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Hsu Research VTF-1 mk3 Ported Subwoofer Review

by September 28, 2017
  • Product Name: VTF-1 mk3 Subwoofer
  • Manufacturer: Hsu Research
  • Performance Rating: StarStarStarStarhalf-star
  • Value Rating: StarStarStarStarStar
  • Review Date: September 28, 2017 00:00
  • MSRP: $ 399.00 (+ $54 Shipping / Handling)
  • Buy Now
  • 10” driver, ported enclosure
  • 250w continuous amplifier
  • 30 Hz- 90 Hz crossover frequency range, by-passable
  • 24dB/octave crossover slope
  • 0°/180° phase switch
  • L/R Unbalanced inputs
  • L/R Speaker-level inputs
  • 0.7-0.3 Q control
  • 300-watt power outlet requirement
  • 42 lbs.
  • Enclosure Dimensions: 18.5”H x 14.5”W x 17”D
  • Dimensions w/ feet, grille, amp: 19.5”H x 14.5”W x 19”D
  • 7 years woofer warranty/ 2 years amplifier warranty

Pros

  • Accurate bass reproduction
  • Affordable
  • Good extension for the price
  • Not large and not heavy
  • Variable tuning points offers a significant difference

Cons

  • Single port mode can chuff obtrusively in very deep bass at high drive levels
  • Sealed mode doesn’t really do much

 

We started our Hsu Research VTF-2 mk5 review off by noting its relatively long history and evolution since its initial appearance. VTF1_product_pic.jpgHsu’s VTF-1 hasn’t been around as long as a model name, but its inception is so closely related to the original VTF-2 that it has to be considered an extension of that product line. The VTF-2 line started with 10” drivers and very similar cabinet dimensions and tuning points as the VTF-1, but the VTF-2 name was promoted to a line of medium sized 12” subwoofers, and the 10” variable tuning subwoofers were given the name ‘VTF-1.’ Essentially, the VTF-1 carries the form that the VTF-2 started with. In evolutionary terms, this would be called common descent: two different organisms that share a common ancestor.

The VTF-1 mk3 makes a more radical change to its form than the mk2, which only added a Q control from the mk1. The mk3 rearranges the cabinet by placing the driver and ports in front. It also gives the amplifier a boost from 200 watts to 250 and makes some alterations to the driver. Rubber feet replace spiked feet, and the satin black finish is now a smooth vinyl finish. Hsu also claims a very significant performance increase moving up to the mk3 along with a substantial price drop. This brief history of the VTF-1 has led us here with the mk3 in our hands, and we will see how these many layers of refinements over the years add up as a subwoofer in our review.

Unpacking and Appearance

The VTF-1 mk3 arrived sandwiched between eight thick foam blocks on every corner that kept the subwoofer away from the box sides and protected it from bumps and shocks. It was bagged in a soft foam wrapping to protect it from scuffs, and a thick plastic bag around the foam bag to protect it from moisture. Since it is not a massive or heavy unit, these efforts should be more than sufficient to keep the it safe during shipping.

VTF1_grille.jpg      VTF1_heroC.jpg

Out of packing, its looks like a fairly typical subwoofer. The vinyl finish has a smooth sheen that is nice, although, as with the VTF-2 mk5, it seems to be somewhat of a downgrade from the satin black finish of the previous mk2. The rounded edges do soften its appearance, especially with the grille on. It is not a very large sub, at least in comparison to the subwoofers I normally review. It should be able to disappear in a dimly lit corner without problem if the user does not want it to stick out. Without the grille, it does look functional with the driver, ports, and grille guides on display. I do like the shiny inverted dustcap of the cone. The VTF-1 mk3 looks like a smaller VTF-2 mk5.

As with other variable-tuning subwoofers, new owners are advised to read the manual to operate them properly, even more so than with regular subwoofers. They are not quite as simple as plug-and-play if you want to get the most out of them. Owners would do well to understand how sealing the ports combined with onboard equalization mode will affect the system.

Design Overview

The VTF-1 mk3 looks like a smaller VTF-2 mk5, because, in many ways, it is a smaller VTF-2 mk5. It shares the same amplifier technology, same cabinet construction and design; only the sizes are different. As with the VTF-2 mk5, the cabinet paneling of the VTF-1 mk3 uses 3/4” MDF, except for the front baffle which is 1.5” thick. There is a piece of cross-bracing supporting the two 12.5” long ports. Each port has a 3.5” diameter. The cabinet is lined with polyfill. The rubber feet are the same, as well as the grille construction that uses rounded metal pins for the grille guide sockets.

VTF1_interiorC.jpg

Inside view of VTF-1 mk3 Subwoofer

The ‘VTF’ in the VTF-1 stands for Variable Tuned Frequency, which is the system that allows the user to adjust the extension of deep bass. For those who are not familiar with how this system works, we will quote from our VTF-2 mk5 review:

The function of ports on speakers and subwoofers is to produce sound more efficiently at low frequencies than the drivers are able to. They do this by using the backward motion of the woofer into the cabinet to resonate the air mass within the port. The port’s length and width affect the frequencies at which the port generates sound; the longer a port is with respect to its width, the deeper frequencies it will produce. However, the wider a port is, the more output it will generate at its resonant frequency. Placing multiple ports in a speaker or subwoofer will act like one port that has the width of all the ports combined. In systems such as Hsu’s VTF subwoofers, the user can exchange output headroom at higher frequencies for lower frequency output by plugging one of its ports, thereby increasing the length of the ports with respect to their collective width. This enables the subwoofer to play deeper frequencies far more effectively but at the cost of output potential at some frequencies above that point.

VTF1_driver_side.jpg    VTF1_driver_bottomC.jpg

The driver lookVTF1_rear_amp_plateC.jpgs adequate for the task but not heavy-duty. It is largely assisted by the generous cabinet size and port area. It uses a stamped steel basket, a decent sized Nomex spider for a 10”, a 2” voice coil, and a single 5” x ¾ magnetic slug. We can see that the backplate has been bumped out to make room for higher excursions, and there is a hole in the pole piece for ventilation. Hsu informed me that the driver uses a shorting ring. On the whole, the driver looks adequate for the task at hand.

The VTF-1 mk3 amplifier is similarly a scaled version of the VTF-2 mk5’s amp. For the VTF-1 mk3, Hsu has upgraded the BASH amplifier to a 250-watt unit, up from the 200-watt amp of the mk2. The BASH (Bridged Amplifier Switching Hybrid) amplifier technology combines the sound quality of AB amplifier topologies with the high efficiency of Class D amplifiers. Among the features of the VTF-1’s amplifier, a Q control is used to manipulate the slope of the low-end roll-off. Speaker-level inputs allow the subwoofer to be used with systems that do not have an LFE output or a line-level output. An adjustable low-pass filter ranging from 30 Hz to 90 Hz gives users control over the subwoofer’s bandwidth for setups that lack bass management. A voltage input switch makes the subwoofer usable in countries with different electrical standards.

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About the author:

James Larson is Audioholics' primary loudspeaker and subwoofer reviewer on account of his deep knowledge of loudspeaker functioning and performance and also his overall enthusiasm toward moving the state of audio science forward.

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Recent Forum Posts:

Bucknekked posts on October 12, 2017 18:01
I may be the odd man out here, but, I use the near field set up today for my little subwoofer and if I replace it with a Hsu I would still do that. Because I'm in a near field listening setup for music, the choice to measure it smack dab behind the listening position makes me smile ! I liked the completeness of the review. Reviews like this give me confidence in making a future selection. Reviews like this and I can call Pogre up and have him come over and make recommendations in person. That does the trick.
shadyJ posts on September 28, 2017 17:39
William Lemmerhirt, post: 1212839, member: 81215
Nice review, but I think the near field review should be accompanied by another one with placement more akin to where most people will use it. As you said shady, it wouldn’t be fair to intentionally place the little 10 in a spot to a disadvantage but conversely, a near field review is equally unfair. (Most people won’t be able to see through the disclaimer early in the review about typical placement behavior).
All of my review subs get placed in that near-field position, because it offers the flattest response for a single sub in my room for my listening position, not because it provides an higher tactile sensation. So the VTF-1 is on a fair footing with the other subs in my reviews, at least for the subjective experiences. If I placed it anywhere else, it would not be fair to it with respect to other subs I have reviewed.

We just have to encourage prospective subwoofer buyers to take the time to place the sub in an optimal position to get good results. Great subwoofers can be made to sound terrible with poor placement, and mediocre subs can be made to sound passable with good placement. It is such a huge factor in how a subwoofer will sound in room that it can not be stressed enough.
William Lemmerhirt posts on September 28, 2017 11:58
Nice review, but I think the near field review should be accompanied by another one with placement more akin to where most people will use it. As you said shady, it wouldn’t be fair to intentionally place the little 10 in a spot to a disadvantage but conversely, a near field review is equally unfair. (Most people won’t be able to see through the disclaimer early in the review about typical placement behavior).
BoredSysAdmin posts on September 28, 2017 08:07
another excellent review James
gene posts on September 28, 2017 00:38
Hsu's latest subwoofer, the VTF-1 mk3, is a little powerhouse on paper with a 10“ driver, 250 watt amplifier, and dual 3.5” diameter ports. We have been interested in seeing what it can do ever since it was announced late last year. Now that we have finally had a chance to give it a few laps around our test track, we are ready to report what is delivered from Hsu's $400 subwoofer (price not including shipping). Read our review of the VTF-1 mk3 to learn about this point of entry to high-fidelity subwoofage.

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