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57BELAIRE
03-23-2005, 01:25 PM
In some recent threads concerning sub-par bass performance from LE15 equipped Paragons, the majority of solutions seemed to center around restoring/replacing the original Lans-a-Loy suspensions that have become stiff and non-compliant with age.

While I agree that will usually help, I'm wondering if the LE15 was actually the best choice for use in the Paragon and why they switched from the 150-4C.

In JBL product literature it clearly states " JBL Linear Efficiency loudspeakers are not interchangeable with maximum efficiency series...maximum efficiency loudspeakers are designed for use in horns and reflex enclosures while the Linear Efficiency group have design features which ideally adapt them to closed cabinets of minimum dimensions".

"The LE15 delivers solid,firm bass in CLOSED CABINETS of 6-8 cubic feet internal volume".

While the LE15's long excursion will move some air, maybe a front-loaded horn is not the OPTIMUM design to bring out it's BEST capabilities.

Anyone?



:blink:

57BELAIRE
03-23-2005, 04:00 PM
...I guess my question is....

"why replace the best 15 in. woofer ever made (in it's time, IMHO), with a design that admittedly had flaws?

Mr. Widget
03-24-2005, 09:56 AM
You are right in pointing out that the 150-4C and the LE15A are most assuredly not interchangeable woofers in virtually all cases. With the Paragon however since the original design is so flawed (From a deep bass stand point) it probably doesn't make that much difference between the two woofers. Obviously JBL felt they could make the change.

Yes I said flawed... it is a short front loaded horn with a very small mouth. It may very well be a properly designed MID- BASS horn, but there is no way in hell that a horn of that scale can produce deep bass at a level anywhere near it's output at 500Hz. I would expect with room gain you could get solid 50Hz response and be a few dB down at 40Hz. Remember when the Paragon and Hartsfield were first designed 40Hz to 10KHz were considered wide-band performance.

I realize one forum member measured 17Hz from a Paragon. I would submit that they were measuring noises from a nearby freeway or measured it during a small earth quake or had faulty test gear. No one has yet produced a subwoofer that is flat to 17Hz without employing some form of EQ or designing it to operate over a very narrow band of frequencies. To have a single low frequency element that could be flat from 20Hz to 500Hz without the use of external EQ in any design would be quite a trick.

I suppose we could all be talking about the same performance if we are using different ideas of what flat means. I would say +/- 5 dB in room is acceptable as a flat measurement. Some might consider that generous, but it is typical of a good system. If you are willing to accept +/- 10 to 15dB you might make the claim that a speaker is flat to 20Hz.

Widget

Mr. Widget
03-24-2005, 10:01 AM
...I guess my question is....

"why replace the best 15 in. woofer ever made (in it's time, IMHO), with a design that admittedly had flaws?

Are you saying that the LE15A is the design that "admittedly had flaws"? What flaws are those? Some would argue that it was the best woofer that JBL ever made. The two woofers are simply polar opposites in design thinking.

Widget

Zilch
03-24-2005, 10:42 AM
I betcha LE15B would be a good upgrade.

Anybody got a pair of 150-4C they want to trade to try? :p

57BELAIRE
03-25-2005, 06:09 AM
Widget....the "design flaw" I was referring to was, utilizing the LE15 in a horn-loaded environment when the product literature clearly states that "the Linear Efficiency group deliver OPTIMUM performance when mounted in totally enclosed, or, at the option of the user, in some circumstances, port-loaded enclosures".

I agree the LE15 is a great speaker, but do you think it is a better choice, especially in the Paragon, than say, the 150-4C or another of the Maximum Efficiency group?

My whole purpose of raising this issue was to answer the complaints of some ( LE15 equipped) Paragon owners whom expressed dissatisfaction with their unit's low end performance....aging Lans-a- Loy suspensions aside.

I personally feel the 150-4C was better suited for the Paragon and wonder why it was replaced with the LE15?

Any speculation on this?

rbh :blink:

Mr. Widget
03-25-2005, 08:31 AM
My whole purpose of raising this issue was to answer the complaints of some ( LE15 equipped) Paragon owners whom expressed dissatisfaction with their unit's low end performance....aging Lans-a- Loy suspensions aside.

I personally feel the 150-4C was better suited for the Paragon and wonder why it was replaced with the LE15?

Any speculation on this?


"With the Paragon however since the original design is so flawed (From a deep bass stand point) it probably doesn't make that much difference between the two woofers. Obviously JBL felt they could make the change."


I think I answered your question... As far as speculation as to why they made the change it may have been that they favored the newer engineering?

I think a more interesting question is why the 150-4C was discontinued. It was only in the JBL stable for a handful of years. The D130, 130A and LE15A were in the stable for decades and the 075 has been since 1956 and is still available!

Widget

Alex Lancaster
03-25-2005, 08:45 AM
:) A while back somebody suggested trying E145´s, 2234/5's, I wonder what came out of that.

paragon
03-25-2005, 10:25 AM
K 145 and LE15A (Red) in Paragon. Standing at wall. Sim distance 2.5m. Lenghth 1.4m, Mouth area 40x42cm, rear chamber 20l, front chamber 3l ????? Who has the right dimensions ???

whgeiger
03-25-2005, 06:07 PM
The use of a horn always equates to a sacrifice of driver bandwidth for a gain in output efficiency. If anyone doubts this assertion, just do a few comparisons between PWT and Horn response plots for a given driver. So, in terms of frequency response (bandwidth), all horn systems appear flawed when compared with their less efficient (wider-band) direct radiator counterparts.

The effective length and mouth size of the Paragon’s bass horns are much larger than their physical dimensions suggest. At low frequencies they act as a single, large, 2-driver horn where the bifurcated mouths are acoustically joined by the curved reflector panel. Furthermore, in a typical ‘at-home’ setting, bass frequencies are radiated into a confined space approaching that of a single spherical quadrant. All of these features combine to provide bass horn loading and output that is quite exemplary. So, to characterize such a design as “flawed” is like characterizing the design of a Lamborghini Countach as impaired due to the fact that it is ‘too small’ to carry four passengers. In the case of the Paragon, complaints of inadequate bass response most likely come from ‘boom-box’ conditioning.

To meet the demands of modern source material, more volume displacement is required than that provided by the JBL LE15A driver ([Xmax]=4.06 mm) or that of the 150-4C. When either is placed in a Paragon, they simply become displacement limited at low frequencies. Upgrading the drivers used, and up scaling the enclosure size over that of vintage JBL implementations will enhance the performance of Richard Ranger’s design. But, his design is not intrinsically flawed any more than any other all-horn loudspeaker system that is size constrained by the room in which it is to be placed. To produce the first two octaves of sound requires displacement of large amounts of air, which in this case, must be radiated efficiently by horns whose (effective) dimensions are comparable to the wavelengths of sound to be emitted. The Paragon enclosure design will fulfill this mission if implemented appropriately.

Regards,

WHG

57BELAIRE
03-26-2005, 08:55 AM
WHG,

Nicely said....I think :blink:

I must admit when it comes to the technical aspects of sound propagation, I'll leave that to the better informed...I go by what my ears tell me.

Concerning Widget's rather scathing inditement of the Paragon " design flaws" ( he readily admits he's never actually heard one) appears to stem not from empirical evidence but from heresay.
I would never assume to judge the K2's performance solely on appearance (they sorta look like your garden variety p.a. column to me) or what I read in some hi-fi review. I will reserve my judgement until the audition....until then "the jury is out".

All the graphs, charts, logarithms and postulates floating about this forum are moot and we can debate ad infinitum...what really matters is....

HOW DOES IT SOUND?

rbh

paragon
03-26-2005, 09:36 AM
Who knows about the parameter of the Paragon bass horn and can tell me ?:)

Thanks, Eckhard

Mr. Widget
03-26-2005, 09:40 AM
Concerning Widget's rather scathing inditement of the Paragon " design flaws" ( he readily admits he's never actually heard one) appears to stem not from empirical evidence but from heresay.

I guess you misunderstood my post. I am not saying they are bad speakers and I would never presume to know what they sound like. Furthermore I really hope to add one to my collection one day.

My point is that with a basic understanding of physics and acoustics it is easy to see that there is no physical way possible for that design to develop bass much below 50Hz. It just can't. Bill Gieger and I are saying essentially the same thing.

Perhaps design flaw is a bit harsh, but they knew the compromise they were making when they designed it and were willing to produce one of the greatest pieces of audio sculpture at a sacrifice of low bass.

Widget

Zilch
03-26-2005, 01:37 PM
All the graphs, charts, logarithms and postulates floating about this forum are moot and we can debate ad infinitum...what really matters is....

HOW DOES IT SOUND?

rbhThe Paragon? Last time I hooked it up, it sucked.

BUT, I ain't messin' with it, no, no.... :scold:

[Maybe I WILL try these nasty LE15B's in it tho....]

whgeiger
03-26-2005, 06:39 PM
The Paragon? Last time I hooked it up, it sucked.

BUT, I ain't messin' with it, no, no.... :scold:

[Maybe I WILL try these nasty LE15B's in it tho....]

Z-Man,

Perhaps you are hearing sounds from a stampede of angry resonant critters escaping the premises. :bouncy: :bouncy: :bouncy:


Regards,


WHG

Maron Horonzakz
03-27-2005, 07:11 AM
The Paragon horn design cutoff is about 50Hz But.. the LE 15 goes below 30Hz can I hear it? You bet your little cookies. But with some added distortion. Can I hear the difference in LE 15 & 150-4 with the paragon horn below cut off? SHURE. The woofer doesnt stop at horn cutoff but its amplitude is affected. Can I hear this? Yes. Its not the bottom end that I obssess about. Its the Poor high frequency spread over the curved panel ( 500Hz to 7000Hz) the rest (075) spits out at you out of that black mouth. Why didnt they aim the tweeter off that curved panel boggels my mind. They do it on the Metragon. They do it on the Minigon. :blink:

whgeiger
03-28-2005, 10:29 AM
MH,

1) Bass Section
Like Klipsch’s corner horn [1], [2] & [4], the Paragon bass horns also employ multiple flare rates and pathway bifurcation. Their mutual effective cut-off frequency [Fc] is approximately 30 Hz. Of course [F3] is higher. Also the cut-off frequency is not an impenetrable wall. As Klipsch clearly demonstrates in a subsequent paper [3], output below the cut-off frequency exists.

2) High Frequency Section
Unfortunately the 2403 [5] circa 1979, came after the Paragon design had been all but abandoned. Need to acoustically 'paint' the reflector pannel properly requires an elliptical horned driver.

Regards,

WHG


[1] Title: A Low Frequency Horn of Small Dimensions
Author: Paul W. Klipsch
Publication: ASA-J, Vol. 13, Oct-1941
Publication: ASE-J, Vol. 27, No. 3, p. 141 (1979) Reprint
Abstract: The first paper on the classical Klipsch-horn (corner bass horn). The loudspeaker horn described is a low-frequency horn so folded as to utilize wall and floor reflections to improve the impedance match at the mouth. Some curves and a lot of enthusiastic talk about how good the horns sound is presented.

[2] Title: Improved Low-Frequency Horn
Publication: ASA-J, Vol. 14, Jan-1943
Author: Paul W. Klipsch, 4 pp.
Abstract: Follow-up to a previous article. Better measurements and some improvements in the design of the horn are presented.
[3] Title: A Note on Acoustic Horns
Author: Paul W. Klipsch
Publication: IRE-P, Vol. 33, No. 7, Jul-1945
Abstract (1): Customarily throat impedance of an exponential horn is portrayed as exhibiting a sharp cutoff characteristic. For those that have tested horns in the acoustics laboratory, the fact that a horn propagates sound waves below its cutoff frequency is not a surprise.
Abstract (2): The present note shows that this discrepancy between theory and practice is reconcilable. Equations based on accepted theory are used to compute the throat impedance below cutoff, and it is shown that both the reactive and resistive components of this impedance remain finite.
Note: Precursor to Reactance Annulling.

[4] Title: A High Quality Loudspeaker of Small Dimensions
Publication: ASA-J, Vol. 17, No.3, Jan-1946
Author: Paul W. Klipsch
Abstract: A complete loudspeaker system using a corner bass horn and complementary high frequency horn is described, along with evaluations using Western Electric 555W driver. If you are contemplating a design/build project of a similar enclosure, study of all of Klipsch’s articles will be beneficial in obtaining a successful outcome.

[5] JBL 2403, Ultra-High Frequency Driver with Elliptical
Horn. http://www.lansingheritage.org/images/jbl/catalogs/1982-pro/page18.jpg

rpstephen
04-01-2005, 02:54 AM
The reason jbl used the le-15a in the paragon was to improve the bass according to Harvey Gerst. Also the owner of Pecar electronics in Detroit told me this in 1965. I doubt that jbl would have done it if it didn't make an improvement. Of course, I would still like to hear the original paragon with the 150C. I have found that the bass is much improved with the 2234 -no more wooly base! Bass definition and low frequency extension are significantly better. Would the 2235 be even better? I don't know, but there is:) a loss of efficiency. Does anyone have a spare pair to bring over? The downside: loss of depth in the soundstage. The likely culprit:
the lx-5 crossover and the probably the reason why jbl never replaced the le-15a with the 2235. They would not likely have allocated money to develop a new crossover for a low volume money losing product.

whgeiger
04-01-2005, 10:23 AM
)snip(
Would the 2235 be even better? I don't know, but there ishttp://audioheritage.csdco.com/vbulletin/images/smilies/smile.gif a loss of efficiency. Does anyone have a spare pair to bring over? The downside: loss of depth in the soundstage. The likely culprit:
the lx-5 crossover and the probably the reason why jbl never replaced the le-15a with the 2235. They would not likely have allocated money to develop a new crossover for a low volume money losing product.

SC,

1) 2235 is identical to the 2234, except the 2235 has a heaver cone [mms]. As [Pe] remains constant and [No] takes a dive, stick with the 2234 for best results.

2) [Re] and [Le] for the 2234 are about ½ those of the LE15A. Crossover changes would be required to get the best performance from the 2234.

3) The next step form here would be to try 1500FE/AL, if it will fit in the Paragon’s back-chamber.

4) For a guide to picking horn drivers, see Small's paper [1].

Regards,

WHG

Reference:
[1] Title: Suitability of Low-Frequency Drivers for Horn-Loaded Loudspeaker Systems
Author: Richard H. Small
Publication: AES-P, No. 1251, Cnv. 57, (1977-05)
URL: http://www.aes.org/publications/preprints/search.html
Abstract: The efficiency, bandwidth and power capacity of low frequency horn loaded loudspeaker systems are directly affected by the parameters of the driver used. Three new composite driver parameters, formed by simple combination of the basic parameters, give a direct indication of driver suitability for horn-loaded operation. These composite parameters also greatly simplify the selection of optimum horn constants and the calculation of system performance and ratings.

Earl K
04-01-2005, 12:09 PM
3) The next step form here would be to try 1500FE/AL, if it will fit in the Paragon’s back-chamber.


- The ME150S would/should also be a good candidate in this application . ( Think of it loosely as the "overhung coil" version of these newer woofers )

- And it's actually affordable, obtainable & a noticable stepup in resolution from the 2234/5 variants .


regards :)

Alex Lancaster
04-01-2005, 06:07 PM
:) Friends: We are talking about what is real vintage, We would not talk about hotrodding a 1932 Rolls Royce, would We?

whgeiger
04-01-2005, 06:56 PM
http://audioheritage.csdco.com/vbulletin/images/smilies/smile.gif Friends: We are talking about what is real vintage, We would not talk about hotrodding a 1932 Rolls Royce, would We?

AL,

Yes, but the 1932 Rolls is not your daily drive, now is it?

You cannot "Hot-Rod" a Paragon by simply swaping drivers; but doing so may improve your daily listening experiance.

In any case, so long as the modification is reversible, no harm is done. Just don't paint your Rolls a different color.

Regards,

WHG