cabinet edges round vs beveled

*Scotty* · « **Reply #20 on:** 22 Jun 2012, 02:41 pm »

TRADERXFAN, the word you are looking for is smeared.
Salk's article is one of the best explanation's of loudspeaker diffraction for the layman that I seen so far.
If people will read Salk's treatis on the subject most of their questions will be answered.
Scotty

redbook · « **Reply #21 on:** 23 Jul 2012, 11:10 am »

Here's a pix to go with my earlier post regarding the little felt pads to reduce defraction. This has had a significant effect .The highs are indeed smoother. ( I have grills that cover all this....LOL)

*Scotty* · « **Reply #22 on:** 24 Jul 2012, 04:45 am »

Here is how I treated the tweeters on my speakers using 9mm thick size 15 double wide felt insoles.

The speaker disappears better and the highs and midrange are smoother and seamlessly integrated.
Scotty

FullRangeMan · « **Reply #23 on:** 24 Jul 2012, 05:15 am »

Quote from: ricardojoa on 12 Jun 2012, 01:56 pm

Well, i got a question regarding difraction from cabinet edges.
If im not mistakne, the edges of the cabinets are usually rounded over to control difraction. My question is, wouldnt a beveled edges have better control since the egdes are straight?

The round corners is important inside the box, where it lesser the resonances, on the out side the effect is low.

Maybe this old thread may help.
http://www.audiocircle.com/index.php?topic=100689.0

*Scotty* · « **Reply #24 on:** 24 Jul 2012, 05:22 am »

FULLRANGEMAN, here is a link to a very good explanation of cabinet edge diffraction you may find interesting.

http://www.salksound.com/wp/?p=160
Scotty

FullRangeMan · « **Reply #25 on:** 24 Jul 2012, 05:27 am »

Thanks I will read, I use 10mm felt on the baffle(outside).

Russell Dawkins · « **Reply #26 on:** 24 Jul 2012, 05:36 am »

An experimental treatment that is dead simple to try and remove is a hood made by a folded towel draped over the top of the speaker and down the sides past the area where the tweeter resides (and the mid driver if there is one), protruding maybe 2-4" to absorb the diffraction.
In my experience, the effect of this can be dramatic. It also can limit dispersion toward the ceiling and side walls which can also be a good thing.

FullRangeMan · « **Reply #27 on:** 24 Jul 2012, 05:47 am »

This reminds me the Duntech 2001.
http://i11.servimg.com/u/11/00/29/62/dscn0611.jpg

Russell Dawkins · « **Reply #28 on:** 24 Jul 2012, 06:18 am »

Notice the saw-tooth edges on the felt.

I think this is important and yet overlooked by too many. Raal does this on their tweeters.
Scotty, I'll wager you would hear an improvement if you were to treat your felt that way.

If felt absorbed 100% of the energy impinging on it, it wouldn't matter - but to the extent that it does not, it does.

I got a first hand taste of this when I tried to record wind through some fir trees. I had to shield the mic from the wind, and to my surprise, I heard a very distinct cavity resonance when the mic was surrounded by pink fiberglass even though the 'glass was one foot away and the cavity was only about a foot deep. Moving the mic in and out of the cavity produced the tell-tale sliding frequency cancellations.

Letitroll98 · « **Reply #29 on:** 25 Jul 2012, 04:17 am »

Quote from: *Scotty* on 24 Jul 2012, 04:45 am

Here is how I treated the tweeters on my speakers using 9mm thick size 15 double wide felt insoles.

The speaker disappears better and the highs and midrange are smoother and seamlessly integrated.
Scotty

Do the cat trees aid in dispersion or absorption?

*Scotty* · « **Reply #30 on:** 25 Jul 2012, 04:41 am »

I guess that would be absorption, yeah that's the ticket.
Scotty

redbook · « **Reply #31 on:** 25 Jul 2012, 08:14 pm »

Good one about the cat tree:

Glad there are members out there doing similar experiments. My wife figured I was nuts but it seems to work well enough so she cancelled my mental appointment.Where do you obtain those felt pads? I was going to make some from snow shoe liners but I went with the little stick on jobs instead.

S Clark · « **Reply #32 on:** 25 Jul 2012, 08:29 pm »

Quote from: redbook on 25 Jul 2012, 08:14 pm

Where do you obtain those felt pads? I was going to make some from snow shoe liners but I went with the little stick on jobs instead.

Member jimdgoulding sells them custom cut for your tweeter. I don't recall pricing exactly but it was cheap.

Scott

*Scotty* · « **Reply #33 on:** 25 Jul 2012, 08:57 pm »

I purchased my felt insoles from Steger Mukluks. It was an experiment and if I had to do it over again I would have bought a pair of the biggest felt liners and had more felt for less money.
Scotty

DaveC113 · « **Reply #34 on:** 25 Jul 2012, 09:00 pm »

I got a sheet of felt from a manufacturer years ago, forget who but the min order wasn't bad. I got 1/4" high density pure wool felt, there are various grade if I remember right. I have found a lot of uses for it over the years, lol.

It turns out diffraction wasn't as big a deal as I thought, going from a class D to a SET amp solved 99% of the issues I was having with the speakers not disappearing. I no longer run felt pads on my baffles but might try it again to refresh my memory...

bummrush · « **Reply #35 on:** 26 Jul 2012, 01:31 am »

And you'll get 50 answers on speaker edges anyway with 9 out of 10 not based in reality of any kind.

Russell Dawkins · « **Reply #36 on:** 26 Jul 2012, 02:37 am »

Quote from: bummrush on 26 Jul 2012, 01:31 am

And you'll get 50 answers on speaker edges anyway with 9 out of 10 not based in reality of any kind.

What reality is your comment based on?

JBLMVBC · « **Reply #37 on:** 26 Jul 2012, 03:00 am »

Quote from: redbook on 23 Jul 2012, 11:10 am

( I have grills that cover all this....LOL)

I applied these directly on the ears and head... I mean that was before my wife called the ambulance. Now I am in a very well insulated room, all white...

But seriously, applied a few on strategic edges and it does make a difference.

JoshK · « **Reply #38 on:** 26 Jul 2012, 03:43 am »

Quote from: ricardojoa on 13 Jun 2012, 11:32 am

If the cabinet is slimmer, the round or beveled edge have less effect on diffraction, is that right?
I also noticed, for example a speaker with 5 inch driver , the overall driver will usually sit on the baffle that is under the interior width of the cabinet. What happens if the frame of the driver actually sit over slightlly over the interior width of the cabinet? That way a slimmer cabinet can be built, but i dont see people doing it, what kind of compromise can that have?

Nope, just higher in frequency....doesn't mean less enoquece (sic)...early diffraction is the most audible (Geddes) of all sins...eliminate that first! Round over to eliminate as low as possible...limit early reflections...nothing to cause ripple, reflection, difraction...etc

*Scotty* · « **Reply #39 on:** 26 Jul 2012, 04:06 am »

Per Russell's recommendations, the new improved Sawtooth edge felt anti-diffraction treatment.

The effect is subtle but I think there is an increase in openness to the high frequencies and maybe more air. It definitely didn't degrade the effectiveness of the felt.
Scotty