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Room Acoustics Treatments


It is estimated that up to 60-70% of audio distortions come from excessive bass and reflections within the listening room. The other 30-40% of distortions are from unwanted resonances within the equipment or from acoustic feedback - structural and airborne. Reducing either of these distortions by at least half will result in a significantly better sound.

Having tried many products over the years, we know that those illustrated below really work. Many other products are on the market but are not all equal in their effect on sound. All will make a difference to the sound but some can make a bad difference. This is because many are panel applications that absorb the frequencies, not the excess energy created in a room. To a large extent these panel solutions work just on the high and mid range frequencies.


Most room acoustics problems occur from too much bass energy that migrates to the walls and then concentrated in all the corners. The Acustica Applicata products are all designed to control and absorb the lowest bass frequencies as well as extending upward across the mids and high frequencies. Hence they control the room acoustics but they do not over damp. The alternative panel approaches do not attend to the lower frequencies. The result is often one of over-damping and a skewed room frequency response.


Acustica Applicata


Diffusion Absorption Acoustic Devices (DAAD)


It is now accepted that approximately 60-70% of an audio system’s distortions are as a result of excessive bass energy and reflections within your listening room. Therefore treating the room acoustic problems can be a very cost effective upgrade path, often costing less than upgrading electronics or speakers.


Most rooms suffer from too much bass energy which concentrates in corners and nodal points along walls. When this is excessive, it reduces transparency right across the frequency bandwidth and causes smearing of the imaging. Removing or reducing this excess bass energy results in more tuneful, controlled bass frequencies, rhythm and timing is more correct. Transparency, detail, imaging and articulation are all improved. 


This Italian manufacturer makes cylindrical pieces called Diffusion Absorption Acoustic Devices, DAAD. As the acronym suggests, these room tuning products offer a unique combination of absorption and diffusion capabilities. Their principal function is to absorb and remove excessive levels of bass energy. They do not remove specific frequencies that other competitive devices do which skews the tonal balance without dealing with the main problem, bass energy concentration.


Most traditional acoustic treatment devices, usually panels fixed to the wall in a haphazard fashion, tend to absorb the medium and high frequencies without any effective reduction of the lower frequencies. This tends to skew the frequency response and does not deal with sound pressure build up.


These alternative systems, are usually reliant on foam, multi-fibre, or fabric based treatments, principally absorbing the highs and mids most without much consideration for the real problem, excess bass energy. This results in over-damping, loss of speed and dynamics – so the sound all ends up being a bit “dull”. The reason the DAADs work better is that they tackle sound pressure issues rather removing actual frequencies, therefore they do not overdamp.


DAADs absorb excess energy, broadband. They start operating well down in the bass frequencies ranges where most rooms have problems, but their effect extends up to 20kHz. This results in a larger sound stage within which it easy to discern the spatial details and clues required to create a truly holographic experience. They also improve tonal balance resulting in a much less bright or forward presentations giving a more natural sound, without loss of dynamics or rhythmic qualities.


They are also extremely effective when placed at first reflection points in a room ameliorating poor articulation. Uniquely, there is also a lobe that diffuses some of the sound, reflecting some higher and mid-band frequency energy back into the room. When placed at strategic reflection points in rooms, the angle of this diffusion side can be used to ‘shape’ the sound stage and the focus the imaging to taste.


They are also very light. Hence they can be placed in position for critical listening sessions and removed when not required. If you move house – or change rooms – they go with you and never become redundant.

DAADs are all in place and are set up as you suggested, and to say I am pleased would be an understatement. Probably one of the best purchases I have made, and one which I should have done years ago if I had known or realised how important room acoustics are. Anyone serious about their HiFi system, must use room treatments such as DAADs to hear the true potential of what they have.

Mr Stephen Fice, south Wales

We were impressed before we got them for home demonstration – their effect is easy to spot in almost any environment – but it’s in the listening room you know best where the real force of the argument is driven home.

Alan Sircom, Hi-Fi+

All current DAADs are now the Mark II version. This is due to a change of materials used just inside the outer circumference which has improved the performance by approximately 15%. The appearance of the the DAADs remains the same.


The DAAD MK II has a new innovative material developed for other high technology industries such aerospace and electro-medical. The structure of this material has a layered section, the density of which varies from one surface to the opposite surface. The characteristic of this progressive structure fits perfectly with the requirements of a wide-band acoustic trap. Using this new material, the sound pressure wave enters into DAAD volume much more easily, but is released out of DAAD much more slowly. Because the sound pressure is absorbed much more quickly, and held onto for longer, the Mark II version is more efficient.


Listening tests with DAAD Mark II have substantiated the claim. The immediate effect is one of more air and space around instruments and voices. The improved reaction speed of the acoustic treatment to the music pressure pulsation, results in increased dynamics, more accurate phase response, richer low frequencies and texture. The increased transparency and the "blacker" background allows low level details to be more easily perceived, especially at lower volumes.


Due to increased costs of transportation and customs tariffs post Brexit, we have reluctantly had to increase prices.

DAAD 2 MkII 110cm x 20cm; efficient from 120 Hz up to 20 KHz £800 each
DAAD 3 MkII 110cm x 28cm; efficient from 70 Hz up to 20 KHz £1200 each
DAAD 4 MkII 110cm x 40cm; efficient from 50 Hz up to 20 KHz £1450 each

EcoDAAD for ceilings and/or wall applications £340.00

Studio DAAD: a DAAD 2 on a telescopic stand adjustable from 23cm to 110cm from the floor. £1000.
Available in white and black.

Discounts available for orders of 6 pieces or more. 2 EcoDAADs count as 1 piece.


Polifemo (1.85m high with ‘iris’) £7000.


A first stage room treatment plan can be achieved from £2650-3150. For a very marked effect on sound, using 8-10 pieces, the investment will be approximately £4800-6990, dependent on the size of DAADs selected. This more balanced sound, with a larger soundstage and better articulation is more noticeable, and more cost effective, than investing the same, or more, in new electronics, loudspeakers or expensive cables. And the investment stays with you forever.


Home Trial Schemes


To evaluate these products we can offer a short demonstration in our studio facilities to hear their effect on room acoustics. Customers can then borrow a small number of DAADs to try in their own home. Usually we recommend 5-6 pieces minimum for this purpose. Alternatively a home visit can be organised and we would demonstrate and advise on their correct placement in your room. A fee for such home visits applies, covering both consultancy time and travelling expenses. Should an order result, the consultancy element of the fee would be fully redeemable against the purchase. Please phone or email for full details. 


How to use them

Generally the first place to treat is the corners of the listening room behind the loudspeakers. There are three types of DAAD; all are 1.1m tall and each type has a different diameter which absorbs across a wide range down to different low frequency points.


It is recommended to have a column of two pieces in each corner. In most of the UK rooms we have found that a DAAD 3 on top of a DAAD 4 in each corner that produces the best results. In the case of small rooms, stand mount monitor type loudspeakers, or electrostatics where high levels of bass energy are not being produced, a column of two DAAD 3s is usually sufficient.


The DAADs in the corners behind the loudspeakers can be rotated whilst listening carefully with a favourite recording, to give the best focus of imaging, the type of soundstage presentation and energy levels desired.

The next stage, if this is possible, is to place a column of DAAD No.3s in the centre of the wall behind the loudspeakers. The effect on ’cleaning up’ the sound-stage is very obvious and very powerful.

Then the first reflection points are treated on the wall behind the speaker and/or the lateral walls. This can be done with either the economical EcoDAAD, or for better results with either the DAAD 2 or DAAD 3.

The last stage is to treat the corners behind the listening position usually with a column of DAAD 3s and/or DAAD 4s.


The EcoDAAD product is a half round absorber. It is designed to be placed at first reflection points on side walls, front and rear walls or on ceilings. They are very light and can be hung with a small nail and removed when critical listening is not taking place. They are very cost effective and less obtrusive than using a DAAD 2 or DAAD 3 for this purpose. They have a very powerful effect on the depth of stage and the focus of image. A DAAD 2 or 3 would be the optimal suggestion for first reflection points but the EcoDAAD offers a less expensive alternative for this application.

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EcoDAADs; DAAD 3 (left) and DAAD 4 (right)


The Volcano and Halifax


Acustica Applicata has developed a new variable resonator product called the
Volcano. It is based on the principle of the successful Polifemo, the narrow band Helmholz resonator, but without the iris. The Volcano is shorter than the Polifemo, about the size of a DAAD 4, and can be applied to a variety of room positions where specific bass energy concentrates. But the principal application is between the loudspeakers, in the same plane, or just behind them. This position is where complex energy turbulences occur and the Volcano is the first acoustic device ever designed specifically to treat this area.

Additional positions for excellent results are on the boundary walls to the sides of the loudspeakers, or on the wall behind the loudspeakers. See photos on right. They are designed to be used
in addition to, rather than replace, DAADs, but substitutions can be made with some small compromises in performance.


When used in the recommended position between speakers, the effect on the sound is nothing less than spectacular. The biggest effect of placing a Volcano here is on the soundstage, and this is extremely evident even after just a few minutes listening. Everything is more holographic, and focus of images within the 3-dimensional stage is more precise. Transparency is increased allowing low level detail to be more easily perceived. True fine detail comes through, such as a singer or instrumentalist moving around the microphone. It is more like a person standing there rather than just a voice or saxophone. Tonal balance is more natural and dynamics improved. The overall impression is more like being at a live event.


The reason for this big improvement in sound is due to the large amount of energy turbulence created by the speakers projecting sound in all directions, not just forwards. Just imagine dropping two spheres into a rectangular swimming pool where your speakers are positioned. The waves emanating from this disturbance flow outwards at 360 degrees, and crash into one another creating turbulences. Further turbulences are caused by the waves hitting the sides and reflected back into the pool. A very complex situation of turbulences quickly builds up. And this is one simple wave pattern. Music in a room is much more complex, and multiple frequencies are involved, so energy peaks build up, cancellations occur. It very quickly become extremely chaotic. A more detailed explanation is presented in the link below.


Acustica Applicata are the first room acoustics company to appreciate and understand this energy turbulence problem between loudspeakers. The Volcano is the first product in the world designed specifically to deal with this problem. And deal with it effectively and simply.


  • Volcano - how and why it works

    Standard Volcano (2 parts) 102 cm (40") (h) x 38 cm (15") diameter

    Additional centre module 42.5 cm (16.7") x 38 cm (15") diameter


    The Volcano is the latest in the family of variable resonators developed and manufactured exclusively by Acustica Applicata. It is the new entry level model in the family that includes the Polifemo and Phemo. It is designed to improve the sound of any audio system, in any room.


    It is not just an ordinary corrective tool, it is has been developed for those audiophiles who seek an improved sound that is more refined, more elegant and that recreates the “live” event. Improvements to the sound stage, the finer details, the nuances created by the musician, the texture and timbre of instruments and their sound.


    In any listening room there are two, or more, loudspeakers that produce a sound pressure into a space surrounded by walls. Only part of the sound produced by the loudspeakers arrives at the listener’s ears directly. A large proportion of the sound arrives at the listener after having bounced off the walls at various reflection points. These reflected sounds are arriving later than the direct sound, and at variable amounts of delay. These reflected sounds also have to pass through the area occupied by the loudspeakers. This all creates distortions and a confused sound picture.


    To illustrate this point in a very simplified manner, imagine a 3-dimensional room as a 2-dimensional surface, rather like a rectangular swimming pool. Then imagine two identical spheres dropped down simultaneously into the pool, away from the sides, at points where you would position of a pair of loudspeakers in a listening room. The two spheres entering the water cause circular waves that move outwards. These waves spread, with a certain frequency, enlarging themselves towards the closest swimming pool walls, and from the point of impact new waves emanate in the opposite direction. These new waves in the opposite direction will either reinforce or cancel the first waves coming from where the spheres entered the water.


    The spheres generate waves in a circular fashion and some of these propagate themselves towards the inner area of the pool, and around the halfway point will “crash” into each other. In this particular position, the waves will interact with each other and very rapidly change so they are no longer like their original form. They will be warped and distorted by all the collisions between them, and from those waves coming back from the walls. They will then travel all over the swimming pool until they gradually disappear.


    Music is obviously much more complex than the simple, single wave. The example illustrated above is of a single, low frequency wave, but the low frequencies generated by an audio system are at many different frequencies, and much more complex and more intricate than a 2-dimensional simple oscillatory motion.


    Playing music in a room generates many different frequencies simultaneously. Additionally, stereophonic sound will be more like two spheres dropped that are not the same size, or the same weight, hence generating waves of different energies and difference frequencies. This whole phenomenon increases in complexity hugely once you consider a 3-dimensional room with a whole bunch of waves colliding in space and creating room distortions.


    In a listening room there 3 to 5 positions where these distortions become extremely significant: Two are along are at the lateral walls closest to the sides of the speakers.

    Two are at the wall behind the speakers, again closest to the speakers.

    The most important position is between the speakers in the middle of the sound stage. This area has the most turbulence where waves are colliding with themselves, they increase their energy or, more crucially, can cancel their energy.


    So treating this area with a suitable acoustic device, designed for this purpose, results in a major improvement in sound quality. The 3-dimensional stage increases significantly, the illusion of hearing into a much bigger space of the recorded venue. Transparency and clarity are noticeably better; a more correct tonal balance ensues with more impact and depth of the lower frequencies. Instruments and voices become more detailed and it is possible to perceive a person standing there, not just a voice. But above all is an outstanding increase in dynamics.


    Acustica Applicata have researched extensively this area of room acoustics phenomena and developed variable resonators such as the Polifemo. Now a new variable resonator has been born, which is easier to use and produce a more balanced and more in-phase sound. The VOLCANO was designed for exactly this position, in the centre of the sound stage, and it always results in an improved and more natural sound quality. The sound is much more like the concert hall experience.


    The standard VOLCANO is 105 cm (41”) tall with a diameter of 38 cm (15”). The body is made from pure transparent Plexiglas with ends made from MDF uniquely shaped to a specific design. The base has a port of 10.5 cm (4.1”) diameter into which is a cylinder made from a flexible acrylic which can be easily moved up and down to tune the resonant frequency to be addressed. The height of this cylinder within the Volcano tunes it to obtain the best depth and speed of the low frequencies within the room.

    By playing a track with good low frequency content for a couple of minutes or so, and moving the cylinder up and down, it is easy to hear the sonic differences. A few changes of height with the same track will determine the best tuning for the bass frequencies, in the position being tested, for the listening room and the audio system being used. There is a scale on the cylinder that allows the listener to raise and lower it with accuracy during the listening tests.

    This adjustment to tune low frequencies takes its inspiration from a device used by lute builders in the early 900s: its name was Tornavoz and was used to increase the sonorous projection of sound and the low frequencies of the instrument.

    In the middle of the VOLCANO is a membrane stretched within a wooden frame which can be orientated from vertical to a horizontal position by an external knob. The membrane is made of a special acoustic material. By angling this membrane it is possible to adjust the high frequencies: the vertical position give more texture and sweetness to the high frequencies, whilst the horizontal position gives more body to the mid frequencies. In most applications, somewhere between the two is tuned to taste.

    The top of the Volcano is specially shaped so that the internal and external curves are different. The underside of the top is a shallow curve of very specific shape. This curved shape and diameter of the crater is of fundamental importance and essential to the performance of the Volcano. There is a fixed hole in the centre which is also shaped with calculated curves and diameters and works in conjunction with the shallow “crater” of the top. These parameters have been extensively studied by Acustica Applicata, going through several prototypes and hundreds of hours of listening and measurement tests. This top part, shaped like a crater with a hole in it, is the inspiration for the name.


    The Standard VOLCANO is in two parts and simply links together by placing the top section onto the wooden flange of the bottom section. These parts are not glued as it just sits into a machined groove within the wooden flange. This also allows for ease of cleaning the internal parts, and for adjustment of the tuning cylinder in the base. (In practice, it is also possible to adjust this tuning port from the outside from underneath the base).

    The standard VOLCANO is effective from 35 Hz and upwards. By adding an additional extension Plexiglas module, the lower frequencies treated is starts from 25 Hz and upwards. The overall height of the Volcano is then increased by 42.5 cm (16.7”) to 144.5 cm (57”). This can extend the use of the taller Volcano to corner positions in very large rooms or attic spaces with angled ceilings or that are mansard shaped.


    The VOLCANO is delivered in one carton, the same size as a DAAD No. 4. The two sections are separately packed inside. It takes no time at all to unwrap these sections and place the lower part in the position to be treated, usually between the loudspeakers. Then place the upper section into the groove in the appropriate wooden flange at the top of the lower section. No fixing or gluing is required.

A recent trial with one of our customers produced this appraisal from him:

I have to say that this device has made the biggest difference to my system of any I have tried to date, whether cables, valves, plugs, even the DAAD’s themselves. The improvement it brings about is profound and transformative. This has to be the best value improvement it is possible to make to any high level system. Absolutely incredible. Thank you for the opportunity to audition – and to buy - it.

DM Oxfordshire

Schuko 8 Bar distributor – 8 Schuko sockets

The Volcano

For those that do not want to use DAADs for aesthetic reasons, the Volcano can be used in corners to good effect but there are some compromises. Similarly the Volcano can also be used on the centre of the wall behind the listening position. By doing so, a Volcano can save the requirement for 2, or even 4, DAADs in such applications, with some compromises.

The Volcano has a fixed port in the top, and a further port in the bottom that is height adjustable to tune it to the bass frequency to be addressed. Inside is a paddle that can be adjusted in angle to improve and tune the higher frequencies.


The standard Volcano comes in two parts that are fitted together easily. No fixing or gluing is required. Where excessive bass energy problems are encountered at lower frequencies, an additional centre piece can be purchased and fitted to increase the height from 102 cm to 144.5 cm. This centre section (42.5 cm high) can be added at the time of purchase, or retro-fitted easily at a later stage.

 

Standard Volcano: height 105 cm (40"), diameter 40 cm (15"). Effective from 38 Hz. £2100
Standard Volcano finished in matt Anthracite or White. £2300
Additional Centre Module: height 42.5 cm (16.7"), diameter 40 cm (15"). Effective from 25 Hz £700             Additional Centre Module finished in matt Anthracite or White £800


The Halifax is similar in design to the Volcano but is shorter and slightly wider. It is designed principally for use in home cinema systems, hence the reason for its lower height, and is only available in matt anthracite. It is effective from a lower frequency than the standard height Volcano, 28 Hz. There is an adjustable tuning port and internal paddle as with the Volcano. However, it cannot be extended in height.


Our listening tests have found it extremely effective in typical 2 channel stereo systems and the lower height can have less of an impact on the room when placed between loudspeakers. Because it is effective from a lower bass frequency, some customers prefer the sound to that of the standard Volcano.

 

Due to increased costs of transportation and customs tariffs post Brexit, we have reluctantly had to increase prices.

 

Halifax: height 88 cm (35"), diameter 42 cm (16.5"). Effective from 28 Hz. £2400
Standard finish matt Anthracite.
Halifax in RAL colours on request £2800

Schuko 8 Bar distributor – 8 Schuko sockets
UK 6 Bar distributor - 6 UK sockets
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