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How to Make a New Wave Biradial Horn
How to Make a New Wave Biradial Horn
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Old 7th December 2017, 05:29 PM   #61
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Chris Koerbel View Post
PS: so bottom line: you would recommend to use a different horn and a different driver... 4435/30 is not a great speaker respectively can be done better?
I owned 4430 for about a decade. They were given to me by John Eargle for the work that we did in bringing about the (temporary) union between Ford and JBL. He hand picked my pair and had them measured. At the time they were good speakers, but I came to like them not so much over time.

It was as a replacement for the problems with the 4430 that I designed the Summa and its ancestors. To me, the Summa was dramatically better than the 4430's. Today, I could not tolerate the harsh sound of the 4430.

And just to be clear again, one can EQ a bad horn at a single point, but diffraction and resonances cannot be fixed globally. No acoustic problem can be "fixed" with EQ, DSP or otherwise. It's a three dimensional problem and one dimensional solutions are incomplete.
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Old 9th December 2017, 01:01 PM   #62
Chris Koerbel is offline Chris Koerbel  Germany
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aha....
so I should check your website!
Some say after changing the 2425/... to a TAD2001 the harshness disappears?
Some say, the 4430 is still one of the best ever speakers up till now?
Looks as if in this thread, there are no "fans"?

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Old 10th December 2017, 07:31 PM   #63
1audiohack is offline 1audiohack  United States
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I can imagine that the 4430 is the best speaker some people have ever heard or owned and they would likely say they’re the best ever. This would be based on their experience.

As a note I gave my 4430’s to my daughter, who loves them. I still have my 4435’s in my office and I love them.

Dr. Geddes has said in some of his posts that he (some times or often?) listens in the 105dB SPL range if I remember right and the 4430/4435’s sound harsh to me approaching that level as well. There has also been discussion that some types of distortion increase in audibility as overall level increases.

The small format driver and 2344 horn combination just doesn't get loud nicely and is something I have just come to expect. Something I did not expect came like this. I bought a Bryston DAC recently and decided to put it in the signal chain of the office system for first test since this is the system I listen to the most.

There are several subtile differences in the sound and one really big one, the 4435’s play considerably louder without harshness than ever before. I hope I can somehow measure what I am hearing, objectively.

I don’t want to derail this into 2344 thread. Do I still like mine? Yup. Do my 4365’s outperform my old 4430’s? In every way? Yup.

I hope this thread turns into the making and measuring of actual horns!

Barry.
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Old 10th December 2017, 08:00 PM   #64
gedlee is offline gedlee  United States
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Just to be clear, 105 dB would not be the norm, but it certainly is possible - at times! - on peaks with "C" weighting. My compression driver is no bigger or better than CD on the 4430's, its pretty much the same. But on my system there is never any harshness. I, of course, wondered why this is. This is why B&C and I did the studies that we did to find out the reasons, which are now perfectly clear to me. I won't belabor this thread with a repeat of all that work other than to say that it is all available - as close as the link below.
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Old 11th December 2017, 12:49 AM   #65
1audiohack is offline 1audiohack  United States
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Thank you sir.

I read.

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Old 11th December 2017, 06:49 AM   #66
USRFobiwan is offline USRFobiwan
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How to Make a New Wave Biradial Horn
For those looking for the Earl and B&C test papers you can find them
here Compression Driver Subjective Test (if Earl doesn't mind I posted the direct link)
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Old 11th December 2017, 04:47 PM   #67
gedlee is offline gedlee  United States
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Posting that is fine, but there is another paper that follows that one. The first one (above) shows that nonlinear distortion in the compression driver is not likely to be what we hear at high SPL. The second paper http://www.gedlee.com/Papers/AES06Gedlee_ll.pdf describes what is likely to be the cause. In my experience the conclusions drawn from these two papers turns out to be exactly correct. We hear the horn, not the driver and minimizing the diffraction by using a well designed waveguide will eliminate the problem.
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Old 13th December 2017, 12:25 AM   #68
ICG is offline ICG  Germany
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Sry for not answering yet.

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Originally Posted by gedlee View Post
Are you suggesting that the motor strength is different at mid frequencies than at resonance? Below where the inductance is significant.
The magnet is always the same in strength, ofcourse. But the EBP (Fs/Qes) says nothing at all about the reproduction above the bass, the Q factor describes the bandwidth/height of the resonance. So the speaker behaves ofcourse a lot different when the system is in resonance (fs) than at other frequencies. Above, the Q does not have much (if at all) influence, that means calculating with the Q are not applicable there. Don't believe me? NP, You'll find a lot of excellent midrange drivers with a Qts above 1.

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And why if we add mass to the cone do we have to stiffen the suspension? Just let the resonance go down.
The suspension has to control the movement. If it's too weak the cone starts to tumble or sag which causes the coil to scrape on the pole plate or -core, don't forget, you'll have to add a LOT of weight, for 30Hz it's 96g, that's more than the whole Mms originally is! And by worsening the Mass/Motor ratio, you'll lose spl - a lot! The Celestion got a (from the parameters calculated) spl of 96,4dB. If you add weight until you reach, let's say just 30Hz, the EBP drops vastly, from 81 to 54 and you'll reduce the spl to meager 91,1dB. Well, it's pretty useless for a 15" then, isn't it?
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Old 13th December 2017, 01:02 AM   #69
gedlee is offline gedlee  United States
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Originally Posted by ICG View Post
The magnet is always the same in strength, ofcourse. But the EBP (Fs/Qes) says nothing at all about the reproduction above the bass, the Q factor describes the bandwidth/height of the resonance. So the speaker behaves ofcourse a lot different when the system is in resonance (fs) than at other frequencies. Above, the Q does not have much (if at all) influence, that means calculating with the Q are not applicable there. Don't believe me?
I don't think that answers my point. The "Q" of a resonance is only defined at resonance (for any resonance), it's not a function of frequency. But the same BL that yields the resonance Qt is the same BL that gives a driver its pass-band efficiency. So, in essence, it means that they are the same thing, just in different domains.
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Old 13th December 2017, 02:04 AM   #70
ICG is offline ICG  Germany
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No, that's wrong. The Q defines the hight and the width ('bandwidth') of the resonance, quite well observable at the fs impedance peak (symmetrical on an ideal speaker) but also on the frequency response or, to be more exact, it's how high the spl at the fs is compared to the average level. That means, it actually is a function of frequency. You can easily try it out with any sealed enclosure simulator. At Qt=1 the spl will always be at exact 0dB at the Fs in that enclosure, no matter what driver you use. For other Qt's you can calculate the level the same way.

The upper bandwidth limit/roll-off of a speaker is not mainly determined by the Qt unless it's in a bandpass enclosure (double/single ventilated bandpass, compression chamber with or without a horn (or the other way around) etc. or mechanical filtering like downfire).
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