Iain Macdonald wrote on Fri, 09 June 2006 15:44 |
Tom,
In between the million and one things you need to do. Could you find time to post a set of meaninful tests for sub cabinets, whatever their type. There are other tests than TEF sweeps, MLS etc. I would add, the multi-tone tests that Dr Anhert? uses. These will show up a badly designed reflex box in a short time. The driver ends up getting a DC like shift in position, then crumples. This test will also blow the back of some other types of cabinet at full power.
Iain.
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Hmm, Praxis will do that (Spectral Contamination).
From the Praxis measurement guide-
(Below are given example values for tone frequencies to use, based on Jon Risch's "New Class of In-band Multitone Test Signals", in AES preprint #4803. This arrangement, based on a log-spaced series of tones with multiplier 1.618, minimizes stacking of harmonics on the resulting modulation tones. Numerous other variations on this method are possible, and you may wish to restrict the tones to certain frequency ranges or to increase the tone density.)
Bandwidth of 10Hz – 500Hz
multiply by factor of 1.618
10
16.18
26.2
42.4
68.5
110.9
179
290.3
469.7
I used this on the Michigan LAB Subwoofer Shootout , but managed to screw up on the multiplication factor. Without realizing I set it too low making the tones so dense the test was useless.
One thing we think might have happened is we may have damaged some of the subs that unloaded under tuning. I did not push very many volts during testing because of a volume restriction (We tested in a building that had office work going on in the complex.) I found it hard to believe we damaged them at the level I was using, but became gun-shy there after.
I was wondering how things went while measuring ported boxes? Was the test done with a proper high-pass on the box or were the tones below tuning deleted?