Coax Know-How

Coax point source - correct timing at any listening position

A loudspeaker plays time-correct when all frequencies of a given signal arrive simultaneously at the listener´s. The criterion of timecorrectness is essential for the ideal loudspeaker, because our auditory sense reacts very sensitively to the time response (phase) of sound signals. For our survival it has always been extremely important to hear: what comes when from where. In this case our auditory sense identifies the direction of a sound with the help of the delay difference between the left and right ears.

A time-correct listening experience at any listening position is guaranteed by ASCENDO´s Coax point source. Treble drivers react considerably faster to an impulse than heavier midrange and bass drivers. This differing reaction speed is compensated in the ASCENDO D-series by meticulously specified filter and chassis geometries. The tweeter is on an axis with a defined offset behind the midrange driver (CoAxial). This spatial offset, together with the precisely matched filter module, results in the perfectly homogeneous time response of the D-series loudspeakers.

In his article “Das Wunder des Hörens (The Miracle of Listening)“, Andreas Günther describes the importance of the criterion of correct timing even for relaxed listening:

Listening becomes work. What was vital for cave-dwellers is equally decisive in the Highend-Process: if we cannot locate correctly the direction of a sound signal, if the sound engineers have perhaps even toyed with the phase, our brain starts struggling. Listening becomes hard work, causes stress.“

SASB MKII - dynamic current-damped external driver and semi-symmetrical bandpass

SASB is ASCENDO´s bass / midrange-technology, which has found its way from fundamental research into the world of audio.

The development of this advanced technology was financially supported by the Federal Ministry of Research and Technology. It contributes decisively to the perfect timing and great signal integrity of the System Series loudspeakers, because SASB combines fast transient response and decay, perfect group decay (timing), with a punchy bass that is both dynamic and reaching far down. This combination of performance and perfect timing is impossible to achieve with classic speaker construction principles, such as bass-reflex loading. Thus SASB is one of the key-technologies of the ideal loudspeaker.

How Does SASB MKII Work?
Several drivers are in charge of the bass / midrange section: a forward-firing midrange driver, mounted in the baffle, and two invisible high-performance 18 cm woofers that operate inside the cabinet.

The external driver has its own, hermetically sealed volume chamber. The internal drivers operate both into a ventilated volume, the reflex chamber, and within a closed volume, the compression chamber. This chamber provides the constant inner damping. In this way the interior drivers constitute a bandpass characteristic with different slew rates in both directions (“semi-symmetrical“). In a second step the two resonance frequencies and the impedance minima of both chassis are synchronized, so that they complement each other perfectly, and simultaneously dampen critical resonances of the external driver.

Double-TOS (D9)

The D9 incorporates 2 operating modes
TOS out: hemispherical radiation effect of a very good studio monitor
TOS on: radiation effect of a dipole speaker.

The switchable rear TOS units produce a wonderfully airy and spatial sound, even with the loudspeaker positioned close to a wall. Sounds decay perceptibly longer, and the spatial impression becomes even more authentic.

In addition to that TOS makes spatial listening possible even when not sitting in the sweet spot. Switching on the second TOS driver even increases these positive effects. Furthermore the double-TOS unit of the D9 allows for an even better adjustment of the sound image to the particular room acoustics, the recording quality or the or individual listening preferences.

TOS (D7)

The D7 incorporates 2 operating modes
TOS out: hemispherical radiation effect of a very good studio monitor
TOS on: radiation effect of a dipole speaker

The switchable rear TOS unit produces a wonderfully airy and spatial sound, even with the loudspeaker positioned close to a wall. Sounds decay perceptibly longer, and the spatial impression becomes even more authentic. In addition to that TOS makes spatial listening possible even when not sitting in
the sweet spot.

C-Floor Decoupling

Only very few listening rooms have solid, vibration-free floors. As a result loudspeakers can generate structure-borne sound at the floor surface. The floor turns into a secondary acoustic source. This common effect can result in a lack of transparency and resolution, or even a muffled, diffuse sound image.

ASCENDO D7/D9 speakers are decoupled from the floor by a combination of plastic absorbers, massive steel feet and further plastic absorbers. These components have differing excitation frequencies. In this way structure-borne sound transmission onto the floor is avoided.

The optional C-decoupling is a combination of a double-layered steel foot - with optimized damping characteristics - with 3 highly effective stainless steel / ceramic decouplers each. The double-layered steel foot, on the one hand, provides broadband interruption of structure-borne sound transmission, while the stainless steel / ceramic decouplers transfer stored energy of the transducer into the steel base with its optimized damping characteristics.

The C-decoupling of the ASCENDO D7/D9 quickens the response behaviour of the speaker and effects a more open and more differentiated sound image.

RMR ( reduction of electronic modulation effects ) Internal Wiring / Furutech Rhodium Terminal

Our RMR internal wiring, developed together with High End Masterclass, reduces electronic modulation from the speaker back to the amplifier. Several differing cable bundles consisting of single, top quality silver and copper cables are manufactured for each driver. The cable bundles are optimized for the specific properties of the treble, midrange and bass drivers, and have a large diameter each. The manufacturing effort for such a cable harness is enormous. So more than 90 meters of single cables are needed for a set of cables for a pair of D9 speakers.

The connection terminal is fitted with Furutech Rhodium binding posts. These plugs are definitely the best binding posts worldwide. For the connection of the Furutech plugs with the RMR cable harness a soldering process is used that has been developed in cooperation with the cable specialists of High End Masterclass.

Though time-consuming this procedure guarantees perfect solder joints, without damaging the heat-sensitive Rhodium of the Furutech binding posts. RMR interior wiring and Furutech Rhodium binding posts reduce the stored energy in the loudspeaker and the electronic modulation feedback with the amplifier. The sound image becomes more open and more differentiated.

In addition the terminals of the D9/D9-C and D7-C with their connecting cables to the crossover are very briefly exposed to extreme heat. This elaborate procedure gives the terminals with their soldered on cables their defined directionality from the terminal to the crossover.

Special ASCENDO Filter Design / Great Separation Efficiency and Simultaneous Phase Neutrality

The functional-selective design of the crossovers is based on first-degree frame filters with a constant voltage core. This integrated complex filter design makes for the separation efficiency of high order filters, and simultaneously for the homogeneous group delay of first-degree filters. These components, together with SASB, are the key factor of the very good group delay and the considerable dynamic reserves of the system.

It goes without saying that only selected high-performance components are employed. This highly complex, interconnected and interdependent circuitry is one of the key factors why ASCENDO loudspeakers come so close to the ideal transducer.

Steep higher order filters are a necessity for broadband, dynamic, high-resolution speakers with a great power handling. These filters make sure that the drivers employed run within their ideal frequency range. Steep filters, however, invert the phase, which is counterproductive to the ideal of the time coherent loudspeaker. Low order filters (6dB / octave) may be time correct, but are deficient in separation efficiency. The employed drivers do not run within their ideal frequency range over long stretches.

The special ASCENDO filter design makes possible a very great filter efficiency without inverting the phase (time correct). This is absolutely unique.

Listening at low volume levels

The synergy between the SASB and the special filter design allows for the lossless transmission of very low-level sounds. Even at low listening levels low and fundamental tones can be heard, and all signals are transmitted dynamically and with great resolution. The sonic characteristics of the D9/D7 speakers do not change with decreasing volume levels.

As a result a concert grand piano is not reduced to a piano or a Pavarotti to a performing lightweight. The ASCENDO Coax-Series is hence predestined to enjoying music at low, but lossless, volume levels.


D9/D7 loudspeakers are versatile in their adaptability to different kinds of room acoustics. The inner woofers operate within a closed volume. Thus their mechanical damping is constant. This is due to a variation of the length of the reflex tube. The shorter the reflex tube the more pressure the D9/D7 speakers generate, and vice versa. So the bass pressure level can be perfectly adapted to the particular listening environment or to individual preference.

If one loudspeaker is positioned in a room corner, and the other in an open space their room response differs considerably in the bass and fundamental range. This results in unstable stereo imaging. Reflex tubes of differing length make it possible to create a uniform pressure level of both loudspeakers. Three-dimensionality is considerably more stable.

Starting from “linear“ the treble range of the ASCENDO D9 can be raised by 5 dB. A lack of transparency and treble presence is a typical effect of highly damped rooms. The system sounds lifeless. This unwanted effect is compensated by the D9 treble adjustment.

The TOS drivers can be activated separately while listening. This allows for an excellent adjustment to different room-specific acoustics and listening preferences.

Selection (D7 and D9)
ASCENDO´s high standard of quality prohibits the use of delivered Coax chassis without testing them. All Coax point source drivers are installed in a testing cabinet and then extensively measured. Based on the measurement data this exceptional chassis is then strictly selected and matched in pairs.

Bauhaus Design (D7 and D9)
Founded in Weimar in 1919 the “Bauhaus“ has been for 90 years one of the most important and best-known design schools of the world.
A radically simplified and functional form (Die neue Sachlichkeit, “The New Objectivity“), as well as the combination of black materials and metal, are characteristics of Bauhaus design.

Placement (D7 and D9)
In most listening environments the loudspeakers are placed very close to a wall. This typical practice was taken into account with the design concept of the Coax series. Even when placed extremely close to a wall it performs in a three-dimensional way, without giving undue emphasis to low and fundamental tones. The rear TOS unit in particular allows for an airy and three-dimensional sound image.

Of course the Coax series also sounds excellent in free field placement.

The uniquely coherent wave front of the ASCENDO Coax series loudspeakers is the result of a combination of SASB, Coax point source and innovative crossover design. This is not possible with conventional concepts.

The result: a fascinatingly authentic sound image with realistic three-dimensionality.