[Ilkka]

Some quick comments:

B&W PV1
Good frequency response for smaller rooms, but quite low max SPL, especially at low end. Really high distortion at lower frequencies. Upper end is extremely clean though. Low group delay and fast decay. Very small and beautiful enclosure.

BK Monolith-DF
Good extension and FR for larger rooms with less low end room gain. Good overall maximum SPL capability. Low power compression. Low overall distortion. Low group delay and fast decay, especially for a ported subwoofer. No high pass below the tuning, meaning the highest sweep made the woofer to bottom out. Not a problem with program material though. Good performance/price ratio.

BK XLS200-DF
Good frequency response for really small rooms with lots of low end room gain. Doesn’t go very with higher crossover setting and in larger rooms. Low power compression. Extremely low group delay and fast decay. Very small and sturdy enclosure.

Chorus Vertigo XLS 07
A Finnish subwoofer. Very flat frequency response above 30 Hz. Doesn’t go very low though. Very low distortion. Max SPL is limited to ~100 dB.

DIY Adire Audio Tumult 15" MK1 sealed 100L
Frequency response shows that the woofer has a very high inductance. No shorting ring either. Good max SPL capability (especially CEA 2010 test), even though the amp clipped during the highest sweep. Low compression up to 110 dB level. Low deep bass distortion, but quite high upper end distortion already at lower levels (could be high flux modulation distortion). Distortion has quite much high order components, which makes it pretty audible. Low group delay and fast decay. Very heavy and sturdy enclosure. It will be very interesting to see how the CSS SDX15 will do.

DIY Peerless XLS 12" ported 85L
Good frequency response for mid-sized and smaller rooms. Good extension. Port resonance at ~150 Hz. Quite gently sloping crossover. Relative good max SPL. Low distortion up to 100 dB, but the amp clips at higher levels. Low group delay down to 25 Hz. Fast decay too.

DIY Peerless XXLS 10" sealed 50L
Very good frequency response for smaller rooms. Quite limited max SPL. Low distortion at low SPL. Low group delay and fast decay.

DIY Rythmik Audio Direct Servo 12" sealed 56L
Extremely good extension. Very versatile frequency response adjustments. Can be used in larger and also in smaller rooms. Upper end of the frequency response rolls off above ~70 Hz. Quite high max SPL, but high deep bass distortion due to amp clipping. Brian says that he doesn’t want to use any limiters, but lets the amp clip/limit the output instead, so it doesn’t limit the dynamics. Low upper bass distortion, so the servo does its job well. Upper bass distortion mainly 2nd order distortion. Quite high deep bass power compression. Low group delay and fast decay. Good price/performance ratio.

DIY TC Sounds 2xTC-2000 15" sealed 140L
My own little subwoofer project. Frequency response shows that the drivers have quite high inductance. Workable with the help of EQ though. Really high max SPL at all frequencies. Extremely low compression. Could have gone higher but the amps clipped (two ~2000W amps). Low overall distortion. Low group delay and fast decay. Extremely “dead” though light enclosure.

DIY TC Sounds TC-2000 15" ported 270L
The very much discussed “LLT”. Very good extension and frequency response for larger rooms. Small rooms may have too much low end gain. Quite strong port resonance at ~160 Hz. High max SPL at all frequencies. Low compression up to 110 dB. The 115 dB was terminated due to amp clipping – not woofer bottoming. Low overall distortion, though the upper end could be cleaner. End cap to end cap resonance shows at ~75 Hz. Very low group delay for a ported subwoofer. Good decay too. The enclosure is naturally huge.

DIY TC Sounds TC-2000 15" sealed 90L
One more TC-2000 based subwoofer. A little bit flatter response, though T/S specs may be off (heavier cone). High SPL and low compression up to 105 dB. 115 dB sweep was terminated due to amp clipping. A little bit elevated deep bass and upper bass distortion. Low group delay and fast decay. The enclosure could be a bit heavier.