Diamond Tweeters - What and Why


What are Diamond Tweeters and why do some manufacturers use them?

Thiel & Partner aka Accuton was inspired to develop a pure diamond tweeter in 1999 having read an article on the production of artificial CVD (chemical vapour deposition) diamonds. The attraction was the stiffness to weight ratio of diamond which is second to none. Ceramic and Beryllium come close to the properties of pure diamond, but the internal damping of Beryllium is inferior and it’s also a toxic material that needs special care during manufacture and disposal.

Stiffness, hardness and mass are essential aspects of tweeter design where greater stiffness or hardness and lower mass are the goals. Youngs Modulus which measures the tensile or compressive stiffness of a material says that mass varies with materials and gives Aluminium at 1.86, Titanium at 1.13, Diamond at 4.92 and Beryllium at 6.97 gigapascals (GPa) (higher is better) but the hardness to weight ratio is also a major contributing factor for good tweeter performance and this gives a different picture where Aluminium comes in at 2,700 Kgm, Titanium at 4,500, Beryllium at 1,850 and Diamond at 3,500. Combining these two factors gives pure diamond the best compromise between stiffness and weight making them the preferred choice for the discerning speaker manufacturer wanting the very best tweeters,

Diamond tweeters have less distortion than other materials, are stronger, lighter and stiffer all of which are essential in a good tweeter. However, this often leads people to wrongly assume that all these positive qualities result in an overly bright and brittle sounding tweeter whereas the reverse is in fact the case. Diamond tweeters have a first breakup mode around or in excess of 75kHz whereas other common materials tend to break up around 25kHz. Because the breakup mode is so far outside the normal hearing range it has little or no effect on those more audible frequencies below 20kHz and as a result they sound smoother and warmer than any other tweeter materials in use today. Pure diamond tweeters actually seem to disappear from the replay chain leaving you listening to the music rather than the drivers.

Accuton use an inverted dome (convex) technology to form their pure diamond tweeters which are now used in some of the most sought-after speakers around including the upper echelons of the Marten speaker range.

The difference between a diamond and a pure diamond tweeter is all to do with how they are manufactured. Standard diamond tweeters are made by depositing artificial diamond dust onto a former or substrate and it’s this coated substrate that becomes the finished tweeter with the diamond used just as a coating to add stiffness. Pure diamond tweeters also initially use a substrate to start the application process of the artificial diamond using the CVD but after many coats are applied the backing substrate is dissolved away leaving just a dome consisting of nothing but pure diamond.

Diamond tweeters let you hear much more information but not with added or long-term fatigue setting in, if anything listening to diamond tweeters is more relaxing than with other materials and once heard there is no going back.

Diamonds are costly and artificial diamonds are no less costly because of the heat and pressures needed to simulate the process that take place inside the earth over millennia. Artificial diamonds first need to be grown which takes several weeks for very small batches and then they must be ground to form a diamond dust that can be used in the CVD process. This means that drivers using this technology are usually in the range of 20mm to 50mm in diameter although Accuton have made them as large as 90mm for midrange units.

The new Parker range of speakers by Marten of Sweden give customers a choice of specifying speakers with standard ceramic tweeters or with pure diamond ones instead. Hover the cost difference is in the order of £8,000 to £10,000 a pair over the ceramic ones.

Reference Audio stock and have on demo a wide range of Marten speakers including those with pure Diamond Tweeters so book an audition today to hear for yourself just what all the fuss is about. We do of course also stock other brands using Diamond Tweeters.

Bob at Reference Audio