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-   -   The ubiquitous 1/2"...um....3/4"...er 1" ?? polycarbonate "dome" tweeter (http://www.diyaudio.com/forums/multi-way/195844-ubiquitous-1-2-um-3-4-er-1-polycarbonate-dome-tweeter.html)

River757 3rd September 2011 12:18 AM

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

planet10 3rd September 2011 03:36 AM

The 1st ones i saw were Audax, and they made some of the best. There are a zillion knock-offs. The gold dome Audax were considered best of the lot.

Quote:

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

dave

River757 3rd September 2011 10:09 PM

Quote:

Originally Posted by planet10 (Post 2696021)
The gold dome Audax were considered best of the lot.

Were these literally gold (gold plated I mean) or just gold colored?


Quote:

either

dave
They vaguely remind me of the "donut" tweeter Advent used, along with the similarly shaped 5" midrange driver used in their 6003/Maestro model til the mid 90s.

planet10 3rd September 2011 10:17 PM

I'm not sure on the 1st -- i do have a pair here somewhere.

Yes, similar to the Advent , the purple Wharfdale tweeters, and the CTS, but much smaller

dave

sreten 3rd September 2011 10:44 PM

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.

Mr. dB 4th September 2011 02:21 AM

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.

http://www.madisoundspeakerstore.com...ew/tw010f1.jpg

Charles Darwin 4th September 2011 08:30 AM

Looks remarkably like the tweeter in the Rogers DB101:
Bafles Rogers Db 101 Origen Uk - Liniers - Electrónica - bafles an

Originally they cost £400 the pair but then Rogers reduced the price to just over half and promised refunds to those who paid full price.
Next thing you know Rogers is bankrupt and Richer Sounds sold them for £99.

enigmaticEntity. 4th September 2011 10:16 AM

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... ;)

sreten 4th September 2011 03:15 PM

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.

http://www.apexjr.com/images/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 :

http://media04-ak.vivastreet.com/cla...529446aecc3c87

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.

planet10 4th September 2011 07:52 PM

Quote:

Originally Posted by sreten (Post 2697424)
http://www.apexjr.com/images/ApexTweeter1.jpg

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

Steve says he is running low on those. I may have some sacrificial ones, so i may be able to "autopsy" one.

dave


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