speaker dispersion behind a grill

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.

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?

Agreed. Taming the tweeter with a few power resistors would be more straightforward if that is the problem.

Check the settings on your existing head unit. Maybe the treble is boosted? I'd use the tone controls in your existing head unit before spending any more money

It looks like you are reading it correctly. Just be sure you use appropriate sized resistors, by that I mean ones that are rated for higher power. Otherwise, you might let the smoke out of them at higher volume. The L-pad link http://www.bcae1.com/lpad.htm has a calculator at the bottom which might help you to determine what power of resistors to use in your case. So with 50watts of amplifier power, it looks like one resistor is just under 15watts and the other one is just above 10watts. If you have a higher power amp, you would need much higher power resistors. Of course, if the amplifier is powering the component set, then you have to figure out how much of that power is going to the woofer and how much is going to the tweeter.

Are your tweeters silk dome or aluminum? It looks like there was an option when you purchased them. The silk domes should have a pretty smooth response. In that case, your headunit upgrade should help. If they are aluminum, then the resistors and/or a headunit upgrade should work (or just the headunit change).

One other option is since the tweeters are behind the factory grill, you could try putting a piece of felt between the tweeter and the grill. This is similar to home speakers with their cloth speaker grills. You might need to experiment with different types of material, but it would also give you some attenuation without needing to add any resistors. I would try just taping some over the visible surface of your speaker grills then do some listening tests. If this worked for you, then you could remove the door panel and install the material as suggested.

Good luck.

Did you get a chance to try some felt? What do you think of the result?

Give it some time and the tweeter will smooth out. New tweeters are notoriously bright.

I have had the same experience with Blaupunkt silk tweeters as well as definitive Aluminium tweeters.

My blaupunkt were the same. Initially i had to dial it down. But 6 months down the road and i had to bring them up.

I've had my MB Quart tweeters with titanium domes for almost 6 years, and they are still too bright, if I were to point them directly toward me. Certain speakers will never really smooth out. They are just inherently brighter. However, I have them pointed toward the middle of the windshield as I mentioned earlier and also have -3dB or so on the crossovers.

Glad to hear you had some luck with the felt. I am sure the L-pad will make a noticeable difference too.