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Third Party Test Results

The Background.

When Harbottle and Funk started out, we made the decision to get our motor topologies tested by a third party independent, Josh Ricci at Data Bass. What these tests reveal is how our motors handle the power they are given.  As the motor geometry has not changed at all, and we are fanatical about our tolerances, these test results are the backbone of all of our products bearing the Harbottle, Cassini, or Funk name. In fact, all products are measured and stacked against these test results by Data-Bass and Josh Ricci's original works. So by extension, all products made are third party verified before they leave our factory.

The validity of these results are not in question. The reason why is because what these tests show is the ability of the motor geometry and this allows us to adjust the TS parameters (driver variables) and predict (to a terrifying level of accuracy) what a driver will do within a given alignment or with specific changes to the cone, coil, magnet, venting, or suspension. This is where the Xmax guarantee and the Range Method of Simulations (see our YouTube channel) comes from and is why we guarantee DIY sims at Xmax given the power and enclosure are representative of the simulation. In fact, there are enough people that have used the Range Method for simulations on our raw drivers and are emphatic about its viability, we feel very confident in making this statement. Please reach out to any of our DIY clients on AVS forums and ask if they used the Range Method and how well it works. It is important to know that Harbottle Audio uses the Range Method on all of our products as well. Yes, we practice what we preach.

The Lineage.

The TSAD driver underwent some changes from its original tested features and became the M1. These changes are found in the suspension and the cone material.

The GUJ driver underwent some changes from its original tested features and became the M2. The changes are found in the cone, coils, and magnet. However the motor geometry is still identical. This gave birth to further and more extreme changes found in the M3 and M4 motors, both of which use the original GUJ geometry and feature more venting/cooling and better power handling and magnetic damping. This shows how powerful and versatile the GUJ geometry is.


Motor Usage.

M1 drivers are exclusive to the Cassini product line.

M2 and M3 are found in the Internet Direct product found in the Harbottle Audio online store and Cassini Raw Drivers.

Test Notes:

The long term output, distortion, and compression tests voltage shows RMS voltage. Please note this.

M2 Geometry Test Highlights

Compression Results.

Compression magnitude shows how much a driver is compressing as compared in total at an applied power level. Compression is a loss of efficiency and is the beginning of audible inconsistency and artifacts that disrupt the immersive experience.

Harbottle product maintains this profile behavior and limits compression to 1 dB within our finished systems.

Note: Compression does not come into full effect until the driver has reached its maximum power handling in the tested 290L (10 ft3) enclosure.

What this result shows is the motor topology has very high efficiency with low and linear compression and high power handling capability.


Distortion by Component Results.
Harmonic distortion is caused by mechanical nonlinear behavior of the driver. The results of this test shows very good distortion behavior with the most distortion happening at the highest power levels, at the lowest frequencies, and at the 2nd and 3rd harmonic. This is of note because the 2nd and 3rd harmonics are the hardest to hear in contrast to the source material (fundamental frequency).  


CEA2010 Burst.
This test is odd because it is generally a horrible way to determine the use and design functionality of a bass system. The problem with burst measurements is that there isn't any other frequencies being played like you would have in content playback. So all it is showing is what that one frequency can do without any context. And without context there is no possible way to determine what the system is actually capable of doing. 

This measure is even worse for raw drivers becuase the burst test is testing:

  1. The driver

  2. The enclosure

  3. The amp

  4. The signal source

  5. The mains power supply

What this means is that to get these results in this exact test, the builder would have to build an identical system and test it under identical conditions.

The only real thing burst measures are good for is seeing how much power the motor can handle above its impedance peak, again, in burst and without any other modulating frequencies attached so the information is extremely one dimensional and incomplete.

Now when we combine the compression magnitude sweep with the CEA burst, what we see is the potential of this motor geometry to remain composed when stressed, which will give you more real world burst capability that will get the design closer to the burst test and may even exceed conventional expectations. 

GUJ Geometry CEA2010.png
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