Reducing H-F distortion in full range drivers

[chuck55]

While most full range driver F-R's can look pretty good, Parts-Express also tests the drivers they sell and they are not so kind. From these graphs, it is obvious why spekaers cross over below 3,000 hz. Here is one from a Pioneer driver. I am looking at paper cones in particular.

http://www.parts-express.com/pdf/290-045.pdf

Coating the paper helps but there is still a lot of H-F breakups. I was wondering:
1) Where on the cone are the HF produced. I realize in a pure rigid pistion it would be all the cone. But in reality, would the center produce more HF while bass would come from the whole cone?
2) If so would putting extra damping material in the center section help redcue HF breakups without causing other problems like adding more mass?

Any other thoughts?

[defect9]

keep in mind that the room and the enclosure itself will change that response graph

[Ty_Bower]

I think the EnABL guys have spent a lot of time studying this kind of thing...

[kevinkr]

Probably one of the reasons why most FR drivers are 8" and under. I suspect it is a case of finding a driver that you can afford with the least break up modes at the highest frequency possible. I'm not sure that there is much you can do, although I assume anything you can do to stiffen the cone (modpodge or varnish?) without adding significant mass will probably help. (This is a swag as I am not that knowledgeable in this area.)

Even with the problems with break-up modes a lot of FR speakers seem to sound pretty good.

Planet10 is one of the real experts on this subject and hopefully will weigh in soon.

I'm slowly getting ready to build a FR half chili using Fostex FE167.. (I might have more to say on this subject wrt to audibility of this phenomena at some point as I am well equipped to measure them.)

[norman bates]

many drivers small or big are in break-up past a couple of khz. Not many are truely pistonic. Thats why there is much research and development so as to make drivers that sound / measure well..............

Hf beakups are issues that perhaps with trial and error can be avveliated.
Some use a coating, some use some coating here and there, some drill a hole in the dustcap, others stay away from dust caps, etc...........

actually that graph isn't that bad, full range drivers don't usually measure flat.
Some of the high spike are alleviated when measured 10' away.

That is the pioneer B20 driver, there is much you can do to improve it.

But I think the Mark Audio drivers are ones to look for (granted they are smaller and more pricy).

Norman

[Spasticteapot]

If you don't want a crossover and can't stand cone breakup, it's basically electrostats or bust. I've heard some very high-end fullrange speakers, and I just don't like 'em.

[chuck55]

I've been following Planet10's formula with Mod-Podge and C37 and it is the best path I have found.

EnAbl is more for clarity and not breakup modes from my understanding.

Markmck has the best solution with selective damping. The problem is finding out exactly where to put it. There is no general formula.

Thanks all

[fastbike1]

Don't forget to actually listen to them. This forum sometimes seems to do more modeling and simulation than actually listening.

Originally Posted by kevinkr

I'm slowly getting ready to build a FR half chili using Fostex FE167.. (I might have more to say on this subject wrt to audibility of this phenomena at some point as I am well equipped to measure them.)

[kevinkr]

Originally Posted by fastbike1

Don't forget to actually listen to them. This forum sometimes seems to do more modeling and simulation than actually listening.

No one would ever accuse me of that, for every hour I spend in modeling or simulating I spend about 100hrs listening. And I do a fair amount of dedicated listening - on the order of 12hrs or more a week.


Frankly if I am guilty of anything it is in spending too much time here...

[Alex from Oz]

Originally Posted by chuck55

I've been following Planet10's formula with Mod-Podge and C37 and it is the best path I have found.

EnAbl is more for clarity and not breakup modes from my understanding.

Actually, EnABL addresses breakup modes - that's where the clarity comes from.

Cheers,

Alex