- Written by John E. Johnson, Jr.
- Published on 26 June 2008
On the Bench
OK, so far, so good. Let's take a look at the numbers.
THD+N tests were within an 80 kHz bandwidth.
At 20 Hz, 100 dB, 1 foot, THD+N was a little more than 11%. Notice that the second order harmonic predominates. Often in subwoofers, the third order harmonic is pretty close to the second at high output, but with this Earthquake P10, the third order harmonic is 20 dB lower than the second, even at 20 Hz. That is impressive. Earthquake uses what they called SLAPS technology in their patented driver design. Seems to work. This is good performance for a small subwoofer.
At 25 Hz, distortion was nearly 9% at 100 dB (yellow graph). When I lowered the output to about 92 dB (magenta graph), distortion dropped to 4%. The second order harmonic (2) dropped considerably, the third stayed about the same, but higher order harmonics (4 and 5) really dropped. I was able to get a maximum output of 110 dB at 25 Hz. This is very good. Usually, in a small subwoofer, the edge of the enclosure comes almost to the edge of the surround, keeping the box as small as possible. Earthquake has opted to make the enclosure a few inches larger than the driver, and this makes a difference in the output.
At 31.5 Hz, distortion was at 5%.
And at 40 Hz, 3% THD+N.
THD+N vs. Frequency indicated that the MiniMe stayed generally below 10% regardless of how low the frequency was.
The room response graph is shown below. As one moves farther away from the subwoofer, the room effects become more visible, so it would be advisable to use some EQ to reduce the peak region between 50 Hz and 100 Hz.
I keep thinking that subwoofer technology improvements have flattened out, but I keep getting proven wrong. The Earthquake MiniMe P10 is a good example of that. It is small, lightweight, easy to set up, and best of all, it delivers.