Some weeks ago, while we were on business in Valencia, we could pay a visit to the main premises of Beyma, leader company in the production of loudspeakers for hi-fi and pro audio systems.
The structure includes both the production and administration premises and is just a few kilometres far from the centre of Valencia; thanks to the hospitality of Paloma Martinez (Marketing and Communication Manager) and Jorge Serrano (Product Manager), we could know a little better this company and discover the innovative TPL-150, a new high-frequency transducer which we will describe in this article. A particularly interesting moment was the visit to the assembly line, which makes use of forefront technologies, and an effective R&D department; unfortunately, we couldn’t take global pictures of the latter, for confidential issues.
Pity, as we guarantee that Beyma’s R&D department is one of the most “unconventional” and fascinating research and development laboratories of the many factories that we visited during our “incursions”.
Led by Jose Martinez, Spanish university luminary and brilliant scientist Mr. Fernando Bolaños and his colleague Pablo Seoane, the laboratory is stacked with the usual tools for acoustic analysis and simulations and with a series of “hand made tools”, rather simple but really effective.
Just to give a hint… imagine a bit of wood, a grid drawn on it and some sand to simulate the acoustical behaviour of drivers and loudspeakers…
An important tool for Beyma is the Bruel&Kjaer Klippel Analyzer 2 analyzer. The team explained us that this analysis and prediction method is one of the most advanced hardware/software platform available today, but the most important factor is that it is dedicated to the quality control of loudspeakers and drivers.
In this context we were able to have a look at the product and the technology that are the “main characters” of our technical “focus on”. But before starting with the technical data, we would like to describe Beyma in a few words to discover how such a high level company operates.
Acustica Beyma was born in 1969 in Valencia and it has got its core business in the production of high-level loudspeakesrs, both for hi-fi/car audio and pro audio.
The R&D department, the great attention to communications with clients and to technological innovation, are the basis of the development strategies of the company, as Paloma Martinez has immediately pointed out in the presentations she prepared for us.
As a matter of fact, the huge number of clients coming from different audio areas (hi-fi and professional), made the cooperation and the continuous feedback exchanges with these realities a real plus for Beyma.
We could visit the new assembly line, characterized by wide spaces and an automation/robotization-oriented organization, with dedicated equipment built according to specifications coming directly from the company.
For example, almost the whole workflow – starting from the magnet up to the various assemblages phases – the loudspeaker is never moved upside-down or moved away from the housing slot on the conveyor belt, which allows precise and safe assemblages.
An important phase is gluing, which makes use of a special mix (obviously secret) of different glues proportioned according to the task. All these processes can be programmed and configured remotely with a specific computer. The last phases of the manufacturing process are diagnostics and listening to the final product.
Besides using various measurement instruments, a specialized technician listens to each loudspeaker and driver; and they say “to have an ear for music”…
In this case, it was particularly funny to see how the technician was able to spot “by ear” an unperceivable problem on a driver created “ad hoc”, that later the machines reported and discarded…
New Beyma TPL-150
Beyma has developed a new type of component for the professional sound, bringing the highest sonorous quality of the most demanding audiophile to the world of live music.
This type of high frequency transducer is based on the AMT technology (Air Motion Transformer). In this type of transducers, invented by the German
Physicist Oskar Heil, the generation of the sound takes place in a very different way than habitual in ribbon tweeters. In figure one, we can see that in this device, the diaphragm is formed by longitudinal folds, like in an accordion. In the straight face of each one of these folds, there is a printed conductive copper thread.
The advantage in this type of device consist in the small and very controlled movement of each fold, accelerating the surrounding air inside each fold, which produces an almost perfect acoustical output, both in amplitude and in phase in all the radiating area of the transducer.
This diaphragm is made in Beyma, on a material able to support extreme temperatures and of a great flexibility. It is used in military and aerospace applications to manufacture flexible printed circuits. It is of great durability and reliability. The operation principle is the same one that in a regular tweeter, but geometry is totally different:
As it is possible to be seen in this figure, the magnetic field is closed happening by where the diaphragm is located. When an alternating electrical current circulates along the copper threads of the membrane, a movement takes place in the folds from left to right. The sound wave is generated when the air between the folds is compressed.
This causes that, being the displacement of each fold very small, the air moves at great speed, producing an important sound pressure. The advantages of this type of tweeter can be summarized in:
– Radiating surface four times the one of a tweeter or an equivalent compression driver, thanks to its folded geometry.
– Mobility transformer of air (Air Motion Transformer) because it causes in the air a speed four times greater than the one of the folds themselves (relation 4:1).
– This confers an enormous dynamics and an incredible transient response, vastly superior to that of any conventional tweeter, including ribbon tweeters and compression drivers.
What Beyma has done has been to develop this technology creating a component for professional use, of which would be possible to emphasize:
– High sensitivity: 99 [email protected], 1m.
– Wide frequency range: from 1 to 23 kHz.
– Admissible power handling without precedents: 80 W AES.
– Directly applicable for Line Array systems, with total coherence of the wave front with no need of any adapter.
– Also suited for other conventional applications, with a horizontal coverage superior to 100º up to 10 kHz.
All these characteristics make of the TPL-150 an authentic alternative to the conventional compression drivers, and contributing an enormous added value to any sound system that incorporates it. The sonic quality, timbre, definition and clarity of this transducer are simply unsurpassable.
By looking to the frequency response, although usable from 1 kHz, it may seems that the sound pressure level until 2 kHz is lower than requested for an equivalent use as a compression driver. It should be taken into account that this response is achieved without any horn or baffle, just with the unit in free air. In these conditions, the horizontal dispersion of the TPL-150 is completely
As it can be seen in the dispersion chart, the horizontal coverage is 180º at less than 1 kHz. By using a small diffuser, limiting the coverage at those frequencies to 90º is very effective to achieve a higher SPL from 800 Hz to 5 kHz, getting more than 4 dB increment, without loosing the spectacular dispersion consistence. No compression driver with horn is able to have 100º coverage angle at 10 kHz. Next we can find a frequency response with a new horn, the TDTPL, to reinforce the low-mid band-pass of the TPL-150.
With the help of this horn, the TPL-150 gets a much higher sensitivity, especially from 1 to 7 kHz, with an average sensitivity about 104 dB, and still maintains a very low distortion figure.
But how does the TPL-150 compare to a normal compression driver? In Beyma, engineers have made an extended and complete set of measurements to illustrate the superiority of the TPL over a conventional compression driver. In the next table we can compare the specifications of the TPL compared to the used compression driver in the comparison:
Let’s start with time definition. A waterfall plot will be very self-explanatory about the difference between a dome with unavoidable resonances and time smearing and a structure where the voice coil itself is the radiating surface at the same time:
As we can see in the Waterfall measurements, almost all the energy in the TPL-150 has gone away in less than 2 milliseconds. However, if we look the compression driver response, even after 5 milliseconds, the diaphragm is still resonating, blurring the acoustic message.
What about distortion products?
Many different measurements were carried out, including but no limited to harmonic distortion, difference tone distortion, inter-modulation distortion, near field measurements and multi-tone stimulus, all of them at three different power levels, 1W, 7W and 23W AES. We can show many of all these measurements, where always the TPL-150 is clearly superior in terms of distortion.
But one of the most spectacular measurements is the multi-tone response, as it can be more related with the behaviour of the unit with musical signals. Using various sinusoidal signals at the same time, many more inter-related distortion products arise, creating a kind of a “noise floor”, extremely interesting to compare, specially in this case.
In the graph, we can clearly see the tremendous quantity of distortion products the compression driver is creating, just with one watt. There is a S/N ratio of less than 45 dB between the main component and the distortion products, along all the band pass of the unit. If we look to the blue trace of the TPL-150, it is incredible how low the distortion is, not even possible to measure it in many frequency regions.
We can also look to the 7W measurement, where it can also be appreciated how the distortion products raises dramatically with power applied in the compression driver, while in the TPL-150, the distortion noise floor is kept proportional to the power applied.
So, not only the distortion is very low in the TPL-150, but also it does not arise dramatically with power applied, as a compression driver does. As a conclusion, this new transducer will be a key component for the next level of professional sound systems of the future, in terms of sonic quality and Live Sound experience.