Fountek FR88EX

Another popular choice for fullrange use, the Fountek FR88EX is tested and results provided below.  For data on the FR89EX click here.

fr88-exPicture courtesy of Madisound.

Thiele-Small and Impedance Test Results

Electrical Parameters
Re 6.43 Ohm electrical voice coil resistance at DC
Le 0.042 mH frequency independent part of voice coil inductance
L2 0.299 mH para-inductance of voice coil
R2 2.53 Ohm electrical resistance due to eddy current losses
Cmes 170 µF electrical capacitance representing moving mass
Lces 12.96 mH electrical inductance representing driver compliance
Res 23.69 Ohm resistance due to mechanical losses
fs 107.2 Hz driver resonance frequency
Mechanical Parameters
(using test encl.)
Mms 2.979 g mechanical mass of driver diaphragm assembly including air load and voice coil
Mmd (Sd) 2.898 g mechanical mass of voice coil and diaphragm without air load
Rms 0.739 kg/s mechanical resistance of  total-driver losses
Cms 0.74 mm/N mechanical compliance of driver suspension
Kms 1.35 N/mm mechanical stiffness of driver suspension
Bl 4.185 N/A force factor (Bl product)
Loss factors
Qtp 0.581 total Q-factor considering all losses
Qms 2.714 mechanical Q-factor of driver in free air considering Rms only
Qes 0.737 electrical Q-factor of driver in free air considering Re only
Qts 0.579 total Q-factor considering Re and Rms only
Other Parameters
Vas 0.7827 l equivalent air volume of suspension
n0 0.126 % reference efficiency (2 pi-radiation using Re)
Lm 83.2 dB characteristic sound pressure level (SPL at 1m for 1W @ Re)
Lnom 81.14 dB nominal sensitivity (SPL at 1m for 1W @ Zn)
Sd 27.34 cm² diaphragm area

fr88ex impedance

Large Signal Analysis from Klippel LSI Module

Displacement Limits thresholds can be changed in Processing property page
X Bl @ Bl min=82% >3.5 mm Displacement limit due to force factor variation
X C @ C min=75% 2.4 mm Displacement limit due to compliance variation
X L @ Z max=10 % >3.5 mm Displacement limit due to inductance variation
X d @ d2=10% 9.6 mm Displacement limit due to IM distortion (Doppler)

fr88ex img_Bl (X) fr88ex img_Bl Symmetry fr88ex Range fr88ex img_Kms (X) img_Kms Symmetry fr88ex Range fr88ex img_Cmes (X) fr88ex img_L(X) fr88ex img_L(I) fr88ex img_Distortion fr88ex img_Temperature_ Power

Frequency Response

On-Axis merged at approximately 500hz, representing 2.83v/1m.  1/24 octave scaling.

Fountek FR88EX 0 deg merged

Response comparison at 0, 30, and 60 degrees.  1/24 Octave resolution.

Fountek FR88EX Frequency Response 0 30 60

Harmonic Distortion

Note:  This test was performed in the farfield, and subsequent to environmental issues such as reflections and noise. Therefore, please disregard data below 200hz as I cannot guarantee it’s accuracy.


Fundamental + Harmonic distortion components (96dB1m) Relative Harmonic distortion (96dB1m)

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