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Goldjazz
10-15-2017, 03:29 AM
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.

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ivica
10-15-2017, 06:25 AM
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
10-15-2017, 08:18 AM
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
10-15-2017, 01:20 PM
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
10-15-2017, 01:29 PM
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
10-16-2017, 11:50 AM
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
10-17-2017, 01:14 AM
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
10-17-2017, 08:02 PM
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
10-17-2017, 10:18 PM
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
10-17-2017, 11:26 PM
But Goldjazz and I use the Radian 1245 diaphragm which is of aluminium with mylar surround. Do they have a similar response ?

Goldjazz
10-19-2017, 01:43 AM
......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
10-19-2017, 01:48 AM
.

.....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
10-19-2017, 08:20 PM
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
10-19-2017, 09:00 PM
" . . . steep waveforms of explosive loudness are effortlessly reproduced . . . "

1976 Components catalogue

Chevelle
10-19-2017, 11:31 PM
One sentence says it all....

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

1976 Components catalogue

Goldjazz
10-20-2017, 05:59 PM
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.

Thanks again Richard, I will start looking for these. Watched a brief video of John Eargle speaking on youtube from several years ago. Seemed to be a true pioneer and I was very impressed with his belief in sharing knowledge.

Goldjazz
10-24-2017, 12:48 PM
So I just got a pair of 2441 on 2309 horns with crinkle lenses. Quite an intense experience. Explosive and effortless indeed, a big sound. I havent got them eq'd in properly yet though. Next I'll be trying some TAD4002's om different horns.

Goldjazz
10-28-2017, 11:02 PM
The Tad's are very nice. More detlicate and detailed than the 2441.

Ian Mackenzie
10-28-2017, 11:52 PM
The Tad's are very nice. More detlicate and detailed than the 2441.

Looks like you are having fun

Itís a chalk and cheese comparison

What is interesting is sometime ago a highly experienced member tried the 4002 and in the end went back to a 2 inch JBL driver. I donít recall what Jbl driver he preferred but the 4002 drove him nuts.

The JBL Sound is what it is.

Itís quite unmistakable.

In the context of the Tads many people still prefer to add the slot radiator.

A lot of these horns apart from the most recent Jbl wave guides loose diffraction control at high frequencies and they beam like a pencil or they change character.

The 2 inch driver will do this naturally at 10,000 hz due to throat diameter. Unless the horn has a narrow vertical diffraction slot, vanes or has a narrow coverage overall it will beam.

Thatís not ideal for home audio.

In the diy situation of course itís about whatever floats your boat
Some people only run the Tad 4002 up to 4000 hz then use the Tad 2002 on a smaller horn like The Living Voice large format systems.


Keep us in the loop on your investigations

Goldjazz
10-29-2017, 03:04 AM
Looks like you are having fun

It’s a chalk and cheese comparison

What is interesting is sometime ago a highly experienced member tried the 4002 and in the end went back to a 2 inch JBL driver. I don’t recall what Jbl driver he preferred but the 4002 drove him nuts.

The JBL Sound is what it is.

It’s quite unmistakable.

In the context of the Tads many people still prefer to add the slot radiator.

A lot of these horns apart from the most recent Jbl wave guides loose diffraction control at high frequencies and they beam like a pencil or they change character.

The 2 inch driver will do this naturally at 10,000 hz due to throat diameter. Unless the horn has a narrow vertical diffraction slot, vanes or has a narrow coverage overall it will beam.

That’s not ideal for home audio.

In the diy situation of course it’s about whatever floats your boat
Some people only run the Tad 4002 up to 4000 hz then use the Tad 2002 on a smaller horn like The Living Voice large format systems.


Keep us in the loop on your investigations



Yes having lots of fun.

I'm using the slot when using the TAD and the 2441, I'm just using the internal crossover HF output connected to the horn, essentially just replacing the 2420 for the other driver and the new horn.

To my ears the 2441 with the crinkle lense delivers a bigger, more effortless sound. It's a very present, live experience. It's a little fuzzier and warmer than the TAD. The 2441 seems to integrate well with the midbass to deliver nice deep notes, or draw out the deep notes better from the midbass and woofer. But perhaps doesn't integrate as well as the TAD does with the slot tweeter, or maybe the TAD is just just sharper in detail up to 9500Hz. Or maybe the 2441 is just maskiing the slot tweeter becuase its not eq'd.

The 2441 is less hissy than the 2420 as previously mentioned, but also perhaps a little less airy. As mentioned, I haven't eq'd the 2441 so I'm sure the HF is raised which is probably contributing to the forward, powerful perception. I think I understand/agree the 2441 setup sounds more "JBL" than the TAD setup.

The TAD 4002 on the Renkus Heinz horn is immediately lighter and more delicate. Perhaps a little faster, and a little more detailed. It's resulted in a lighter, faster, more laid back, less forward experience. It picks up nice layers of details like you'll notice a gentle synthesizer layer that you hadn't before. So delicate layered music is better on the TADs. But bold simple tracks like big soul tracks where everything is on one forward layer and boldness and engagement are key the 2441 sounds better. The TAD on the Renkus heinz horn occasionally shouts at me. Which the 2441 doesn't do on the crinkle horn. Piano and strings are nicer on the TAD, piano particularly sharper and more defined. Vocals are starting to almost float on gentle songs, whereas they don't really on the 2441.

I think the next step is to make some measurements and adjust resistors (since I removed Lpads) to get both drivers flat. I feel a lack of EQ is causing the 2441 to feel a little one dimensional, whereas the TAD seems to have fallen closer to a flat setup to my ears.

At this stage I can't make a call as to which I prefer. Will report back after those adjustments and more listening.

RMC
10-30-2017, 04:48 PM
Hi Goldjazz,

In my post # 8 I discussed differences between 2440 and 2441 compression drivers. Now time to mention some difference between 2441 and TAD's 4001-4002.

ASSUMING the 4001 and 4002 have SIMILAR frequency response curves (since I don't have such for 4002, however both models have Beryllium diaphragm and Aluminum voice coil, the former being ribbon and the latter edge-wound), it seems to me it would not be unreasonable to think the frequency responses of both should look about equivalent.

Therefore, looking again at John Eargle's comparison of the compression drivers mentioned in my post # 8, the additional detailed sound perceived from the TAD driver may be explained objectively. As I said before in that post, the 2441's response is rolling-off from about 6 khz. However, the TAD remains reasonably flat up to 15 khz or so, then its response rises a lot (secondary resonance explained by Eargle earlier) with a peak at about 17 khz followed by a steep drop...

Between about 6 khz and 11 khz, the high frequency output of the TAD is roughly + 3 db higher than the JBL which is rolling-off. Plus, in the following range of about 11 khz to 15 khz the TAD has almost +5 db more output than the 2441 (this is without considering the TAD's peak at 17 khz I mentioned above).

Seems to me at least three db more output in the high-end is bound to put forward more detail and integrate better with the slot tweeter sound (you mentioned up to 9500 hz ). Floyd E. Toole's extensive research shows frequency response and power response (off-axis) are of utmost importance regarding the quality of perceived sound from a speaker... Regards,

Richard

Goldjazz
11-01-2017, 01:46 AM
Hi Goldjazz,

In my post # 8 I discussed differences between 2440 and 2441 compression drivers. Now time to mention some difference between 2441 and TAD's 4001-4002.

ASSUMING the 4001 and 4002 have SIMILAR frequency response curves (since I don't have such for 4002, however both models have Beryllium diaphragm and Aluminum voice coil, the former being ribbon and the latter edge-wound), it seems to me it would not be unreasonable to think the frequency responses of both should look about equivalent.

Therefore, looking again at John Eargle's comparison of the compression drivers mentioned in my post # 8, the additional detailed sound perceived from the TAD driver may be explained objectively. As I said before in that post, the 2441's response is rolling-off from about 6 khz. However, the TAD remains reasonably flat up to 15 khz or so, then its response rises a lot (secondary resonance explained by Eargle earlier) with a peak at about 17 khz followed by a steep drop...

Between about 6 khz and 11 khz, the high frequency output of the TAD is roughly + 3 db higher than the JBL which is rolling-off. Plus, in the following range of about 11 khz to 15 khz the TAD has almost +5 db more output than the 2441 (this is without considering the TAD's peak at 17 khz I mentioned above).

Seems to me at least three db more output in the high-end is bound to put forward more detail and integrate better with the slot tweeter sound (you mentioned up to 9500 hz ). Floyd E. Toole's extensive research shows frequency response and power response (off-axis) are of utmost importance regarding the quality of perceived sound from a speaker... Regards,

Richard


Thanks Richard, what you say certainly makes sense with what I experienced. I've just attached a plot of all 3 drivers. This image was taken from another post on this forum.
http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=3304&stc=1&d=1094057771

Goldjazz
11-01-2017, 03:01 AM
Just went back to the TADs after listening to the 2441 for a day or two. Lowered the 4343's so the TAD drivers were closer to ear level. They are pretty great sounding now. Will go back and listen to the 2441 also at the better height, but the clarity I'm hearing from the TAD-4002's is pretty hard to beat.

Ian Mackenzie
11-02-2017, 10:32 AM
Just went back to the TADs after listening to the 2441 for a day or two. Lowered the 4343's so the TAD drivers were closer to ear level. They are pretty great sounding now. Will go back and listen to the 2441 also at the better height, but the clarity I'm hearing from the TAD-4002's is pretty hard to beat.

Okay

Putting it in perspective there are three key aspects to the changes

1. Technologies- early aluminium roll surround diaphragm versus advanced beryllium surround and diaphragm
- driver phase plug design and construction. Jbl have some technical papers in the reference section of forums on compression driver design.

2. Response - each driver will interact differently with a particular horn depending on the drivers natural resonance, phase plug and throat design and the diaphragm design and materials.

The Jbl compression driver design was largely unchanged for many years. They did change the diaphragm surround and materials . In recent Jbl drivers the design is almost throatless to take advantage of diffraction wave guides.

The larger diaphragm has more output and lower distortion at the low end

3. In the network design there are four key aspects

The slope of the pass band
The frequency range of the pass band
The flatness or tilt of the pass band
Voltage level or amplitude

JBL carefully customised the pass band filter to suit a particular compression driver in their factory Prof Series studio multi monitors

In the not too distant future l will publish an article on the above

Please keep us in the loop and continue to have fun

Ian

Goldjazz
11-02-2017, 01:34 PM
Okay

Putting it in perspective there are three key aspects to the changes

1. Technologies- early aluminium roll surround diaphragm versus advanced beryllium surround and diaphragm
- driver phase plug design and construction. Jbl have some technical papers in the reference section of forums on compression driver design.

2. Response - each driver will interact differently with a particular horn depending on the drivers natural resonance, phase plug and throat design and the diaphragm design and materials.

The Jbl compression driver design was largely unchanged for many years. They did change the diaphragm surround and materials . In recent Jbl drivers the design is almost throatless to take advantage of diffraction wave guides.

The larger diaphragm has more output and lower distortion at the low end

3. In the network design there are four key aspects

The slope of the pass band
The frequency range of the pass band
The flatness or tilt of the pass band
Voltage level or amplitude

JBL carefully customised the pass band filter to suit a particular compression driver in their factory Prof Series studio multi monitors

In the not too distant future l will publish an article on the above

Please keep us in the loop and continue to have fun

Ian

Thanks for those interesting points. The point about integration and the crossover and other drivers is of particular interest. See plot below. Seems to integrate a little poorly as there's a noticeable dip at the crossover point of 1250 Hz. I do reacall the 2420 as being a bit more seamless in it's integration that both the TAD, the 2441, and 2440. The TAD being the "worst" for subjective integration. However the clarity and speed of that TAD is pretty undeniable, certainly appreciate the advances in material science etc that it leverages and how wonderful a performer those JBL drivers are given then have been largely unchanged. As stated in a previous post us JBL fans can "claim" the TAD due to Locanthi. So i'm able to retain my JBL pride while appreciating the TAD.

I am interested in playing around with integrating the TAD better. I'm going to get a second active crossover and try a 3-way implementation of the 4343. So use the TAD up to 20K and not the slot. This will let me dial in a better crossover point and slope and I'll see what results I get. I'm sure the results will still be not as integrated as the 2420 on the stock crossover, some smart people went to a lot of trouble to get that result.

The fun continues :)

Ian Mackenzie
11-03-2017, 01:35 PM
Going down the Rabbit hole.

There are lots of things going on in terms of integration

Unfortunately none of this is a plug and play situation

Are you using a 2121 mid cone?

Goldjazz
11-03-2017, 05:11 PM
Going down the Rabbit hole.

There are lots of things going on in terms of integration

Unfortunately none of this is a plug and play situation

Are you using a 2121 mid cone?


Not afraid of the Rabbit hole ;) 2121H.

Ian Mackenzie
11-04-2017, 09:50 AM
There are two possible approaches in terms of tightening up on the integration.

Choose a known passive network update Or

Tri or quad biamp with active crossover

Unless youíve got a lot of technical resources design of your own passive crossover is quite difficult
But a well designed passive crossover for your final choice of horn will mitigate the complexity of using several amplifiers, wires and problems with noise.

However, if you want to experiment with several horns and your active crossover has some flexibility this is much easier for the diy person.

The closest pre design passive network for bi amp woofer only is the 3155 charge coupled network

Swap out the 2121 with the 2123 10 inch Mid and this network is reported to work with the 2445 2 inch driver/2311/2308 and the 2405

This could be your baseline passive network for comparison purposes

For the later some people are using Hypex modules with built in dsp active crossovers.

Goldjazz
11-04-2017, 06:11 PM
There are two possible approaches in terms of tightening up on the integration.

Choose a known passive network update Or

Tri or quad biamp with active crossover

Unless youíve got a lot of technical resources design of your own passive crossover is quite difficult
But a well designed passive crossover for your final choice of horn will mitigate the complexity of using several amplifiers, wires and problems with noise.

However, if you want to experiment with several horns and your active crossover has some flexibility this is much easier for the diy person.

The closest pre design passive network for bi amp woofer only is the 3155 charge coupled network

Swap out the 2121 with the 2123 10 inch Mid and this network is reported to work with the 2445 2 inch driver/2311/2308 and the 2405

This could be your baseline passive network for comparison purposes

For the later some people are using Hypex modules with built in dsp active crossovers.


Thanks Ian, Some good options there. What I'm trying next is basically Tri-amping with two active crossovers. Omitting the 2405 and using the TAD 4002 for 1250 up to 20K. Will post some impressions and plots late on this evening. I'll be using the First Watt B4 for the crossover of the 2121H to the 4002 so I've got a lot of crossover and slope options.

Regards.

Ian Mackenzie
11-04-2017, 06:22 PM
Cool

Goldjazz
11-05-2017, 12:22 PM
Chose 12db/oct and around 1000Hz for the 2121H to TD-4002, and was stuck with 24db/Oct (because of crossover) and chose around 200Hz for the 2231H to 2121H. This got me the flattest response I could get, haven't played around with phase that much.

So it's sounding fairly well integrated at the moment with regards to freq and SPL, but still not quite sure I prefer it. I'll need to listen a bit more to understand.

While it does have that nice clarity from the TAD, the whole experience is "Different". It kind of isn't JBL I guess, as discussed before. Perhaps it's lacking some presence and punch. It seems the TAD just has a different sonic character and this perhaps doesn't match the other drivers as well as when using the 2420 etc. And/or when Tri-amping the differences in amps, makes it hard to get the whole thing to come together.

My gut feel is that in the stock 4343 the "whole is greater than the sum of the parts" and this is due to the genius of those that designed it. Adding a "Better" driver into the mix may not result in a better overall result, because it's not as well matched in character and the compromises in tri-amping may outweigh the benefits. I'm not even sure that a passive network could be designed for this driver combination to make the whole greater than the sum of the parts, becuase the TADs character just doesnt match, it's too delicate and sweet. The TAD is lovely, I do love when you're picking up so much detail you kind of hear the echo of studio at certain parts in songs that you never heard before.

If I could get just a little more of that berylium detail in the 2420 but still maintain the punch etc I think this would be the best overall solution. Will keep playing.



78893

Ian Mackenzie
01-28-2018, 01:20 AM
What cone kit have you got in your 2231H?

Dr.db
06-10-2018, 12:51 PM
So I just got a pair of 2441 on 2309 horns with crinkle lenses. Quite an intense experience. Explosive and effortless indeed, a big sound.

Is there any advantage at all of the big 2390 lens compared to the smaller 2392 when using a high crossover-frequency of 1,2khz :confused:
I love the looks of the 2390, but Iīm afraid at 1,2khz it might be rather disadvantaged due to a much deeper horn messing up the time-alignment.