Woolf felt on tweeter

[brianpowers27]

I am wondering which felt is appropriate for a tweeter. I plan to place the felt underneath the tweeter. The tweeter will no longer be flush mounted.

Here is a link to mcmaster carr that rates the felt based on grades. Am I looking for birbation reduction? http://www.mcmaster.com/#felt/=mr2tz

[gowa]

Wow! That stuff is expensive.

[dlr]

I am wondering which felt is appropriate for a tweeter. I plan to place the felt underneath the tweeter. The tweeter will no longer be flush mounted.

Here is a link to mcmaster carr that rates the felt based on grades. Am I looking for birbation reduction? http://www.mcmaster.com/#felt/=mr2tz

What do you mean by under the tweeter? You definitely should not surface mount a tweeter.

If you're interested in felt for diffraction with info on the felt to use, check out the diffraction pages at my site.

dlr

[Wolf]

What do you mean by under the tweeter? You definitely should not surface mount a tweeter.

If you're interested in felt for diffraction with info on the felt to use, check out the diffraction pages at my site.

dlr

He has a stepped baffle with the joining egde at a 45 degree angle. I'm pretty sure he means to place the felt at the step-transition to improve diffraction below the tweeter, and not physically underneath it.
Later,
Wolf

[brianpowers27]

He has a stepped baffle with the joining egde at a 45 degree angle. I'm pretty sure he means to place the felt at the step-transition to improve diffraction below the tweeter, and not physically underneath it.
Later,
Wolf

I guess that I was originally thinking it would benefit me to put a (real wool felt) ring underneath the tweeter. I would consider using wool felt on the step.

I have read the baffle diffraction pages over at Dave's site. I am hoping to get some davice or participate in a discussion regarding the different types of felt and their relative application.

I picked up some craft felt (100% wool.). Will this be effective?

[dlr]

I guess that I was originally thinking it would benefit me to put a (real wool felt) ring underneath the tweeter. I would consider using wool felt on the step.

That was my impression. I would not use felt as a gasket or mount material. The typical stuff works fine.

I have read the baffle diffraction pages over at Dave's site. I am hoping to get some davice or participate in a discussion regarding the different types of felt and their relative application.

I picked up some craft felt (100% wool.). Will this be effective?

If you have a stepped baffle, the June 2005 issue of audioXpress has an article of mine that shows application of felt with a good set of measurements that documents the change with each additional piece. I've never taken the time to transfer it to a web page. It's far more detailed than my current web pages. I've done a lot of experimenting with felt types and configurations. There's a trend that arises in almost every case that has led me to the configurations that I use.

The best felt is the low to medium density, the higher the real wool content the better. I've used the F-11 and F-13. F-10 might be best, but it's way too expensive. I've used the F-13 for most of it, as much because it can be purchased with a self-stick backing. I'm using 1" F-11 more now simply because it's more effective.

On my stepped baffle, I use 1/2" thick felt, but 3/4" would work and look better since it would match the offset of the 3/4" mdf I use on midranges.

The F-11 is more grayish, the F-13 can vary due to it being mixed more with synthetics. I've seen purplish running in it. Both could be dyed, but I haven't done that.

dlr

[brianpowers27]

If you have a stepped baffle, the June 2005 issue of audioXpress has an article of mine that shows application of felt with a good set of measurements that documents the change with each additional piece.

That sounds like an interesting article. I would love to read it. I went to the Audioexpress website and there is no way to get just that article. The only way to get the article is to order the whole year.

P.S. Do you think that a chamfer on the step produces more diffraction than a roundover?

[Face]

http://www.diffractionbegone.com/

[brianpowers27]

http://www.diffractionbegone.com/

I saw this website earlier. I am imagining that the felt they sell be bought at a lower price from mcmaster-carr. Part of the reason for the expense it their custom sizing of the wool.

I am still having a hard time imagining how I can work this into the design so that it doesn't look like something that belongs ina lab.

What do you suppose would work for gying felt? Would food coloring work or would you need a special fabric dye?

[dlr]

I saw this website earlier. I am imagining that the felt they sell be bought at a lower price from mcmaster-carr. Part of the reason for the expense it their custom sizing of the wool.

I am still having a hard time imagining how I can work this into the design so that it doesn't look like something that belongs ina lab.

What do you suppose would work for gying felt? Would food coloring work or would you need a special fabric dye?

It is far cheaper buying from McMaster-Carr. It's also not a good idea to use circular openings. It may be far simpler to have them cut that way, but a circle is the least effective shape. If overall aesthetics is an issue (not surprising), just buy a short length of 1" x 1" x 36" F-11 and cut strips using an x-Acto knife or similar by press cutting (no sawing). A single 6" long strip between the tweeter and the mid or midwoofer will be very effective for the offset baffle section and the adjacent driver itself that also adds its own diffraction to the tweeter response.

dlr

[dlr]

That sounds like an interesting article. I would love to read it. I went to the Audioexpress website and there is no way to get just that article. The only way to get the article is to order the whole year.

P.S. Do you think that a chamfer on the step produces more diffraction than a roundover?

I really should add it to my site.

AFA the cut, I suspect that a chamfer will be better in this instance. The roundover terminates in a 90 degree angle at the main baffle. If you use felt, it'll be almost a non-issue. Do whatever looks best.

dlr

[brianpowers27]

It is far cheaper buying from McMaster-Carr. It's also not a good idea to use circular openings. It may be far simpler to have them cut that way, but a circle is the least effective shape.
dlr

I was actually considering placing a whole sheat over the top step with a hole cut out of the center. Is the effect of a round opening highly detrimental or minimally detrimental?

What thickness do you recommend? I notice that McMaster Carr doesn't sell F11 at all. The only self adhesive sizes are 1/4" and 1/8" in the f13 grade. Is a 1/4" enough?

Also, This cabinet is not yet finished. Will I be able to remove this and reuse it? Maybe I could buy plain and use something like rubber cement?

[brianpowers27]

--What if you were to apply the same principal to the backside of the baffle?
--Would the placement of felt on the rear yield an improvement in diffraction?
--Could Mineral wool (High Density fiberglass - Rockwool, 703/705) be used for similar purposes?

[dlr]

I was actually considering placing a whole sheat over the top step with a hole cut out of the center. Is the effect of a round opening highly detrimental or minimally detrimental?

What thickness do you recommend? I notice that McMaster Carr doesn't sell F11 at all. The only self adhesive sizes are 1/4" and 1/8" in the f13 grade. Is a 1/4" enough?

Also, This cabinet is not yet finished. Will I be able to remove this and reuse it? Maybe I could buy plain and use something like rubber cement?

It will still work with circular cutout, but felt is partially reflective and it has a tendency to horn load to some degree, especially if it's too close to the dome. What I can say is that a square cutout centered, better yet slightly offset or a rectangular one will be much more effective for the same reason that a tweeter offset on a baffle reduces the diffraction signature. A circular opening with the tweeter centered concentrates the reflected part into a very narrow region, whereas the other geometries spreads it out.

I forgot that M-Carr dropped the F-11 line. That's too bad, I'll have to find another source when I want some. I had only used the F-13 because of the backing. At least they still sell that. I thought, though, that they still had the thicker in that grade. You should get at least 1/2". 1/4" doesn't help a lot. For it to work inany meaningful way, the sound waves have to pass through it, not over it, especially as frequency drops. It takes experimentation to find the optimum for any setup, but 1/2" will provide a very good improvement.

It can be re-used, just be careful with anything other than the type with a backing, as 2-sided tape doesn't adhere well to the bare felt. I'll leave that part to you, since I've only used the original backing and at times added 2-sided self-stick tape. If you glue, I'd suggest a glue that does not attack the finish if you're concerned with removing it at some later time. Experiment with some spare wood with a typical finish if you can. But it doesn't take a lot to hold it in place.

Forget the back side.

The other materials are not nearly as effective as the wool primarily due to density. And having fiberglass on the outside would not be my preference.

dlr

[critofur]

I saw this website earlier. I am imagining that the felt they sell be bought at a lower price from mcmaster-carr. Part of the reason for the expense it their custom sizing of the wool.

I am still having a hard time imagining how I can work this into the design so that it doesn't look like something that belongs ina lab.

What do you suppose would work for gying felt? Would food coloring work or would you need a special fabric dye?

In terms of dying, just google "dying wool" and I bet you'll find lots of info

I'm getting some white grill cloth. You could carefully make a little pillow out of white grillcloth and try various "stuffings" to determine which worked best.

I suppose I could send you a couple samples of stuff you could put in the pillows.

The other materials are not nearly as effective as the wool primarily due to density. And having fiberglass on the outside would not be my preference.

dlr

I have some materials which may be more effective than felt - and putting them in a grill cloth pillow could contain them. Another option for the "pillow case" maybe gauze? Spray it with some "scotch guard" so it stays clean?

[brianpowers27]

I just submitted my order from the Grainger company for 1/2" x 1" x 120" adhesive backed f13 felt. When I get the felt I will likely place two strips the full width of the baffle.
--One strip right above the step.
--One strip accross the chamfer on the step.

I am also likely to round the top edge over using a 3/4" roundover.