PSB SubSeries 100 Mini Desktop Subwoofer Review

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The Perfect Subwoofer for Small Spaces?

Brent Butterworth

At just 6.75 inches high, the PSB SubSeries 100 is the smallest sub I've heard in 20+ years of speaker testing. What good is such a tiny sub? After all, with just a 5.25-inch woofer, there's no way it can play super-deep bass, right?

Right. But desktop audio systems don't need super-deep bass. They just need a little more bass, and that's what the SubSeries 100 is designed to deliver. I guess you could use one or two in a super-compact home theater system, but the SubSeries 100 is mainly designed to work with desktop audio systems like PSB's Alpha PS1.

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PSB SubSeries 100: Features

Brent Butterworth

• 5.25-inch woofer
• 50 watts RMS/100 watts dynamic peak Class D amplifier
• RCA stereo analog input
• 0-180° phase switch
• 50 to 150 Hz crossover frequency knob
• USB charging output
• Dimensions 6.38 x 6.38 x 7.88 in / 162 x 162 x 199 mm (​hwd)
• Weight 6.05 lbs./2.75 kg

The SubSeries 100 has pretty much the same feature set as a typical large subwoofer, except that it adds a USB output that you can use to charge portable devices.

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PSB SubSeries 100: Setup and Ergonomics

PSB speakers

I used the SubSeries 100 in a desktop stereo setting with a set of Alpha PS1s, and in a home theater setting with an Outlaw Model 975 preamp/processor, an AudioControl Savoy seven-channel amp, and a 5.1 system using Sunfire CRM-2 speakers. With the Alpha PS1 system, I fed the SubSeries 100 from the PS1's subwoofer output. With the home theater rig, I used the Outlaw's subwoofer output.

Setting up the SubSeries 100 was totally ordinary with the Sunfires, or with the Alpha PS1s used on stands near the wall behind them. The settings PSB recommended for use with the Alpha PS1 system (seen in the image above) worked great. The SubSeries 100 blended well with the Alpha PS1s and the Sunfire system.

In a desktop setting, with the Alpha PS1s sitting on the rectangular kitchen table I often use as a desk, setting up the SubSeries 100 was a lot fussier. The table boosted the bass output of the Alpha PS1s. With both the sub and the speakers putting out substantial bass, the sound was bloated and boomy. I had to turn the sub's crossover frequency down to 80 Hz; flip its phase switch; and turn its level down. It took about 10 minutes to get it dialed-in in the desktop setting.

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PSB SubSeries 100: Sound Quality

Brent Butterworth

Once I got the SubSeries 100 dialed in properly, I was pretty thrilled with it. It seemed to me like a much better-sounding version of the subs that come with inexpensive 2.1-channel soundbar systems. Those subs tend to sound a little boomy (or a lot boomy) and undefined, partly because they're usually made with relatively flimsy cabinets and tuned more for output than for sound quality.

The SubSeries 100 had about the same output and deep-bass extension as one of the smaller soundbar subs, but delivered a much better sense of punch and definition. On the English Beat's I Just Can't Stop It, a CD filled with the relentless bass lines typical of ska, the SubSeries 100 totally pumped, giving me a great sense of the natural "growl" of the electric bass. The melodic bass lines in saxophonist Sonny Criss' joyous, upbeat version of "Up, Up and Away" sang, each note sounding well-defined, even in level and consistent in tonal character.

Even when I played "Drawing Flies" from Soundgarden's intense Badmotorfinger, the SubSeries 100 gave me all the extra bottom end I wanted.

Of course, I had to find the little sub's limits, right? Plain ol' rock won't do that because a standard electric bass goes down to only 41 Hz, a frequency well within the SubSeries 100's bandwidth. So I played "Falling" from electro-pop group Olive, which features a synth bass line with a 32.7-Hz low C. The SubSeries 100 played it, but at a much-reduced volume and with audible distortion. And while the SubSeries 100 sounded just fine with the Sunfires when I played normal, plot-driven movies like The Talented Mr. Ripley, the sound got a little thin during the speeder chase scene from .

PSB's founder and chief designer Paul Barton sent me four SubSeries 100s so I could experiment with adding more for greater output and smoother response. In desktop applications, though, you really don't need any more level than a single SubSeries 100 can muster. I went ahead and plugged in a second one, placing it about 8 feet from the first one in my desktop setup. While I had to turn down both of them to a pretty low level to get a good balance, I did enjoy the extra smoothness in the bass response. The studio-slick bass line from Steely Dan's "Aja" sounded incredibly precise, with perfect pace, punch, and rhythm.

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PSB SubSeries 100: Measurements

PSB-Sub-Sonic-100 frequency response
Brent Butterworth

Frequency response
±3 dB from 38 to 142 Hz

Crossover low-pass function
-17 dB/octave

CEA-2010A bass output
• Ultra-low bass (20-31.5 Hz) average: 83.3 dB
20 Hz        78.1 dB
25 Hz        81.4 dB
31.5 Hz     87.6 dB
• Low bass (40-63 Hz) average: 100.2 dB
40 Hz        94.1 dB
50 Hz        99.3 dB
63 Hz        104.3 dB L

I measured the SubSonic 100 using my Clio 10 FW audio analyzer, with the microphone placed 1 meter from the front of the subwoofer. The graph above shows the frequency response with the crossover frequency set to maximum (orange trace) and with the crossover frequency set to 80 Hz (purple trace). This response is about what I expected from my listening tests.

CEA-2010A output measurements were taken at 1 meter, adequate in the case of this sub because it's so small and because it's a sealed-box design. Averages are calculated in pascals. The output from the SubSonic 100 isn't high, but the fact that I got measurable output way down at 20 Hz is just amazing. A lot of much larger subs can't do that. Also, the output in the low-bass (40-63 Hz) octave is impressively consistent considering how small this sub is.

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PSB SubSeries 100: Final Take

Brent Butterworth

No doubt the SubSeries 100 is a cool little creation. For something its size, it plays surprisingly low and loud, and it delivers much better fidelity than most of the crummy little compact subs that come with 2.1-channel soundbars, compact audio systems, etc.

However, for a little more money you can get something like the Hsu Research STF-1, which will sound great and give you a lot more output than the SubSeries 100. And you can get any number of pretty decent 8-, 10- and even 12-inch subwoofers off Amazon for less. But of course, all of those products are much, much larger than the SubSeries 100, and much harder to fit under your desk.

People happily pay $100 for a little extra foot room on just one airline flight. With the SubSeries 100, you pay about the same premium but you get that extra foot room every day.