself. I never got a chance to see one of the most soulful blues artist of all time. Before I go completely off on a tangent though...

Texas Flood is the title track from the debut album for Stevie and his band, Double Trouble. It's actually a cover of a song from a little known 1950's artist named Larry Davis. Stevie makes it his own though, changing it into a typical SRV tune with a gritty blues feel to it. The recording is excellent, balancing all the instruments in such a way as to make for a rich full-bodied sound. Tommy Shannon's bass guitar was articulate and expressive, with the undeniable power that a blues song absolutely must have. Chris Layton's kick drum had a 'snap' to it, replete with sharp transitions and a potent sound. This is what blues should be, a heavy bottom end and abundant guitar solos. The VTF-3 MK5 HP ate up this challenge with ease, and I was the benefactor of it.

On audio forums an all too common question is some variation of "what subwoofer should I buy for XXX amount of money?". There are a handful of Internet Direct (ID) manufacturers mentioned repeatedly, but all too often those potential candidates do not include anything from HSU Research. That's rather interesting when you consider how long this company has been around. Truth be told I was among those who only gave their products a passing acknowledgment, but after having lived with the VTF-3 MK5 HP for over a month I won't be omitting them any longer. Put succinctly, this subwoofer is amazing. It wants for absolutely nothing and can hold its own with any product being sold for under a grand. When you consider all the tuning options, and realize the flexibility that affords, you quickly come to the conclusion it has few legitimate rivals. The HSU VTF-3 MK5 HP should be on your short list if both quality and quantity is what you're after.

Please use the HSU Research VTF-3 MK5 HP Discussion Thread for questions and comments​

These measurements were taken using XTZ Room Analyzer II Pro. The unit was indoors, physically positioned in the center of my listening room. The sub was laying on its side with the microphone 1 foot from the driver in sealed mode and 1 foot from an equidistant junction of both ports and the driver when in bass reflex mode. Gain was at 12:00, phase 0 degree's, Q Control 0.5 and crossover disabled. Please disregard the bump at 23Hz in the frequency response charts and spectrographs. I've identified a potential issue with the microphone which is most likely causing it. The native response of the subwoofer does not exhibit that tendency.

This represents the frequency response when both ports are plugged and the EQ switch is set for 1

This represents the frequency response when both ports are plugged and the EQ switch is set for 2

This represents the frequency response when the 3" port is plugged and the EQ switch is set for 1

This represents the frequency response when the 3" port is plugged and the EQ switch is set for 2

This represents the frequency response when both ports are open and the EQ switch is set for 2
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