>> "On the 2344's - I had a stock pair in my living room for years. The imaging was pretty good considering the placement dictated by the other half... "
What? She had you turn the lobes around to face the wall, did she?
I hear that John Ashcroft has a pair of 4430s, but he covered them with $10,000 worth of JBL blue grill cloth. (Ba dump.)
Well lets just say that black sabbath's IRON MAN dusted one end of the high back couch pretty good...
Dah...dah... dah duhn duhn...
It would be interesting to line up the 4343, the 4430 and the DMS1 in the same room.
From the white paper it appears a next generation 4430 but heard little about it other wise.
The horn driver was superior and a different type of horn also.
By the has anyone played with the 275ND?
My gut feel is that the silica shower effect you "Dam Yankees" Err complainin about is related to resonance damping at certain frequencies along the inner surface of the horn.
My brothers 4343 have the original Ali bottle tops, they definately tingle on certain program material and my Ti bottle tops sound more mellow.
Old bottle tops should be pitched out every few years, probably half the issue here if truth be known......Bo what is your comment having replaced yours?
The effect is more noticable in the narrow straight exponentials I agree.
Tractrix king Bruce Edgar has studied the anomalies very closely and I recall ages ago reading an article about vibrations traveling down the horn sides in a very thin air layer causing a fine jaggered edge super imposed on the overall frequency response only seen under high magnification.
See the continuing posts and a revealing link to an interview with Bruce Edgar.
Ian
Last edited by Ian Mackenzie; 12-06-2003 at 04:02 AM.
> "vibrations traveling down the horn sides in a very thin air layer"
Interesting. I know that with Formula One cars that they "discovered" the ground effect in 1978. They found that they'd get a certain amount of downforce with a given wing, but when the wing got close to the ground the force increased greatly with respect to drag.
From memory the Lotus engineers found this in the wind tunnel when they fashioned the side radiators into a kind of a wing shape. One of the suspension supports broke, the car lowered, and the downforce readings went nuts.
Before long, all the teams were using huge underbody wings surrounded by sliding skirts to maximize the suction cup effect. The drivers could corner on rails, but if you lost suction all hell broke loose. It didn't take long before the skirts were banned and minimum ground heights were enforced.
To make a long story short, weird things happen at the boundary between surfaces and air. These days wind-tunnels even have "rolling roads", since the fixed floors just didn't behave like a road being traversed at 180 mph.
Then to make things even stranger, we're dealing with dynamics (frequencies) rather than statics. It's not quite quantum mechanics, but it's not as intuitive as static physics either. Welcome to the imaginary plane of phase.
No doubt. Horns are as much an art as a science.
Jon,
Your response is quite thought provoking.
Here is the link to the Edgar interview where he discusses the wisdom of modern day horn design.
http://www.positive-feedback.com/Iss...rinterview.htm
Some key points:
With exponential horns, theory predicts that the wave form going down the horn is plane or flat, but the wave front has to drag along the horn walls.
The issue of concern is the wave front exiting the mouth of the horn, causing a bulge that is essentially a discontinuity. This gives rise to recflections which travel back to the throat and set up a quarter-wavelength resonance condition.
The curve nature of the wavefronts that minimise these reflections is the Tractrix curve.
Ian
Last edited by Ian Mackenzie; 12-06-2003 at 04:03 AM.
Here is a recent picture of Bruce Edgar with his new Titan horn design. Note the curved wave fronts.
You may recall in a previous post the rant we had over the 2307 sea shell effect and experiments by a diy friend who has tweaked his JBL exponential horns with application of thin foam pads around the circumference of the horn mouth and under the slant plate lens.
Perhaps this is at least a partial remedy to the above reflections?
Ian
Dr. Edgars tractrixs are very nice sounding indeed. Those speakers were a very nice treat at the 2003 MAF hosted by Mike B. Spent a good amount of time listening to them.
Rob
4430-4435
hello Leif,
I exactly made this test with the 4430 and the 4435 and I think that its easy to explain:
The only diff is the deep bass which is about +6dB with the 4435 under 80 Hz.
I think the reason is only that in the area under 100 Hz the second 2243 works parallel , and this in the bigger box.
short: the low bass of the 4435 is fantastic.
Hanspeter
I have looked high and low but cannot find the documentation. I recieved a note from jbl with some 91 horns saying to not smooth the rough paint inside the expo horn as it was that way deliberatly to improve the sound.
That's really interesting!
When was this ?
<> Earl K
OK - look at this picture. It is a jbl / urei horn used in the coaxial 12' 809C studio monitor.
the horn *sides* go from smooth, to rough foam to closed cell foam ( rounded ) on the horn edge.
This is designed to correct reflections and control the pattern....
sub
Earl
That was in 1975.
Hey, Widget - what you know about all this?Originally posted by subwoof
...the horn *sides* go from smooth, to rough foam to closed cell foam ( rounded ) on the horn edge.
This is designed to correct reflections and control the pattern....
bo
"Indeed, not!!"
Urei Horns
The foam edges are also there to help control diffraction effects of the horn and the woofer about 3 inches behind it. The last version of the larger horn on the 15's had slots cut into the horns close to the foam pads inside. They crossover around 1k.
Rob
Last edited by Robh3606; 12-11-2003 at 09:21 PM.
In the case of the Urei, I believe the foam has to do with the fact the horn is mounted in the woofer and it is to reduce their interaction (read to prevent the two sources from mucking each other up too much) It probably helped dampen the ringing as well. Always a problem with thin walled horns especially if they aren't terminated into a massive baffle. As for texture on the Urei, I am not sure I could speculate.
As for the JBL exponential mentioned by Jandregg, my guess is they would try anything to make those sound better... oh no, am I starting another one of those threads..
Actually in reading the interview with Dr. Edgar that Ian posted on one of these threads, Dr. Edgar mentions reflections traveling down the sides of exponential horns... might have something to do with that, or it might have been lore. I think there were folks at the factory that were smokin' a bit too much back in the '70's. Heck that's when they came up with your favorite speaker the L- what was the number?
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