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
