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Post by norpus on Feb 26, 2007 5:04:48 GMT -7
Some speaker manufacturers locally here have recently mentioned that loudspeakers have relatively high distortion in general, especially compared with say amplifiers
One opinion was that for subs it can be up to 30%
Is it really that high at normal listening levels? or just at high spls?
And is it because we use multiple drivers and only a small mount of the available xmax typically that our IBs have less distortion audibly? How much distortion would one expect, relative to a smaller box sub I wonder?
I tried to do a search on the forum on this but alas no decent hits were found by me sorry
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Post by chrisbee on Feb 26, 2007 5:33:55 GMT -7
Ilkka Rissannen has published lots of test graphs of subwoofer distortion. Do a Google search. Ported subs seem to go orbital on distortion around the tuning point. I have attempted to torture Thomas into giving us a ballpark figure for likely IB distortion levels but he just wouldn't break.  Ilkka refuses to test an IB out of doors as it's too cold in Finland for 9 months of the year.  |
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Post by ThomasW on Feb 26, 2007 8:09:55 GMT -7
Given the physics involved, it goes without saying that mechanical transducers (loudspeakers) will have significantly higher distortion levels when compared to electronic devices like an amplifiers. And it certainly isn't new information that ported designs have the higher amounts of distortion compared to virtually any variety of sealed box (small or IB) I find it odd that people tend to fixate on distortion figures for subs. The comparatively minor differences in distortion in higher quality subs may make good fodder for debate on an internet forum, but in the real world such differences probably aren't relevant. The consensus is that human hearing isn't sensitive enough to perceive 'moderate' levels of distortion at low frequencies. This is why people like Tom Nousaine routinely test the output levels of subs at 10% distortion. Regarding IB sub drivers, it's a rather academic discussion unless one is prepared to replace their drivers with one's known to have lower distortion, then reverse mount 50% of those drivers to optimize the situation. (Note, those wanting low distortion drivers for their IB need look no farther than this Aura Sound 15") Ilkka certainly can test an IB anytime he wants. How/Why? Well the distortion of an IB will be that of any single driver mounted in an open baffle. BTW if someone wants to donate $1000 for the purchase of Spectra Plus, I'll be happy to run some distortion plots....... |
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Post by norpus on Feb 26, 2007 21:10:08 GMT -7
Thanks
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Post by chrisbee on Mar 2, 2007 4:19:32 GMT -7
Ilkka certainly can test an IB anytime he wants. How/Why? Well the distortion of an IB will be that of any single driver mounted in an open baffle. We can't possible allow you to get away with such an easy answer. How does testing one driver in a modestly-sized baffle equate to multiple drivers in an IB? Each extra one of which surely helps to lower distortion? An 8 x 15" IB must offer lower distortion overall (at any chosen frequency) than a single 15" using drivers of similar quality? The test baffle for the single driver under test would surely have to be very large to offer a frequency response similar to a true IB. Otherwise how could VLF distortion levels be measured when the single driver is approaching Xmax at 20Hz? (rather than the tiny cone movements required of a multiple driver IB playing the same frequency ) Or is distortion completely independent of cone excursion? |
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Post by htnut on Mar 2, 2007 6:43:44 GMT -7
I like to use my MK 5 earball. If it sounds good, I really don't need too much information to confuse my pea sized brain.
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Post by ThomasW on Mar 2, 2007 10:52:12 GMT -7
Or is distortion completely independent of cone excursion? The higher the excursion the greater the distortion. These are all basically the same question. A nearfield measurement can provide distortion info at various excursion levels. The distortion at a given Xmax stays the same whether there's one driver or a hundred. With a multiple driver IB we can run at lower Xmax levels, and get higher SPL and lower distortion compared to fewer drivers driven at higher Xmax levels. |
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Post by chrisbee on Mar 3, 2007 1:30:31 GMT -7
A nearfield measurement can provide distortion info at various excursion levels. The distortion at a given Xmax stays the same whether there's one driver or a hundred. With a multiple driver IB we can run at lower Xmax levels, and get higher SPL and lower distortion compared to fewer drivers driven at higher Xmax levels. Thankyou, Thomas |
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