JBL 2440 vs TAD4001

[Mr. Widget]

Originally posted by PSS AUDIO


I will not discuss about TAD drivers as I do not know them...


With a “poor” amplifier the TAD will sound better as this driver is inferior to the 2441 as I think that TAD drivers rubs some harmonics.

With a “good” amplifier I think the 2441 (1K-8-9K) will outperform all TAD drivers!

I do have both the TAD 4001 and the JBL 2441 (with fresh diaphragms) and have listened to both extensively. In my comparisons I found the most important difference to be the additional detail the TAD brings to the music. I found this to be more significant than the extra bandwidth. The level of detail approached the electrostatic panels I have owned. Even though I really enjoy the dynamic sound of compression drivers on horns, almost all of them have tended to mask the inner detail (for lack of a better term) on my discs.

I certainly can't say for sure as I haven't had the pleasure of listening to your speakers, but what you are describing sounds like classic diaphragm fatigue. When did you last replace your 2441 diaphragms? With your "good" amplifier it might improve even further with fresh diaphragms.

I fully agree with Mike, that if he prefers the sound of a 2440, that it is the best compression driver for his use, but before you jump to the conclusion that the 4001 is a euphonic device that masks deficiencies in "poor" amps, you should probably try to borrow a pair of 4001s and give them a listen. With your "good" amplifier, you may discover even more to enjoy in your favorite albums.

Widget

[PSS AUDIO]

Originally posted by Mr. Widget
When did you last replace your 2441 diaphragms? With your "good" amplifier it might improve even further with fresh diaphragms.
Widget

I bought the speakers as is and I never changed the diaphragms!

I thought they were responsible, but as I heard the same on high-end speakers (same and different amplifiers), that is why I left my 2441 as is.

By changing the diaphragms, the speakers will certainly sound even better.

Where can I found some in Europe?

As I must ship a "good" amplifier to Scott he can compare his 244x and his TAD 400x and let us know...

[Mike Bates]

Originally posted by johnaec
What's your preference for high frequency reproduction now?

John

I'm using a closely spaced pair of Audax (Harman) PR170MO 6.5" pro wide-range midrange drivers 250-6K on an open baffle in place of the compression drivers. Wired in parallel they are around 106 db sensitive with a watt - sound is even smoother and more detailed than the 2440 in round tractrix horns - plus no crossover 250-6k. In an offset MTM position is the inexpensive Eminence APT80 tweeter with a rear firing slightly modified LeSon TLC1.

This combo is very dynamic and 'fast' sounding (much like the TAD 4001 but with wider range and more "life-like mids) yet doesn't have the fatique I hear with all the compression drivers I have tried to live with.

[Maron Horonzakz]

Yuri.......Im sorry to tell you the 2441 performance cannot match the TAD 4001. Drop a 2450SL diaphram into the 2441 & listen to the pain go away. The aquaplas coating on that diaphram (2450SL) smooths things out & is as sweet sounding as the aluminum but without the pain. But the 4001??? Ahhhhhhh. I think the 5 slit phazing plug has something to do with it.

[johnaec]

Originally posted by Mike Bates
...This combo is very dynamic and 'fast' sounding (much like the TAD 4001 but with wider range and more "life-like mids) yet doesn't have the fatique I hear with all the compression drivers I have tried to live with.

Interesting. Thanks for the info.

John

[PSS AUDIO]

Originally posted by Maron Horonzakz
Yuri.......Im sorry to tell you the 2441 performance cannot match the TAD 4001. Drop a 2450SL diaphram into the 2441 & listen to the pain go away. The aquaplas coating on that diaphram (2450SL) smooths things out & is as sweet sounding as the aluminum but without the pain. But the 4001??? Ahhhhhhh. I think the 5 slit phazing plug has something to do with it.

2441 is NOT paining anymore unless with some single frequencies with very particular recording (imagine a whip in the ear)!

Since my last modification this whip almost disappeared.

Amplifier is responsible of this pain in the ear and it means that all those “new” drivers have been “modified” to fit with actual amplifiers (as the amplifier is hard, lets rub what is bad with the drivers/diaphragms)…

Read what Scott said about the smoothness of the amplifier and you may then have an idea why I say that 2441 sounds so mild, like sugar in your throat with “millions” of itsi pitsi tiny details…

Lets make a test!

Everybody knows or heard “The Girl From Ipanema” (Getz/Gilberto) original recording from Verve. If not try to get it and listen to it.

There is some piano with some right hand notes.

By 3’48 minutes there is a small piano solo.

Is it a mechanical or an electric piano?

Depending of the quality of your driver and/or amplifier it will change from one to the other!

Guess witch is the good one!

[Figge]

isnt TAD = Pioneer/Exclusive?

so your saying pioneer is better than JBL?


dammit! and i just sold my HPM-70:s for 80 bucks!

[Figge]

Originally posted by paragon
the TAD goes flat to highest frequencies, while the JBL
"oszillates"

well flat isnt allways good! i prefer some curves!

[whgeiger]

The following notes provide information germane to the subject of this thread. WHG

1) BNL
Yes! TAD drivers have BNL written all over their designs.
For those interested, his son has produced the following web page in his honor:

Bartholomew Nicholas Locanthi II (1919-1994)
http://www.sabl.com/~bart/bnl2/index.html

2) Be
Aquamarine and emerald are precious forms of the mineral beryl, [Be3Al2(SiO3)6] from which beryllium (Be) is extracted.

The acoustical superiority of beryllium as a diaphragm material can be clearly seen when its mechanical properties are compared to those of titanium (Ti) and aluminum (Al)

For a given diaphragm size and geometry:

a) Sound Velocity
(for longitudinal waves),
determines at what frequency the first breakup mode occurs.

[Be] 12,890 m/s
[Al] 6,420 m/s
[Ti] 6,070 m/s

b) Density
determines moving mass for a given diaphragm size

[Be] 1.85 g/(cm^3)
[Al] 2.70 g/(cm^3)
[Ti] 4.51 g/(cm^3)

c) Rigidity Modulus
determines how well the diaphragm resists deformation (stiffness)

[Be] 132 GPa
[Al] 26 GPa
[Ti] 44 Gpa

3) Phase Plug
Each annular slit in a phase plug is designed to suppress a specific radial standing wave mode that occurs in the front cavity of a compression driver. Such modes occur because acoustic energy must flow radially away from a larger diaphragm into a smaller horn throat so that the desired compression ratio may be achieved. The wider the bandwidth of the driver, the more silts are required to suppress the additional modes of increasing frequency. For those interested in phase plug design, the following work of Bob Smith should be studied:

Title: An Investigation of the Air Chamber of Horn Type Loudspeakers
Author: Bob H. Smith
Publication: ASA-J, Vol. 25, No. 2, pp. 305-312, Mar-1953
Affiliation: Division of Electrical Engineering, University of California
URL: none
Abstract: The front air chamber design is treated as a boundary value problem which yields a solution of the wave equation for the general case in which the horn throat enters the air chamber in a circumferentially symmetrical manner.
The following specific cases are analyzed: (1) the case in which the horn throat enters the air chamber by means of a single orifice, (2) the horn throat enters the air chamber by means of a single annulus of radius [r] and width [w], and (3) the horn throat enters the air chamber in [m] annuli of radii [r1],[r2],...[rm] and widths [w1],[w2],...[wm].
The analysis reveals that the radial perturbations caused by the horn throat excites higher order modes. At the resonant frequencies of these modes the horn throat pressure becomes zero and the loudspeaker does not radiate. By suitable choice of annulus radii and widths the first [m] modes may be suppressed and the corresponding nulls in the output pressure eliminated.

Title: An Application of Bob Smith's Phasing Plug
Author: F. M. Murray
Affiliation: Jamse B. Lansing Sound, Inc.
Publication: AES-P, No. 1384, Cnv. 61 (1978-11)
URL: http://www.aes.org/publications/preprints/search.html
Abstract: The war of the phasing plugs still rages after more than 25 years. Compression driver phasing plugs have vacillated between annular rings, salt shakers, teardrops, and now radial slots again. When Bob Smith provided simple design criteria for optimization of the annular ring type, little did he realize how studiously he would be ignored. His design is now incorporated into a large compression driver capable of operating to the high frequencies where this design is important

4) PWT
To measure frequency response of a driver, a plane wave tube (PWT) should be used. Here power response is measured and horn artifacts that mask the true capabilities of the driver under test (DUT) are avoided. For details see the following:

Title: Building a Plane-Wave Tube: Experimental and Theoretical Aspects
Author: Roberto Magalotti
Author: Carlo Zuccatti
Author: Paolo Pasini
Publication: AES-J, Vol. 47, No. 7/8, p. 596, Jul/Aug-1999
Abstract: The primary purpose of this report is to describe the building and testing of a plane-wave tube for measuring compression drivers in an audio laboratory. A new method for testing the tube for undesired reflections was devised, with and without sound absorbing materials. The experimental results show good agreement with the predicted behavior outlined in the AES document on plane-wave tubes, and confirm the predictions on usable bandwidth limits.

Title: Plane-Wave Tubes: Design and Practice
Author: AES Standards Committee
Publication: AES-ID, No. 1id-1991, Rev. Jun-2003
URL: http://www.aes.org/standards/b_pub/a...1991-r2003.pdf
Abstract: The "AES Recommended Practice — Specification of Loudspeaker Components Used in Professional Audio and Sound Reinforcement" in its 2.2.1 calls for the use of plane-wave tube measurement of horn drivers. Because many variations and results are possible, depending on the details of construction of plane-wave tubes, this document discusses those variations for the purpose of encouraging further experimentation.

[sa660]

To achieve sound the TAD4001 look to please most of your JBL fans.

I am very thankfull for all your comments.

I just need the right Horn for the TAD4001.

Regards,

[still4given]

Is it possible to get drawings for those Westlake horns? I would like to try building a pair.

Thanks, Terry

[whgeiger]

Originally posted by sa660
.

I just need the right Horn for the TAD4001.

Regards,

If you send me an e-mail I will send drawings for the "right horn".

[email protected]

In the meantime, here are some examples:

http://members.aol.com/araiyuichi/

Regards,

WHG

[Don McRitchie]

This gets mentioned every so often, but it has been a while so that a refresher is probably in order. The similarities between the 375 and TAD 4001 are no accident since they were designed by the same person - Bart Locanthi. This is the BNL that WGeiger referenced in a previous post.

Bart Locanthi was responsible for engineering at JBL for two decades. He started as a consultant in 1950 to fill the engineering void that resulted from Jim Lansing's death. He later joined the company full time as Vice President of Engineering in 1960. Unfortunately, there was a falling out with the new management of JBL when Bill Thomas sold the company. Locanthi left the firm in 1970 to first join Altec, and then Gauss, before ending up at Pioneer in the mid 70's.

At Pioneer, Bart was responsible for the HPM series of loudspeakers. This is why the first speaker in that series, the HPM100, bore a striking resemblence to the L100. To Figge, you should of held out for more than $80 for your HPM 70's since there is actually some demand for that series.

Pioneer considered it quite a coup to gain Bart's services since JBL was the single most revered loudspeaker brand in Japan. Pioneer gave Bart virtually unlimited resources to build the highest performing loudspeaker components possible for the first TAD product line. I have been told anecdotes of his being treated like royalty when visiting Pioneer's Japanese headquarters during the development process. At meetings, Pioneer's management would hang on every word and transcribe his comments as absolute orders to be followed to the letter.

The first TAD compression driver was specifically designed as an evolution of the 375. Bart had done the design work on that driver in 1953. It was pretty much a copy of the WE394, but replacing the field coil motor with an Alnico PM. The new TAD driver took the basic motor structure from the 375 and introduced berylium as a diaphragm material and changed the phase plug design to accommodate the extended bandwidth of the new diaphram material. The bass drivers were similarly derrivative of JBL designs, with the TAD 1602 borrowing from the LE15A.

The primary proponent of TAD in the US has been George Augspurger and his studio design firm, Perception Inc. George was also a previously long term employee at JBL and an associate of Bart Locanthi. George has designed most of the large format monitors that use TAD components for some of the highest profile studios in the industry. He mainly specs TAD due to the extended response of the compression drivers that allow for two-way deisgns. However, if this is not a requirement, he has used JBL compression drivers. Recently, he developed a hybrid monitor that used 4-12" JBL drivers from the LSR-32 for the bottom end.

[Figge]

thanx Don!

the wealth of knowlage on this board is amazing!

as for the HPM:s...i was glad just to get rid of them

however i had a pair of hpm-30 in my youth wich i liked very much! im still holding an eye open for those...dont see em to often on the used market...however they would be squished by a pair of 4301 any day.

[Oldmics]

Is there any information regarding what Mr.Locanthi was involved in during his stay at Gauss?

Oldmics