JL Audio C5-400cm Midrange

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.

IMG_5066 IMG_5062 IMG_5071 IMG_5073

IMG_5074 IMG_5075

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

Electrical Parameters
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
Mechanical Parameters
(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)
Loss factors
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
Other Parameters
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)
Sd 53.59 cm² diaphragm area

c5-400cm impedance


Large Signal Analysis with Klippel’s LSI Module

Displacement Limits
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

c5400cm blc5400cm bl symmetryc5400cm kmsc5400cm kms symmetry c5400cm cms jl c5400cm lex c5400cm lei


Frequency Response

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.

JL Audio C5-400cm FR

Harmonic Distortion

This test was performed in the nearfield at an SPL level equal to 96dB at 1 meter.

c5400cm FR HD with PHD Harmonic distortion (Relative to 96dB1m)

This is the same as above, just zoomed in for legibility.

Harmonic distortion Zoomed (Relative to 96dB1m)

HD Comparison

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.

HD comparison

I did not pursue IMD testing of this driver simply due to time constraints.

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