LE15 for Paragon

[57BELAIRE]

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?

[57BELAIRE]

...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]

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]

...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]

I betcha LE15B would be a good upgrade.

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

[57BELAIRE]

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

[Mr. Widget]

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]

A while back somebody suggested trying E145´s, 2234/5's, I wonder what came out of that.

[paragon]

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]

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]

WHG,

Nicely said....I think

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]

Who knows about the parameter of the Paragon bass horn and can tell me ?

Thanks, Eckhard

[Mr. Widget]

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]

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

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

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

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

[whgeiger]

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

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

[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.


Regards,


WHG