4343 vs 4430 experience

[Mr. Widget]

Yeah, like Rob said.


Or I prefer the scientific term. Muck.

[Robh3606]

Urei horn from the C versions

[Ian Mackenzie]

Looks like a good case for wave disscontinuity given the short horn length.....

Ian

[Earl K]

Hi

- Thanks Jan / SubWoof. I had never before seen a connection made for the use of a rough texture coating within the 2307 ( to give a bit of resistive loss/damping to control throat reflections ) .

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?

- Most of what's quoted above can be given a lot of illumination & insight by reading Harry F. Olson "Acoustical Engineering". His studies of for a group of exponentials ( & other types ) clearly show the resultant acoustic effects derived between relationship of horn length vs mouth opening. The chapter called "Acoustical Elements" display graphs showing the measurable " throat acoustical impedance" characteristics for different types of horns including conicals (or straight sided ) . The studies are with round mouthed horns. Once a person sees the graphs and relates them to the 2307/2312 round-mouthed, exponential family - one will understand whats' behind the comments of hearing the "ocean" when the horn is used to capture sound as a hearing aid. Not nearly as well understood is how JBL moved to sidestep the issue by crossing over above the obvious anamolies or maybe more importantly "averaging-down" the impedance of the anamolies ( with a lot of resistive loss ), derived mostly from their most sophisticated crossover designs.

Re; on the Urei foam & slots;

An article in db Magazine , August 1981 written by Dean Austin ( of United Recording Corp. ) really underscores all the reasons these bits came into being. The topical area is called "Therapy For SoundWave Trauma" . Great pics of a 2.3 kHz Tone-Burst , before and after the foam buffer/and other mods have been added. The extreme amplitude trauma to the horns' lower response ( around flare cutoff ) is also shown in a overall Response Graph.

- Too bad I don't have a scanner.

- All this really underscores the need for thoughtful termination for all types of circuits .

Ian Mac; your friends foamed termination of 2307/2308 combos will find some support from all of the above mentioned references .

<> Earl K

[Ian Mackenzie]

I may invite Rodd to comment further.

I think it would help flesh out the issue for us JBL er's

Ian

[Earl K]

Ian;

I did quite la ot of experimenting to modify the pattern of a 2308. This was done by inserting thin strips of acoustical transparent material in between the flat plates ( in certain areas ). The idea was to create different pressure or velocity changes/points within the lense itself. I found a lot could be accomplished- but - ADD overcame me before I could arrive at usable findings.

<> Earl K

[boputnam]

Originally posted by Earl K
...ADD...?

Acoustical Deficit Disorder? You talkin' about me...?

[Ian Mackenzie]

Acoustic disfunctional disorder ...no he ain't refering to you Bo

Earl,

I have sent an email to Rodd for some insights.

Rodd is an authority on these tweaks and has taken ownership of some new horns I understand......the larger of the slant plate horns and the Tad driver

Bo, why don't you put a 2308 in front of your L100's , would that make them 43xx current......muhahahahah...the pot is already black.

Ian:o

[Earl K]

Hi Ian / Bo

I was wondering if Rodd was considering an MTM setup with those 4, le10s he has ?

<>EarlK

[Tom Loizeaux]

After reading and thinking about points made in this thread about horns, flare rates, disturbed and reflected waves, etc., I added a large piece of felt to the front panels of my 4343s (don't worry, they're very removeable). I put them directly behind the slant plates, running from one velcro strip to the other. My hope was that they would tame some of the HF reflection off the back of the slant plates.
Did it help? I don't know! They might sound ever-so-slighty smoother. I wound up turning the HF amp up just a taste.
They still sound GREAT, so I guess I didn't create a problem!

BTW, the insides of my 2307 horns are quite smooth. Is that a bad thing?

Tom

[boputnam]

Originally posted by Tom Loizeaux
BTW, the insides of my 2307 horns are quite smooth. Is that a bad thing?

We all suffer with that, Tom. Wondering Aloud...? Earl's post made me want to try a lightly sand-blasted surface, but then again, I'm really not up for altering anything on my 43xx large formats.

Originally posted by Earl K
one will understand whats' behind the comments of hearing the "ocean" when the horn is used to capture sound as a hearing aid.

Well, I can't know about all that, but I do know that if you hold a rock up to your (good...) ear, you can hear the desert...

[Mr. Widget]

Every H91 and 2307 I have owned (all 70's vintage) was smoothish on the inside. I say smoothish because due to flaws in the casting there were random scratches, bumps, and divots here and there and I am quite sure they were not put there intentionally. That is why I used the word "lore" in my previous post.

I certainly wouldn't worry about it. Whether you call it the ocean or desert it is still has an unnatural sound to my "tin" ears.

[Don McRitchie]

Originally posted by Robh3606
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

I agree. The Titan's were my choice for "best sound" at MAF by a wide margin. However, I have yet to warm up to the visual aesthetics. In fact, I have a hard time not snickering whenever I see them. It just looks too much like a cartoon character or that baseball mascot with the air horn for a nose

[JonFairhurst]

>> "I agree. The Titan's were my choice for "best sound" at MAF by a wide margin. However, I have yet to warm up to the visual aesthetics."

Thankfully, JBL has never produced a horn with comical visual aesthetics.

[Alex Lancaster]

And, what can You tell us about the cabaret speaker that had the horn actually polished?

I had some 2312´s cast and sandpapered with a die grinder, could not really hear a difference.

Alex.