If I Told You What It Takes to Reach the Highest High...

Zilch · Feb 12, 2009

toddalin said:
As to through the crossover or not, is irrelevant becvause whatever I use will be through the crossover regardless of what the rest of the band is doing.

Your filter is operating right smack in the middle of where you're claiming to have made improvement. Take it out of the equation to see what's actually going on.

toddalin said:
Actually, I think the 2402 is like a woofer in a box that's too big. It lets the cone flop around creating a resonant frequency (~10KHz). I've decreased the size of the "box" and this controls the cone movement.

If the 2402 "box" is too large, that's because it was designed to play as low as two octaves below where you're hoping to optimize it:

http://www.jblpro.com/pub/obsolete/2402.pdf

It's larger horns that load lower, and unlikely that any "flopping around" is going on in the diaphragm at 10 kHz.

For higher frequencies and more usable dispersion, JBL subsequently designed the 2405:

http://www.jblpro.com/pub/obsolete/2405.pdf

And later still, the constant-directivity 2404, which does all of that, and much more, using the 2405 diaphragm:

http://www.jblpro.com/pub/obsolete/2404.pdf

Note the term "obsolete" in each and all of those links; JBL has since moved on to better ring radiator/waveguide technologies.... :yes:

Kegger · Feb 12, 2009

Zilch said:
The extension is the same, actually. He's doing HF comp with the rubber band, and any concomitant consequences are indeterminate at this point. Clearly, the band is introducing discontinuities in the internal flare that are not present in the original design, which obviously went to considerable effort to provide smooth transitions in generating the engineered flare.

Could you, and I mean YOU, Kegger, flatten the HF response with a Parham HF comp filter or equivalent, instead, without introducing any such unknowns?

Yes I see what your getting at, I'm sure with comp the same thing could be had.

And I agree we don't know what else might be happening with that rubber band,
I like what I see on the output though, the rest needs to be tested to see/hear
what might be going on, as Todd mentions there "may" be improvements in some
other areas, but at the same time there "may" be anomalies were not seeing.

----------

As to others mentioning the output being down, as has been said these things
have higher sensitivity then the other drivers in a system but the xover will be
knocking that back with padding, the way it is now Todd will just use less pad.

toddalin · Feb 12, 2009

"Your filter is operating right smack in the middle of where you're claiming to have made improvement."

Where have I claimed improvements at the 7-8kHz band? Still, if you look closely, you will see definite improvement there as well.

I made improvements across the band in the range that the tweeter is to operate. I don't know what you are looking at.

"If the 2402 "box" is too large, that's because it was designed to play as low as two octaves below where you're hoping to optimize it"

Fine, I've taken a "general use" upper midrange/tweeter and made it into a true tweeter. Nothing wrong with that if that is now its intended use.

"It's larger horns that load lower, and unlikely that any "flopping around" is going on in the diaphragm at 10 kHz."

There is a pretty obvious resonant peak at ~10-11 kHz with all of these 24XX tweeters. I've just tamed it.

"For higher frequencies and more usable dispersion, JBL subsequently designed the 2405."

Maybe more dispersion, but it won't go as high as smoothly the modded 24025.

2405:

Banded 24025:

"And later still, the constant-directivity 2404, which does all of that, and much more, using the 2405 diaphragm."

Sorry, don't have that one. But I do have the 2404 (Baby cheeks) with the 2402 diaphram, and it is pretty sickly looking affair:

And this is the regular 2402 before my modifications:

Other than yourself, I don't think that anyone here would deny that for tweeter duties my mods:

Beat the stock setup hands down:

As you can see, I've improved the response everywhere, even down in the crossover range. But until you actually listen to a banded 24025, I just can't take you seriously. Like I said, only takes a minute to assemble and is completely reversable.

Zilch · Feb 12, 2009

toddalin said:
Where have I claimed improvements at the 7-8kHz band? Still, if you look closely, you will see definite improvement there as well. I made improvements across the band in the range that the tweeter is to operate. I don't know what you are looking at.

Uhmm, right here in Post #1?

toddalin said:
I was also able to turn a ~10 dB dip at 8-9kHz to about 2.5 dB.

That was your stated purpose last week, as I recall, at which time you touted the VHF extension from using the 2405 diaphragm as an "ancillary benefit."

toddalin said:
Fine, I've taken a "general use" upper midrange/tweeter and made it into a true tweeter. Nothing wrong with that if that is now its intended use.

Seems more like stripping wallpaper is the intended use here, actually. The stock 2402 diaphragm will play that as well with HF comp in the filter, and yes, it's easier to do that with the 2405 diaphragm, as that requires less comp to accomplish the same, but the problem is the beamwidth diminishes to 22° (-6 dB) at 20 kHz with the 2402's exponential horn, making it virtually pointless to extend the VHF response. That's why JBL engineering employed a different approach to accomplishing this in 2405, which maintains rational beamwidth in the topmost octave.

toddalin said:
There is a pretty obvious resonant peak at ~10-11 kHz with all of these 24XX tweeters. I've just tamed it.

Said resonance generating a peak or a notch? Define that, please, so I might formulate a rational response, please. Delirium is what's most in evidence, thus far.

toddalin said:
Maybe more dispersion, but it won't go as high as smoothly the modded 24025.

Fiction. Any competent filter designer can make 2405 play perfectly flat up there without introducing spurious anomalies, as Kegger just affirmed, above. EV did it with ST350B thirty years ago, for example:

http://archives.telex.com/archives/EV/Horns/EDS/ST350B EDS.pdf

toddalin said:
Sorry, don't have that one. But I do have the 2404 (Baby cheeks) with the 2402 diaphram, and it is pretty sickly looking affair....

It's 2404H-1 you're looking at there, Todd, which specifically and intentionally trades VHF extension for increased power handling in those Cabaret series products which used it. You cannot see that the 2402 diaphragm is in total control of the VHF extension there? Again, it's your filter doing what's happening at the low end. If you have some 2404s, put the stock 2405 diaphragm in them and measure the "improvement." Stock 2404H used the 2405 diaphragm and I've already linked you and everyone else to our measurements comparing them. Anyone familiar with the difference can instantly tell which diaphragm is installed in a particular 2404H without ever opening it up by looking at the VHF extension, even on RTA.

toddalin said:
Other than yourself, I don't think that anyone here would deny that for tweeter duties my mods ... beat the stock setup hands down....

What, sticking a 2405 diaphragm in a 2402? JBL made that product, 2402H-5 and listed that particular diaphragm swap as an acceptible mod, so long as the consequences are acceptible for the particular intended use. It's further instructive that you continue refusing to use the "correct" factory designation, 2402-5; you don't own this mod, Todd, and neither do you yet know or appreciate its tradeoffs.

toddalin said:
As you can see, I've improved the response everywhere, even down in the crossover range. But until you actually listen to a banded 24025, I just can't take you seriously. Like I said, only takes a minute to assemble and is completely reversable.

Fact is, and you've already admitted to it, you're too cheap to buy 2405's, the UHF driver designed by JBL for your intended purpose, which is used precisely as you intend in the entire line of 43xx large-format Studio Monitors, highly regarded as industry standard for many years and still widely used in recording studios worldwide.... :yes:

SPL db · Feb 12, 2009

Kegger · Feb 12, 2009

While I would agree he could buy 2405's and get the same if not simular results, but
if he can do it with what he already has and just buy diaphragms that'd be the way
I would go about it. (That is if everything checks out)

My stance is still the same as it was, a worthy test and possible outcome.

(If for no other reason, price and already having the components)

toddalin · Feb 12, 2009

"Seems like that was your stated purpose last week, at which time you touted the HF extension from using the 2405 diaphragm and an "ancillary benefit."

I wasn't even on this site last week. "What happens in Vegas, stays in Vegas."

"The stock 2402 diaphragm will play as well with HF comp in the filter"

No it won't. I want to see you take your 2402 and just using a filter, produce a totally flat curve between 10-20kHz. Post these results to show us that it will.

"but the problem is the beamwidth diminishes to 22° (-6 dB) at 20 kHz with the 2402's exponential horn, making it virtually pointless to extend the VHF response."

22 degrees is plenty of dispersion when one sits in the "sweet spot" 99.99% of the time.

"Said resonance generating a peak or a notch? Define that, please, so I might formulate a rational response, please."

Pretty obviously a peak from all the plots.

"It's 2404H-1 you're looking at there, Todd, which specifically trades VHF extension for increased power handling in those Cabaret series products which used it."

Sure, increased power handling and that's why the 2404H-1s that I have were hammered such that their diaphrams were shattered into dozens of pieces. They still can't take the power.

"If you have some 2404s, put the stock 2405 diaphragm in them and measure the "improvement." Stock 2404H used the 2405 diaphragm and I've already linked you and everyone else to our measurements comparing them."

Sure..., just as soon as you put a 2405 diaphram in a 2402 and post your results. While I don't have any 2405 diaphrams around (except for the one under test that is not mine), I know that you have these components in hand.

"What, sticking a 2405 diaphragm in a 2402? JBL made that product, 2402H-5 and listed that particular diaphragm swap as an acceptible mod, so long as the consequences are acceptible for the particular intended use. It's further instructive that you continue refusing to use the "correct" factory designation, 2402-5; you don't own this mod, Todd, and neither do you yet know or appreciate its tradeoffs."

I never claimed to "own" this mod, but there never was a "2402-5." (Get your nomenclature right. It was only in the ferrite H version.) I did come up with the concept of the "band."

Also, as you are well aware, there was no common knowledge of the 2402H-5 when I started my experimentation, and this knowledge only came to light because of my work.

Nor do we know what really comprises a 2402H-5 and how JBL may have tweaked this model to get the 2405 diaphram to work in it. (Orange County Speaker has tried unsuccessfully to put the 2405 diaphram in the 2402.) As you well know, this is a relatively unheard of model that was not produced in AlNiCo and is poorly documented. Please point me to ANY JBL literature on the 2402H-5.

"Fact is, and you've already admitted to it, you're too cheap to buy 2405's, the UHF driver designed by JBL for your intended purpose, which they used precisely as you intend in the entire line 43xx large-format Studio Monitors, industry standard for many years and still widely used in the recording industry."

Please enclose and mail me $1,200 so that I can buy three of these 2405s and ensure that I get JBL diaphrams. Or are you too cheap?

Zilch · Feb 12, 2009

Kegger said:
While I would agree he could buy 2405's and get the same if not simular results, but if he can do it with what he already has and just buy diaphragms that'd be the way I would go about it. (That is if everything checks out)

The results are not similar. Not even remotely so.... :thumbsdn:

The same issue arises with LE85/2420 on the exponential horn/diffraction lens combo with which everyone is well familiar. Can we HF comp that driver to play VHF and obviate the necessity of adding a tweeter in the first place? Yup, but the HF beams equivalent to that of 2402, rendering the effort moot.

What's the answer? Put that same driver on the 2344(A) constant-directivity Biradial horn, and you've got something to work with, which became the 4430 Studio Monitor. See Todd's first pic in Post #1.... :thmbsp:

toddalin · Feb 12, 2009

Kegger said:
While I would agree he could buy 2405's and get the same if not simular results, but
if he can do it with what he already has and just buy diaphragms that'd be the way
I would go about it. (That is if everything checks out)

My stance is still the same as it was, a worthy test and possible outcome.
(If for no other reason, price and already having the components)

If you are in Southern Cal, you are welcome to come by and "listen."

toddalin · Feb 12, 2009

Zilch said:
The results are not similar. Not even remotely so.... :thumbsdn:

You'll never know because you won't try it. :no:

GordonW · Feb 12, 2009

One word to the wise-

Once installing an 077/2405 element into a 075/2402, you should observe more bandwidth limitation.

IME, I doubt that it would last very long, pushed hard at below a 5KHz crossover point. OTOH, on most of the speakers where this tweeter is used (3-way systems), this should not be a problem.

Those very few systems that use these tweeters with N2400 or N2600 crossovers (i.e, the 030 setup with the D130 and such) will put the 077/2405 diaphragm in peril...

Regards,
Gordon.

Zilch · Feb 12, 2009

toddalin said:
No it won't. I want to see you take your 2402 and just using a filter, produce a totally flat curve between 10-20kHz. Post these results to show us that it will.

I have ZERO interest in investing more effort into "improving" the applicability of 2402s than has already been deleted elsewhere. It's a fruitless endeavor, for the reasons stated.

toddalin said:
22 degrees is plenty of dispersion when one sits in the "sweet spot" 99.99% of the time.

Only if you ignore power response and its impacts, as you are apparently willing to do, without understanding it, even.

toddalin said:
Pretty obviously a peak from all the plots.

Cool. I'm glad we're clear on that point, that the native response has a peak, whatever the source. I'll take a more comprehensive look at that.

toddalin said:
Sure, increased power handling and that's why the 2404H-1s that I have were hammered such that their diaphrams were shattered into dozens of pieces. They stiill can't take the power.

By idiots, primarily. JBL gave up on this, ultimately, and the 2405 diaphragm is now the recommended replacement.

toddalin said:
Sure..., just as soon as you put a 2405 diaphram in a 2402 and post your results. While I don't have any 2405 diaphrams around (except for the one under test that is not mine), I know that you have these components in hand.

Not my job, mon. This is YOUR contrivance, and thus, your responsibility to suss it out.

toddalin said:
I never claimed to "own" this mod, but there never was a "2402-5." (Get your nomenclature right. It was only in the ferrite H version.) I did come up with the concept of the "band."

Good, I'm glad its now clear that the sum total of your "Claim to fame" as innovator here is derivative of sticking a rubber band on the bullet phase plug of 2402-5, and we can now focus on the alleged merits of this "enhancement" specifically.

toddalin said:
Also, as you are well aware, there was no common knowledge of the 2402H-5 when I started my experimentation, and this knowledge only came to light because of my work.

Not one of JBL's most successful components, for obvious reasons.

toddalin said:
Nor do we know what really comprises a 2402H-5 and how JBL may have tweaked this model to get the 2405 diaphram to work in it. (Orange County Speaker has tried unsuccessfully to put the 2405 diaphram in the 2402.) As you well know, this is a relatively unheard of model that was not produced in AlNiCo and is poorly documented.

Nobody but you ever gave a whit about it, apparently.

toddalin said:
Please enclose and mail me $1,200 so that I can buy three of these 2405s and ensure that I get JBL diaphrams. Or are you too cheap?

And you'll send me some rubber bands as a gesture of appreciation, or do I get broccoli, as well? :tongue:

packrat · Feb 12, 2009

Zilch said:
.............Note the term "obsolete" in each and all of those links; JBL has since moved on to better ring radiator/waveguide technologies.... :yes:

What are they doing now for 10kHz and up? Is there a PT waveguide being used?

Cosmos · Feb 12, 2009

toddalin said:
Now, "If I told you what it takes to reach the highest high, you'd laugh and say nothing's that simple."

So, how do we "narrow the window?"

I've tried a few things and this is what I've found to work best (but testing goes on). (Those with pacemakers please look away as you will surely die laughing.)

Yes, it is exactly what it looks like..., a plain old rubber band that came off a stalk of broccoli! :lmao:

The photo shows the approximate placement of the band on the phase plug. The idea is to use one that is about the same size as the plug so it easily slides on the plug with little friction.

I told you that you wouldn't believe it!

Todd, Need is described as the Mother of Invention and there it is.. the Mother...

Now, can you run full battery of tests to determine if Pink, Green, Blue or plain old brown rubber bands sound better and which has the best spectral balance? :scratch2:

Inquiring minds want to know...

Perhaps a shaved O-ring? O-rings are available in various materials/elastomers.. or far out of the bax a textured condom over the whole bullet?

Kegger · Feb 12, 2009

Well Zilch we'll just have to agree to disagree.

I see merit and accomplishment here in what Todd is doing/trying.
I understand where he is coming from and what it is he's getting at.
(No it's not all done or spelled out completly)

No not a ton of people are going to be interested in this or find it
to be worthy even, but that does not deem it any less warrented
if even just 1 party finds it works for them. Not everyone has to be
enlightened or feel the need for this experiment.
(As long as someone does is all that counts)

Yes you've posted about "other" tests that have been previously done,
I just like Todd feel there is still a lot left not tried/tested.

You've got your thing your interested in and find have merrit of taking
your time to figure them out, others have there interests, the 2 do not
have to jive with one another. Nor the testing platforms have to be the
same nor the results wanted/achieved have to be the same.

Zilch · Feb 12, 2009

packrat said:
What are they doing now for 10kHz and up? Is there a PT waveguide being used?

Most commonly, yes, with 2407H or 2408H ring radiators. The ferrite-magnet 2406H has been discontinued, I believe, but BMS makes a similar, as I recall.

Here's an example using "entry level" components:

http://www.jblproservice.com/pdf/AE Series Compact Models/AC16-WH.pdf

Kegger said:
You've got your thing your interested in and find have merrit of taking your time to figure them out, others have there interests, the 2 do not have to jive with one another. Nor the testing platforms have to be the same nor the results wanted/achieved have to be the same.

As I believe Todd will himself attest, no one has been more supportive of his work in these forums over the years than the Zilchster.

While it may not be apparent from the discourse, we also happen to be friends.... :thmbsp:

Kegger · Feb 12, 2009

Zilch said:
As I believe Todd will himself attest, no one has been more supportive of his work in these forums over the years than the Zilchster.

While it may not be apparent from the discourse, we also happen to be friends.... :thmbsp:

I hear yu, I have seen some of it, I'm just saying the guy is playing with things he wants to
play with and finds they may work for him, you are onto different things and don't find them
to be what your into, that is fine but others may be looking for something else.

Not everyone is after a Waveguide for every speaker.

Cosmos · Feb 12, 2009

I vote for Orange rubber bands if we can match the orange in the JBL foilcal.

BTW, if Todd can make the 2402-5 sound liveable.. all the more power to him. I have yet to hear them in a system that I really liked them. Perhaps, if the HP was high enough to just add air... But then the question becomes, is that needed now?

tentoze · Feb 12, 2009

Kegger said:
Not everyone is after a Waveguide for every speaker.

O dear. You might want to be careful about opening unexpected packages from California from now on.

Zilch · Feb 12, 2009

tentoze said:
O dear. You might want to be careful about opening unexpected packages from California from now on.

There's no denying that California broccoli is simply the best anywhere available! :thmbsp:

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