Funky Waves FW 12.X Subwoofer Review Measurements and Analysis

The first part of testing was to measure the frequency response from a modest output, all the way to the point where the system was clearly compressing and had hit the output wall, so to speak.

 
Funkywaves  Frequency Response at Various Output Levels

Only some slight compression can be seen at the top most curve.  If I had to guess (I am guessing) I would say this lessening of output is due to turbulence of air through the port. Since the curve does not tilt up prior to the cutoff (Like the Hsu does) it indicates the Driver is not losing motor force, nor should it be as the port and amp are doing all the heavy lifting at 20 Hz.  Like all the other systems, this box was tested at 1 meter, lying on its side, microphone placed midway between the center of the port and the center of the driver so as to get the most accurate reading with the microphone very close.  A 14 second sweep was used, and the data was smoothed to 1/24^th octave resolution. (Translation, we don't make our curves with a ruler and graph paper like some folks...).  We can also see that this driver loses about 3db of sensitivity from 50 Hz, by the time it reaches 100 Hz. 

CEA 2010 Test Results

The next part of testing was to disconnect the Clio box, and connect the Earthworks M-30 microphone to a True Systems P-Solo mike preamplifier.  This is set for minimum gain (click stop) and connected to the input of the computer's soundcard.  We are running Don Keeles CEA test program version 1.62 which runs under Igor Pro which runs under Windows XP professional. (Whew!) The CEA program generates pulses 1/3^rd of an octave wide, and centered at standard ISO frequency centers.  (Meaning the 20 Hz pulse is -3db at 16 and 25 Hz.)  This is superior to traditional tone burst testing and is the standard for which these measurements are gathered.

To understand the meaning behind the graphics below and testing methods used, please refer to the prior article (Subwoofer Shootout Measurements Overview) on this method. The process is a simple one.  Drive the input to the system to the point where either the amp, its compressor, or its speaker simply refuses to give you more output, or the distortion created at that output level exceeds the CEA “redline”.  In EVERY system tested, the result (if not the peak SPL) was similar in one regard.  For ALL the other subwoofers tested, at the highest frequencies in the sub's bandwidth, we ran out of amplifier power, or the compressor refused to put out more power than the amp could cleanly deliver.  The Funkywaves sub was different in this regard, and that may be due to its tuning, or possibly the fact that the peak powers the voice coil is experiencing is considerably higher than the other shootout entrants.  Usually, at the lowest frequencies, the subwoofer runs out of excursion. With the Funkywaves, that does not happen at 20 Hz, as the port is doing all the work.  Below is a spectrum capture of the Funkywaves FW 12.X system at maximum usable output for each of the 1/3^rd octave centers from 20 to 63 Hz.

Signal Spectrum at Maximum attainable Output of system 1 Meter Groundplane

Below are the results of the CEA  peak SPL's are tabulated:

Max SPL Output Data of the FunkyWaves FW 12.X Subwoofer

Why not test this speaker up to 80 Hz? Surely it is important, no?  Yes of course.  Two primary reasons I believe that the CEA standard excludes an 80 Hz measurement.  Any large sub will be amplification limited by the time it is going as high as 63 Hz.  While looking at 80 Hz will add little to the value of the testing, in the case of the Funkywaves sub, the driver sensitivity does roll off significantly over 50 Hz.  This is because of the unusual set of parameters and driver construction particular to this model speaker.  In short, our effective sensitivity, already low to start, has been halved again by the time this sub is up to 100 Hz.  This may be in some part due to the drivers high mass, and no doubt the relatively high voice coil inductance. (Le)  Let's also bear in mind the CEA pulse signal centered at 63 Hz is only 3dB down at 80 Hz, so the loss of sensitivity there is showing up in the “63 Hz” SPL number.

Update: 9/27/11

In order to make it easier for our readers to compare our CEA data between subwoofers tested prior to our new Subwoofer Measurement Protocol, we scaled our 1 meter peak CEA data to 2 meter RMS by subtracting 9dB for each frequency.