Originally Posted by arnyk
The primary effect of the spacer is that it puts a ring around the driver's periphery. The technical effect of this ring is that it may reduce the dispersion of the driver at some frequencies, it might create diffraction that would actually increase its dispersion at other frequencies, and that it may cause a bump in response followed by a roll off at other frequencies yet.
The frequencies at which this ring has a significant effect is determined by the wavelength of the sound as compared to the height of the ring. For this ring to have negligible effects its height needs to be less than 1/10 the size of the speaker, which is clearly not the case when it is 1 1/2 inches high around a 6.5 inch driver. It is creating a cavity resonance which you may be hearing as excess brightness.
Just to clarify, the ring is currently .5" in height around the 6.5" driver, and the idea would be to raise it to 1".
It seems less likely that the 6.5" driver is causing a cavity resonance since the doors have been well-deadened inside and out with 60 mil sound deadener
, as well as a little bit of PS Ensolite closed cell foam
behind the speaker to break up any sound wave reflections.
Originally Posted by MagicTK
And that ring modification is not likely to make any difference in balancing the sound if the tweeter is bright. Most likely angling the tweeters so they are pointed somewhere toward the middle of windshield is the better solution. This is how I have my MB Quart tweeters mounted. If not, they would be terribly bright if pointed toward the listening position.
Just curious, what brand of speakers are they? and do you have a picture or drawing showing the whole mounting configuration?
The speakers are Diamond Audio 663S components
, and the tweeters have already been attenuated -2db using the built in jumper in the crossover. The car is a 2008 Honda Fit, and here is a picture
of what the door panel looks like. The tweeters are mounted behind the factory tweeter location pointed directly in perpendicular to the door. Because of the size of the tweeter and that location, it's difficult to aim them anywhere else, and I don't want to install them elsewhere visibly in the car.
I think what I might end up doing is upgrading the head unit. Turns out that Pioneer has released the DEH-80PRS
in 2012 that appears to be incorporating their MCAAC technology. It has L and R 16 band adjustable EQ with auto EQ and microphone for taking measurements at the listening position. Pretty cool that this technology is now making its way into car audio. Since I have a lower model Pioneer (which could be a little bit of the problem), this would be an SQ upgrade even without the auto EQ feature, and that auto EQ can probably tame the tweeter response much better than the five band EQ in my model.
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