AR 2ax grilles: Will this be a problem?

[JKent]

Finishing up my 2ax's and had to replace the grilles. The originals were destroyed when I removed them. I bought a pair on ebay, but these things are really flimsy. There is a big rectangular cutout for the mid and tweeter--guess they just continued to use the pattern for the AR2. You can see the outline of the original board's cutout on the new one, and a pair of original boards is leaning against another speaker, to the left in the 1st photo.

Anyway, I decided to make some new ones out of 1/4" Masonite and just cut holes for the drivers. Here is one with the mid and tweet holes--they are 4 1/2" in diameter. I have not cut the woofer hole yet--will need to make a jig for my router.

My question is: Is there any problem with holes this size (diffraction?). Any comments welcome.

Thanks

Kent

[Jess]

Finishing up my 2ax's and had to replace the grilles. The originals were destroyed when I removed them. I bought a pair on ebay, but these things are really flimsy. There is a big rectangular cutout for the mid and tweeter--guess they just continued to use the pattern for the AR2. You can see the outline of the original board's cutout on the new one, and a pair of original boards is leaning against another speaker, to the left in the 1st photo.

Anyway, I decided to make some new ones out of 1/4" Masonite and just cut holes for the drivers. Here is one with the mid and tweet holes--they are 4 1/2" in diameter. I have not cut the woofer hole yet--will need to make a jig for my router.

My question is: Is there any problem with holes this size (diffraction?). Any comments welcome.

Thanks

Kent

Since you have the holes cut I would try them out just as they are once you have the woofer set up but don't attach the grill cloth yet. If you don't feel that the sound has been affected by the modified cutouts then leave them and attach your new cloth. I for one would cut the opening to match the original grills to keep them as close as to the original look of the AR's.

Just my 2 cents.

[tysontom]

Finishing up my 2ax's and had to replace the grilles. The originals were destroyed when I removed them. I bought a pair on ebay, but these things are really flimsy. There is a big rectangular cutout for the mid and tweeter--guess they just continued to use the pattern for the AR2. You can see the outline of the original board's cutout on the new one, and a pair of original boards is leaning against another speaker, to the left in the 1st photo.

Anyway, I decided to make some new ones out of 1/4" Masonite and just cut holes for the drivers. Here is one with the mid and tweet holes--they are 4 1/2" in diameter. I have not cut the woofer hole yet--will need to make a jig for my router.

My question is: Is there any problem with holes this size (diffraction?). Any comments welcome.

Thanks

Kent

Kent,

I definitely think there will be a diffraction issue with your new grill panels. The off-axis dispersion of the dome tweeter is so wide that you are definitely going to have some issues with the grill cut-out. For the woofer or the midrange, it's not so big of an issue, but the tweeter will have interference problems with the panel, particularly since it is up above the level of the dome. You should consider making the panel similar to the original AR-5 and AR-2ax grill panels, and you will not have any problem whatsoever with the sound.

Bear in mind that diffraction is more of an issue in the near field of sound propogation, and less so in the far field, but with so much intereference that your panel cut out suggests, the high-frequency dispersion (and thus the overal power response into the room) will be adversely affected by what you are doing. This is not absolute, but just looking at what you are doing suggests a serious diffraction problem.

--Tom Tyson

[genek]

You should consider making the panel similar to the original AR-5 and AR-2ax grill panels, and you will not have any problem whatsoever with the sound.

From the pictures, it appears that that's what he already had.

Later AR grills were fixed in place with velcro around the perimeter. My 2ax's have 6 patches, and even the slightly thinner frames that Larry Lagace supplies hold in place just fine. The new grille frames may seem "flimsy" when they're held, but they're still quite a bit stronger than the old frames were (greater flexibility means greater strength), and I have to wonder why this is even an issue. It's not as if they need to support anything more than the fabric or do anything more than cover the drivers.

[tysontom]

From the pictures, it appears that that's what he already had.

If I understand him correctly, he wanted to know if he could simply use the cutout hole over the drivers, as shown in his image, rather than cutting out the larger hole as with the original grill panel. Simply leaving the holes over the drivers will cause the diffraction problem. He said:

"Anyway, I decided to make some new ones out of 1/4" Masonite and just cut holes for the drivers. Here is one with the mid and tweet holes--they are 4 1/2" in diameter. I have not cut the woofer hole yet--will need to make a jig for my router. My question is: Is there any problem with holes this size (diffraction?). Any comments welcome."

In other words, the grill panel should be cut the original way similar to the two shown to the left of speaker in his image.

--Tom Tyson

[genek]

In other words, the grill panel should be cut the original way similar to the two shown to the left of speaker in his image.

What I meant was, it appeared to me that he already had frames with the correct cutouts (the ones on the side), and I couldn't see much point in wanting to make new ones cut like the originals but 1/4" thick.

If I out 1/4" thick masonite plus the thickness of the fabric front and wrapped around and of the velcro strips on my 2ax's, the result would be too thick to fit correctly into my speakers.

[JKent]

Thank you all. As I suspected, AFTER I started to make the new frames, diffraction would be an issue, as Tom said.

I've been away a couple of days and could not answer.

Yes--I have some originals, as shown in the photo, and I will use those. The ones that were on the speakers got destroyed when I tried to remove them--the glue and staples were too much and I did not want to risk marring the walnut veneer. The pair of frames on the left in the photo were an ebay purchase. I'll use those.

Kent