We have put together some answers to the most frequently asked questions.
If your question is not answered below, please feel free to contact us.
Are ceramic domes very fragile?
Correctly built into a speaker unit, they are not. With a clean, appropriate music signal, you definitely cannot destroy them. Even more, they will last longer than any other driver unit because the membrane material will not weaken in time. Treated carefully, even your grandchildren will still love them. Despite the fact that our ceramic membranes are very thin, (50 microns the tweeters and 100 or 150 microns the midrange- and bass-units) they do not break under normal listening conditions.
Ceramic and diamond cones are however brittle and therefore sensitive to severe overload conditions (i.e. excursion of more than double the rated Xmax - see driver specs). Both are also sensitive to touching by fingers or hard items - comparable to an eggshell. Actually, after we had equipped our drivers with a strong metal protection grid, claims of broken domes dropped to almost zero.
Are you really the only one to manufacture ceramic drivers?
Yes, we are the one and only company to produce real ceramic cones of tweeters as well as bass drivers. We have seen other companies claiming to have ceramic membrane drivers but this is bogus material and not pure corundum. These membranes usually have an undefined white coating on an aluminum cone and do not carry the physical properties of our ceramic units. The features and benefits of a real corundum membrane cannot be accomplished by these "so called" ceramic units.
Do you have any relation with the US-based THIEL company?
No, not at all. The inventor of the ceramic membranes is called Bernhard Thiel. This name "Thiel" is quite common in Germany and we have a simple equity of names here with the late american born Jim Thiel. To avoid any mix-up of company names, we have used and registered the brand name accuton® for our loudspeaker drivers long ago. These are all manufactured in the same factory in Bexbach, Germany. For more information, please refer to our company history. The accuton® company is called "Thiel & Partner GmbH" for legal reasons applicable in Germany by the founding time 1994.
What is the difference between your drivers and common tweeters?
Cheap tweeters use the same material (cloth, silk, aluminum, titanium or whatever) for both, the surround and membrane, which is easy and inexpensive to manufacture. It is not the best solution however, since membrane (stiff) and surround (flexible) serve completely different functions in a driver. On top of that, at higher frequencies, parts of the membrane will decouple from sound radiation. This gives higher on-axis sound pressure but unwanted phase shift and worse energy distribution.
Our accuton® ceramic membranes work - unlike others - like an ideal piston over the entire recommended frequency band. This is due to the fact that we use an extremely hard membrane material that doesn’t bend and a soft fabric surround which yields an undisturbed and phase-stable piston-like motion. The concave shape of our ceramic dome gives a better distribution pattern than ordinary tweeters have and much lower distortion. It has in essence the design of a minute bass driver. Needless to say that all components that we use are of the best quality material we can get. The frontplate - for example - is made of heavy, acoustically inert zinc or milled aluminum instead of plastic. We are using up to five times more parts than in conventional tweeters and it takes - in average - more than one hour of assembly time to make an accuton® unit.
What is the purpose of those black cutouts?
All hard membranes tend to have break-up modes at higher frequencies. The "ears" are a very efficient method to acoustically cancel membrane resonances and to cancel these unwanted peaks. Yet they are very difficult and costly to manufacture. The small "ears" of the tweeters are assembled under large binoculars to ensure the correct position. However, the cutouts also weaken the membrane and cause partial movement of the membrane around the cutouts, which serves as acoustic cancellation of the dome resonance on axis. For the CELL series, we re-engineered the membrane / voice coil / surround assembly, so that the dome resonance is shifted to much higher frequencies. As side effect, the dome resonance has much less tolerances in series production.