Monday, 28 October 2013

Setting the scene for success...

Running an efficient demo...
It was a couple of years ago, I attended a demo given in a prestigious place, run by a distributor of AV equipment.

A complete Home Theater system was hooked up, albeit fancy leather armchairs which were not really within the scope of this demo anyway, the equipment alone was worth about £150,000 and I knew all of it was first class.

The demo began with music first. 

  • The first soundtrack was a vintage recording of the Beatles (from the middle sixties, in mono). 
  • The second one was from Pink Floyd “Dark side of the moon”, and 
  • The third was a New Orleans style brass band.

These old recordings did not do any justice to the expansive audio system, but there was something worse…

An automatic Eq had been used, from a measurement made with an average of X microphone positions.

One obvious problem (there was more than one, actually, but this one was so obvious to me that all the others were hidden) was that by averaging different microphone positions, the analyser measured the acoustic power response, not the pressure response. As the loudspeakers were not of the constant-directivity horn type, the directivity increased with frequency, which is typical of consumer grade speakers. So, for a flat on-axis response, the power response was decreasing with frequency.

As the analyser measured a naturally rolled-off power response, the automatic analyser boosted the HF.

The result was a very prominent on axis HF response, which sounded incredibly harsh.
The whole demo was a disaster, and quickly shut down my attention. I can’t even remember what the videos were.

So, from this experience I deducted three things:
1)      If the sound is not right, you don’t even notice the videos
2)      Never use a vintage recording
3)      Never use an automatic equalizer (unless it is the only thing you are trying to sell)

This was only one demo, but I have seen  hundreds…
So I will try to put together my thoughts, following for your review, in an organized way.


1 The whole demo must be perfect from a technical standpoint
2 The organisation of the demo must be a perfect selling machine

Let’s start with 1

A perfect demo from a technical standpoint is when you reach immediately this “suspension of disbelief” that only happens when nothing distracts you from the action.
This means that:

  • The image must be perfect
  • The sound must be perfect
  • The image and the sound must be in perfect coherence
Actually, nothing is perfect in the real world. So we can afford an approximation we will call “perfect” which is immediately perceived as perfect and when after a while, no serious flaw is perceived.

Achieving this in imaging is not very difficult, you only need:

  • A good projector (with a lumen output suitable for the screen size)
  • A good calibration of the projector
  • A good screen (this you already have if you are my client)
  • A dark room
Now you need a good sound.

This is very, very difficult. Believe me, as an acoustical engineer having been designing sound systems for 33 years now, I am still discovering new things quite often.

The sound is about the sound system, its layout, the signal routing, and the room acoustics. All these are strongly interacting, so if you get one thing right, it might not be suited to another one.

This is what I will develop in details in the next series of articles, as it deserves a proper study.

Finally, you need the sound to be in coherence with the image. This is not very complicated. 

First, you need to place the L,C,R speakers behind the screen, like in commercial cinemas. This means that the screen has to be Acoustically Transparent (A.T.)

The problem is: Only one projection surface is Acoustically Transparent and does not deteriorate the image, It is the Enlightor 4K. Fortunately, you are familiar with it, and that is a good start.

Now that you have installed the front speakers and the screen to insure a good spatial coherence, you need to adjust the time coherence.

To achieve this, you need a manual lip-sync adjustment function in your AV processor (if there’s none, change the processor) and a test signal. I have sent you a test signal, but if you lost it, please download it following this link:

Now, back to the future!

I assume that you have had all the articles about the sound (please be patient), that you have got everything right from a technical standpoint, and you only need to get some prospects or customers to be blown away by your demo.

I am not a marketing consultant, so I am not going to explain you how to get prospects or customers to your demo room. Still, if you need it, I can send you some interesting literature dealing with the subject (just ask me in that case).

At this stage, you need to organise your demos. Let’s look at 2

You have to be introducing the system before you start. Describe the system in details, and explain your prospects that this time, it is going to be different. This grabs their interest: they are longing to see and hear something, and your explanation is a teaser.

Further, if you have described the system, they will not spoil the magic with spurious questions.
Then you fire your first track. It has to be grabbing their B----! Don’t start with music. It has to be breathtaking, it has to be action!

The idea is that when the first track is over, they come back to reality and immediately think: 
“this is THE system I want”

To achieve this, you must put together the following ingredients:
  • It has to be an action movie
  • It has to be in daylight (the scene, not the room!)
  • It has to be credible (so, avoid Sci-Fi, Batman, Robots, etc…)
  • It has to be loud
  • It has to be scary

I can think of two tracks which are a real good fit. One is the ship battle in Master and Commander. The low-frequency sound of the cannons firing has to be perfect though. I have seen it disappointing on so many occurrences that it is to be used only if you are certain that your LF is tuned the right way. BTW, this is my favourite for checking the LF of a system.

Another one is the Marksman in action scene from Saving Private Ryan. When you see the cannon of the tank pointing at …YOU, this is really scary.

Still, in this movie, I would try to avoid "gore" scenes, like on the beach. This can really put your client off.

After the first track, you can explain that they have seen only one aspect of the system capability. Now you must draw their attention on what to observe in what they will see.

I remember Julian Vereker and Ivor Tiefenbrun, respectively from Naim and Linn were very good at that in the 70’s (in demonstrating audio only). They have built their brands mainly on a demo protocol.

The second track should be about dialogue.  It evidences the coherence between the sound and image, and, as you will explain, it depends both on the nature of the screen and on the lip-sync fine tuning.

For this, you should select a dialogue or better, monologue scene. It must be the original version. Definitely discard any dubbed scene. If possible, if available in original version, select a scene in your client’s native language. This is easier in English or in Chinese than in Swahili, of course, but you need your client to understand easily what is being said without subtitles.
By the way, do not demo anything with subtitles: It is very disruptive.

Then, for the third (3rd) track you should show a train, a plane, a car or any noisy object travelling from one side of the image to the other side. This will demonstrate that you need the sound to be coherent with the image so that it travels following the same path as the noisy object. With solid screens the sound has to go down and then up when it goes from one side of the image to the other one. See:
Finally, for the fourth 4th AV track you have the choice between two options, according to you client’s profile if you know it (you should investigate this before if you can).
  • If he is a mainly a “videophile”, you should present him a scene with stunning pictures. Documentaries with landscapes are always bringing a nice touch of magic.
  • If he is mainly into audio, then a video from a concert is ideal. Be very careful though, about the image quality. Also, do not play “Hotel California” if your client is less than 50!

At this stage, your client has still a potential objection: If this is the system he wants for AV, he still is not so sure about the audio. You have to demonstrate that the system is much better than his Hi-Fi.
This is actually true. Remember, you have already gone through all the audio and acoustic optimisation I have (I will, remember: we are back to the future!) described to you.

Now you have to demonstrate the audio.

Here you don’t have to explain what he will have to pay attention to, as it could become boring and get on your client’s nerves. You have already done that with videos.
Start with a track # 1 containing blues-rock, a clean recording and an interesting voice.
I’d select “Black velvet” from Analah Miles or “Rock’n’roll dream” from AC-DC, for example.
Avoid tracks with too complicated sound effects, like Peter Gabriel for instance (although I quite like listening to it, but I wouldn’t use it for a demo).

Then you can play track #2, which has to be jazz, but a cool one. Use a track with a closed-mike recording of a female voice. Discard any free-jazz or brass band.

Finally, this one must be the last track:

You should play track N 9, “Solveig’s song”. This is an absolute killer: It would sell any decent sound system to (nearly) anybody.

Now your demo is over, it is time to sell.

To recap:

Films scenes:

  1. Saving Private Ryan
  2. Monologue (I like the owner of the island coming to the fridge and opening champagne in the first Jurassic Park)
  3. Train going from one side to the other
  4. Video of a rock or blues artist live concert. There’s a nice one with John Lee Hooker, Eric Clapton and the Rolling Stones together, for instance.

Audio only:

  1. Black Velvet
  2. Close mike recording of a female jazz singer
  3. Solveig’s song

Please comment...
All the best for now!

What do you think is the most important piece of equipment in a Home Cinema?

What do you think is the most important piece of equipment in a Home Cinema?

The spontaneous reaction to such a question might vary according to the person. 

Some might say “the projector” if they are image-minded, while others will mention “the speakers” if they are audiophiles. Others might say “a server” and Grand Dad will opt for the armchairs… and to some degree they are all correct as the beauty is in the eye of the beholder... 

On the other hand,  think a little bit deeper...

What do you see in a cinema room, when the light is off?
The screen

What do you hear when the movie starts?
The screensound travelling through the screen

Where does the action happen?
On the screen

This is a fact, once the lights are dimmed, the screen is all you perceive.

The screen is your window to virtual reality, and all the other pieces of equipment are dedicated to support the suspension of disbelief.

The screen is defining the size and the shape (flat or curved) of this window and it will be –for the duration of the show / movie - to support of the whole cinematic experience.

Now, would you regard the screen as an “accessory”? 
Would you accept a cheap screen to be given as a side gift to help promote the sale of a projector?

Definitely not, the screen is really capable of making your Home Cinema great success or a severe disappointment.

How to design your best Home Cinema

Plan your room

The first step is to start from the plan of your room. You will first define the audience area.
From this, you will define the size of the screen so that the rearmost seat provides a viewing angle of more than 36° and the front seat a viewing angle of less than 46°

This gives you a good indication of the screen width. 

Curved or Flat Screen

Now, you have to select between the curved and flat shape. Typically, a curved shape is more immersive and cinema-like. A flat shape will be better suited to sports or TV programs. 

Aspect Ratio

Then you will want to decide a native aspect ratio. Again, the 2.35/1, 2.37/1, 2.40/1 are best suited to most contemporary movies, whereas 16/9 corresponds to the vast majority of TV programs and sport events. So the aspect ration depends on your favourite programs.

Note that a 2.37/1 screen should be wider than a 16/9 screen, typically. So you should aim at a viewing angle of about 45° for a 2.37/1 (WS) screen and rather 40° or less for an HD (1.78/1) screen at the best seat location.

Acoustic Transparency

Now if you are sensible, you will want the sound to come from the image and not from elsewhere. This means that your screen has to be Acoustically Transparent.
Of course, you need to select among screens those offering the best Acoustic Transparency.

Of course you don’t want any spurious moiré effect or any artefact. This discards all perforated or “microperforated” screens that provide a visible regular pattern interfering with the pixels pattern. It also discards coarse woven screens, for the same reason.

Infinite Black Velvet

Not to be distracted by a defect on the whole presentation, you will need to slightly overscan the image so that the screens black borders exactly re-frame the picture. So you need the frame to be absorbing efficiently all the light projected on it.
So your screen needs to provide a frame with a “blacker than black” velvet coating.

Ultra HD

Next, you will realize that Ultra HD (aka 4K resolution) is becoming the new standard in video projection, approaching film-like imaging quality. So you will need a screen projection surface that does not limit the video resolution –in other words, that does not exhibit any visible weave pattern – This is more difficult, but it is what you really need.

Now you “tick all boxes” and you will have the specifications for your ideal screen. 

The good news is that such a screen does exist. It is a Screen Excellence with the Enlightor 4K projection surface.

Enquire now about Screen Excellence, and get your free gift when registering with us.

As you begin your design for the perfect home theatre / cinema - it should start with the screen as that is where all the focus will be placed.

3D Compatibility....

Screen Excellence Screens and 3D...

There are various 3D technologies around: 

  • Anaglyph, 
  • Active shutters, 
  • Polarization.

Some high - end products use a recent evolution of the Polarization (Runco, Cineversum) which is not compatible with any other screen technology than solid or perforated. The reason is that they request the screen to be metallized, which is impossible with woven screens.

Some projectors use both polarized and anaglyph (Sim 2 stacks)

Our Enlightor 4K material is fully compatible with all technologies not using polarization, and hence with >95% of the projectors, including all DLPs, Sony and JVC (Both of these not being DLP).

One of the main issues with 3D projectors is the loss in brightness. About 70 % of the projector brightness is lost in the 3D processing. The motto of most projectors manufacturers is "just use a screen with gain", which of course is a problem for Acoustically Transparent screens. We could reply "just use a brighter projector", but of course this increases the cost.

Fortunately, 3D images are not requiring so much brightness as the 2D ones do. As a matter of fact, JVC projectors are making 3D demos with our 160" screen, although their projectors are not among the brightest in the market.

Perfect Projection Surface...

Perfect Projection Surface...

This article describes a perfect surface for a home theatre screen.

As I walked my dog down the lovely smooth flat sands of East Anglia, I thought it was a perfect surface for playing ball; it bounces perfectly!  

East Anglia Beach, UK
So what is a perfect surface? In Tennis, is it Grass, Clay or Hard court?  My preference is grass as it adds unpredictability to the game, however, unpredictable results in a home theatre would not be welcome.

For a home theatre, that produces a true cinematic experience, the surface should be a white fabric that is acoustically transparent with little or no gain.

The perfect surface is a surface that diffracts light evenly, without artifacts, hotspotting or the like. 
It should not have any visible structure, and in no case larger than the smallest pixel of the projected image This last criterion is particularly difficult to combine with a proper acoustic transparency, especially if considering Ultra HD –that is 4K – projection.

It should not incur any moiré artefact by interfering with the pixels grille as projected.

It should not distort the colours.

Screen composition...

Most acoustically transparent screens are made woven of fibre glass strands coated with PVC. Although such designs bring a considerable improvement in terms of acoustic transparency over the traditional microperforated vinyl surfaces, they are limited by the mere diameter of the thread with respect to resolution.

In short, they are fine when the screens are very large (> 6m), but as the smaller the screen, the smaller the pixels are, and the image resolution is no longer limited by the projector but by the screen itself.

Further, when the step of the fabric structure is of the same order as the step of the pixels grille, moiré is very likely to occur.

We have addressed all these issues as far back as in 2009 when we launched the ultimate projection surface, the Enlightor 4K

Made of a very fine yarn (about 0.08 mm) which is twisted to avoid any visible structure, it has no visible difference with a solid projection surface.

Still its acoustic transparency is unique, as its frequency response is intrinsically flat, providing a uniform 2.5 dB attenuation throughout the 200Hz to 20 kHz frequency range.
This attenuation is only due to absorption, not incurring any backwards reflection, no time domain alteration, no directivity modification.

Enlightor 4K Fabric

This uniquely woven fabric is available exclusively from Screen Excellence.  Its look height allows us to build screens up to 290 cm high, reaching 260” base width in 2.40 aspect ratio.

Why Acoustically Transparent?..

In every movie theatre (or Cinema) you can experience an AT (Acoustically Transparent) screen at work. The seamless synchronisation of image and sound in the same location is fundamental in the art of suspension of disbelief. It’s the ability to absorb the audience in the ’reality’ of large-scale pictures that gives the cinema its enduring appeal.

In a professional cinema, all three (L/C/R) front soundstage loudspeakers are installed directly behind the screen with the centre channel being positioned where is belongs, behind the centre of the screen.

So the right question is not so much “why choose an A.T. Screen  ?”, but “how much is lost by not using an A.T. screen  ?” There’s far more to the answer than you might imagine.

If   a non-A.T. screen is used, the centre channel loudspeaker is located below or above the image. When viewing the film, we become aware that the origin of the sound is clearly different to that suggested by the image. The larger the screen, the more obvious it is. The mismatch between sound and image location is all we need to realise we’re listening to a sound system rather than a live scene. The suspension of disbelief is gone.

Another issue is the poor sound quality due to immediate floor or ceiling sound reflection of a speaker placed too close from a hard surface.

But neither of these two shortcomings are as severe as the total dislocation of sound and image when the centre speaker is not placed where it should be: behind the screen, at its centre.

The Lip-sync

Whether or not we are aware of it, we can all read lips and we notice when sound and lip movement are not synchronised. Lip-synchronisation is essential to overall intelligibility. In its absence a common solution for improving intelligibility is typically to raise the sound level of the centre channel speaker.

Such a level increase, often as much as 6dB (that is, multiplying power by 4) has significant consequences in both speaker distortion and perceived balance of the front soundstage.

Next time you go to Cinema notice how easy it is to accept sound and image as one. Now, ask yourself, do you wish for a Home Theatre or a true theatre in your Home? 

Only an Acoustically Transparent screen can help to realise your dreams.

Freqency Response

For a true cinematic experience you want the sound to pass through from behind the screen. The viewer will see and hear the difference.

Some manufacturers do this with micro-perfing (small holes in the screen) which is not noticable in large screens like an IMAX theatre screen. However, as you bring the screen size down the hole patterns can create a moire' effect which distorts and blurs the image. Additionally, a micro-perf will require EQ to compensate for the loss in db and specific frequencies. This cannot reduce the time-related distortion due to the sound bouncing back off the rear surface of the screen, then on the front panel of the speakers or the rear wall, and then on the screen again…

Using our Enlightor 4K projection surface, we are allowing the sound to flow from behind through the screen with minimum absorption and no distortion or frequency response degradation.


"Overall, the benefits of placing the loudspeakers behind the screen in order to have spatial coincidence between picture and sound by far outweigh the picture and sound degradation issues." - Widescreen Review

With a low to medium gain in AT screens you will want to use a bright projector in a darkened room. Ideally, you’d select an Ultra HD,4K projector to enjoy the maximum available resolution by today’s standard.

In conclusion, for a true cinematic experience you will require an acoustically transparent screen capable of not limiting the resolution of the projector by any standard, whatever the size of screen you choose.

Screen Excellence provides AT screens in a variety of standard configurations as well as custom screen sizes to meet your exacting needs.

Design of a Dubbing Theatre...

"Although the design of a dubbing theatre need to be balanced in many ways, my primary goal is usually to achieve the best sound that I can without significantly compromising the other aspects. 

For four years, now, I have almost exclusively requested the use of woven screens, the majority of which have been the Screen Excellence Enlightor 4K. 

In fact, although it is often claimed that perforated screens have better optical properties, no client that I am aware of has ever commented negatively to the dubbing theatre operators about the image quality when using the Enlightor 4K screens, and the acoustic properties have been beyond reproach. "

Philip Newell
Acoustic Design