Anti-Diffraction Surrounds for Speaker Tweeters

I'm a stereo tweeker and thought I'd share some info regarding the latest thing I've successfully tried.

Read about speaker tweeter felt surrounds (see ad in AGon dated 12/3, under Accessories, Tweaks: "Anti-diffraction products for the removal of early reflection") in AudioCircle, and decided to give them a try. Anyway, the short version of the story is that owner Jim Goulding did a wonderful piece of custom felt surround work for each pair of tweeters for my Polk SDA 1-C speakers.

So, does the product work as advertised? That's a resounding "yes" in my system to my ears. The results I'm hearing are better imaging (and the speakers imaged well before), speakers seem to disappear, improved depth of soundstage (which I felt was already good to go), more realistic high frequency reproduction. Additionally, the Polk's SDA effect has been even more enhanced (which at first thought seems reasonable and consistent with the improved imaging others have mentioned; however, Polk does the SDA effect with a combination of 4 drivers in each speaker (2 regular, 2 SDA), so somehow my brain is interpreting the change to the tweeters / highs as improving the SDA effect.). My 1Cs are absolutely more enjoyable to me. I'm wicked glad I've held on to these speakers; Jim's product has brought them to a new, improved level of refinement.

I note that each Polk speaker has a pair of tweeters that are: 1) positioned vertically one above the other, 2) positioned atop (not flush) with the speaker face board, and 3) time aligned with the drivers. Jim's craftsmanship / ability to custom cut the felts to relatively close tolerances was impressive and necessary for the installation to succeed in this application. Also, I needed additional Velcro attachements as compared to simpler installations, which Jim was happy to provide. So, thanks again Jim for a job extremely well done, and I'm pleased to consider myself a 100% satisfied customer.
You can go to any material store and purchase felt. I would experiment with density by cutting it and taping it and placing it in place in different thickness.
I guesstimate that theses dense wool felt surrounds are about 1/3" - to 1/2". I don't have a specialized machine to make the precise cuts that Jim provided. Also, I've never seen this particular thickness of material in any store.
I agree with Djbnh that Jim's surrounds are a terrific tweak. I just posted a Positive Audiogon Feedback for Jim. I've got Acoustic Zen Adagio speakers, and they image like crazy... but being a tweaker like Djbnh... when I saw Jim's ad I couldn't resist. My Acoustic Zen Adagio's are so good my wife hasn't said one word about them. When she doesn't beat me up for buying something new, I know I'm on to something good. Jim's surrounds improved the imaging on my Acoustic Zen Adagio speakers beyond my expectations. To make a long story short, singers now sound like they're standing up instead of sitting down.

Besides the fact that I question whether someone could find surround material as substantial as Jim's product, I agree with Djbnh that there's no way someone could fabricate the surrounds as expertly as Jim did for me.

Jim's surrounds are the best tweak I've purchased in a long time.

After a slight difficulty, partially due to my own stupidity, I have mounted a pair of Jim's surrounds to my NSM 10S minimonitors, and have spent the afternoon and evening listening to favorite CDs (classical and jazz) with a new appreciation of their contents. Even Ives' 3rd symphony makes perfect sense to me, now that the complexities of his scoring have become much more evident.
This is a really excellent and effective tweak, which will no doubt become a permanent part of my system.
$49 very well spent.
Thanks, fellas. Makes me happy anytime I can help bring a man and his music more closely together. Recieved a Golden Ear Award from Robert E. Greene in TAS and hope discriminating listeners with box speakers everywhere take note and make contact. Cheers.
Some pictures of custom fitted examples can be see in the Classified section 10/07. The so called wool products to be found in fabric and hardware stores are composed largely of synthetic materials that are themselves reflective. The pads under discussion from are made from natural wool in the necessary depth and density. Short and spreading waveforms that would otherwise be reflected (diffracted) by naked baffles and cabinet edges and late arriving make contact with the wool instead and are absorbed. What a user gets at the listening position is purer and unadulterated information.

FYI, when diffracted waveforms sum in at the listening position, they combine to cause a bump and ripples to frequency linearity in the lower bandpass of tweeters. Not only is proper time and phase preserved, so is frequency response.