The SA-100 has an MSRP of $74.99, which makes it a very reasonably priced subwoofer. Emerson Mobile's representative states the subwoofer works well in small sealed, bandpass, and ported enclosures. Upon inspection of the drivers I found the following: plastic trim ring, large rolled rubber surround, bright blue chrome-plated injection poly cone, 70 oz. magnet assembly, 2-inch voice coil, vented pole piece, bumped back plate, heavy duty binding posts, and a heavy stamped steel basket with an interesting texture coat. The SA-100 has a rated power handling of 350 watts RMS. During my testing I determined that to be a peak power rating, as the subwoofers were driven to the point of audible distortion at or before that point. Power handling before audible distortion is also dependent on the frequency of the source material as well. I found this to be an accurate rating in the upper bass frequencies, but the subwoofer could be driven to audible distortion with less power in the lower audible frequency range.
Now with subwoofers and information in hand I decided it was time to sit down and do some enclosure modeling. I entered the driver parameters into WinISD to begin modeling enclosures. WinISD shows this driver to be optimal in a vented enclosure (ported) or a 6th order bandpass. I wanted to look at it sealed as well, since the manufacturer stated this would yield good response. In the response graph below I modeled the SA-100 in a sealed enclosure of .75 cubic ft. per driver, as well as 1.5 cubic ft. per driver.
I decided to take WinISD at face value and look at a vented enclosure for them. I chose a fairly large vented enclosure of 2.35 cubic ft. per driver tuned to 29 Hz. This makes for a pretty large enclosure for a pair of 10-inch subwoofers. However, those of you who are familiar with vented enclosures know that the more internal volume and vent area you can come up with the more SPL you will attain as a result. The vented enclosure appeared to have a nice smooth frequency response. According to WinISD this large vented enclosure should provide a lot more output then its sealed counterparts between 20 and 50 Hz.
I was concerned about low frequency extension with the sealed enclosures. However, I already had a .75 cubic ft. and a 1.5 cubic ft. per chamber sealed enclosure for a pair of 10-inch subwoofers so I decided to begin there.
Now on to the fun part! Being the creature of habit that I am, I started out with the 1997 version of the IASCA test disc. I skipped through to track 5, "The Vikings from Pomp & Pipes." Fourteen seconds into the track the organ starts with a tremendous amount of low frequency energy. The fundamentals should be felt more then heard. My fear of insufficient low frequency extension from the SA-100 subwoofers in a sealed enclosure was confirmed. They were not able to reproduce this low frequency information with any authority. However, the drum beat 20 seconds into the track had a solid impact. I strolled through the other tracks on this disk. Each time I was satisfied by the impact that these subwoofers had on musical tracks. However, when you switch to something with a lot of low frequency energy (below 40 Hz) then it was easy to drive them into audible distortion at fairly low levels. Overall sound quality was a little lacking. I sampled through a Johnny Lang CD, "Save the Last Dance," and Crystal Method's "Vegas" briefly after this. With musical information this is a reasonably capable subwoofer in a sealed enclosure, but not the most musical in this application. The larger sealed enclosure offered marginally better low frequency response. However, excursion limited power handling was reduced along with much of the impact. In the .75 cubic ft. per driver enclosure in-car response was down 6 dB at 25 Hz and down 3 dB at 63 and 80 Hz with an 80 Hz low pass filter at 24 dB per octave. Maximum SPL for the pair of subs before audible distortion was at 119 dB in the smaller enclosure. The smell of voice coils getting hot was quite noticeable at this point and I ended the evaluation of the subwoofers in sealed enclosures.
Now it was time to try out the vented enclosure. Since the RTA was already out I decided to measure frequency response first. The frequency response in the ported enclosure was not as stable as it was in the sealed enclosure, but it was at a much higher level with 25 Hz being 3-6 dB down; flat from 31.5 to 40, 50 Hz 3 dB down; and 63-80 Hz being 6 dB down. That was kind of surprising to me after modeling the enclosure. It turned out with other source material these deviations were not noticeable.
Moving back to track 5 on the 1997 version of the IASCA test disc the low frequency response was better from the organ 14 seconds into the track. The fundamentals could be felt at a higher level then in the sealed enclosures. Moving through the tracks I found the subwoofers to be more musical with more impact and low frequency extension. This was a definite improvement over the response of the sealed enclosures. However, it was still fairly easy to drive the subwoofers to the point of audible distortion. (It should be noted that the amplifier used for testing is capable of producing in excess of 900 watts with less then 1% distortion into that load.) I moved on to Faith Hill's "Breathe" and the subs provided a very reasonable rendition of the low frequencies. I decided from there that it was time to move to some more aggressive software so I dropped in Crystal Method. I was greeted by a 126 dB response on track 1. That surprised me, getting that from a pair of $75.00 subwoofers. From there I moved into Limp Bizkit's "Three Dollar Bill" CD which has some fast hard-hitting kick drum low frequency information on it. The subwoofer system pulled them off surprisingly well even with the faster bass passages (as long as I didn't "drop the knob"). Finally I moved on to listen to the Eagles' "Hell Freezes Over" and Selena Anthology CDs. I was surprised by the performance of the SA-100 subwoofers in the vented enclosure with this material. They were capable of producing solid bass with volume levels in the 110 to 118 dB range without audible distortion. The Selena Anthology disc 1, track 1 belted out 128 dB which also matched the peak SPL on track 32 of the IASCA Test Disc which is where the maximum SPL before audible distortion was recorded.
Conclusion
The SA-100 is a very affordable subwoofer that will please many listeners. However, I was not particularly impressed with its performance in sealed enclosures. If you have the space for the vented enclosure the SA-100 subwoofers are capable of a very respectable performance with moderate power levels. And the SA-100 is a viable option for budget-conscious consumers. This sub will provide you with a healthy low-end response with good overall attack. For $75.00 each the performance is surprising.