Seems RAAL is not interested in selling me any transformers. The two only real competitors in the high-end true ribbon business seem reluctant to do any mods on each others products. Bet I can wind my own using AMCC-4 magnets. Using the Infinite monkey theorem, I should manage it after about 1 million attempts.
Shape.
In their ads they claimed it was highly optimized.
One difference is that hole straight through the center, and the way that it relates to the next
ring...
One would have to look at other phase plugs to see the differences clearly.
But I put a picture up a few posts back...
In their ads they claimed it was highly optimized.
One difference is that hole straight through the center, and the way that it relates to the next
ring...
One would have to look at other phase plugs to see the differences clearly.
But I put a picture up a few posts back...
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I won't say anything about the phaseplug. When comparing against Radian 750-8 and Ti-diaphragm compression drivers, I always thought the biggest advantage of the JA6681B was the aluminum diaphragm and the copper suspension. It is difficult for me to imagine how differences in phaseplug affect the sound. That is too complicated physics.
Anyone eager to buy the patent and reproduce these wonderful drivers are welcome to do so.
Dr. Geddes could explain it if he wanted to.
But as far as I can tell a major difference comes in the shape of the wavefront exiting the driver. The other aspect comes as the goal of the phase plug (I am told) is to get the HF energy from the diaphragm out to the throat exit together, in phase. This extends the HF response up from a situation with a bad phase plug or no phase plug.
I'd *guess* that a WE 555 driver would go higher in freq with a modern phase plug.
But as far as I can tell a major difference comes in the shape of the wavefront exiting the driver. The other aspect comes as the goal of the phase plug (I am told) is to get the HF energy from the diaphragm out to the throat exit together, in phase. This extends the HF response up from a situation with a bad phase plug or no phase plug.
I'd *guess* that a WE 555 driver would go higher in freq with a modern phase plug.
Yes it could go higher, but the original WE 555 phase plug is also an acoustic bandpass which filters out upper harmonic distortion, a nice feature for a small diaphragm being used as low as it was.
Klaus,
Looking at pictures of an old throw sheet from the 4115H (which I have had in my files from when I was an owner back in 1978!) I found it used the JA4201, aftermarket diaphragms have been available for them since the 1990s.
Appears the aftermarket diaphragms are made of titanium rather than the original aluminum.
Does anyone know whether the JA 4201 phase plug has slits like the JA 6681, or lacks them like the old WE555 ?
My throw sheet does not have enough clarity to see, and my old partner Willy (RIP) was the one that burned and replaced 4115H & 2115H stage monitor diaphragms back then, so I don't recall ever seeing the insides of one.
Art
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I think it is important to differentiate between the 6681's slits and almost all other slits, they're a bit different.
Can't see from ur post what is there, but I guess you couldn't see either.
The Yamaha HF drivers that I have are ring radiators, afaik, with a center phase plug thingie. Not sure of the model at the moment, but they have a similar back cover to the 6681, but are smaller diameter overall...
not sure this helps the discussion any.
Can't see from ur post what is there, but I guess you couldn't see either.
The Yamaha HF drivers that I have are ring radiators, afaik, with a center phase plug thingie. Not sure of the model at the moment, but they have a similar back cover to the 6681, but are smaller diameter overall...
not sure this helps the discussion any.
I was dead wrong about Raal. Alexander is very helpful in explaining solutions for custom ribbon trafos and other things. He sure knows what he is doing. He even knows things about the history of my Transmission Audio ribbon drivers. How Transmission Audio were selling these to a company started by Mark Levison. I have heard this before but never could confirm it. Earlier this year I think I found someone who got the job to improve Mark Levisons Transmission Audio ribbon driver transformers, because he was not happy with them.
About the JA4XXX, its plug must have been designed for even higher frequencies than the JA6681B. And that is all I can say.
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The 4281B annular (ring) type diaphragm can use very simple phase plugs effectively.
Still wonder whether the JA 4201 phase plug pictured in post #213 used in the 4115H and 2115H has slits like the JA 6681, or lacks them like the old WE555 ?
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Art,
the 6681 has a unique phase plug, I haven't seen one quite like that, although for all I know all sorts of newer drivers have adopted that general scheme. It's afaik somewhat different than the usual slit method first used in the WE394 (? do I have that right) and then copied down the line by JBL and Altec, and almost everyone else since.
So are you asking if it is slit type or a slit type like the 6681?
Hmmm... that's axial phase plug slits, right?
_-_-
the 6681 has a unique phase plug, I haven't seen one quite like that, although for all I know all sorts of newer drivers have adopted that general scheme. It's afaik somewhat different than the usual slit method first used in the WE394 (? do I have that right) and then copied down the line by JBL and Altec, and almost everyone else since.
So are you asking if it is slit type or a slit type like the 6681?
Hmmm... that's axial phase plug slits, right?
_-_-
The 6681 phase plug contains both an axial and a bifurcated axial slit, the latter being unusual.
My question is whether the JA 4201 phase plug has slits, or is like the old WE555 with a single slot around the diaphragm's perimeter?
More likely it has slits, but from the old picture, can't tell.
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