2440 (2") Driver in a 4343 cabinet

[Goldjazz]

Just a little experiment I thought some may be interested.

I put a 2440 on a short horn into one of my 4343 cabinets to compare it to the stock longer horn with 2420 1" driver in the other.

The driver fits perfectly, makes me wonder if they intended it to fit.

I actually didn't adjust any of the attenuation settings or anything, just put it in. The 2440 is actually the same sensitivity as the 2420. I guess the different length and shorter horn may have an effect on time alignment and stuff. Just made a quick spl sweep measurement of the and the driver speaker was still pretty flat through the HF range.

So now I'm able to pan to the speaker with the 2" driver and back to the one with the 1" driver to compare.

So the 2" speaker has more authority in that hf range, it's sort of fatter sounding . The 1" speaker is a bit thinner and drier sounding, maybe more delicate and slightly more detailed. I haven't made up my mind which one I prefer. But i think it would definetley be worth getting second 2" driver and short horn to be able to hear the pair like that.

Attachment 78671Attachment 78672

[ivica]

Just a little experiment I thought some may be interested.

I put a 2440 on a short horn into one of my 4343 cabinets to compare it to the stock longer horn with 2420 1" driver in the other.

The driver fits perfectly, makes me wonder if they intended it to fit.

I actually didn't adjust any of the attenuation settings or anything, just put it in. The 2440 is actually the same sensitivity as the 2420. I guess the different length and shorter horn may have an effect on time alignment and stuff. Just made a quick spl sweep measurement of the and the driver speaker was still pretty flat through the HF range.

So now I'm able to pan to the speaker with the 2" driver and back to the one with the 1" driver to compare.

So the 2" speaker has more authority in that hf range, it's sort of fatter sounding . The 1" speaker is a bit thinner and drier sounding, maybe more delicate and slightly more detailed. I haven't made up my mind which one I prefer. But i think it would definetley be worth getting second 2" driver and short horn to be able to hear the pair like that.

Ho Goldjazz,

On my 4333 DiY speakers I prefer 2441 (Radian) with 2311&2308 relative to the 2420 with 2312&2308, as a kind of
"hhhssssing " is fare less pronounced (better to say without such artifacts), and it seems to me that 2441 is about 1~2dB more efficient as You said "the 2-inch speaker has more authority in that hf range", so I have adjusted the crossover network.

regards
ivica

[Chevelle]

I also have a pair of 2445/Radian 1245 with 2311&2308 in my 4333. And I also realize a 2-3db higher level that I adjusted in the Nelson Pass mod crossover. Find mid and hf more "present" and "direct" especially without the 2308.

Ho Goldjazz,

On my 4333 DiY speakers I prefer 2441 (Radian) with 2311&2308 relative to the 2420 with 2312&2308, as a kind of
"hhhssssing " is fare less pronounced (better to say without such artifacts), and it seems to me that 2441 is about 1~2dB more efficient as You said "the 2-inch speaker has more authority in that hf range", so I have adjusted the crossover network.

regards
ivica

[Goldjazz]

Ho Goldjazz,

On my 4333 DiY speakers I prefer 2441 (Radian) with 2311&2308 relative to the 2420 with 2312&2308, as a kind of
"hhhssssing " is fare less pronounced (better to say without such artifacts), and it seems to me that 2441 is about 1~2dB more efficient as You said "the 2-inch speaker has more authority in that hf range", so I have adjusted the crossover network.

regards
ivica

Ah yes well described, I agree that the 2420/2312 combo has a "hissing" sound in comparison. Yeah I replaced my Lpads with fixed resistors, this actually cleaned up a fair bit of "Hiss" in terms of constant noise floor for the 2420 and the 2405. But I agree the 2420/2312 is hissy and also a little thin and weak in a way. The 2440/2311 combo has that authority and is a perhaps a bit more relaxed and effortless? I Also think, even with only one speaker with the 2440, that the soundstage has opened up a bit. Quite keen to get a second 2440/2311 in the other cabinet as well to properly evaluate this. Once I do that, and properly adjust the Lpad resistors etc, I think this change could be a keeper.

[Goldjazz]

I also have a pair of 2445/Radian 1245 with 2311&2308 in my 4333. And I also realize a 2-3db higher level that I adjusted in the Nelson Pass mod crossover. Find mid and hf more "present" and "direct" especially without the 2308.

I also prefer the 2440/2311 without the lens. I also tried the 2440 just on a 2309 with a crinkle lense and preferred the 2311 without the 2308 to the 2309 with the crinkle lense. Although the 2309 with lense seemed more dispersed, but in my small listening room I don't think I need this, If I was trying to fill a big room evenly then maybe. Something is lost with the 2308 (when used with the 2311) in my opinion, like a bit of directness and tiny bit of extra clarity without the lens is prefferred for me.

It seems to me the 2308 lens is less of a problem on the 2420/2312, the clarity and "edginess" is still maintained.

[Ian Mackenzie]

Do you know what actual diaphragm you have in the 2420 and 2440?

How old are the diaphragms?

A new or fresh diagram is always going to sound different

Might be an idea to check and state that in your observations ?

Are the capacitors in your 4343 stock parts

What amp are you using?

(There is no doubt you are hearing a difference)

[Goldjazz]

Do you know what actual diaphragm you have in the 2420 and 2440?

How old are the diaphragms?

A new or fresh diagram is always going to sound different

Might be an idea to check and state that in your observations ?

Are the capacitors in your 4343 stock parts

What amp are you using?

(There is no doubt you are hearing a difference)

my 2420 diaphrams are original from my 4343b's. The 2440 I borrowed from a friend, it looks like its had a hard life and probably as old as the 2420. Yeah caps are all original, haven't got around to changing them yet.

[RMC]

Hi Goldjazz an Ivica,

RE "So the 2" speaker has more authority in that hf range, it's sort of fatter sounding"

This may well be explained objectively, from info readily available, rather than trying guessing why/how. In his Handbook of Sound System Design, P. 72-3, John Eargle (JBL) compares three compression drivers (2440, 2441 and TAD 4001) and explains the differences. The response curve of each driver is shown on the same graph which is quite useful for comparison purposes. I think that graph explains most of the "more authority" and "fatter sounding".

BTW, I seem to remember from a late 70s JBL components catalog, still in my library, that the 375 compression driver from the hi-hi range, identical to 2440 in Pro lineup, "can reproduce effortlessly explosive transients"!

In the spec sheet and Eargle's book, the massive 2440 has a progressively rising response (2-3+ db) in mid/high-mid around 2 khz, but mostly from 4 khz to 8 khz or so, and this may be the cause of the 2440 sound, other than being larger and more powerful than 2420. That amplitude no doubt puts forward some added "presence" or "authority" in 2440 response, the 2420 does not have according to the spec sheet's flatter response curve in that range. However, the flat (2 khz to 9 khz or so, then dropping) 2420 spec sheet response curve doesn't explain the perceived hiss from the driver, as it normally would from a "peaky" high-frequency response curve.

As for the 2441, again in both the spec sheet and in Eargle's book, it has a flatter but falling response in the high-mid/high range from about 5 khz...

These differences are bound to lead to different sounding compression drivers, even if they were all new and original. The different responses are explained by Eargle with "The role of secondary resonances":

"Figure 4-7 shows the response of three compression drivers mounted on the same horn. All three have a diaphragm diameter of about 100 mm (4 in.), but differ in diaphragm material and surround treatment. The JBL 2440 has a "half roll" surround which produces a gradual rise in response to about 9 khz, above which point the response drops rapidly. The model 2441, through the use of a different surround treatment, distributes the secondary resonances in such a way that smoother, but somewhat reduced, response is extended out to about 18 khz. The TAD model 4001 driver has the same surround detail as the 2440, but it is made of a much stiffer material, beryllium. Because of the added stiffness, a response peak similar to that of the 2440 is observed, but it is raised about one octave to about 17 khz.

Secondary resonances can be used in two ways: to elevate the response out to some cut-off frequency (RMC: 2440), or to extend the response beyond that cut-off frequency, but with some reduction in output (RMC: 2441)."

In his "Loudspeaker Handbook", P. 146-7, Eargle provides the same explanations, with a little more details. So, this technical explanation does appear to make a lot of sense here. Regards,

Richard

[Ian Mackenzie]

Richard make a valid

Historically we have been over the differences between the 2420, the 2421 and the 2425 1 inch diaphragms.

The 2421 diaphragm is nla but was recognised as an upgrade over the 2420

The 2425 was introduced because of its more durable titanium material over the aluminium

In my own experience casting some 37 years the 2420 diaphragm is noisy and gave fame to the 4343's live sound character. They are still in my diy 4343's l built in 1980.

The later diaphragms with the diamond surrounds are superior.

Jbl themselves started treating all their Hifi designs with acquaplas dusting to further damp resonances.

A few forums ago we all but stamped out the hiss you describe with diy acquaplas dusting and charge coupled crossovers. I have personally used dusted diaphragms for years in my diy 4345 system

This has been well received.

It's hardly surprising the 4 inch driver is subjectivity different but it's not an apples for apples comparison until you look deeper as Richard suggests

There are some good Jbl tech notes on the subject of harmonic distortion in compression drivers that rises with frequency (no surprises there) and why a 4 inch driver is preferred in "some" applications.

In my own experience "louder" and more "authority"is not the answer to more details or resolution and transparency for home applications.

Of course in diy audio each to his own and the beating of the loudest drum is only important and relevant to your own situation and circumstances

[Chevelle]

But Goldjazz and I use the Radian 1245 diaphragm which is of aluminium with mylar surround. Do they have a similar response ?

[Goldjazz]

......In his "Loudspeaker Handbook", P. 146-7, Eargle provides the same explanations, with a little more details. So, this technical explanation does appear to make a lot of sense here. Regards,

Richard

Thanks for the very interesting post Richard. I'm going to track down a copy of this book. Glad to know there seems to be a basis to the observations. Thanks.

[Goldjazz]

.

.....A few forums ago we all but stamped out the hiss you describe with diy acquaplas dusting and charge coupled crossovers. I have personally used dusted diaphragms for years in my diy 4345 system

Thanks Ian, very interesting. I'll look up these older posts and read them with interest. Thanks for the comments.

[RMC]

Hi Goldjazz,

Thanks for your good word.

RE "I'm going to track down a copy of this book."

If you're going to track down a copy of John M. Eargle's "Loudspeaker Handbook", Chapman & Hall, 1997 (first edition, which I have, paid in 1997 $84. plus tX and shipping, but seen today B/O on Amazon at $130.), or the newer second edition from 2003 (with about 100 pages more than mine), this one published by Springer-Verlag New York Inc., you should be aware the latter book may well be on the expensive side, like $200+ ! even on Amazon, still worth it in my view for 2nd ed., especially if you also have his "Handbook of Sound System Design", 1989, ELAR Publishing Co. Inc, as I do. With that complementary duo, you're seriously into sound/JBL knowledge. Real sad that Eargle passed-away some years ago... (RIP).

John Eargle was not only a trained musician (Bachelor and Master degrees in Music), but also a trained Engineer (Bachelor and Master degrees in Electrical Engineering). In addition, he was a renowned Recording Engineer for RCA and Mercury records (he wrote books on Recording Engineering/Mics-also transducers), and worked for Altec and JBL. At JBL, if my memory serves me well, his last position was V-P or Senior Director of Product Development and applications. That should ring a bell re my post # 8 where you thanked me! He was also a noted expert in Cinema Sound, studio monitors, etc. Plus, he was JBL's pen or writer, having authored with G. Augspurger the famous "Sound System Design, Reference Manual", and written MANY articles in the "Journal of the Audio Engineering Society", with JBL Engineers, covering anything Loudspeaker. Almost an encyclopedia, a rare breed of fellow, not the first "Audio Joe" met on the street corner. Many other smart fellows at JBL, but none as good as him for sharing Loudspeaker knowledge...

If you can't get your hands on the two above-mentioned books, then my advice is: "beg, borrow or steal", as they say. These are often used at University level as tutorial and reference material for Audio Engineering.

The first edition of "Loudspeaker handbook" (less expensive, but still quite good) may be out of print, as for the "Handbook of Sound System Design", however you may be able to puchase a used copy of each on Amazon or E-Bay, still well worth it, as long as in good condition. Regards,

Richard

P. S. Electroacoustical Reference Data, Chapman & Hall, 1995, is another one of his books... JBL Audio Engineering for Sound Reinforcement, 2002, by John Eargle and Chris Foreman MAY be an update or an alternative to Eargle's Handbook of Sound System Design, but I wouldn't bet on that, title not the same.

[speakerdave]

" . . . steep waveforms of explosive loudness are effortlessly reproduced . . . "

1976 Components catalogue

[Chevelle]

One sentence says it all....

" . . . steep waveforms of explosive loudness are effortlessly reproduced . . . "

1976 Components catalogue