The ubiquitous 1/2"...um....3/4"...er 1" ?? polycarbonate "dome" tweeter

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The ubiquitous 1/2"...um....3/4"...er 1" ?? polycarbonate "dome" tweeter

Here's pretty much the version that has been around for decades i.e. small magnet + cone/dome design + glossy black surface + acoustic lens with pinhole in it:

Nuance TW5-2LR 1/2" Mylar Tweeter

This tweeter, in varied versions, has been around since the early 80s and seems to have been used by just about every low-end to mid-fi manufacturer since then, and not always constructed of polycabonate. I've seen it with a titanium surface layer, a clear blue cone/dome, and various other combinations.

So:

* is it a dome tweeter with a large surround? Or a very small cone tweeter with an acoustic lens? :scratch1:

* who originally manufactured it? And all the various versions over the years - were they designed by the same company or did the original company license the design?

A couple months ago I bought a pair of Philips SPA7210 PC speakers that are equipped with these tweeters (they are a light bronze color but no lens structure), so now I get to look at them a lot nowadays, which is partly why I finally posed this question! :D
 
Hi,

The driver was developed by Audax. The dome profile allowed a formerless
ribbon wound voicecoil to be immersed in the ferrofluided magnetic gap.

Countless cheap look a likes exist, especially in car audio, and they are
very poor compared to the Audax types. Copper coils on standard paper
formers compared to edge wound formerless aluminium for example.

Be careful out there, they are not all the same, some utter garbage,
and conversely some way far better than others if they are built well.

rgds, sreten.
 
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One way to tell the real Audax ones is that they have a square plastic cover over the magnet, and the whole motor assembly can be removed from the faceplate with a simple twist-lock.

tw010f1.jpg
 
My pair of "Hi-Fi" speakers have this design, they use a very fine aluminium former with copper coils immersed in FF, and a 4-5cm ferrite motor. Compared to the cheap "button" neo magnet found in the "co-axial" speakers I bought (for the woofers, lol), they are quite ok for the sound of the speaker.

There is something nice about the sound of the "balanced dome" tweeters, but they all seem to have some HF peak, i.e. cymbals are more "hiss" than cymbal... ;)
 
Hi,

The later neo versions do only need a button magnet, not necessarily
cheaper or any worse. AFAICT diagphragm material is more about
offering options than any real performance benefits.

ApexTweeter1.jpg


Thse Apex jr $1 specials are allegedly made by Audax and allegedly good.

Only way to be sure is buy 3 and strip one to check for the formerless
aluminium axially wound ribbon voice coil. (i.e. the coil has no layers,
its as thick as the ribbon is wide, quite difficult to make I assume.)

Some have experimented with opening up the pinhole, for tuning.

Typically filtered with just a capacitor, this combines with the ~
3kHz Fs to give an ~ 3 KHz 3rd order acoustic roll-off as in these :

An externally hosted image should be here but it was not working when we last tested it.


Used them as nearfield desk moniotors in a small studio.

As shown above this is the rectangular option of the faceplate
the actual driver could lock into, instead of the above circular.

rgds, sreten.

It is the tweeter in the DB101, that based on the HiFi News
small kit speaker that used the Audax with a Rogers unit.
Both drivers in the DB101 are Audax made.
 
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Can that pinhole make a significant difference as far as sound quality?
Because the other domes I have seen with lenses (phase plugs?) that
include a hole, that hole is much larger than this tweeter's pinhole.

Hi,

One would assume the pinhole makes next to no difference, its styling.

I remember a UK kit speaker that claimed the provided tweeters had
an optimised modified opened up central hole, easy to say, but no
real hard evidence I recall that this was the case. Your right IMO
to have an effect the hole must be a lot larger. There again there
are fine tweeters with no central hole at all, so what gives ?

I don't know, here only measurements tell the truth.

rgds, sreten.
 
How about a Foster 9324 tweeter? It looks to be a polycarbonate, it has a lens/ waveguide with three plastic arms holding a small cylinder above a black diaphragm.

In terms of what kind of dispersion it has, is all of the diaphragm that is visible the moving surface? I'm seeking a tweeter that would start beaming at about 10 kHz, and am wondering if the Foster would fit the bill.

Regards,
Pete
 
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