Up for test is a JL Audio C5-400cm midrange. This is sold as a single unit (though, rarely in stock as such) or part of the JL Audio C5-653 component set. I was interested in this driver as it seems to be of reasonable cost given the small form factor and mounting options in addition to the fact that it uses a Kurt Müller cone design, which is a well known cone manufacturer.
As shown in the pictures below, this driver comes with a mounting ring which allows it to be installed in a manner using the ring and covering grille (not shown). The alternative, shown in the above provided link, is to use the driver with the mounting tabs. When I initially received this driver I removed the tabs for install purposes and therefore this particular test is done with the mounting ring in place. Keep this in mind when viewing the frequency response measurements.
To illustrate the difference with the ring attached, I have shown the driver with and without the ring. Again, however, note that I have removed the tabs for my particular application.
Note in the pictures above the little bumps on the cone. My guess is these 6 bumps are designed to help mitigate modal issues. However, without testing this driver and cone without these bumps, it’s just an educated guess.
Physical Dimensions (from JL’s site)
|Frame Outer Diameter* (A)||3.94 in / 100 mm|
|Grille Tray Outer Diameter** (B)||4.76 in / 121 mm|
|Magnet Outer Diameter (C)||2.83 in / 72 mm|
|Frontal Coaxial Tweeter Protrusion (D)||N/A|
|Frontal Grille Protrusion*** (E)||0.83 in / 21 mm|
|Mounting Hole Diameter (F)||3.625 in / 92 mm|
|Mounting Depth (G)||1.62 in / 41 mm|
Thiele-Small Parameters and Impedance Measurement
|Re||3.32||Ohm||electrical voice coil resistance at DC|
|Le||0.168||mH||frequency independent part of voice coil inductance|
|L2||0.237||mH||para-inductance of voice coil|
|R2||2.21||Ohm||electrical resistance due to eddy current losses|
|Cmes||362||µF||electrical capacitance representing moving mass|
|Lces||4.55||mH||electrical inductance representing driver compliance|
|Res||13.23||Ohm||resistance due to mechanical losses|
|fs||124||Hz||driver resonance frequency|
|(using test encl.)|
|Mms||4.87||g||mechanical mass of driver diaphragm assembly including air load and voice coil|
|Mmd (Sd)||4.427||g||mechanical mass of voice coil and diaphragm without air load|
|Rms||1.017||kg/s||mechanical resistance of total-driver losses|
|Cms||0.338||mm/N||mechanical compliance of driver suspension|
|Kms||2.96||N/mm||mechanical stiffness of driver suspension|
|Bl||3.668||N/A||force factor (Bl product)|
|Qtp||0.751||total Q-factor considering all losses|
|Qms||3.731||mechanical Q-factor of driver in free air considering Rms only|
|Qes||0.935||electrical Q-factor of driver in free air considering Re only|
|Qts||0.748||total Q-factor considering Re and Rms only|
|Vas||1.3742||l||equivalent air volume of suspension|
|n0||0.269||%||reference efficiency (2 pi-radiation using Re)|
|Lm||86.5||dB||characteristic sound pressure level (SPL at 1m for 1W @ Re)|
|Lnom||87.32||dB||nominal sensitivity (SPL at 1m for 1W @ Zn)|
Large Signal Analysis with Klippel’s LSI Module
|X Bl @ Bl min=82%||1.5||mm||Displacement limit due to force factor variation|
|X C @ C min=75%||1.7||mm||Displacement limit due to compliance variation|
|X L @ Z max=10 %||1.7||mm||Displacement limit due to inductance variation|
|X d @ d2=10%||9.5||mm||Displacement limit due to IM distortion (Doppler)|
|Asymmetry (IEC 62458)|
|Ak||40.93||%||Stiffness asymmetry Ak(Xpeak)|
|Xsym||0.58||mm||Symmetry point of Bl(x) at maximal excursion|
The following measurement was done by merging nearfield and farfield results together at 500hz to yield a quasi-anechoic result. More details can be found on this method here. The results are given at 0 degrees (on-axis) as well as off-axis at 30 and 60 degrees.
This test was performed in the nearfield at an SPL level equal to 96dB at 1 meter.
This is the same as above, just zoomed in for legibility.
For those who may be curious how output levels drive the non-linear performance in terms of harmonic distortion, I have provided an example below. In Red is the THD measured at 90dB/1m. In Blue is the THD measured at 96dB/1m.
I did not pursue IMD testing of this driver simply due to time constraints.
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