Info on the Yamaha JA-6681 compression driver

[Radian]

Funny, I'm raving about the sonics of my Radian 850PB and people
keep contacting me about the Yamaha JA-6681.

Because I think that this driver deserves it's own thread
and because I don't want to keep answering the same questions over
and over again, here are some facts and thoughts:

Yes, that thing sounds absolutely fantastic.
Altec, JBL, B&C, BMS....no contest.
TAD? I don't know, I never heard one, but prior to my purchase I contacted
three people who possessed both drivers and two of them preferred the Yamaha,
while one said they are equally good but different in sonic signature.
Take it for what ever it's worth. YMMV.

It's not an alnico magnet driver despite the look. It is actually only a
1” driver with a cast aluminum conical extension. In fact, the cheap
looking Yamaha 6603 driver is identical except for the phenolic diaphragm
and the missing conical extension. If you know how to correct shifted
magnets, and you want to use a tweeter anyway, there is your chance.
I'm using my 6681 with the phenolic diaphragms and I think they even
sound a bit more organic, if you know what I mean.

No, there are no diaphragms out there anymore. Money, or a friend
who works at Yamaha etc. will not get you any diaphragms. Zero. Nada.
You could get some from Meyer Sound and carefully scrape that stuff off
from the Copper Beryllium suspension, butt $$$$$.
Or you rent some Meyer Sound …...ups I killed......
OK,OK, just kidding.

Yes, it can give output from about 250hz on up, but who would want to do that.
Remember, there are no diaphragms anymore and one mistake is all it needs.
500hz first order to a good paper cone sounds more natural anyway and the
radiation pattern up high is way better.
I would still use a good tweeter, even with the aluminum diaphragms, as it just
adds that extra ambiance and realism and because you will not be stuck to a one chair
sweet-spot. It's just allot more fun to listen to good music with some friends
and nobody is missing a whole octave which makes a big difference.
That's actually why I prefer a slot tweeter instead of the normally used bullet.

Anyway, I think this is all about the Yamaha JA-6681 that is relevant.
If you have any more information about this driver please feel free to
add it below.

Greets,
Klaus

[el`Ol]

I listened to this system which combines the Yamaha with a 1" TAD. I never listened to the Yamaha alone, but this combination sounds smoother and more musical than TAD alone, what I heard in Cessaro speakers.
homepage
When I listeded to it there was the standard TAD slot playing on one side and the same driver with a little horn on the other side, and I found the version with horn definitely more natural.

[Jmmlc]

Hello,

I own myself 2 pairs of that driver.

But you should know that this driver IS NOT a 1 inch driver but is
1.375" in throat diameter ( diameter = 34.925mm).

So using it with an horn having a 1inch throat is questionable. (Also better to use another horn than the original Yamaha horn)

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally Posted by el`Ol

I listened to this system which combines the Yamaha with a 1" TAD. I never listened to the Yamaha alone, but this combination sounds smoother and more musical than TAD alone, what I heard in Cessaro speakers.
homepage
When I listeded to it there was the standard TAD slot playing on one side and the same driver with a little horn on the other side, and I found the version with horn definitely more natural.

[Radian]

Originally Posted by el`Ol

I listened to this system which combines the Yamaha with a 1" TAD. I never listened to the Yamaha alone, but this combination sounds smoother and more musical than TAD alone, what I heard in Cessaro speakers.
homepage
When I listeded to it there was the standard TAD slot playing on one side and the same driver with a little horn on the other side, and I found the version with horn definitely more natural.

Now, that kind of configuration is absolutely beyond me.
There is no way the TAD 2001 can be interrupting the JA-6681's top end without penalty.
But if it was just added from lets say 7khz on up, a good Rinrradiator with a moving mass of a fifth of the TAD's diaphragm would do a much better disappearing act, for a lot less money.
I agree that for the last hair of shimmer and precision a bullet tweeter is better than a slot, but for me an 8 to 10 degree radiation is unacceptable, for the mentioned reasons.
Yes a slot has a more ragged response, but I found this in reality less critical than most people make it to be. If working with a slot tweeter, flat walls are not what you would want as reflections kill imaging. But if one uses some bookshelf's on both sides of the room, or some other means to prevent coherent reflections, the benefit of the slot will come into play big time, as more people can enjoy the show now.

[el`Ol]

Originally Posted by Jmmlc

Hello,

I own myself 2 pairs of that driver.

But you should know that this driver IS NOT a 1 inch driver but is
1.375" in throat diameter ( diameter = 34.925mm).

So using it with an horn having a 1inch throat is questionable. (Also better to use another horn than the original Yamaha horn)

I was talking about the TAD. These guys are really using a TAD and a Yamaha in one system.

[Radian]

[QUOTE=Jmmlc;2124937]Hello,

I own myself 2 pairs of that driver.

But you should know that this driver IS NOT a 1 inch driver but is
1.375" in throat diameter ( diameter = 34.925mm).[QUOTE]

Hi Jean Michel,
You probably never took yours apart.
I could take it apart and show you but I am to lazy.
Instead I have taken some pics to show you.
If you take both black parts off you will have exactly
what you see on my 6603. A 1" throat driver but without
the screw holes.

Greets,
Klaus

[Radian]

Hard to believe but that's how cheap it looks if you take both ends off.
It probably did not cost more than any other 1” driver to manufacture.

I had many people asking me where they can by spare diaphragms.
Now if we would just find some company that is willing to manufacture
them. Maybe Radian would be a good address to talk to.

Or maybe someone is willing to buy the whole manufacturing tools
form Yamaha and make some money building great sounding
compression drivers for us audio-nuts.

Greets,
Klaus

[Radian]

Actually I think that this driver could sound better if the conical extention part would be
taken off and be replaced by, say a Walnut wood piece having the first 3 inches of the
tractrix or LeCleach contour already in it.
If the back cover is than made of the same wood. Wow
Dreaming is allowed, isn't it.

Greets,
Klaus

[djn]

I can't believe how timely this thread is. I just got, but have not picked up, a pair of old Yamaha stage monitors. They have a 15" woof and aluminum horn with, I think, the driver we are talking about here. It is a Yamaha cab will all the stock components. The horn is a rounded lip horn, not the flat faced one we see in the new stuff. They will be going to a friend that is broke so he can build up a pair of speakers. I know nothing about the drivers but when I hooked them up, I was very impressed.

It is too bad there are no diaphragms any longer. Could it be posible that Yamaha used someone elses diaphragms????

[Radian]

If you got the 6115H or the 6215H Monitor then there is the JA-6681b in it. If you got
the 4115H then there is the JA-6603 in it.
The Motor of both are essentially the same but sadly the 6603 has most of the time
a shifted magnet do to road handle which needs to be recentered.
No, there are no more Diaphragms available.
Someone needs to talk Radian into it.

Greets,
Klaus