Project Brass 2402H

[MatthiasA]

Hello Everyone!

today i saw some brass pics of 2402H
i want make it by myself with a CNC machine

i found this pic's but there are no dimensions about the 2 pieces..
has anybody exact dimensions about the 2402?

greetings Matthias

[John W]

I have a couple of these parts sitting around that I am not using. I could loan them to you. But, it might make more sense to purchase a complete 2402 and then you would have both the aluminum model and the driver to test your new brass horns with once they are finished.

[MatthiasA]

thats a good idea but the 2402 are very expensive...
do you sell yours ?

greetings Matthias

[John W]

Actually I am using the drivers for my wood horn 3-way (http://www.audioheritage.org/vbulletin/showthread.php?t=5951&page=1). I don't want to loose the original horns just yet.
PM me if you want to borrow just the parts shown in brass.

[Uncle Paul]

The Technical Manual has an engineering drawing that may give you some of the dimensions you need:

http://jblproservice.com/pdf/Discrete%20Sales%20Models/2402H.pdf

[Mr. Widget]

thats a good idea but the 2402 are very expensive...
do you sell yours ?


I bet you can get a pair of oxidized ugly 2402s or 075s cheaper off eBay and have them plated for less than the price of 4 large slugs of machine grade brass.

Of course, if you want to have bragging rights about having made them yourself... that's a different story.

Widget

[MatthiasA]

Hello!

thanks a lot for your offer John!
but Today i bought one 2402 driver without the 2 Horn pieces for 25 Euros
(without a diaphragma)
and one complete 2402 without dia for 45 Euro

i will make brass horn pieces!
if anyone wants the same! please PM me

Greetings Matthias Asselborn

[rek50]

Is the "Brass Section-Orchestra" solid brass or brass plated ?

[Marty]

Why do they call them RING RADIATORS ? What is the diaphragm like ?

[MatthiasA]

solid brass

[Mr. Widget]

Why do they call them RING RADIATORS ? What is the diaphragm like ?

Here is a photo that Rob posted a while back. The blue ring is the diaphragm's mounting frame. The actual diaphragm is the aluminum ring that is around the clear phase plug. The voice coil is on the other side. The diaphragms for the 075, 076, and 077 all look virtually identical. Depending on the year of manufacture the thicker aluminum mounting frame can be blue, silver, gold, and perhaps other colors as well.

Widget

[rek50]

"solid brass", That's what I thought. I didn't think you would go through the extra effort for "Looks" although they would look very nice. A "CNC" job?

[Mr. Widget]

If it isn't "just for looks" then why do it?

Changing the material of the horn certainly won't take the first plot and turn it into the second plot. ;)

Widget

[MatthiasA]

here's a pic of the diaphragm
i think it would be a cnc job

[johnaec]

Changing the material of the horn certainly won't take the first plot and turn it into the second plot. ;)
And what exactly IS that second plot, Widget??

John

[louped garouv]

And what exactly IS that second plot, Widget??

John

nearly flat :rotfl: :rotfl: :rotfl:

[Mr. Widget]

And what exactly IS that second plot, Widget??

John

It is made of pure unobtainium.:D

The point was, it is cool to dress up the bullet, but don't get fooled into thinking you will be getting something you aren't.

Widget

[JBLnsince1959]

It is made of pure unobtainium.:D


Widget

yes, that's what we've all been wanting for so many years. :D , the perfect metal....

[Mr. Widget]

yes, that's what we've all been wanting for so many years. :D , the perfect metal....

It's not quite perfect. It is very toxic. Once you've heard drivers made of it you go completely mad.:(

Widget

[Mr. Widget]

Hey, sorry to derail your thread. I think the brass 075/2402s could be quite stunning looking.:thmbsup:

Widget

[MatthiasA]

Hey, sorry to derail your thread. I think the brass 075/2402s could be quite stunning looking.:thmbsup:

Widget


no problem!!! its ok! but.....

is the extreme difference from the first to the second plot due to another material ??????

:blink: :blink: :blink:

[JBLnsince1959]

It's not quite perfect. It is very toxic. Once you've heard drivers made of it you go completely mad.:(

Widget

that's OK, the first time I heard JBL's I went crazy :D , so going mad would not be to far away

[Mr. Widget]

no problem!!! its ok! but.....

is the extreme difference from the first to the second plot due to another material ??????

:blink: :blink: :blink:


...it was a joke... no tweeter is that good, but I wanted to point out that the 075/2402 is far from the ultimate in performance. No change or modification to it short of diaphragm replacement and horn contour will change that much.:(

Widget

[Marty]

The blue ring is the diaphragm's mounting frame. The actual diaphragm is the aluminum ring that is around the clear phase plug.

Widget

I don't know what to think of this tweeter. It's unique , no other company has
has gone down this road. The response looks quite rough.

JBL's commitment to quality in unquestioned, but they had some strange ideas in
the 1950s.

[Mr. Widget]

JBL's commitment to quality in unquestioned, but they had some strange ideas in the 1950s.
I think they had some fantastic ideas and ideals in the 1950s, but technology has allowed for many improvements since the 075 was introduced. The fact that it is still popular is a testament to it's quality. It is still a beautiful piece of sculpture, and it sounds OK under the right circumstances.

Widget

[Marty]

.. technology has allowed for many improvements since the 075 was introduced. .

Widget

Yeah, it's interesting, JBL has abandoned this strange technology - in fact their latest horn
supertweeter (for the K2) more closely resembles the 1930 Western Electric 596 !
-- it even has the same VC diameter (1") and nearly the same throat (.35") !

JBL is best when they are copying Western Electric: Example : JBL 375 is a copy of the W.E. 594.

[MatthiasA]

Hello Everyone!

Today i got one complete 2402H driver without a Diaphragma
and one Driver without the Bullet and the radial Horn

i see its very ....very difficult to copy the Bullet and the Radial Horn
but i will try it :-)

greetings Matthias

[Steve Schell]

Mattias, one freedom that you will have in making your own parts is changing their shape if you care to. I built some field coil ring radiator tweets a while back, and my brother drew up a tractrix flare for me in Autocad. Another possibility would be to go with a conical outer flare to help control the directivity... the possibilities are endless when you DIY.

Brass is much heavier than aluminum, so the resonant frequencies of the parts you make may be quite a bit lower than the stock parts. This may be better, worse, or unnoticeable, you won't know until you try. Sometimes these subtleties are heard, but not shown by conventional measurements.

If you have the skills and equipment to machine these parts, you may want to make a diaphragm forming tool and experiment with diaphragm shapes. The 075 diaphragm cross section is a shallow V; these surfaces function as both radiating area and suspension. Although the movements are admittedly tiny, I believe this is why the 075 and variants tend to measure and sound ragged. The only way the thing can move is by distorting its shape, creating all sorts of oilcan resonances. Emilar used an S shape for their ring radiator diaphragm cross section; these reportedly are much smoother. My ring radiators used an M, or double half roll shape for the diaphragm. These measured and sounded very smooth; the first breakup mode was up around 35kHz. Problem was, I couldn't get the mass low enough so the sensitivity was poor.

If you want to pursue this, I can send you some .002" duralumin and copper clad aluminum wire- just let me know.

[Marty]

My ring radiators used an M, or double half roll shape for the diaphragm. These measured and sounded very smooth; the first breakup mode was up around 35kHz. Problem was, I couldn't get the mass low enough so the sensitivity was poor.

.

Hey Steve

Check out these drivers. MCM offered them for a while. They have a strong magnet,
1.3" VC, and double half-roll suspension. I am making a custom horn and will
start a thread on final product soon.

[paragon]

Think, next week i will know how much is the cost for a horn and a phase plug in brass. I will give the original alu-parts to the man who may build this parts in brass on his machines. He is about 65 years old and has very old machines (40`s) and he may build parts within +- 0,002 mm .
His room isn`t cooled down wit an AC-control.
Isn`t it good enough ??
He`s grinding tolerances about +- 0,002 mm for our factory.
I think he may build this parts very well.
By the way, there is a difference to the old 075 and newer 2402 Horn and phase plug ??

Eckhard

[Alex Lancaster]

:) Paragon: .002 mm?, .00007874"?, 40´s machinery?, did He get it from the V2 program?; I´ve never seen such precision.

[paragon]

Yes Alex, he is grinding parts for our factory in range of +- o,oo2mm ! with his old machines !!
We have to grind some steps in this range (CD, DVD parts).
The 075 (2402) horn tolerances don`t need this.
I think horn contour and phase plug within +- 0,01mm ore more is enough good.

??, Eckhard

[paragon]

075 Brass parts are in work now.
We will see more next weekend.

Eckhard