A fellow on tech-talk sent me four of these drivers to test and check for consistency. I normally don’t see the need but figured it’d be interesting so I obliged.
I tested each driver’s impedance, frequency response and relative harmonic distortion. I added each driver’s respective result to the same graph for comparison purpose. I then chose one of the drivers to do further testing on. So what we have is the typical suite of data plus unit-to-unit comparison data. I hope you enjoy!
Driver Comparison Testing
Let’s first start with the comparison data. All four drivers were tested in the exact same fashion. One was tested, then removed from the baffle and the next was added. The mic never moved and all the impulse responses were windowed to the exact same time(s). Therefore, the only variant in each test is the driver itself.
As stated above, I received (4) of these drivers to test. However, I didn’t sweep the first driver sample for impedance so there are only (3) samples in the impedance data.
Frequency Response Comparison
The comparison testing for FR & HD was done at one-half meter, with 2.83v input signal. The results on the FR below were each attenuated 6dB in order to provide a normalized 2.83v/1meter response SPL.
This response is in the horizontal plane only. I did not test repeatability in the vertical plane.
Harmonic Distortion Comparison
End of Comparison Testing….
Single Driver Testing: Sample 3
After completing the comparison testing above, I chose Sample 3 to test further as it seemed to have the better response in FR and HD. Yes, this is cherry picking but you’ve seen the variance above.
|Re||6.28||Ohm||electrical voice coil resistance at DC|
|Le||0.006||mH||frequency independent part of voice coil inductance|
|L2||0.01||mH||para-inductance of voice coil|
|R2||0.29||Ohm||electrical resistance due to eddy current losses|
|Cmes||1264||µF||electrical capacitance representing moving mass|
|Lces||0.77||mH||electrical inductance representing driver compliance|
|Res||1.1||Ohm||resistance due to mechanical losses|
|fs||161.2||Hz||driver resonance frequency|
|Qtp||1.194||total Q-factor considering all losses|
|Qms||1.403||mechanical Q-factor of driver in free air considering Rms only|
|Qes||8.032||electrical Q-factor of driver in free air considering Re only|
|Qts||1.194||total Q-factor considering Re and Rms only|
Frequency Response: Horizontal Axis
Frequency Response: Vertical Axis
Harmonic Distortion (Horizontal Axis)
Note the response rises throughout. Therefore, the SPL level used to determine 96dB/1m was based on the fundamental mean SPL from 300hz to 5khz. This is the same as I do on all my tests, albeit with some more wiggle room here by a couple dB. Overall, this is comparable to my other test results.
Cumulative Spectral Decay