[cporada]

This weekend I was reading about Duntech speakers, which are supposed to be legendary for their imaging.  Each Duntech speaker has a patented star-shaped felt cut-out around the recessed time-aligned tweeter, which supposedly turns the tweeter into a true point source.  Since my ACI Alpha project has time-aligned drivers (I think), I set about making my own version of the patented tweeter ring using felt and soft/dense weather stripping.  Below you can see a picture of the finished project installed on my tweeters (Sorry, I guess you can't; I can't figure out how to insert a picture.  I tried clicking the button to insert an image, but it doesn't ask me to choose the file I wish to insert.   Can anyone help with this?).  The effects are very interesting!  Each orchestral instrument now comes from a discrete position both in height and in side-to-side location.  Some discs are astonishing now.  On Pink Floyd’s DSOTM SACD, you can now tell that Waters and Gilmour are singing into the same mic, but from opposite sides.  Being a trumpet player, I always listen to brass instruments on recordings.  You can now clearly tell that the trumpets are to the left of the trombones and the horns are left of the trumpets (if sitting looking at the “stage”).  All in all, I’m quite pleased for an outlay of about $10.  Are there any downsides to a tweak like this?  Is this a good idea for a horn-loaded tweeter?  I think most designers that use something like this have dome tweeters.  Is the star cut-out about the right size, or should it be smaller/bigger based on the size of the horn?  Any feedback on this idea would be greatly appreciated.
Thanks
Chris

 

[cporada]

I still haven't figured out how to insert an image here, so for those of you who are interested, you can see the image at my post on DIYAudio:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=86731

Thanks in advance for any suggestions
Chris

[cporada]

Sorry, I guess the image in the link only works if you're registered at DIYAudio.  Can anyone tell me how to insert an image on this forum so that people can see what I made and tell me if it's a good idea or not?
Thanks
Chris

[Skipperrik]

I took a look at the pic of your tweak over at DIY (and yes, I had to register) and I'm curious about how you attached the felt.  Is it glued to the diaphram of the tweeter?  I agree with the post on the DIY site; if it sounds good, it is good!  I don't think I could do the same type of configuration with my speakers but it has me thinking!  Thanks for sharing the tweak.   

[cporada]

It's attached to the plastic flange of the tweeter (where the screws go through to mlunt it to the baffle) just using the adhesive on the back of the weatherstripping (the felt was sel-adhesive as well).  So, the beauty of the tweak is, if it doesn't sound better after more extensive listening, I can easily peel it off and go back to the way I had things since the glue is just sticky enough to hold it there.
Thanks for your comments!
Chris

[ooheadsoo]

Check out David Ralph, long time speaker builder's experiments - http://www.speakerdesign.net/home.html

Felt articles.

[AB]

To insert an image the best thing to do is to create your own gallery here on AC then link to its images by using the image tag.

Looks like this:
img]http://www.audiocircle.com/gallery/albums/userpics/etc.etc[/img]

The "etc etc" is your album id and the pics file name. You need to close the bracket too.  I had to leave the first off to prevent the tag from disappearing.
I want to see this tweek so I hope my directions are correct.

[laserman]

Hi Cporada,

Very interesting thread you started for sure. Ooheadsoo, thank you for posting Dave Ralph's website again.  I remember reading about felt rings somewhere and you provided me with the answer and confirming my Deja vu moment.

Cporada, is the felt you are using synthedic or wool?  What is the overall thickness of the felt plus weather stripping?  Did you use the close celled or open celled weather stripping?  Please let us know if you decide to enlarge the ring too.

Keep on experimenting,
L
 

[cporada]

Hi everyone
Thnaks very much for the helpful feedback.  In answer to Laserman's questions, I'm pretty sure the felt is synthetic, since it was from Walmart's craft section and was quite cheap.  The total thickness of the wetherstripping plus felt is right aroud 5/8", since this is the distance my tweeter is set back/recessed from the baffle with the midrange drivers, so I thought it best (I don't know enough to be sure, it just seemed a good idea) to make up the difference with some absorbant material.  As to the open cell or closed cell, the weatherstripping was left over from a subwoofer project, and I no longer have the packaging from Home Depot to be sure, but it appears to be closed cell, since it is very dense looking with no obvious pores.  I chose this one based on a website I had seen from someone who sells a self-adhesive tweeter ring that is made from neoprene.  Unfortunately, the commercial version has too small an opening for me, swince it is designed for small dome tweeters, not horn-loaded ones like mine.  I will try today to create a gallery and post a picture of the "tweeter star" to see what all of you think about it and if anyone has any suggestions for improvements.
Thnaks again
Chris

[cporada]

Here is a link to my gallery showing the tweeter tweak and my DIY supertweeter project that is being discussed in another thread (and also my latest DIY subwoofer project):
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=833
I hope the link works...
Chris
PS actually if you just go to the audiocircle gallery home page, my latest uploads appear there.

[AB]

Here you go.

[cporada]

Wow!
Thanks.  How did you do that?
Chris

[AB]

Go to your AC album, left click on the thumbnail of the pic you want to post. Then right click on the full size pic and choose properties. A dialog box will appear with the title "Element Properties".

Copy the URL after "location" and paste the URL between the image tags

img]http://www.audiocircle.com/gallery/albums/userpics/48432/tweeter_mod.jpg[/img]

in your post.

You need to close that first bracket for the tag to work.

[cporada]

Thanks AB. 
If it's not too much trouble, I'm wondering if Mike Dzurko might be able to offer his opinion on the utility of this mod, since he designed the Alpha limited project, and would know better than anyone whether something like this would work well with this particular speaker, especially given the horn tweeter.  I know from posting on Audio Asylum, some people have raised concerns that the felt is intruding too far onto the tweeter flange and may affect refequency response, while others have stated that since the tweeter is horn-loaded, it is already a point source and anti-diffraction devices shouldn't have any effect at all, since the sound waves don;t move out over the flange.
If anyone can help a non-engineering audiophile out here, I would greatly appreciate it
Thanks
Chris