Some more frequency response fun for the E12.
1) ClieOS's review of E12 v1 ("first batch" or initial production run). Note how the frequency response curve matches that James provided on the first units in the post quoted by waynes world:
2) Jensigner's comparison of E12 v2 (regular production) and the E17. This curve goes below 20Hz. Note how the natural response of the E12 starts to fall off at around 30 Hz, and the v2 bass boost puts its maximum gain at 50 Hz but with a steeper rolloff below that, so that the gain at 10Hz is down 3dB from 20Hz when the bass boost is on.
In fact, it looks like the E12 bass boost on the production run units would probably sound similar to that of the E17 with bass control at +4dB. The hinge frequency of the E17 tone controls and E12 production bass boost look to be about the same. ClieOS has done the frequency sweeps for the E17 with full bass boost (+10dB), so I'm guessing a bit here on what +4dB would do, taking into account the frequency tilt of the E12.
Actually, if I had an E12 production model, I'd try the listening test myself (I've got the E12 v1 and the E17).
EDIT: Tyll's July 2013 amp data sheet on innerfidelity.com also shows the rolloff below 20Hz for the E12. It is pretty obvious when comparing it to the other amps in the data sheet stack.
Edited by jazzman7 - 9/16/13 at 3:42pm