Product Review - HSU Research HRSW12Va Subwoofer - May, 1997

By Stacey Spears



Hsu Research HRSW12Va Subwoofer; Downward firing 12" driver in ported cylindrical enclosure; size 22.5" H (including 2.5" spiked feet) x 23" diameter; black cloth cover on sides; Zolatone (granite) paint finish on top (light oak and dark walnut available for $75 extra); weight 50 pounds; separate 250 watt amplifier included; connections for left and right inputs from preamplifier (RCA) and speakers; 91 Hz active low and high pass filter - fourth order; other crossover frequency modules available at $15 each (28 - 155 Hz); $1,000, Hsu Research, 14946 Shoemaker Avenue, Unit L, Santa Fe Springs, California 90670; Phone (562) 404-3848.

The subwoofer is, without a doubt, one of the coolest pieces in a home theater or hi-fi system. Whenever home theater equipment is being demonstrated, there is usually a film that is full of explosions, or a selection of music like the 1812 Overture in the case of a high fidelity audio system. There is no better way to awe anyone than with a seismic event. But you and I both know that quantity of sound is not everything. Obviously, quality takes front seat to quantity any day. Most chain stores do not understand this concept and usually give a very poor presentation, often, with distorted bass. The store environment does not sound like your family room anyway, so what you hear in the store is most likely not what you will hear when you get the equipment home.

Enter Hsu Research. Hsu sells factory direct with no middle person to raise the cost or give a poor presentation of their product . The only problem with factory direct is that unless you live in the area, you will only be able to audition the Sub in your house. THAT'S THE POINT!

Two years ago, John Johnson gave praise to the HRSW12V in Secrets. After several refinements, Dr. Poh Ser Hsu has unleashed upon us a new updated version. Is it as good as its predecessor or better? Let's take a look.

In the Beginning

Originally, Hsu had the amplifier built into the bottom of the 12V. It was later removed and put into an external case that matched the top of the subwoofer. The amplifier was removed to cut down on the heat created from being in an enclosed environment and also to minimize any effects that the vibration from the subwoofer might cause. With the 12Va, the amplifier is now in a 19" wide full size case. It is much more attractive than the little cube that it resided in before. It is also a beefier amplifier now producing 250 watts of power (into 4 ohms); the previous amp was rated at 150 watts.

Also inside the amplifier case there is a crossover, phase, and soft clipping protection circuitry. On the front of the amp you have the power switch and level control. On the back there are line level and speaker level inputs, outputs, as well as the phase, crossover on/off, and soft clipping switches. The phase is selectable between 0
0 and 1800. The crossover is a plug-in module with the factory setting of 91 Hz. If your surround processor has a built-in crossover, you can bypass the Hsu crossover. Other modules are available; they come in sets of three, one for the low-pass and one each for the hi-pass channels. Soft clipping is a protection system; it should be used when you have those friends over who like to turn up the volume when you are not looking. This feature rounds off the square waves when the amp starts to clip.

While the 12Va is identical to the 12V on the outside, when you take a peek underneath, you will notice the first difference, namely the presence of two ports. The 12V had one 3.75" diameter port flared at only one end, while the new 12Va has two 4" diameter ports that are approximately 42" long, flared at both ends. The 12V was able to reproduce 20 Hz, but the 12Va at 20 Hz is MUCH, cleaner. The 12" driver has also been improved; it now contains two magnets instead of one and has about double the excursion. (This baby moves!)

The Hsu may very well have "Spouse Acceptance Factor". The other day my parents were over, and my step father asked me why I was fiddling with the end table When I informed him it was a subwoofer he was very surprised. I could see the look in his eyes; he can now sneak some extra subs into their house and tell my mom that it is new furniture. Yes, my parents are hip, they have a little LD collection going, along with DSS, a 50" 16:9 TV, and the full home THX setup.

There are three tops available for the 12Va. The standard is Zolatone
[click here for photo], while an oak top [click here for photo], and a walnut top [click here for photo] are optional.

Taking a First Look

When I first plugged in the sub, I positioned it as a coffee table; this is the recommended setup from Hsu (however, the amp is not compatible with caffeine). The first thing I noticed was that the sub started to rock back and forth, kind of like R2D2 from Star Wars, when I put on ID4. I put a little weight on the top, and that held it in place. The reason it is so light is because it is made out of paper (the body is a cardboard cylinder), not wood like traditional speakers. A cylinder is very rigid and eliminates standing waves because none of the sides are parallel. (The top and bottom are parallel.)

Like all loudspeakers, the placement of the sub is very important. I have experienced the worst case scenario from absolutely no bass to extremely boomy bass just by placing it wrong. While I lived in my last house, I brought home a sub one day and put it where I had room, i.e., the entrance by the front door. When I hit "play", there was NO bass from my listening position; instead all of the energy was by my front door. What I ended up doing was placing my sub at my listening position, putting on pink noise, and running around the room looking for the best response from the speaker. When I found the spot, this is where I placed the sub. Voila, I had good bass at the listening position!

Hsu goes to great lengths to help you place the sub in the correct position. When I obtained the 12Va, Dr. Hsu had me draw a diagram of my room, and he then proceeded to recommend a couple of starting places. As I said before, I started by placing the sub in front of my couch as a coffee table. This is their recommended position, as it is supposed to help with the time alignment of the sub with the main speakers. I then moved the sub to the front left corner of my listening room, and the bass was improved, although a little boomy. My surround processor allows the delay of any channel; this gave me a little more flexibility in the subwoofer placement. I finally settled with the sub along the left wall, a few feet out from the corner; this is where I felt the bass was the cleanest.

The Bottom Line (or notes)

I have three letters: D.T.S.!!! If you want to take advantage of DTS, you will need a sub that can handle it. The Hsu had no problems with the incredible bass of anything I threw at it. For those who have experienced "Jurassic Park" on your Pro Logic system, you will be blown away when T- Rex stomps in DTS. I was afraid that while playing the disc that either (A), my house would collapse, or (B), a Cal Tech scientist would come knocking on my door saying something about the epicenter. With "Apollo 13", I thought the 12Va was going into orbit along with the Apollo 13 capsule! Not once did the 12Va have any problems reproducing the low frequency information. On the THX WOW disc, there is a rattle test that plays from 20 Hz to 200 Hz, and is used to find all the rattles in your listening area. Not only did the Hsu find every rattle in my house, but in the neighbors' homes as well.

For me, how the sub worked with music was the real key, because any sub can boom-boom with movies. The first thing I listened to was the CD included with the sub: "Virgil Fox" (LaserLight 15 313). WOW!. This CD dips below 20 Hz, and the Hsu goes with it. I then proceeded to listen to "Pomp & Pipes" (Reference Recordings RR-58CD). This CD has been known to damage some speakers, but the Hsu performed flawlessly. Then there was "The Great Fantasy Adventure Album" (Telarc CD-80342), which is another sub killer, and the Hsu prowess continued to be evident. With DTS CDs, such as Marvin Gaye's "Forever Yours" (DTS CD 1002), the bass was awesome. "I heard it through the grapevine" was incredible! The last song brought with it some visions of dancing raisins in my head (remember the TV commercial?)

While testing the 12Va, I had it configured in many different ways. For most of the time with the 5.1 soundtracks, I had it set up as a dedicated LFE channel. I used the crossover built into the processor, which was set at 120 Hz. When I would listen to music and standard Dolby Surround material, I reconfigured the sub as a "mono" sub like in the traditional THX sense. I would send all 80 Hz and below info from all channels to the sub. Again, I used the crossover in the surround processor with it like this, and the crossover frequency was 80 Hz.

I didn't bother with the usual frequency response chart, because the sub was obviously producing tremendous bass, and I was more than satisfied. However, I will give you one value that I measure in my listening room from my usual spot, and that was a whopping
108 dB at 20 Hz!!! I also took the sub to work and put it in the middle of our parking lot, which is about 20 feet from the building (early in the morning before anyone arrived - the outdoor idea came from Dr Hsu himself), and at 1 meter, I measured 100 dB at 20 Hz. So you can see that there was some boost because of my room.

Associated Equipment

Along with the Hsu, a Pioneer (CLD-97 with Faroudja Comb Filter) played the LDs. Toshiba (SD-3006) supplied the DVD experience. Audio Alchemy spun the CDs. Meridian (565 w/ 7.1) provided the surround sound experience. Amplification for the other 5 channels was courtesy of Sunfire (Cinema Grand), and the loudspeakers were Mirage and B&W. Equalization was provided by Audio Control with the Bijou THX 7 channel EQ. The video display was a Pioneer (PRO-77) and a Toshiba (TW40F80). Various laserdiscs were used in DTS, Dolby Digital, and Dolby Surround as well as several music CDs, in DTS and standard stereo.


Subs have always been great additions to home theaters, because a movie soundtrack is usually full of LOUD, DEEP effects. Subs have not always been welcome in a high-end audio system because, quality of the bass becomes an issue, NOT just quantity . Well, Bo may know a lot of things, but Hsu knows subs, and Dr. Hsu has fine-tuned the 12Va. It blends as well with music as it does with movies. At $1,000 this is one of the best deals on the market.

If you are looking for even more bass, a second 12Va would further improve things. Stereo subs add quite a bit to the sound stage, and in today's market, $2,000 for this much low frequency power is not terribly expensive. If you already own a six channel amp, you can purchase the subwoofer unpowered for $550. Be sure that the amp can provide 250W rms into 4 Ohms.

Stacey Spears

Copyright 1995, 1996, 1997 Secrets of Home Theater & High Fidelity
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