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Discussion Starter #1 (Edited)
The testing discussed here is in reference to Frequency Response and Harmonic Distortion testing done via SoundEasy; Not Klippel.
To make sure the point hits home:


Software & Hardware:

Baffle and Room Treatment:
Testing is done in a 17x25 ft room, upstairs in my home away from noisy environments. The room is temperature controlled and fixed within a certain temperature range.
The driver is attached to a 66x81" scaled model of the IEC baffle.
This baffle is constructed of 3/4" MDF of 66x81" dimensions, with another layer of 3/4" MDF - 36x48" - on the rear. This rear layer has a 12" diameter cut out which allows for attaching the baffle inserts to the baffle. The total baffle weight is approximately 140 lbs.
There is no obtrusion on the front of the baffle (as you may see on others' test baffle).
Bracing on the rear was added for support. The picture below is a former model of the stand which has since been beefed up a tad with extra cross bracing. The baffle easily handles 96dB @ 1/2m from a 7"/89dB (1w/1m) driver running HD sweeps.
All drivers are flush mounted with a 45* chamfer on rear.

For on and off-axis testing, I will be using a homemade jig of wood marked at 15 degree intervals and PVC cut to X length. A laser is attached to the mic boom at the back to avoid reflections so that the mic can be pointed directly at the driver's center.


The room is treated with absorption panels at the 4 first reflection points: ceiling, floor, sidewalls.

Testing Requirements:

Thiele-Small & Impedance:
  • Parameters generated with woofer tester 2 automatically.
  • T/S Parameters will be included within Impedance Measurement window for my own ease of posting and to make sure the data always stays in pairs.
  • Impedance curve will be publushed as best can be shown to accurately read any potential blips in the response.
  • Drivers will be measured on the baffle

Frequency Response:
  • Mic @ ~ 33"
  • Levels between 80-90dB
  • Window @ 15ms*
  • Smoothing to 1/24 unless otherwise noted
  • On Axis Testing results will be scaled to 3dB **
  • On/Off Axis Comparison Testing results will be scaled to 5dB***
  • On/Off Axis Comparison Testing will be done at 0, 15, 30, and 60 degrees.
Note: Due to room modes, data is good down to approximately 150hz. Below this, the baffle and driver rolloff take precedent.
The level SPL represented in FR data is not calibrated and therefore not entirely accurate. Do not use this to compare against other drivers to see how the sensitivity compares. For sensitivity use either my posted data (if I post this) or use the mfg spec (most are always within close range to measured).

*This correlates with resolution down to 66hz and is allowable only due to absorption panel placement and room size.

**3dB scaling is done so you, the viewer, can see the details of the response in close up view. I realize that most mfg data is posted at a 5dB or 10dB scale. However, IMO it's too easy to miss details of a driver and this is the prime reason I've chosen a higher resolution scale for this testing. I think it is best for everyone to see the scale in high resolution so they can see what is going on in the fundamental response.

***For on/off axis comparisons, scale of 5dB is used for easier viewing.

Harmonic Distortion:
  • Mic @ 1/2 meter (to help tame reflections but not clip mic input at loud levels) on axis (0 degrees)
  • SPL level at 90-95dB, depending on driver and relates to SPL @ mic distance. Level will be stated when data is posted. I may choose to show distortion at multiple levels, too. The levels will be stated.
  • F2-F5 will be tracked
  • Tweeters will be ran from 500-20khz. 2-3 inch mid/fullranges from 100-20khz. All other drivers from 20-20khz. HF response is software dependent due to sampling rate of program/card.
  • THD is shown in the thick green line on a scale of 10% increments. This line is typically all the way at the bottom of the distortion plots.

Sample Videos:

To help you get a better understanding of the testing, here are a couple videos:
  • Frequency Response:
  • Harmonic Distortion:
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