.25mm HQ speaker

[Dr Mordrid]

Story.....


Warwick U. announcement.....

New Flat Flexible Speakers Might Even Help You Catch Planes And Trains

ScienceDaily (Apr. 1, 2009) — A groundbreaking new loudspeaker -- less than 0.25mm thick -- has been developed by University of Warwick engineers. It's flat, flexible, could be hung on a wall like a picture, and its particular method of sound generation could make public announcements in places like passenger terminals clearer, crisper, and easier to hear.

Lightweight and inexpensive to manufacture, the speakers are slim and flexible: they could be concealed inside ceiling tiles or car interiors, or printed with a design and hung on the wall like a picture.

Pioneered by University of Warwick spin-out company, Warwick Audio Technologies' the 'Flat, Flexible Loudspeaker' (FFL) is ideal for public spaces where it delivers planar directional sound waves, which project further than sound from conventional speakers.

Steve Couchman, CEO of Warwick Audio Technologies, believes it could entirely replace the speakers currently used in homes and in cars, as well as in public address systems used in passenger terminals and shopping centres.

He says: "We believe this is a truly innovative technology. Its size and flexibility means it can be used in all sorts of areas where space is at a premium. Audio visual companies are investigating its use as point of sale posters for smart audio messaging and car manufacturers are particularly interested in it for its light weight and thinness, which means it can be incorporated into the headlining of cars, rather than lower down in the interior."

All speakers work by converting an electric signal into sound. Usually, the signal is used to generate a varying magnetic field, which in turn vibrates a mechanical cone, so producing the sound.

Warwick Audio Technology's FFL technology is a carefully designed assembly of thin, conducting and insulating, materials resulting in the development of a flexible laminate, which when excited by an electrical signal will vibrate and produce sound.

The speaker laminate operates as a perfect piston resonator. The entire diaphragm therefore radiates in phase, forming an area source. The wave front emitted by the vibrating surface is phase coherent, producing a plane wave with very high directivity and very accurate sound imaging.

"Another great application would be in PA systems for public spaces," says Steve. "The sound produced by FFLs can be directed straight at its intended audience. The sound volume and quality does not deteriorate as it does in conventional speakers, which means that public announcements in passenger terminals, for example, could be clearer, crisper, and easier to hear."

The FFL was first developed by Dr Duncan Billson and Professor David Hutchins, both from the University of Warwick, with early trials using just two sheets of tinfoil and an insulating layer of baking paper to produce sound. Since then its design has significantly evolved and the technology is now ready for commercial exploitation

The company is currently in negotiations with a number of commercial partners and continues to welcome fresh approaches. It expects to launch its first commercial product later this year.

[NetSnake]

WOW! just wow!

It would be perfect for ultra-portable notebooks also...

[Dr Mordrid]

From the company website -

Overview:

We have developed a new form of mid-range loudspeaker technology, the Flat Flexible Loudspeaker, FFL.

Using principles similar to ESL*, we have re-engineered the materials and electronics to bring the benefits of high quality audio to a wider marketplace. ESL is the technology of choice for the audio standardisation industry. To date, such speakers have been large, heavy and rigid constructions, requiring expensive amplification.

Using a unique combination of optimal acoustic materials, we have improved on established design fundamentals to bring the worlds first FFL to market.

* Electro Static Loudspeakers

Features & Benefits:

All our FFL products feature the combination of ultra-thin (0.2mm), lightweight and flexible materials used to produce directional high quality audio. The surface materials used in the construction process are printable and are cut to customised shapes where audio requirements allow.

Ultra-thin and lightweight speakers lend themselves to easy and convenient mounting positions on walls and ceilings. The speakers are easy to conceal or if you prefer they can be printed with any image, neatly featuring the speaker in your room. Using FFL means audio is simple to install and secure from unauthorised removal.

Sound pressure levels are of 80-105dB are achieved. Actual SPL depends upon the area of the laminate selected. Laminates are offered in a variety of areas between the standard European paper sizes A5 through to A3.

The speaker is voltage driven and draws very little power. Unlike the power hungry alternatives very little electrical current is wasted as heat.

The FFL sound is not distorted by magnetic fields, so you won’t suffer audio distortion from nearby equipment or from irritating mobile phone signals.

The directionality of the sound produced by the FFL is controlled by flexing the laminate, allowing sound properties to be modified in a similar way to the image in a curved mirror.

The laminate is suited to large scale manufacturing and printing processes. Resulting economies of scale result in low cost, high quality FFL speakers.

The combination of features and benefits of FFL technology are best experienced in group situations or public spaces. These environments tend to suffer most acutely using conventional speaker technologies. Modernising your multimedia platform with FFL technology overcomes many of the every day challenges of using audio in modern environments.

How it works:

All speakers operate on the principle an electrical signal is converted into sound using a mechanical device. A conventional cone speaker takes the electrical signal, which in turn generates a varying magnetic field, in turn vibrating a mechanical cone, so producing the sound. All these energy conversions lead to a very inefficient speaker.

FFL technology produces sound using a far more efficient process. We directly apply the electrical signal to the laminate, which vibrates in time with the electrical signal. The laminate is composed of two conducting surfaces, called Membranes, separated by an insulating layer. Hence an electric field (rather than a magnetic field) forms over the laminate. The design and construction of the laminate is unique and protected by the Intellectual Property of Warwick Audio.

FFL are driven over the entire surface area, providing a near linear response at sound pressure levels suitable for many applications. By closely controlling the separation of the membranes, we achieve reduced active drive voltages compared to ESL.

It is important to note that by significantly improving the electrical to audio efficiency, we have broken the conventional link between the power rating and the loudness of a speaker. The loudness of cone speakers is often linked to the electrical power consumption. This is not a relevant relationship for the FFL.

[Umfriend]

I wonder, this is not aimed at hi-fi at all, is it? I see no frequency ranges and wonder about distortion. As a notebook sound driver, I doubt it. I get the impression that it can bring up to 80 db in an A3 size. Bit large for a notebook methinks.

[Brian Ellis]

Good one!! (ScienceDaily (Apr. 1, 2009))

[VJ]

It is not *that* far fetched...

I agree with Umfriend though: the article mentions PA applications and merely hints at car audio. The soundbug had similar aspirations (turning car windows and dashboards into speakers), but also hasn't succeeded (yet?).

[Marshmallowman]

announcment for Warwick U. was 31 March.

Its not a groundbraking, but it certainly a good evolutionary step electrostatic speakers...which have been around for a quite a while.

I am not sure about the potential uses they talk about, while flat electrostatic flat speakers do produce a planar sound wave that travels well with low loss due to dispersion, it also means you have to be in the "beam" to hear it, but I guess if a whole wall is covered it will have a good coverage.

A few years ago there was some flat speakers which they demonstarted generating "spot" sound. eg A ceiling mounted speaker that could only be heard by people directly under it.

[Dr Mordrid]

IIRC somewhere in my readings on this it was stated that if the emitter were curved in a shallow arc the dispersion would cover a wide area and not be a "beam".

[Umfriend]

A few years ago there was some flat speakers which they demonstarted generating "spot" sound. eg A ceiling mounted speaker that could only be heard by people directly under it.

IIRC, they were only able to produce frequencies between 300 and 8000 hz or so though.

[Brian Ellis]

Well, I'll tell you why it's a farce. I experienced an electrostatic speaker, or rather an array of them, about 45 years ago. The moving parts were a pretensioned metallised polyester membrane sandwich. The bass membrane was a rectangle about (from memory) 60 cm x 50 cm and was spaced from the fixed perforated electrodes (front and back) by about 1 cm. The inbuilt electronics generated a voltage in the 10 kV range for the low frequencies in order to generate an electrostatic field strong enough to move the membrane distances of up to 5 or 6 mm to reproduce e.g., 32 foot organ pipes. In other words, bass reproduction requires a massive amount of air moved. There is no way that a 0.25 mm thick device could possibly displace enough air to generate anything under a bat's hearing range.

If you look at conventional moving coil speakers, the better quality woofers are 30-45 cm diameter and have a linear movement of about ±1 cm at full volume 30 Hz signals. The popular compact speakers have a smaller diameter, but compensate for this with a longer coil and a shorter permanent magnet field, allowing for a longer movement before distorsion sets in, so that there is still a large volume of air displaced, although it is doubtful whether they are much good at 30 Hz (sometimes compensated partially by a bass reflex cabinet design).

The speaker is voltage driven and draws very little power.

Albeit voltage driven (with possible insulation problems), to displace air requires energy. A typical speaker system has an efficiency of the order of 1% because the coupling between the diaphragm and the air volume is poorly matched. This is improved by the rigid cone shape of a moving coil diaphragm. A flat one is even less efficient and would require a much larger baffle to prevent pressure equalisation round the edges. This would defeat its use in small equipment, such as laptops. However, my point is that to reach 100 dB sound levels at low frequencies in an average sized living room requires something like 3 W of acoustic power. At 1% efficiency, which I believe to be optimistic, this means that you need 300 W of electrical power, so the quote above is senseless. I remember that the electrostatic speaker array mentioned in my first paragraph required a 1 kW power connection. We drove it from a Leak Point-One amplifier (2xKT66 power amplifier valves) as its input transformer had a standard 15 ohm impedance, but its audio power input was low, the internal high-voltage amplifiers providing the power and heating the room. If I remember correctly (and I'm not sure here), I think the bass amplifier had two Class A push-pull 813 beam tetrodes, working at 750 V on the anodes, feeding the high voltage transformer. The mid-frequency ampli almost certainly had KT66s and the high-frequency one may have had 6V6s or similar. Certainly, power there was! Unfortunately, my memory fails me on the speaker maker; it MAY have been Leak but the leak is in my neurones. I know it was a commercial failure as it was far too expensive and it did have a slight hiss at high power inputs due to air ionisation. We got an evaluation sample as, at the time, I was working for Kudelski (the makers of THE pro Nagra portable tape recorder used by Hollywood, TV and radio stations throughout the world). Stefan Kudelski was (still is, I think) one of the most respected names in pro audio and a very interesting personality.

[Umfriend]

I don;t get it. What does thickness have to do with the volume of air being moved?

Also, I did not read a claim that they were able to produce adequate bass frequencies.

Not sure if your numbers are based on typial coil-speaker systems or full-range electrostatic but I've experienced 12" woofer systems being driven by 70W RMS Class-A PAs that easily fed 100 dB (efficienct around 90 db/w/mtr, so I guess about 8w to get to 102dB?).

I have yet to come across 8" woofer systems that can do 30 Hz well. 40 somewhat though.

[Brian Ellis]

I don;t get it. What does thickness have to do with the volume of air being moved?

How is an A3 sized sheet able to piston the same volume of air as a conventional 30 cm cone moving ±1 cm, when the total assembly is 0.2 mm thick?

Also, I did not read a claim that they were able to produce adequate bass frequencies.

True, but the thread title is HQ (high quality)

Not sure if your numbers are based on typial coil-speaker systems or full-range electrostatic but I've experienced 12" woofer systems being driven by 70W RMS Class-A PAs that easily fed 100 dB (efficienct around 90 db/w/mtr, so I guess about 8w to get to 102dB?).

My estimated 1% was for electrostatic. I've since looked at some web pages for modern electrostatics and they seem more efficient than the one I described and possibly work at lower voltages. They now use a fixed polarising voltage, while the old system, if I remember correctly, used push-pull dynamic polarisation. Your figures seem reasonable for an efficient MC LS. Less reasonable for the modern compact l/s which are less efficient (which is why "music power", as opposed to RMS power has increased exponentially over the years!). If I put even 50 W into my Goodmans, it would blow the cones across the room! I have a 2x25 W Class A ampli with a 0.1 ohm output impedance which damps the 15 ohm impedance of the l/s beautifully. You never heard a more crystal-clear sound, To hell with valve amplis with their high output Z.

I have yet to come across 8" woofer systems that can do 30 Hz well. 40 somewhat though.

200% agree, but the 40 Hz is usually artificially peaked by the cabinet design!

[Umfriend]

How is an A3 sized sheet able to piston the same volume of air as a conventional 30 cm cone moving ±1 cm, when the total assembly is 0.2 mm thick?

Ah, I did not assume that all motion would be within 0.2mm, just that what would move, the foil, was 0.2mm thick (and apparantly with the electronics integrated within as opposed to ES or ribbon etc. He, I do not claim to actually understand all this ).

True, but the thread title is HQ (high quality)

ROFLMAO! The days when HQ claims meant something is long gone IMO.

[TransformX]

Would this be a hoax too?

[Brian Ellis]

Quote from TX's non-hoax, which is EXACTLY what I've been saying (my bolding):

The problem of creating LF is not just size, rather the problem is that in order to create amplitude at lower frequencies, simple vibrations of the common exciter used in this technology would not be enough. Large movement would have to be created, which will take a device with long enough Xmax (the distance from 0 Volt or rest to full forward excursion of the coil at Max power) and a less rigid surface, and lots of power.

Flat speakers, per se, have been around since the 1920s, but, generally, the flatter they are, the poorer their performance. One early one I saw (possibly c. 1930) was in a portable radio. It consisted of a foil of low-remenance magnetic alloy, perhaps about 20 cm diameter, behind which was a massive flat iron-cored coil. There was an adjustment which could vary the distance from the core to the diaphragm, which was the volume control! The sound quality was atrocious, of course, but it worked. It had 2 Osram LP2 triodes in a superregenerative circuit and was possibly one of the first portable radios (provided you didn't mind lugging around a 2 V wet accumulator and a 90 V HT battery. I think the whole caboodle must have weighed about 10-15 kg!!!).