Initially, MLS time domain measurements were performed for the HRS-12s to determine frequency response and output characteristics.  Unfortunately, subsequent review of the measured data indicated problems with the measurement itself after the subs had been returned to the manufacturer and as such, the plots will not be presented.

As part of the measurement process, I typically run an independent measurement with an SPL meter to provide a reference point when back checking the primary measurements.

Measurements performed nearfield at the approximate acoustic center of the driver, about 2 inches (5 cm), indicated a peak SPL of 120 dB.  At this point, the protection/limiting circuitry kicked in and additional preamp gain would not increase the output.

Sunfire claims the maximum output that the HRS-12 subwoofers are capable of is 108 dB at 1 meter with room reinforcement.  Acoustic losses into free space are widely known to be –6.02 dB for each doubling of distance from the sound source.  The addition of reflective surfaces that are large compared to the wavelength of the sound near the source decreases the loss.  With a single surface, also known as an acoustic half-space, the loss is –3.01 dB for each doubling of distance.

Correlating nearfield SPL output with the more common 1 meter anechoic measurement results in an acoustic half space yields the following results:

The calculated result is consistent with Sunfire’s claim of 108 dB at 1 meter in room where the addition of one or two walls to the presence of the floor would provide additional SPL reinforcement.  The result is also consistent with my subjective observations about the HRS-12s ability to provide substantial bass output under real world usage conditions.  This is a significant amount of output particularly when considering that it comes from a 38 lb sealed subwoofer with an internal cabinet volume that is defined by dimensions that are no larger than the diameter of the driver in any direction.

Conclusions & Recommendations

The Sunfire HRS-12 is quite a potent little package.

To get good monster bass, usually some fairly mongo subs are required.  Brutes the size of tables, denizens of the corner, which make their presence obvious even without speaking.  Those who have been constrained by space or WAF have had to go without.  The HRS-12 can provide those poor, deprived souls with the bass they need without taking up significant room space or upsetting the Misses, at least, not too much.

It is rare to find a sub this small that can not only provide copious bass output, but also can provide deep and accurate bass output as well.  Cabinet size, maximum SPL, and deep frequency response are competing demands in subwoofer design and these conflicts are more easily solved by throwing money at a design than by skillful balancing at a price point.  While not cheap by some standards, the HRS-12 subwoofers do an excellent job balancing the design and providing outstanding performance without skyrocketing the price.

The HRS-12s represent what can be done in comparison with extreme designs and these Sunfire subs can certainly hang in there with products at that level even if they can not best them in an absolute sense.  Considering that the HRS-12s can easily provide better than two thirds of the performance of subs like the Fathoms at a mere one third of the price, the HRS-12s are a well engineered, high value product that represents a very good bargain for anyone looking for extreme levels of bass performance at less than extreme prices.

The HRS-12 subwoofer can certainly belt out the bass, definitely making an excellent choice for anyone looking for depth, clarity, and good high SPL performance at a more reasonable size or price.

Sunfire Corporation

1920 Bickford Ave
Snohomish, WA 98290
800-554-0150
Canada 800-387-9101
www.sunfire.com