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Hsu Research VTF-TN1 15" Subwoofer: Deeper Bass, Lower Cost!

Hsu VTF-TN1 15" Subwoofer

Hsu VTF-TN1 15" Subwoofer


  • Product Name: VTF-TN1 Subwoofer
  • Manufacturer: Hsu Research
  • Review Date: March 14, 2024 10:00
  • MSRP: $1,200
  • First Impression: Gotta Have It!
NEW HSU VTF-TN1 15" Subwoofer for $1,200?!?

  • Woofer: 15" high-excursion driver
  • Speaker Type: Bass reflex with down‑firing port
  • Amplifier Power (RMS): 600 watts
  • Variable Phase Control: 0° or 180°
  • Inputs: Stereo line level (2), balanced XLR (2), and speaker level (2)
  • Dimensions: 18.5" D x 18.5" W x 30" H

TN1 with Dr HsuNew 15" HSU Flagship Sub ONLY $1,199!

It has been a while since Hsu Research launched a new subwoofer (the terrific but now-discontinued VTF-1 mk3, for anyone keeping track). However, that has now changed with today’s release of the VTF-TN1. The VTF-TN1 replaces the venerable VTF-15h MKII. For a long time, the VTF-15h MKII was one of the leaders in high-performance bang-for-the-buck deep bass, but Hsu has figured out how to improve performance while cutting the price by cleverly reconfiguring the enclosure. In an era of rapidly increasing prices for the same qualitative characteristics, Hsu’s improved performance yet lowered cost has to be considered a minor miracle. The VTF-15h MKII was $1,245 but the VTF-TN1 is $1,199!

VTF-TN1 Performance Advantages over the VTF-15h MK II

To be sure, the performance improvements aren’t likely to be a huge step up from the VTF-15h MKII. But where it does improve performance is significant: the VTF-TN1 aims for a lower tuning frequency than the VTF-15h MKII and should offer superior deep bass. That should enable it to tackle some serious deep bass since the VTF-15h MKII could be tuned to 22Hz in ‘Max output’ mode or 16Hz in ‘Max Extension’ mode. By comparison, the VTF-TN1 can be tuned to 18Hz in ‘Max Output’ mode and an astonishing 15Hz in ‘Max Extension’ mode. This is a noteworthy move in today’s subwoofer marketplace where other brands are giving up on sub-20Hz bass to focus more on easy gains above that point. The VTF-TN1 accomplishes this by moving away from the triangular ports of the VTF-15h MKII in favor of a pair of massively flared, 4” diameter cylindrical ports that should improve stability and output in the port-generated bandwidth. In fact, Hsu was able to record passing 12.5Hz bursts tests of the TN1 which wasn’t something they were able to achieve with the VTF-15h MKII.

TN pair angle

In addition to the improved port design, Hsu has re-oriented the ports to a down-firing configuration which brings in other advantages. Firstly, the confining space between the floor and ports can increase the port air mass and thus improve low-end performance. Secondly, by repositioning the ports away from any angle that would face the listener, any unintended higher-frequency port artifacts would be masked. That isn’t a big concern with a sub that has such large and optimized ports, but in my experience as a subwoofer reviewer, all ported subs can be driven into port turbulence at a high enough drive level without any exceptions that I can remember, and moving the ports away from the listener should grant a bit more headroom before any noticeable nonlinearities occur. Another advantage of down-firing ports is that users with pets or small children will be less likely to interfere with the ports as opposed to exposed and vulnerable ports. 

One interesting design decision that Hsu has made with the VTF-TN1 is that the enclosure has moved upward, or, to phrase it another way, it has traded depth for height versus the VTF-15h MKII. This gives it similar performance for a smaller footprint, and it also helps to avoid bends in the port which further reduces any potential port turbulence. In fact, the VTF-TN1 has the same footprint as Hsu’s sealed ULS-15 MKII. Hsu has also added more internal bracing into the cabinet versus the VTF-15h MKII, so users can have a better-built enclosure at a lower cost. What is more, Hsu hasn’t sacrificed finish quality, and the VTF-TN1 uses a true smooth satin black finish as opposed to the textured vinyl that many other manufacturers somehow claim is ‘satin black.’

TN1 angleThe VTF-TN1 still retains a 600-watt RMS amp and 15” driver, so, spec-wise, it isn’t much different from the VTF-15h MKII except for enclosure dimensions, but the enclosure makes such a profound difference that Hsu has measured the VTF-TN1 to have some real deep bass gains versus their outgoing sub. As its name indicates, the VTF-TN1 still retains Hsu’s famous ‘variable tuning’ (where VTF stands for Variable Tungin Frequency), so users can trade lower deep bass for louder deep bass. Port plugs will be included so users can easily switch between operating modes including a fully sealed operating mode. The VTF-TN1 does not lose the 15h MKII’s plethora of input options, so users still get RCA line-level inputs as well as balanced XLR inputs and speaker-level inputs. It keeps Hsu’s Q control so users have additional freedom to shape the low-end response of the sub to get it tuned to perfection. It also has a lower standby power (1W) as compared to the 15h MKII. 

Naming the HSU TN1 Subwoofer

One interesting note about the naming of TN1 is that it’s a nod to the well-known subwoofer maven Tom Nousaine who passed away about ten years ago. This isn’t the first subwoofer that Hsu used to tip their hat to Tom, since some of their bygone cylinder subs, the TN1220HO and TN1225HO, also reference Nousaine in their titles. Nousaine was a passionate critic of nonsense audiophilia and a kindred spirit to Audioholics in his day (one example courtesy of Wayback Machine: Urban Audio Legends). He was also an avid subwoofer reviewer and a leading proponent of subwoofers that could dig down to truly deep frequencies (read The Truth About Subwoofers). I think he would be pretty happy to have his name attached to a subwoofer that could produce serious output at 16Hz and even pass a 12.5Hz burst test.

VTF TN1 Single Port Response 

While there are improvements over the outgoing VTF-15h MKII, the big news here is that the cost is less. It’s hard to imagine a shareholder-owned corporation lowering pricing for an improved product after a bout with inflation, but as a small business, Hsu is free to set pricing to whatever they wish. It may still be the most profitable move to entice buyers in such a fiercely competitive segment, but whatever their motive for such aggressive pricing, consumers win, so I can’t complain. To up the ante even further, Hsu now adds the 5-year electronics warranty as standard whereas before it could only be purchased as an extension. This gives the VTF-TN1 one of the best warranties in the business when their 7-year woofer warranty is considered. What is better, there will be a $100 discount on pre-orders between March 14th and April 12th, 2024 until stock runs out. The pre-order does require a non-refundable $200 deposit, but to get an equal-to-better VTF-15h MKII performance for roughly $1100 (not including shipping) is an insanely good deal. For those who want to learn more about the VTF-TN1, Audioholics will be running a full review sometime in the spring, so stay tuned to these pages to see what Hsu’s latest sub brings to the table.

Unless otherwise indicated, this is a preview article for the featured product. A formal review may or may not follow in the future.

About the author:
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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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