8351 Stereo-Paar

Minimum Diffraction Coaxial (MDC™) Driver Technology reproduces outstanding sound image.

Typical coaxial designs suffer from a somewhat ragged frequency response due to diffraction problems inherent in their unrefined design. However, crossover issues due to the non-coincident location of sources are solved with a coaxial configuration, so a coaxial solution without diffraction problems is the ideal. Genelec’s Minimum Diffraction Coaxial (MDC™) Driver Technology provides all the benefits of coaxial design while overcoming the typical shortages – solving the diffraction problem.

The first step is to minimise the cone displacement, in other words to limit the low frequency bandwidth of the driver. Next, is to avoid all sources of diffractions. The main structure of the MDC design consists of an integrated MF diaphragm-suspension tweeter construction. The visible part of the coaxial driver is formed by the curved flexible skin with the dome tweeter assembly in its centre. The inner section joins the cone to the tweeter without any acoustical discontinuity, and the outer one does the same between the cone and the driver chassis.

As there are no acoustically observable discontinuities between the tweeter and the cone, just a smooth surface, there is no diffraction either. The cone profile is very carefully optimised to form an integrated directivity control waveguide for the tweeter radiation. The driver outer edge is terminated to a normal Genelec DCW in order to control the dispersion of midrange radiation as well. The response is very smooth both on and off-axis and free from any anomalies – and directivity is well controlled.

This breakthrough in coaxial design provides improved imaging and overall sound quality on and off-axis, extremely smooth frequency response leading to outstanding clarity and definition of the inner details of the music.

The main novelties of Genelec combined DCW™ and MDC™ designs:

• Diffraction-free joint between tweeter and midrange diaphragm.
• Diffraction-free joint between midrange diaphragm and DCW™ waveguide.
• A proprietary midrange diaphragm technology – laminate structure combining a rigid cone and elastic, lossy materials including the suspension itself.
• A midrange diaphragm-suspension pair which cancels all possible non-linearity.

Advantages:

• Smoother frequency response.
• Ensures the drivers couple coherently over their full operating bandwidth.
• Significantly improves the directivity control in the critical frequency range.
• Provides balanced suspension dynamics to minimise acoustic distortion.
• Optimises the use of the front baffle area while maintaining the 8000 Series appearance and benefits.

Acoustically Concealed Woofers (ACW™) for controlled directivity down to low frequencies.

The 8351 Acoustically Coaxial Three-way system features our novel Acoustically Concealed Woofer (ACW™) technology. The Acoustically Concealed Woofers radiate through slots located on both ends of the enclosure.

The 8351 features two woofers and the positions of the two woofers have been chosen to extend the coaxial acoustical radiation concept towards low frequencies. In terms of low frequency directivity, when two woofers are used, separated by a distance, the system of two woofers behaves acoustically like one giant woofer spanning the distance between the two woofers. Also, such a dual woofer design extends the control of the directivity to low frequencies along the largest front baffle dimension.

The ACW technology makes the woofer openings and the woofer drivers acoustically invisible to the acoustical radiation from the minimum diffraction coaxial (MDC™) driver responsible for the midrange and tweeter frequencies. The radiation openings are optimized for size and curvature to minimize any acoustic diffractions.

The ACW solution also allows us to use the whole front baffle surface of the 8351 as one giant Directivity Control Waveguide (DCW™) that is part and built into a Minimum Diffraction Enclosure (MDE™).

The 8351 ACW arrangement creates a monitor that has a physically compact size yet behaves like a much larger system in terms of low frequency directivity.

Such controlled low frequency directivity translates to improved quality of monitoring and smaller low frequencies interaction between the monitor and the room.

Active crossover operating at low signal levels.

Audio electronic crossovers allow the audio signal to be split into separate frequency bands that are separately routed to individual power amplifiers, which are then connected to specific transducers optimised for a particular frequency band.

Active crossovers come in both digital and analogue varieties. Genelec digital active crossovers include additional signal processing, such as driver protection, delay, and equalisation.

Genelec analogue active crossover filters contain electronic components that are operated at low signal levels suitable for power amplifier inputs. This is in contrast to passive crossovers that operate at the high signal levels of the power amplifier's outputs, having to handle high currents and, in some cases, high voltages.

In a typical two-way system the active crossover needs two power amplifiers — one for the woofer and one for the tweeter.

The active crossover design offers multiple benefits:

• The frequency response becomes independent of any dynamic changes in the driver's electrical characteristics or the drive level.
• There is increased flexibility and precision for adjusting and fine-tuning each output frequency response for the specific drivers used.
• Each driver has its own signal processing and power amplifier. This isolates each driver from the drive signals handled by the other drivers, reducing inter-modulation distortion and overdriving problems.
• The ability to compensate for sensitivity variations between drivers.
• The possibility to compensate for frequency and phase response anomalies associated with a driver’s characteristics within the intended pass-band.
• The flat frequency response of a high-quality active loudspeaker is a result of the combined effect of the crossover filter response, power amplifier responses and driver responses in a loudspeaker enclosure.

Using the active approach enables frequency response adjustments and optimisation of the full loudspeaker system, placed in various room environments, without expensive external equalisers. The end result is a simpler, more reliable, efficient, consistent and precise active loudspeaker system.

Directivity Control Waveguide (DCW™) for flat on and off-axis response.

A revolutionary approach was taken by Genelec in 1983 with the development of its Directivity Control Waveguide (DCW™). We have developed and refined this technology over more than 30 years to greatly improve the performance of direct radiating multi-way monitors.

The DCW technology shapes the emitted wavefront in a controlled way, allowing predictable tailoring of the directivity (dispersion) pattern. To make the directivity uniform and smooth, the goal is to limit the radiation angle so that the stray radiation is reduced. It results in excellent flatness of the overall frequency response as well as uniform power response. This minimises early reflections and provides a wide and controlled listening area achieving accurate sound reproduction on and off-axis.

Minimised early reflections and controlled, constant directivity have another important advantage: the frequency balance of the room reverberation field is essentially the same as the direct field from the monitors. As a consequence, the monitoring system's performance is less dependent on room acoustic characteristics.

Sound image width and depth, critical components in any listening environment, are important not only for on-axis listening, but also off-axis. This accommodates not only the engineer doing their job, but also others in the listening field, as is so often the case in large control rooms.

DCW™ Technology key benefits:

• Flat on and off-axis response for wider usable listening area.
• Increased direct-to-reflected sound ratio for reduced control room coloration.
• Improved stereo and sound stage imaging.
• Increased drive unit sensitivity up to 6 dB.
• Increased system maximum sound pressure level capacity.
• Decreased drive unit distortion.
• Reduced cabinet edge diffraction.
• Reduced complete system distortion.

Intelligent Signal Sensing (ISS™) for power consumption reduction in stand-by mode.

Introduced early 2013, Genelec’s Intelligent Signal-Sensing technology has been developed to meet with both European Union ErP Directives and Genelec's own ambitious sustainability standards.

The Intelligent Signal Sensing, ISS™ circuitry tracks the signal input of the loudspeaker and detects if it is in use. If the ISS circuit does not find any audio on the input for a period of time, it sets the loudspeaker to a low-power sleep state and the loudspeaker will consume less than 0.5 watts. When an input signal is detected, the loudspeaker immediately turns itself on.

Additionally an ‘ISS Disable’ switch is located on each product’s back plate next to the other room response controls. First, when the mains power switch of the loudspeaker is set to 'ON', the ISS™ auto-start function (low-power sleep state on/off) of the loudspeaker is active.

If this function is not desired, the ISS™ function can be disabled by setting the 'ISS Disable' switch on the back panel to 'ON' position. In this mode, the monitor is only powered on and off using the mains power switch.

Note that the mains power switch will always turn the monitor off completely.

Vibration decoupling Iso-Pod™ stand improves sound image definition.

Although it is advisable to use sturdy and stable floor stands together with free-standing loudspeakers, a very common solution is to place loudspeakers directly on a table or on a console meter bridge.

This causes several detrimental side effects. Aiming of the loudspeaker axis towards the listener is rarely implemented, also, unwanted mechanical vibration do propagate from the loudspeaker to the mounting surface, and first order reflection on the work surface causes comb filtering and hence ripples in the frequency response.

To solve these very common problems Genelec developed an efficient and very practical solution. We designed a loudspeaker stand called Iso-Pod™ - Isolation Positioner/Decoupler that is attached to the aluminium enclosure. It has four shallow feet and it is made from special lossy rubber-like material. It is firmly attached to the enclosure so that it can be slid along the curved bottom or side surface to allow for a ±15° tilt of the loudspeaker.

The loudspeakers’ acoustical axis can then be pointed precisely towards the listener by adjusting the enclosure’s inclination with the Iso-Pod. The vibration isolation and damping properties reduce midrange coloration caused by unwanted vibration transmitted to supporting surfaces.

This innovative solution is an integral part of Genelec loudspeaker design and provides clear benefits in usability and sound quality.

Minimum Diffraction Enclosure (MDE™) for uncoloured sound reproduction.

A common problem with standard free-standing loudspeakers is that the front baffle discontinuities cause diffractions and the loudspeaker sharp corners act as secondary sources through reflections.

In order to improve the flatness of the frequency response and the power response of free standing loudspeaker systems, Genelec have designed a highly innovative enclosure optimized to match the properties of the monitor drivers, featuring rounded edges, and gently curved front and sides. In addition to achieving an unsurpassed flatness of the frequency response, the enclosure having minimum diffractions yields superb sound stage imaging qualities.

To achieve such a smooth and elegantly curved cabinet surface and to reduce the outer dimensions of the enclosure, maximising at the same time the internal volume for improved low frequency efficiency, we designed a cabinet made off die-cast aluminium. Aluminium is lightweight, stiff and very easy to damp to yield a “dead” structure. The cabinet walls can be made fairly thin, providing at the same time good EMC shielding and excellent heat sink for the power amplifiers. Die-casting is made in two parts, front and rear, and they are easy to separate for potential servicing needs.

The DCW waveguide has been integrated in the MDE aluminium enclosure to provide improved control of the loudspeaker’s directivity. Basically, the low frequency limit for constant directivity is determined by the size of the waveguide, so the larger the surface the better the control. With a very controlled off-axis radiation, the listening window becomes consistent, which is of utmost importance with multi-channel audio monitoring. Controlled directivity also reduces possible first order reflections on surfaces near the loudspeaker, helping to provide consistent audio reproduction in different acoustical environments. In fact, the entire front baffle is gently curved and the acoustically transparent grilles are part of the outer cabinet aesthetics, blending perfectly with the various other curved surfaces.

Each transducer is driven by its own optimised amplifier.

Audio electronic crossovers allow to split the audio signal into separate frequency bands that can be separately routed to individual power amplifiers, which are then connected to specific transducers optimised for a particular frequency band.

In a typical 2-way loudspeaker system, the active crossover needs two power amplifiers — one for the woofer and one for the tweeter. The power amplifiers are connected directly to the drivers of an active loudspeaker, resulting in the power amplifier’s load becoming much simpler and well known. Each driver-specific power amplifier has only a limited frequency range to amplify (the power amplifier is placed after the active crossover) and this adds to the ease of design.

The active design principle offers multiple benefits:

• The power amplifiers are directly connected to the speaker drivers, maximising the control exerted by the power amplifier’s damping on the driver’s voice coil, reducing the consequences of dynamic changes in the driver electrical characteristics. This may improve the transient response of the system.
• There is a reduction in the power amplifier output requirement. With no energy lost in the passive crossover filter components, the amplifier power output requirements are reduced considerably (by up to 1/2 in some cases) without any reduction in the acoustic power output of the loudspeaker system. This can reduce costs and increase audio quality and system reliability.
• No loss between amplifier and driver units results in maximum acoustic efficiency.
• Active technology can achieve superior sound output vs. size vs. low frequency cut-off performance.
• All loudspeakers are delivered as a factory aligned system (amplifiers, crossover electronics and enclosure-driver systems).

Sophisticated drive unit protection circuitry for safe operation.

When working in critical audio production environments it is essential that monitoring systems remain reliable and functional at all times. One of the main reasons behind Genelec’s excellent success in broadcasting environments is the reliability of our products and a key element behind the reliability is the internal protection circuitry found in all products since 1978.

The protection circuitry prevents driver failures by detecting signal levels, and in case of sudden peaks or constantly too high levels, taking the signal level down automatically. Of course this feature does not affect the sound quality in any way when working within the specifications of the loudspeaker, but only prevents inadequate input signals from breaking the loudspeaker.

Protection circuitry features and benefits:

• Reduces the output level when required, (e.g. when driver voice coil temperature reaches the safe limit), which highly improves system reliability.
• Appropriate protection circuitry design in every loudspeaker and subwoofer enables the maximisation of system output sound level.

Advanced reflex port design for extended low frequency response.

Genelec’s choice for vented, or reflex, enclosures dates back to the S30 model, the first Genelec product from 1978. Port performance has been improved and refined over the years with the aim to increase the woofer’s low frequency extension and sound pressure level capability to provide outstanding bass articulation and definition.

Both driver and vent contribute to the total radiation of a reflex enclosure. Most radiation comes from the driver, but at the vent-enclosure resonant frequency the driver displacement amplitude is small and most of the radiation comes out of the vent.

To minimise the air speed in the tube, the cross sectional area of the vent should be large. This in turn means that the vent tube has to be long which presents quite a design challenge.

The long, curved tube maximises airflow so deep bass can be reproduced without compression. The reflex tube terminates with a wide flare located on the rear of the enclosure, minimising port noises and providing excellent bass articulation.

The curvature of the tube has also been carefully designed to minimise any audible noise, compression or distortion. The inner end of the tube has proper resistive termination to minimise once again audible chuffing noise and air turbulence.

Proper reflex port design allows also to significantly reduce the woofer’s displacement, improving the linear low frequency output capacity.

Versatile mounting options for all installation needs.

In addition to perfect acoustical design and advanced tailoring options to optimize the loudspeaker’s behaviour to the room environment, Genelec loudspeakers offer a variety of mounting options for easy installation in different applications.

Our wide range of accessories and fixed mounting points on the back of our aluminium enclosure products offer solutions to all common installation situations. M6 support points have been integrated in the die-cast enclosure for wall and ceiling mounts.

Some models also feature a 3/8” thread at the bottom of the enclosure to fit a robust microphone stand. Other larger and heavier models feature M10 fixing points. Special floor stand plates have been designed in order to fit the Iso-Pod stand that is part of our product design.

With these features our loudspeakers have found their way to a variety of applications beyond the professional audio and studio world, for example in commercial and AV installation projects as well as in home environments all around the world.