The problem is now well known: there is a sudden change in mechanical impedance where the wave passes from the cone to the surround, which itself radiates sound and has a "boomerang" effect, causing deformation of the cone. Many attempts to resolve this have been considered by Focal's competitors but none is satisfactory, since all are detrimental to cone travel and cause dynamic compression.
Following the discovering of these issues, Focal had to conceive the approach to solve them. The solutions already known for increasing the damping properties of the suspension all result in an increase of the mass which consequently alters definition. The answer came from a technology used in earthquake-resistant skyscrapers and which is also used for the suspension on racing cars! This technology is called a "Tuned Mass Damper": an additional mass oscillates in opposition to the resonance frequency to control it.
It was used with great success in the suspension of the Renault R25 F1 car in 2005 and was quickly banned because it was considered anti-competitive by the FIA. It is also the basic principle of anti-seismic systems for modern skyscrapers. This device offers major advantages. The speaker engineers were able to:
Thus Focal are able to combine benefits which were previously irreconcilable: low mass, optimum damping and extension of the frequency response. This leads to several benefits at the listening level:
To clarify the last point, the resonance of a conventional surround blurs the soundstage, especially when the resonance is marked. TMD suspension eliminates the problem at its source.
Focal's Tuned Mass Damper (TMD) consists of two tubular rings moulded onto the surround. This simple solution, perfected thanks to new software, stabilises the dynamic behaviour of the surround according to resonance, thus avoiding deformation of the cone without afflicting the dynamics.
Two moulded circular beads in the surround form the tuned harmonic damper. While this appears to be a simple solution, over a hundred different configurations were tested to optimise the result.
A committed research project thus enabled Focal to develop a remarkable solution by addressing the problem at its source, without limitation of cone movement, using a "TMD" suspension for which a patent was filed in the third quarter of 2014.
VISUAL ANALOGY OF THE SURROUNDS- Left shows no TMD or default configuration, Right shows with TMD suspension
The precision and detail of audio reproduction depends on the stability of the drivers magnetic field. This stability is compromised by three factors which tend to modulate the magnetic field:
To implement this solution Focal developed a new midrange driver magnetic circuit for the Sopra line. A central Neodymium magnet is topped with a ferromagnetic pole piece brought to saturation by a second Neodymium pellet above it. The field is looped by a ferromagnetic circuit dimensioned to avoid saturation. Finally a Faraday ring is carefully positioned further to reduce distortion below 1kHz.
Focal have now applied two major developments to the Sopra's midrange driver: the harmonic damper suspension "TMD" and the new magnetic circuit "NIC".It is interesting to see the combined effect of these two innovations on overall performance. The results can definately be heard in listening tests:
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The tweeter remains central to the design of the Sopra, it is the "eye" of the product that captures the eye of the onlooker. Its positioning is not just aesthetic, it is highly critical to the sound as it predetermines the speaker's spatiality, what Focal call "Focus Time".
Due to its incredible rigidity, Beryllium represents the ultimate material for a tweeter dome. Focal, after two years of research and development, produced a world first: a pure Beryllium inverted dome, able to cover more than five octaves (1000Hz 40kHz). You may ask yourself, why strive for an extended response at 40kHz, if the human ear can only hear up to 20kHz? If you can extend frequency response, you will improve the perception of transients and other micro details. As well, the linearity of the speaker's response curve is mainly a function of three opposite parameters: lightness, rigidity and damping. To this day, Beryllium is the only material which permits a joining of these three parameters. The result is a sound wave propagation three times faster than Titanium and two and a half times faster than Aluminum. In the end, the linearity of the frequency response curve, the acoustic transparency and the impulse response of the Beryllium tweeter are maximized and offer near-perfect sound.
The inverted dome tweeter is perhaps the perfect transducer. This design permits very high-efficiency, precision and energy. The particular advantage of the inverted dome tweeter is the optimisation of the mechanical coupling between the voice coil and the dome.
Conventional Positive Dome Tweeter Inverted Dome Tweeter
The voice coil is fixed at mid-height on the dome and uniformly moves the cone entire surface. The positive dome is only joined at its edge, causing it to be inactive beyond 16kHz for a flexible surface. The inverted dome directly radiates into the air, with maximum efficiency, which is translated by an extremely precise soundstage. The dome's response curve is clearly more linear than that of any positive dome. It provides better space dispersion and very low directivity, contrary to ribbon tweeters. The inverted dome tweeter offers unequalled dynamics, enabling sound engineers to very precisely control compression. The image precision (height, width and depth) is outstanding and makes the positioning of each element very easy, as well as allows one to exactly assess the reverb tails.
The requirement for Sopra to be compact meant that as much of the cabinet as possible had to be used for the bass. The Focal Design team had to explore a new system for loading the tweeter. Their Beryllium tweeter features an incredibly light and extremely rigid dome. Its main limitation comes from the compression of air in the cavity behind it. To overcome this, the ideal would be to have a nearly infinite volume.
With the Utopia IAL 2 tweeter Focal worked on improving the flow of the rear-directed wave from the dome. In Utopia III the tweeter has its own enclosure with a large volume to absorb the back wave very gently, as would an infinite space. With Sopra, the need for compactness meant they could not devote the necessary volume for this. So their thinking has led them to imagine a rear acoustic load on the tweeter that approaches the ideal by gradually absorbing the rear radiation. Located on the back of the tweeter a progressively damped horn-shaped duct evacuates smoothly the rear radiation of the dome and has the advantage of being the most effective solution in terms of compactness, thereby preserving internal volume for the bass section.
The rear of the Beryllium tweeter is loaded via a small cavity which is connected to the exterior of the enclosure by a horn. The inside of the horn is filled with a damping material. Thus, sound waves from the rear of the tweeter are delicately and gradually absorbed. Its acoustic impedance approaches zero so that no resistance alters the movement of the dome. This pushes definition to its maximum. Moreover, a lot of effort went into isolating the tweeter from any interference from vibrations. The injected polyurethane mono-bloc tweeter frame provides the optimal mass and damping in a reduced space.
Thus, the Focal design team were able to get the most out of the woofers to enhance bass performance while having an ideally-positioned tweeter, and all this in a reasonably-sized cabinet.
In our next installment we discus the Sopra's Mid-range section.
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We all love to get excited about the "next new thing", and the latest "new thing" is undoubtedly 4K or now rebranded UHD. Unfortunately the industry has put the cart before the horse in many respects. UHD will eventually become mainstream but today it is probably only of real benefit at sizes of 80 inch and over. Future implementation of wider colour space and greater bit depth will lead to even greater benefits, but as of today it's only true advantage is resolution. If you buy a UHD TV today you are just buying and expensive upscaler. Your 4K content options are limited to a few streaming services but with our decrepit internet infrastructure the approximately 20Mbps bandwidth required to stream UHD means you will need to book your show a day or two in advance. The recently announced UHD Blu Ray player will be available late 2015, but until then upscaled SD & HD will have to suffice. My main gripe though is not the lack of content, but rather the lack of a firm set of standards, in particular something called REC2020. HD uses a standard called REC709, this specifies things like frame rate, resolution, bit depth and colour space. REC2020 is a working standard which means it is still not fully cooked. The danger is that people buying UHD TVs today may not be able to utilise features implemented further downstream. In fact the recent release of the HDCP2.2 copy protection spec has already rendered any TV or Receiver sold up to this point redundant due to them being unable to handshake with any HDCP 2.2 compliant device and therefore unable to display UHD content. Our advice is to forget UHD for the moment and buy the best 1080p HD equipment you can afford. If you have to have UHD then talk to a speacialist in order to get the best advice you can so that you can make an informed decision and then , proceed with caution......
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Storm season is once again upon us with the weather bureau predicting a stormy week for NSW next week. While I do enjoy a good storm, I'm not so enamoured with the collateral damage of a nearby lightning strike. Therefore the point of this blog post is two-fold, firstly to save you the heartache that accompanies the destruction of your beloved Hifi/Home Theatre system by a wayward lightning bolt, and secondly to expose you to a new avenue for improving the performance of your system.
There are two main objectives of a good quality power protection system. The first and most obvious, is protection, to stop your precious audio and video equipment from being turned into an expensive pile of molten carbon and plastic. The second, and less considered, is power filtration, to improve the quality of the power being fed to your gear. Power is the first input to any home entertainment system; it flows through the system, used by each component in turn to create the signal that moves the speakers’ drive units and delivers the pixels on the screen. What we see and hear is fashioned from, and by, mains electricity – it’s the ‘raw material’ from which the ‘art’ is created. Your musical or cinematic enjoyment will be reduced by mains noise contamination.
Let's take a closer look at the how's and why of 'Protection' and 'Filtration':
Joules is the measurement of absorption of a surge protective product. If Joules is likened to a sponge, the bigger the sponge, the more it can absorb and the better the power protective product. Joules are sacrificial; they cannot regenerate or be used again so once used up, the device can no longer absorb any excess energy. This can be catastrophic for protection on 'big ticket items' as the power protector is no longer a 'protector' it is effectively turned into a basic power strip. As power boards commonly sit behind cabinets, shelves or under desks however, unfortunately it is not commonplace for a board to tell you it is no longer protecting. Thor's Power Check Technology is unique and is critical to protecting any connected equipment. Thor's Power Check Technology shuts off a circuit automatically once the surge protection properties are used up, instantly alerting the user that the board needs to be replaced.Filtering & Conditioning
Power line noise is a natural by-product of the distribution and use of electrical power. It is present in every electrical circuit and can pose huge problems with performance, reliability and longevity of any digitally sensitive circuit. Let's throw a few analogies around, who doesn't love a good analogy. A high performance sports car will not perform to it's maximum unless it is run on the very best available fuel. It can have gold plated fuel lines, platinum spark plugs and a state of the art fuel pumping system, but if the fuel tank is full of vegetable oil the performance potential will never be realised. Similarly, your HiFi system is unable to function to it's maximum potential because the fuel supplied to it from the mains is contaminated. HiFi source components are very sensitive to electrical pollution because the audio signals they process are at a very low voltage, and this signal must be amplified in order to drive the speakers. This causes a cascade effect within the electronic circuitry, resulting in a polluted amplified signal.There are a number of benefits you will realise from a good power conditioner:
•Improved front to back layering and an extended and involving soundstage
•Effortlessly natural and open sound and far more 3D vocal image
•More attack and definition on the instruments and a Vanishingly quiet noise floor.
•Greater overlaying of harmonies, textures and detail
•Greater focus and bass articulation
Thor- Thor make a great, affordable range of power protection and conditioning products for all budgets and applications. If you have unreliable power quality or are in a lightning-strike prone area, then there is a Thor product for you. Thor Technologies is 100% Australian and proud of it. All research, development and engineering is undertaken in Australia, even today their hardwired range is still 100% manufactured here. They really stand behind the products they sell, and all products are designed specifically for australian conditions and have a clamping voltage of 275V. You can rest assured that A Thor product will catch the spike and stop it before the smoke gets out, guaranteed. Check out their website, give us a call or drop into the store to learn more.
Isotek- Where Thor is a product for everyone, the butcher, the baker and the candlestick maker, Isotek build more esoteric products, aimed at the purist audiophile. Isotek's primary focus is on improving sound quality, their products are more about chasing the ultimate in audio performance, power protection is an added bonus. They claim to deliver the world’s best power cleaning solutions for lovers of high-quality sound. All Isotek products are designed and hand crafted in the UK. Check out their website, give us a call or drop into the store to learn more.
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