SA2K has been through the new measuring equipment and now I can bring a round of updated acoustic and electrical measurement results on the older gentleman.The Loudspeaker Q113 project is about creating an improved successor to SA2K, in an open development process where all interested parties can give their opinions and experiences. Or just follow along, of course. That's why it makes sense to refresh memories, partly about the technical and just as much about the subjective: the sound. On the technical side, we can take measurements of the speaker's acoustics, in an attempt to identify some areas where a successor could do a better job. Later in the process, the new heirs will be subjected to the same tests.

How we measured

The loudspeaker is measured at a distance of 1 metre, raised 1 metre from the floor. The software used is Praxis from Liberty Instruments, exported to and displayed with Leap Crossovershop from LinearX. The measurements are valid to about 300 Hz. The measurements are not smoothed. The stimulus (measurement signal) is a chirp, deriving the loudspeaker impulse response in the time domain and, using FFT (Fast Fourier Transformation), the loudspeaker response in the frequency domain. Phase curve is corrected 3 ms, corresponding to the measurement distance of 1 meter.
Link to Liberty Instruments
Link to LinearX

How to measure SA2K

Frequency response on axis + phase response. 1 dB per measurement step. Sensitivity: 86 dB.

 On axis and off axis response. 0, 15, 30, 45 and 60 degree angle, respectively to the right and left of center. 1 dB per measurement.

 Total frequency response + separate contributions from bass/midrange and tweeter. Telephone frequency around 3-3,500 Hz. 1 dB per measurement.

 Impedance and phase curve. Tuning frequency of bass reflex system: 46-47 Hz. Impedance min.: approx. 200 Hz. Electrical phase is within +/- 45 degrees.

Partial filter on six components. L1 and C1 belong to the bass/midrange speaker. C2, L2, C3 and R1 are for the tweeter.