Any word on when beryllium tweeters and midranges will be available for DIY?

[tswinter]

Tang Band now has the 25-1743S 1" Beryllium Dome Tweeter.

[mowry]

The Tang Band TW 25-1743S is not Beryllium at all. It's a beryllium copper alloy that is typically 1.8 to 2.0 % beryllium by weight! Here's a message that I sent to Tang Band and their reply.

Dear sirs/madams:

Kindly be advised that the Tang Band TW 25-1743S (http://www.tb-speaker.com/detail/1230_04/25-1743s.htm), which you advertise and represent as a Beryllium Tweeter is not Beryllium. Your claims are false and deceptive. The dome material is actually a common material used in everything from electronic toys to termination in several electronic system products. The material is actually Beryllium Copper, also known as BeCu; CDA 172, CB101, ISO CuBe2, CEN CW101C, A4/2, beryllium bronze and/or Alloy 25. The material is typically only 1.80 to 2.00 % beryllium by weight. To call this material Beryllium is like calling Beer Whiskey but frankly it's statically much worse.

There are really three pieces of evidence.

1. The price is too low for a Beryllium diaphragm.

2. The color of the dome is just not the color of Beryllium. Beryllium is steel gray.

3. The only manufacturer of Acoustic Grade Beryllium Foil (98% or better) on the planet xrayed two samples. This is what they said. "We have performed x-ray fluorescence analysis of the Tang Band "beryllium"tweeter diaphragm. Our analysis indicates that the diaphragm is primarily copper. The technique we used for the analysis is not designed to precisely quantify the composition of the sample, but I am confident that the copper content in the Tang Band tweeter diaphragm is greater than 90%.Therefore, Tang Band may be using Be-Cu for their diaphragms, but I am certain they do not use beryllium as claimed. Please let me know if you would like additional information concerning our analysis of the Tang Band"beryllium" tweeter diaphragm.

The material properties of the BeCu and Be are vastly different.

1. Material Properties summary for Be:
Density 1844 kg/m^3
Young's modulus: 300 x 10^9 Pa
Poisson's ratio: 0.1
Speed of sound: 12800 m/s
http://www.matweb.com/search/DataSh...658d4a4f&ckck=1

2. Material property summary for BeCu

Density: 8250 kg/m^3
Young's modulus: 125 x 10^9 Pa
Poisson's ratio: 0.3
Speed of sound: 3900 m/s
http://www.matweb.com/search/DataSh...a06b668c&ckck=1

The TW 25-1743S seems like a nice product; however, it is being represented as a "Beryllium Tweeter". Please change your description on your websites and in your advertising documentation to "Beryllium Copper Tweeter" at your earliest convenience.

Yours,

Steve Mowry

http://www.s-m-audio.com/steve_mowry.html

Hello Steve,

Thanks for your comments on the Beryllium, we will correct the name to be "Beryllium Alloy". Our engineering team had ever done the experiment for different Beryllium materials from different vender and source for the dome tweeter and did lots of measurements and listening. The performance, THD, sounding and even the production control, the current one we use fit the best. Therefore, we prefer to use this Beryllium Copper to be the dome for tweeter. Anyway, thanks for your comments.

Sincerely,
Diana Huang
TB Speaker
ISO 9001-2000 certified
E-mail :info@tb-speaker.com
Web : www.tb-speaker.com
Tel : 886-2-26570282

[Shonver]

>The TW 25-1743S seems like a nice product;

Steve

Thanks for that info.

1. How does BeCu compare with aluminium/magnesium & titanium alloys and other materials typically used for tweeter domes?

2. How good do you rate this TB tweeter? Does the specific material give it any particular performance advantages?

Regards
Shaun

[mowry]

The only reason I can see to use a material like CuBe2 is the Be. CuBe2 is closer to lead in properties than Al, Ti or Mg. CuBe2 is a poor choice for tweeter domes. Get the silk cloth version, TW 25-1742S. Everything else is the same.

[Shonver]

Steve

Thanks for the prompt reply. I discovered a wealth of information on your web site. Thanks for sharing your knowledge so freely. I will most likely send you an enquiry soon.

Regards
Shaun

[mowry]

There are other considerations. For example common 304 Stainless Steel has superior mechanical properties to CuBe2.

Density:
CuBe2 8250 kg/m^3 304 SS 8000 kg/m^3

Modulus:
CuBe2 125 x 10^9 Pa 200 x 10^9 Pa

Poisson's ratio:
CuBe2 0.30 304 SS 0.29

Speed of Sound:
CuBe2 4000 m/s 304 SS 5000 m/s

The reasons for not using 304 SS for a transducer diaphragm are obvious. So why use CuBe2? Could it be fundamentally related to intent to deceive?

There are other companies that are even more flagrant in their quests, SONIC (http://www.yingpo.com/english/index.htm) for example. Their Beryllium is 88.47% Titanium and 0.6075% Beryllium (http://www.badongo.com/file/12388488), yet they represent their domes and cones as "Beryllium". They even give them a coat of paint to match the color of Acoustic Grade Be, 98% or better (http://www.electrofusionproducts.com/web/bpdweb.nsf/AllDocsByID/A056E254C789C3DA88256E160024517E/$File/China_Be_Domes_Report.pdf). Here's a picture of Fake Be on the left, the cone and Real Be on the right, the dome, http://www.badongo.com/pic/4833197. The cone has a density of ~3750 kg/m^3. Titanium has a density of ~4000 kg/m^3.

Are companies using SONIC's domes and cones and representing and advertising them as "Beryllium"? Oh yes some that are considered "High-End" and my investigations are ongoing.

You can help. I have been able to locate only one source of Beryllium foil and/or formed beryllium domes. Beware, I cannot identify any source for cones except TAD (Pioneer) but they are used in the TAD Reference Series only. Can anyone identify any supplier(s) of beryllium foil? Can anyone identify any other companies that misrepresent their speakers as "Beryllium Tweeters et al."?

Kind regards,

Steve

http://www.s-m-audio.com/steve_mowry.html

[marvinzzmartian]

The best tweeter/mid I have ever heard in my life is the ESS Heil AMT (Air Motion Transformer). If you can find a pair of these BUY THEM.