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Old 06-05-11, 12:42 PM   #1
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Dale Rasco
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Sunfire HRS-12 Subwoofer Review

Sunfire HRS-12 Subwoofer Review

One of the neat things about reviewing equipment is the things you learn along the way. Not just around the technology, but around the people that design, develop and build the equipment. I was fairly unfamiliar with Sunfire, much less it’s founder Bob Carver, when I began this review, but since then I have come to be quite familiar with the history of the brand as well as the history of the man.

Launched in 1994, Sunfire is the creation of Bob Carver of Carver brand fame. Carver, a well-known expert in the field of audio engineering, started the brand after a falling out with Carver Corporation. Carver also received some notoriety in the mid-80s for issuing a challenge to two well-known audio publications. The challenge; Carver stated that he could model some very high end amplifiers so accurately with his own less expensive components that the writers of the publications would not be able to tell the difference in a blind audio test and in the end Carver won the challenge.

Shipping and Packing:
This baby was triple boxed and had plenty of internal bracing between the box and sub so the unit did not move at all in transit. Sunfire does a great job of packing these units before they leave the factory.

Sunfire’s HRS (High Resolution Series) line of products is the company’s middle of the road speaker and subwoofer product line. Using a combination of Sunfire’s Tracking Downconverter in the amps and High Back EMF (Electromotive Force) voice coils, Sunfire is able to create an incredibly powerful, yet compact forward firing sealed subwoofer.

The HRS-12 utilizes a 12” driver housed in a 13.5” cube with a gloss black finish. The technology documentation makes some pretty bold claims and I will do my best to address each of them to the best of my ability. First, the High Back EMF for the driver motor is a patented technology that Bob designed which increases the number of windings on the woofer voice coil. That, combined with an extra-long throw woofer, is claimed to have increased the excursion of the driver to a whopping 5 times that of a normal 15” driver. Based on Sunfire’s documentation, the HRS-12 has a displacement of around 250 cubic inches, which is fairly staggering when the unit footprint is taken into account.

What had me concerned about the unit after reading the technical information was that more excursion normally means more distortion and when you are getting the woofer out 2.5 inches, 5 times that of a normal 15” woofer, I couldn’t imagine the results being very good at all. However; I also will be the first to admit that technology advancements happen all the time that can fix certain scenarios, but we are talking about physics here…

Build Quality:

I have to admit, this is one solid little unit. Weighing in at 38lbs, it is fairly lightweight overall, but seems heavy for the space it takes up. The unit is constructed of ¾” MDF and space is limited inside. The internal bracing consists of corner braces as well as braces along the seams glued together as can be seen below. The plate amp is one intricate looking piece of hardware with just about every possible spot of available silicon being used to supply power and manage the output.

The driver is about as solid as the rest of the unit. The 12” extra-long throw driver is heavy thanks to the oversized motor assembly and I have to admit that I was very tempted to take it apart and peak under the hood, but luckily better judgment prevailed and I didn’t go that far. I will admit that the build quality of the HRS-12 as a whole is simply outstanding and I have to say ‘Job well done’ to Sunfire’s manufacturing process.

Setup and Options:
The HRS-12 hosts the normal options available on most subwoofers these days.
  • Speaker Level Inputs
  • Line Level Inputs
  • High-Pass Outputs
  • Crossover Frequency Adjustment
  • Phase
  • Volume
  • Auto On/Off
The setup was fairly easy and anyone familiar with setting up a home theater system these days should not have any issues. The Line Level left channel provides the quick LFE input for common “sub-out” connectivity on a receiver however; those without this option can utilize the speaker level outputs or a split signal from the processor main outputs to provide the full range signal. For this review I used the LFE input. Overall setup was quick and almost painless except I had to move the Axiom EP800 out of the way and at 113lbs, that isn’t an easy task!

Unfortunately I figured out very quickly that a single HRS-12 would not provide sufficient bass in my room, this is not a deficiency of the HRS-12, it is just that the dimensions of my room does not lend itself to a single sub unless it is a monster like the EP800. That being said, I corrected this situation by re-positioning my listening position within a 13X13 area instead of the 16X19 area I normally utilize. I recalibrated my equipment based on the new listening position and went from 9 to 7 channels by taking the rear surrounds out of the scenario.

After recalibrating to the new listening zone and repositioning the HRS-12 to the left front corner, I found that the sub performed much more efficiently within the new listening zone.

Subjective Listening:
After my last review, I found it necessary to focus my efforts on searching out bass that can’t be easily disguised when it is distorted. I wanted to be able to hear deep impactful bass without sacrificing the integrity of the signal. In other words, I wanted the bass to be reproduced as clean as possible at the loudest volume.

Stereo.1 Listening:
Bassotronics & Bassmekanik – ‘Bass, I love you’
‘Bass, I Love You’ is an instrumental song that has a great piano melody, but delivers some great foundational bass. While the feel of the song is fairly light and airy, the bass anchors it solidly and provides a great listening experience. I found that the HRS-12 did a great job of delivering a clean and powerful bottom end while at the same time giving the music a smooth and elegant feel.

BassBoy – ‘Blinded by the Bass’
Blinded by the Bass has become one of my favorites for testing subwoofers. The bass in this song lends itself very nicely to audibly identifying deficiencies in a subwoofer’s sound quality. The bass is so predominately thick that distortion will be easily identified by the pounding repetition as each measure passes. The HRS-12 again displayed it’s “can-do” attitude as it reproduced the low end with perfect bass reproduction and utmost clarity. This is the one song in my music listening tests that by far impressed me the most and I give the HRS-12 an A+ for its ability to reproduce a quality sounding bottom end.

Clint Mansell – Requiem for a Tower
I really enjoy this piece of music every time I hear it. It is very inspirational and evokes a feeling of overcoming the odds every time I hear it. There is plenty of percussion throughout the song, but it is mostly localized to the bridge sections and is very emotional in nature however; throughout the build of the song, there are some awesome timpani moments that really give the song its soul and the HRS-12 delivered once again with flying colors. When played through the right system, this song always gives me chills and this time was no exception.

Multi-Channel Reference:
War of the Worlds (2005)
I need a new scene for testing as I am beginning to tire of the emergence scene. From the time the ground starts to rumble until the time that the tripod starts destroying everything that moves, the HRS-12 delivered. The impact of this little subs bass could be felt from beginning to end. The only shortfall was the moment when the tripod stands and there is a low frequency that did not come out as predominately as I would have liked to have heard.

Tron: Legacy
The lightcycle scene has become one of my recent favorites to test with. The bottom end laden audio track suits a subwoofer test very nicely. From collisions and low frequency cycle hums to the Daft Punk soundtrack, there is plenty to hear and feel. The HRS-12 was able to accurately reproduce the frequencies and give a firm vibration that allowed me to become immersed within the scene in my make shift listening area.

Cloverfield is another one of my favorite movies to test with these days. The bass is just awesome and ground shaking as the giant monster rampages through New York City and destroys everything in its path. This is the one time in all of my listening tests that I thought the HRS-12 fell just a bit short. The thing I felt was missing was the deep roar that sort of penetrates when Clover is stomping around. It was there, just not as much as I would have liked to have felt.
Meaurement Methodology:
The frequency response measurements were taken using REW. The in-room space that was used to measure was my dedicated home theater room that has a volume just short of 2900 cu. ft. and had a listening position that was approximately ten (10)ft away. The measurements that are posted reflect SPL only.

Reference and Test Hardware:
Test Gear
  • Microphone: IBF-Akustik EMM-8
  • SPL-calibrator: IBF-Akustik SC-1
  • Pre-amp: IBF Akustik MP-1R
  • Sound Card: Creative Sound Blaster X-Fi Surround 5.1
  • PC: Dell Latitude E6400
  • OS: Windows 7 Ultimate Professional
  • Software: REW


The graphs reflect open field and in room measurements from 0-150Hz, 12-200Hz and Sunfire's stated specs of 16-100Hz. As you can see in the open field measurement, the roll-off begins around 20Hz and drops about 13db between 20 and 16Hz. However; the third graph reflects "in-room" response and the it has a much better response down to 16Hz. The open field responses were taken with no equalization applied. The in room responses were run through Audyssey, but not the DSP1124P.

Open Field:

In Room:

Overall the Sunfire HRS-12 performed admirably and is a formidable subwoofer with outstanding sound quality and great performance. That being said, with an MSRP of $899, I personally think that it is a bit on the high side. Similar subs with matching performance can be had for about 20% less, but that is the only thing that keeps me from making it a top pick. If you can find a good deal on them and are in the market then by all means, pick up a pair because you won’t be disappointed.

To discuss this review, see the Sunfire HRS-12 thread in the Home Audio Subwoofers forum.

Conclusion: Recommended

Dale Rasco

“Opportunity is missed by most people because it is dressed in overalls and looks like work." -Thomas A. Edison

Dale Rasco and Temple of Boom REDUX

Shiva 12" Build

Last edited by Dave Upton; 08-26-11 at 04:00 PM.. Reason: Picture Change

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