TH loudspeakers were created to combine the precious musical message of the Thesis electronics and absolute fidelity with the ambition to be completely transparent, leaving room only to the emotion evoked by the music.
The search for the best acoustic result was based upon overcoming the intrinsic limits of traditional loudspeakers. Through a finite element simulation software (FEM) conceived by the Audison R&D team, a mathematical model was developed in order to create, with an intense prototyping activity, the ideal transducer. With the Thesis II speakers, the Audison R&D team has reached a significant revolution: producing a speaker system that can “drain every last drop” from the Thesis amplifiers.
Unique and groundbreaking: beyond the absolute.
The TH 1.5 II project can be defined with only one word: unique. The materials, tolerances and assembly process were designed from scratch, without any compromise, to overcome the absolute. Extensive research has been dedicated to the selection of proper fiber size, textile weaving and profile geometry of the natural silk dome to obtain an extremely linear phase and frequency response up to 26 kHz, an exceptional goal for a 29 mm dome.
The Top plate and T-Yoke are made of low-carbon content steel CNC machined from solid.
A magnet tailored to the Audison TH 1.5 II has also played a key role on its compactness allowing cables, in pure OFC 16 AWG section copper, to cross the whole magnetic/acoustic structure from the point of electrical contact with the coil terminals to the exit on the bottom case. In this way the cables are integrated without increasing the footprint.
Only a 34mm coil would allow the TH 1.5 II to express its best in the most complex musical passages thanks to the low dynamic compression. A single layer CCAW wire is wound on an aluminium former, a material selected for optimal damping. The choice of the single layer and a higher than average electrical resistance of the car audio tweeters (6.1 ohms) derives from the need to combine a low thermal resistance to a relatively low weight winding considering the size of the voice coil.
The magnetic circuit was sized with a flux saturation which can guarantee a low residual inductance at high frequencies, thus not requiring a magnetic short-circuit solution, such as copper rings, which reduces the flux into the magnetic gap.v
Even more than in a cone speaker, the tweeter membrane is directly responsible for its sonic characteristics. Therefore, even before designing and testing the profile, the designers have selected the suitable varieties of silk membrane cataloguing them by the weaving material, density and damping treatments to characterize them with the use of the Klippel Scanning Vibrometer.
Only after a thorough physical analysis of the various materials available and the creation of a refined model of vibro-acoustic simulation was it possible to offer a set of 11 different dome profiles. These profiles matrix-combined with the material variants in the finite elements simulation software, generated 33 different combinations for as many frequency and phase responses, of which only three have seen the light and have then been tested and subjected to extensive listening assessments, which have made the current structure used in the TH 1.5 II successful.
The solidity of TH 1.5 II is also well noticeable in its mechanical all-metal structure, for a considerable weight of 370 g. Each part was designed exclusively for the TH 1.5 II, screws included.
The faceplate, also made of die-cast aluminium, is a perfect example of harmony between elegance and technique.
The Audison logo, obtained from the solid, is finished with a CNC high precision machining, while the radial profile of the faceplate is engineered for minimum acoustic impact ensuring optimal frequency dispersion. Unparalleled low-frequency roll-off has been achieved by a sophisticated air-loading system. A high precision aluminium die-cast bottom case offers an electro-acoustic load to lower the system total compliance for a resonance frequency below 800Hz.
Twelve radial vents around the T-yoke center hole guarantee uniform pressure between the gap chamber and the bottom case.
A high density porous absorber under the dome combined with a disc of compressed felt minimizes the resonances caused by internal geometries for a smooth frequency response over the whole range.
All these measures result in an incredibly natural low-midrange reproduction and allow for crossover point with woofer starting as low as 1.5 kHz/ 12dB Oct.
All efforts in the design would have been vain if the industrialization of assembly processes had not been obsessive. The dome/coil combination encompasses the real “heart” of the TH 1.5 II, for this reason its assembly is totally independent from the rest of the production, in a high automation department, using a highdensity support reinforced with glass fibers.
Allowing a 34mm diameter coil to extend at high frequency up to 26 kHz would have been unthinkable unless supported by an exhausting phase of tuning of the dome/former junction coupling, both in terms of choice of glue and geometry. A special hitechnology glue is applied using 3D robotic systems to ensure high repeatability of glue quantity and perimeter of application.
The TH 1.5 II tweeter has been developed according to targets of highest performance as well as flexibility of in-car integration.This is why the R&D has offered two types of electro-acoustic load: bottom case or bottom disk.
By using the bottom case the low frequency response of the tweeter further extends so that the crossover point with the woofer can be lowered, for the benefit of the acoustic scene. When space is limited, the bottom case can be removed and space saved using the bottom disk, while still maintaining a high-performance level.
The human auditory system processes the range of medium frequencies with maximum sensitivity and selectivity because it makes the voice intelligible from the rest of the audio spectrum.
The R&D team started from this simple principle to design a speaker dedicated to this fundamental range of frequencies from scratch, with the simple as well as ambitious target of extreme linearity, in order not to add or hide anything of the signal reproduced, enhancing in this way every nuance.
overcoming all the limits dictated by compromise-oriented design choices.This philosophy allowed us to obtain extreme performance and a design projected into the future, faithful to the inspiring principle of maximum transparency of the musical message.
TH 3.0 II Voce and TH 6.5 II Sax both feature N38 and N48“H-grade” Neodymium magnets, releasing a very high quantity ofenergy and ultra stable in temperature, ensuring an unparalleleddynamic.
The geometry of the magnetic group has been optimized througha finite element simulation software to maximize efficiency byconcentrating the magnetic field in the gap.
A great deal of research has been carried out to reduce themodulation of the voice coil inductance by magnetically saturatingthe motor pole and using an aluminium short-circuit ring that alsoallows a greater extension towards the mid frequencies.
The development of the suspension system, a crucial element foreach transducer, required a long research work: the developmentteam created computational models to simulate every aspect ofthe multi-physical behavior of the loudspeaker.
The spiders were designed thanks to a long series of mechanical simulations performed to define its structure: a large elastic surface with 5 waves, ensuring an improved distribution of the elastic force; waves profile and gluing optimized to obtain the best symmetry in the voice coil and basket connection areas; spider composition made of a mix of two fibers to achieve the best elastic linearity, without mechanical compression effects even at high excursion levels.
Like the spider, the surround was also designed using mechanical simulations. The result is guaranteed by: use of natural rubber IIR; profile optimized to ensure wide excursion; maximization of linear elastic behavior without mechanical compression effects.
TH 3.0 II Voce and TH 6.6 II Sax feature respectively a 30,5 and
a 50 mm mobile coil in CCAR (Copper Clad Aluminum Ribbon),
wound with flat wire to obtain a very compact winding, maximizes
the force factor and at the same time allows for optimal heat
The mechanical structure of the TH 6.5 II is a perfect combination of design and performance. The aluminium alloy basket incorporates all the components ensuring high precision in the various couplings.
The structure featuring four pairs of spokes allows for solidity and damping of the vibrations offering very low resistance to the cone air flow. The wide spider distributes the elastic load optimally. A generously sized hole, protected by a filter cloth, prevents air compression phenomena under the spider, eliminating deleterious resonance at medium frequencies. The central opening in the bottom-plate ensures optimal ecompression of the air column inside the voice coil and the output expanded material diffuses the turbulences and protects it from ingoing foreign bodies.
The R&D team selected TPX® thermoplastic polymer, with excellent acoustic and mechanical features. More specifically, its low density and its high mechanical damping contribute to produce an exceptionally smooth frequency response in all possible listening positions. Being transparent, it leaves the precious Thesis diamond logo built from a solid block of aluminium in full view.
TPX® is injection molded, a technique that has made it possible to create a variable thickness profile, which gives the structure even more rigidity.
Taking advantage of innovative finite element calculation methods that allow the simulation of the speaker overall vibro-acoustic performance, the R&D team designed a monolithic cone (one block including diaphragm and dustcap), obtaining an extremely rigid structure with a single gluing point with the voice coil (unlike the two traditional cone-coil, dustcap-cone). This particular structure allows the cone vibration modes to be “moved” (i.e. the frequencies in which the cone is deformed introducing irregularities in the frequency response) as much as possible towards the high frequency range, leaving the entire mid-frequency band free from irregularities: this provides the speaker with an extremely transparent and detailed “voice” in the mid-range.
TH 3.0 II Voce is a pure mid-range specialized in the reproduction of the 250 / 3.5k Hz range. It integrates perfectly with tweeters and woofers in a 3-way system elevating the emission point in order to create an astonishing sound stage.
The optimized force factor (BL) together with an FS lowered at 100 Hz allowed to obtain a QTS value of 0.48, ideal for a perfectly damped behavior in the 400-800 Hz frequency range. All electroacoustic parameters have been optimized to maximize performance in small volumes, such as in A pillar and PODs installation.
The TH 3.0 II Voce directivity map is refined both on-axis and off-axis as can be seen from the response curves, a fundamental characteristic to obtain a correct and realistic reconstruction of the sound stage in the car cabin.
Producing the frequency response as smooth as possible in all listening positions (in axis, off-axis, any direction), this is the ambitious goal of our designers, pursued by optimizing the map of the woofer directivity, to obtain an acoustic energy distribution without distortion in the frequency response both in axis and off-axis.
This allows the TH 6.5 II to play optimally when in-door mounted,a condition in which the listener is not aligned with the speaker.