STF-2 Subwoofer

"produced an almost startling solidity"
Home Theater Magazine

From the sun drenched, earthquake riddled coast of California comes an exquisite rumble that will stir the soul. Since its inception in 1991, HSU Research has delivered a secret blend of high quality, high output, high value bass that simply “sounds good.”

The STF line is the result of hundreds of hours of development by Dr. Hsu and his team. All costs go to a powerful BASH amplifier, defeatable auto-on switch, defeatable/continuously adjustable 24 dB/Oct crossover, phase switch, gold plated binding posts and RCA jack, spiked feet, custom driver with extremely good cone control (low Q), 3 inch diameter flared port, quality black matte finish, and our traditional rounded corners.

STF-2 Frequency Response Curve

Freq Response Curve with 1 Port Open, EQ1


CEA 2010 Measurements (1 Meter, Peak)


Tone Burst Center Frequency (Hz) Maximum SPL CEA 2010 Rating
20 94.2 104.7
25 107.1
31.5 112.7
40 114.0 116.5
50 116.9
63 118.6
80 118.4


Industry Reviews

"produced an almost startling solidity...a sort of 'are these really speakers?' effect...the sub is a keeper"

Home Theater Magazine (March 2004)


"The STF-2 performed better than its price tag would suggest...exceptionally clean, and when placed appropriately, with the levels carefully calibrated, blended perfectly with the rest of the system."

Secrets of Home Theater and Hi-Fi


Read More Reviews

"will give an average-size room the absolute lowdown"

Affordable Audio (Mar. 2006)


" a genuine bargain"

Widescreen Review (March 2005)


"high-quality sound, for both hometheater and audio use"

The Audiophile Voice (Vol. 10, Issue 6, 2005)


Customer Testimonials

"This STF-2 is every bit as good ,if not better, than the Sunfire Mark II"



"Dear Dr. Hsu,

A couple of years ago I bought your STF-2 Subwoofer.

The short version of my report to you is that I'm most pleased and satisfied with my investment.  In fact it's one of the best purchases I have ever made.

I've had time to play with it and adjust it to my tastes.  I've played a good deal of my collection on it.  I am happy as can be.  Much of my collection is classical music and there is some wonderful bass in many of the pieces, especially the pipe organ (theatre and concert types).  I also listen to an eclectic range of electronic music, percussion, didgeridoo, sound effects, steam engines, African music, country, movie sound tracks, jazz and you-name-it.

The STF-2 integrates beautifully with my eclectic collection of speakers, including Altec Lansing and Klipsch.

Thank you for the time and effort you have invested in making a wonderful and affordable subwoofer.  It's a great step up from the AR subwoofer I used to own.  I am most pleased, satisfied  and content with my subwoofer."



"I must applaud your design I have yet to find a sub which I like more than my STF-2"



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Product At a Glance

Amplifier Power (RMS) 800 W Short Term, 200 W Continuous
Frequency Response 25 - 100 Hz, +/- 2 dB
Woofer Down Firing 10 Inch
Crossover 30 - 90 Hz, Bypassable
Crossover Slope 24 dB/Oct
Phase 0°/180°
Inputs Line Level (1), Speaker Level (2)
Power Outlet Requirement 250W, 120/240V
Enclosure Dimensions 17" H x 14" W x 17" D
Dimensions with Feet & Amp 19" H x 14" W x 1734" D
Weight 37 lbs
Warranty 7-years on Woofer, 2-years on Electronics
Designed and Engineered in the U.S.A.


Owners Guide

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