Should I placed a ultra high twetter on top of 4430

[4344]

Hi,

I just wonder if I should add an ultra high unit on top of my JBL 4430.
Probably, I will buy UT 505, welcome any advise on this ?

thx

[Mannermusic]

Hi,

I just wonder if I should add an ultra high unit on top of my JBL 4430.
Probably, I will buy UT 505, welcome any advise on this ?

thx

The simple, honest, answer is NO. There are multiple posts/threads here re this question you can read. But, these bi-radials have unique crossovers / dispersion not easily compatible - if at all - with an additional UHF driver. An "interesting experiment" but not JBL recommended. Others?

[grumpy]

I've entertained the notion of putting a 2404H on top ... similar radiation pattern and look.
It won't hurt anything. You might like it, or not. I doubt I'd hear an actual supertweeter...
maybe if crossed over at 9-10KHz (?) People have been adding supertweeters to systems
for decades (for better or worse).

I kind of like the 4430's as they are though... so I've not bothered to try (yet)

[Ian Mackenzie]

In think you feel the sound is missing something?

If you are your right

All compression drivers have a mass roll off frequency governed by the mass of the diaphragm

Above this frequency Jbl use the diamond surrounds secondary resonances to extend the hf response with the titanium diaphragm

On paper it looks good but driver is working harder and harder to deliver high frequencies accurately (A due to the mass of the diaphragm and (B due to the self resonance of the surround

The harmonic distortion of the driver rises with frequency on paper

In this driver the mass roll off frequency is around 3-4 khertz

On these bi radial monitors Jbl passively compensate for this with a customised high pass filter which produces a flat response overall

Subjectively these system have brilliance that was well accepted back in the 1980’s

This tends to give the impression of a lack of precision in the highs compared to jbls more contemporary systems that use a wave guide and a more advanced diaphragms

These systems also employ a super tweeter in the form of a small horn

The crossover point is unusually high.

One member Guido reported significant improvements using a Tad driver with a beryllium diaphragm

But that is a very expensive option

If you had never heard another system to compare you might well accept the 4430.

I personally spent several hours comparing the 4435 to the 4343b side by side at John Nebels home.

I preferred the 4343b on jazz music

On classical music l preferred the 4435 at the time

That was back in 2004 and a lot of water had gone under the bridge since then

On the diy front there is scope to improve either system subjectively

[toddalin]

I would think that if you went this route, you would want to use a 2404 with a 2405 diaphragm. If going this route, it might also be nice to replace the 2425 with a 2421 diaphragm.

[4344]

Dear all,

Thank you so much for the advice.....


Ian, you are correct and pin point the problem exactly with detail explanations.

As result, "so I've not bothered to try" (quote from grumpy)

Cheers

[turnitdown]

the dispersion of the horn (2344) disperses the HF SO much that you feel you don't hear its upper end because your (my) hearing is a bit weak up there and a, say, 60x40 horn beams the frequencies in question in a more compact pattern that contains those HF within a smaller front so you like it better?

[Ian Mackenzie]

Good observation

It’s good and bad

They need good side wall absorption to image properly

Your subjective view might change then

In terms of low cost improvements here are a few tips:

You might try a lightly dusted acquaplas titanium diaphragm

This does damp those self resonances

Then try some modifications to gently attenuate the response above 10 k hertz

This can be done with the HF extension adjustment

Then bring in the 2405 sharply above 10 k hertz using the 43xx 2405 filter using an L pad

This should deliver a definite improvement in the crystalline clarity of the system

[turnitdown]

"They need good side wall absorption to image properly"

Well, doesn't that change their dispersion? Side walls make it closer to a reduced horizontal dispersion, no?