Tuesday, 18 February 2014

What are Comfort Monitors?

Comfort Monitors are visual displays that are used to assist presenters during their presentation.  

These come in a few forms:

Timer Monitors

When a conference or presentation needs to run to a specific schedule it is worthwhile to give presenters the ability to see both how long they have been speaking for, as well as how long they have left for their speech.  A time monitor shows both of these in a simple bold format.  SXS have proprietary software that allows for specific timing data to be shown.  We can also show other data on the screen as required by the event.

Timer comfort monitors for conference and awards event production

Presentation Comfort Monitors

A presentation comfort monitor is a screen that allows the presenter to see what is being shown on the main screen without moving away from the audience. This is typically done with a plasma screen or LCD monitor either in front of the stage, at the back of the room, or flown overhead.  It is best that this monitor is not far from the audience so as to allow the presenter to generally keep their attention toward the audience.

Presentation comfort monitors for awards shows and conferences


Teleprompters are also known as Autocue - they refer to the same thing and the phrases are used depending on context, industry and region.  These work by having a thin sheet of glass standing at eye level and on a 45 degree angle.  A monitor is then placed on the ground so that the reflection can be shown in the glass.  When used correctly these devices are invisible to the audience.

Autocue teleprompter comfort monitors for conference and awards events production

Read more at www.sxsevents.co.uk
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Power Distribution for Events - The Basics

This article is directed towards inexperienced people to enable them to easily understand Power Distribution.  I have omitted in-depth technical information as this is probably not helpful at this stage and is more likely to be of interest to a power technical.  Consequently, this article should not be criticised for lack of technical detail.

Why Power?

Electricity is the only form of energy used to deliver power to a variety of appliances. 

Mains Power

'Mains' refers to power from 'the grid'.  The grid is the national power network of power lines, substations, transformers etc.  This is where the electricity comes from which delivers power to people’s homes.

For events we always aim to use mains power where possible.  The reason for this is that it is reliable in the UK (not always the case in other parts of the world), readily available and has a very low unit-cost compared to installing generators.
Many event locations have ample power coming into a building but a common issue is that there is not an appropriate method of attachment to the existing system.  I am regularly told by site managers that “there is loads of power” but this does not help when a specific type of connection is required. In these cases it is often possible to negotiate for a dedicated power socket to be installed as this is frequently cheaper than hiring generators.  Having a socket installed needs various considerations, such as distance from the power distribution board, gaining approval from landlords, agreeing on who is covering the cost and sometimes even permission for use in listed buildings (in the UK).

Wall Sockets

Traditional consumer wall sockets do not deliver large amounts of power (UK sockets allow a draw of 13amps – enough to power three typical theatre lights).  The phrase “there is loads of power” is not always accurate for power use at an event. A large number of sockets is not what is needed for medium to large productions due to the manner in which power is distributed with professional production equipment.  Please contact our team so that we can speak to your venue about power and we will find a suitable solution for your specific needs.


Generators are devices that produce electricity on their own without the need for attachment to the main grid.  In most cases generators are a diesel engine attached to a dynamo. A dynamo you may recognise is one that attaches to the wheel of a bike to power the bike light. Dynamos in generators are much larger.  The basic engineering principles behind generators are simple and long-established but many generators have sophisticated control and synchronisation systems.
As generators are powered by a diesel engine, they are generally reliable.  However, it is always sensible to have a back-up in case of failure. Uninterrupted and reliable power is essential for events and a generator breakdown, although unlikely, can mean failure of lighting, catering, audio, tills etc.
Therefore, I would always advise clients to have a backup 'set' (the name for the generator unit) and insist upon it if our company is providing the generators for essential parts of an event.
There are several ways of having a backup system.  The most effective and reliable is using two generators in synchronisation.  This means that both generators work together to create electricity, and if one set fails the power continues without any gap in the continuity of the event.  This is our preference but requires the use of modern generators with a skilled operator.
The second option is using an 'AMF' or switch-over panel. These systems detect when one generator has failed, starts the other, and switches the power over.  These are ideal for building sites or other locations where 'clean' consistent power is not vital.  For events these are - in my view - best avoided as it is essential that technical equipment is checked over by a skilled technician before being turned on again.  A lot of equipment (especially audio and IT equipment) needs to be turned on in the correct sequence to avoid any problems.
The third option is a 'manual change-over'.  This is simply to have one generator working and another sitting next to it, but not connected.  With this arrangement a technician needs manually to move all attachments from one generator to the other.  If done properly this is a safe and thorough system,  but can result in down time of anywhere from 1-15 minutes depending on the size of event.

As with all production design, it is necessary to choose an appropriate solution based on all factors such as budget, time, space, available resources, the nature of the event and the importance of each aspect of the event.

Battery Power

Our team recently had a brief from a client to manufacture a high-power mobile sound system to be moved around a shopping centre without any cabling.  To do this we used an array of 'leisure batteries' (similar to car batteries) with an inverter (a device that provides mains style power from a low-voltage system).  This was an effective system that allowed for 12 hours of performance without any cables.
Battery power can be considered for some applications but only where it is very difficult to access mains power.

How Much Power?

The answer to this question is determined by the specific needs of an event.  As a power distribution contractor we ask clients to list as many of the items or areas that require power and how much power is needed.  Our calculation model then gives us an indication of the maximum power requirements for an event.  We have had a great deal of experience in this area and suggest you speak to our team to discuss this in more depth.

Water, Weather and IP Ratings

Needless to say, water and electricity don’t make good bed fellows! For all outdoor or covered events in the UK special consideration must be given to water and the risks it poses.  Firstly it should be assumed that a torrential down-pour is possible at any time of year.  This assumption has led us to ensure all outdoor equipment is rated to a level that can withstand this.
Equipment that is used outdoors (i.e, subject to the elements or ingress from the elements) should have an appropriate IP rating.  IP ratings relate to how well electrical equipment can withstand dust and water.  A minimum requirement for outdoor use is IP55.  Any equipment without this rating should not be used outdoors as it can present a real risk of electrocution or at least a power failure.


Single phase and Three phase

To understand what phases are and how they work you need to have a in depth knowledge of electrical theory.  For the purpose of general understanding it is important to know that single phase power is one lot of power, whereas three phase works like three lots of power from one socket.
So a 63 amp single phase supply can only provide 63 amps.  A 63 amp three phase supply can provide up to 189 amps of power.  The size of cable and connectors between both these supplies is similar.  Three phase is more commonly used as it is a more efficient way of distributing power as all three phases share the same earth and neutral, which means less copper, less weight and one cable instead of three.
Generally speaking event power is provided on connectors which are known as 'cee-form', 'commando sockets' or a name defined by their current rating.  These connectors come in ratings of 16amp, 32amp, 63amp and 125 amp.  Single phase connectors are blue and three phase connectors are red.  If a power supply is defined by a current rating that is not one of these numbers then the reliability of the information should be questioned.
For power supplies above 125 amps systems such as 'Powerlok' or lug-based systems are used and typically provide up to 400 and beyond amps in three phase (1200 amps total).   This type of equipment is very specialist and only used for projects where very large amounts of power are being used such as arena concerts and large marquee events.  We hold a wide range of power distribution equipment amounting to many kilometres of cabling.


Breakers work in the same way as a fuse – if current beyond their rated amount is drawn they will 'trip'.  This causes the power to that supply to cut out immediately to avoid any damage or danger.
The reason breakers are used is to protect equipment and cabling.  If too much current is drawn cabling can overheat and catch fire.
Breakers can be tripped because of over-loading, but also because of a short circuit in a system, including light bulbs blowing.  Breakers tripping are not uncommon and in a well-designed power distribution system this should not cause major issues as each area should be isolated.
From our experience we have found that it is often catering equipment and catering areas that cause power to trip most frequently.  Consequently we tend to isolate these areas from other power users such as audio, lighting, IT, tills etc.


An RCD is probably the single most important safety device in an electrical system.  RCD stands for Residual Current Device and will “trip” in the same way as a breaker when triggered. RCDs work by detecting when current has gone astray from a closed system by looking for a current difference between the active and neutral supply within a supply.  This situation can occur when there has been a fault and current is feeding to ground or into a person.
RCDs come in different sensitivities (30mA, 100mA and 300mA for most applications) and this sensitivity relates to how much current has to be disappearing before they trip.  In the UK any power supply that is feeding appliances in contact with people should have a 30mA RCD on it.  This means that if more than 30mA is going astray the power trips.
RCDs and breakers are often combined into the same unit.


'Earthing' is another very important safety function within power and it also plays a unique role with audio equipment.
An earth is essentially an additional wiring system that runs throughout a power system that ultimately connects into the ground via a long copper rod, underground grid or similar. 
The idea behind an earth is that if there is a power fault the current will be directed into the ground rather than into people.  In such a case an RCD or breaker should trip, indicating to the user there is a problem that needs investigating.
Often the cable route from appliance to ground can be very long and contain a great deal of resistance.  For this reason we conduct a routine called 'earth impedance testing' which ensures the route to ground is good. This is an essential part of the 'sign off' process once equipment has been installed.

Sign Off

A competent power contractor will provide an installation sign off upon completion of their work.  This is an important process and acquiring this documentation is vital for an Event Manager.
The process checks that each area has been installed correctly in a formulated and thorough checklist approach.  The sign off states that all equipment has been installed properly and safely.

PAT Testing

PAT stands for Portable Appliance Testing. This is an annual test procedure that should be carried out on all equipment that distributes or uses electricity.  This applies to all electrical items both at events and in commercial environments such as offices or warehouses.
Upon completion of a test an appliance should have a sticker attached stating the date of the recent test, when the next test is due and who did the test.  This should also be logged in a database so that a full report of all assets can be provided upon request.  Some operators may choose to use a bar-code system that allows them to recall the test history for an item.
At SXS we apply new stickers whenever a test is done.  This shows test date, re-test date, product code, product unique identifier, who did the test.  Our stickers also have a printed barcode to allow us to scan the item in our system to see its past tests.  Our custom-made test database is part of our integrated company intranet and allows staff to access all data when onsite.
On occasion an item may fail a PAT test, in which case it is typically repaired immediately and re-tested.  Sometimes a piece of equipment may be condemned and disposed of.
PAT testing is a legally binding safety procedure as it will flag up faults that are not obvious in normal use (in particular a faulty earth bond).  However this is an annual test and only states that the equipment was compliant on the test date – much the same as an MOT (annual car test in the UK).
Visual inspections take place at every use of equipment with a subsequent reporting procedure and are vital.  All our staff are trained to look out for visual faults and remove the item from stock for immediate repair and re-test f any are found.
Safe management of equipment requires annual testing, visual inspection at every use and, most of all, experienced staff and an open culture with a focus on safety.

Power, Current and Volts

These are complex and highly technical due to - for example - impedance and voltage drop.  But for the purpose of a general understanding it may be a useful non-technical explanation:
Power – the relationship between volts and amps – this is how much actual energy is being used.  Power is measured in watts, kilowatts and is sometimes expressed in kVA (beyond the scope of this article).  Watts can be translated into calories as both are a unit of energy used. Sometimes a supply may refer to watts; in which case the provider is suggesting what the maximum is that can be taken from the supply.  A kettle may use 2000 watts, a TV 100 watts, a desk lamp 20watts, a powerful theatre light 2000 watts or a large followspot 7000 watts.
Volts – volts are what come out of a socket. What is plugged into the socket does not have an impact on voltage.  The volts are forced through an appliance.  Sometimes voltage drops (usually due to long cable runs) which can have a range of implications.
Amps – amps are a measure of current and mostly relevant to equipment used for power.  Cable and connectors are generally defined by how much current they can safely handle.
People often define electrical systems in amps or watts.
If volts drop, amps go up.  It is important to allow excess capacity in equipment to withstand an increase in amps (current).

Read more at www.sxsevents.co.uk
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Monday, 17 February 2014

6 Types of Video Screens

 As content becomes increasingly digital, the display of video content is an important factor in retail, event, exhibition and other spaces.  Video and other digital content is shown on video screens which there are many types of. This article outlines the main types of screen.  This article was written in 2013.

1. Plasma

'Plasma Screen' is one of those phrases that has become generic and refers to almost any flat panel video screen.  In reality Plasma is a very specific form of video display and one of the first to become widely available.  Generally speaking most screens over 40” released before 2012 were most probably plasma.  From 2013 onwards plasma has become increasingly rare as LCD/LED is more popular.

  • A very consistent image quality across the whole screen
  • Even luminance across the whole screen
  • Heavier than LCD
  • More fragile than LCD due to glass panels
  • 'Burning' where the same image shown for long period is permanently burnt into the screen

2. LED

LED stands for Light Emitting Diode and can be regarded as a light source similar to light bulb for the purpose of developing a basic understanding.  LED Screens are made up of many red, green and blue LEDs. When controlled individually these form 'pixels' which are the basic building blocks of any digital image.  Sometimes the red, green and blue LEDs are separate and sometimes are used in a 'tri-colour' arrangement whereby the individual colours cannot be distinguished.
LED screens are typically seen as digital bill boards, at large outdoor events and in stadiums.

  • Very bright to the point that they can compete with full daylight
  • Generally these are the only solution suitable for large screens or for outdoor use 
  • Generally quite costly (although reducing in price)
  • Generally lower resolution than Plasma or LCD (although at time of printing 3mm pixel pitch screens are becoming available)
  • Generally heavier that LCD
  • Risk of 'dead pixels' where a pixel stops working which can ruin the effect of the entire screen

3. LCD / LED

LCD stands for liquid crystal display and is the technology seen on digital wrist watches and most mobile phone screens and nearly all computer monitors. Increasingly LCD screens have become referred to as 'LCD/LED' or simply 'LED' screens. This is because LED is used as the light source to illuminate the Liquid Crystal Display. Liquid Crystal does not emit light naturally so requires a light source behind it.

  • Lightweight
  • Cost effective
  • Thin-bezels (in some models) allowing for 'video walls'
  • Very bright  
  • Uneven brightness across panel (but only to the experienced viewer)

Terminology of the above

This writer feels that these terms are becoming confusing for clients so our company refers only to “Plasma Screen”, “LED Screens” and “LCD Screen with LED Backlight” to avoid any confusion.

4. Projection

Projectors are one of the most common ways of showing video content at events.  These work by shining light of the video image onto a surface which can then be viewed by an audience.  The most common example of projection is at a cinema. 
This is a very common method of content delivery as it is often very simple to setup; a single projector can be plugged in and pointed at a surface.  Whether this is for a small presentation right up to larger awards shows this can be quicker and more effective than erecting LED video walls or video screen walls. 
Video projectors range in size from as small as a paperback book up the size of a large fridge (cinema-grade equipment).
  • Single unit to setup and rig
  • Cost effective at almost all sizes
  • Minimal support and structure needed
  • Can project onto existing surfaces such as walls and buildings 
  • Limitations on brightness
  • Need for specialist lenses dependent upon application
  • Need for low light levels in rooms where they are used
  • Need for a screen or other projection surface


HOLOX is a holographic effect developed by SXS for live events.  This uses projection technology mixed with classic theatre design principles to create a holographic effect that impresses audiences.

  • Impresses audiences
  • Makes the content more memorable
  • Allows for theatrical interactions between presenters/performers and content
  • Requires low ambient light levels
  • Not suitable for highly technical content, such as engineering diagrams

6. HolActive

Holactive is another type of content reproduction developed by SXS which uses a mixture of augmented reality and pepper’s ghost holography. Holactive gives the user experience of interacting with a hologram.
This works by the user controlling the movement of a live 3D CAD rendering which is then projected within a holographic space. The effect and experience is incredible.

  • An incredible experience that helps people remember the content
  • Usable in any space
  • Quick to setup
  • Cost

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Stage and Performer Management

Efficient stage management is crucial to the success of your event. I have written this article to help you learn the basic principles of stage management, learn some techniques, and understand some common mistakes. A lot of our clients do not book acts or performers regularly, so the idea of doing this for a major event can be quite daunting.

Who Does What?

Before consideration is given to what acts to book, it is a good idea to think about who is doing what within your team. Sometimes your team can just be yourself, but typically you will be working with other people, agents and an event production company like SXS. Below are the key tasks that need to be delegated.

Sourcing acts

Given that this is key to the strategy of your event and budget, it is a very good idea to for the main event organiser to have a high level of involvement in this. The SXS team can assist with this process.

Negotiating with Acts

Even on smaller events there will be an element of negotiation with performers with regards to what they are doing, what they are bringing, performance times etc. Given the potential intricacy of this work it is best for an experienced professional to do this. SXS offer a free Performer Broking service as part of a larger production solution whereby we broker the deal to ensure everything has been covered and everyone is getting value out of the relationship. The event organiser may also decide to do this, but it is wise to get input from an experienced professional.

Artist Liaison

This is the role of speaking to all performers about the event in advance to ensure that everything will run smoothly. This includes discussing logistics, kit storage, stage layout, technical requirements, sharing of instruments, food, dressing rooms etc.

Performance Scheduling

This is the job of deciding what act performs when. This also involves creating a running order. This needs to be done with careful consideration of what else is happening at the event, such as catering, off-stage entertainment etc.

Stage Management

This is one of the most important jobs and takes place on the day of the event (plus advance planning). The job of the stage manager is to ensure that the performers and production team all know what is happening and what each party needs to do. The stage manager is also responsible for ensuring performers get on and off stage at the right times. This role requires good people skills, excellent organisation and the ability to think quickly and be flexible. It is also helpful for a stage manager to have strong leadership skills.

Stage Crew

Stage Crew are the people who move equipment on and off the stage.  They may also assist with helping load the performer's equipment in and out of the venue.  They will typically also ensure the stage is kept tidy.  In general stage crew are support staff to everyone else. 

Sound Engineers

The sound engineers do everything relating the technical side of the music - so microphones, cables, mixing, sound effects etc. Sound engineers will also reposition microphones and other audio equipment for each band.  Sound Engineers are not to be confused with stage crew.  On smaller events the sound engineer may also help  with stage crew work - but only on performances as small as a pub gig.  On multi-performer projects (corporate events, festivals, student balls etc) the sound engineers will need to focus all their time and energy on ensuring everything sounds perfect and all the equipment works well.

House Kit

House Kit is the general term given to performance equipment provided by the event organiser that can be used by multiple performers. This typically includes drum kits, guitar amplifiers, stage risers and keyboards. The benefit of house kit is that making it available can significantly reduce the time required for one band to get off stage and another to get on. The other benefit is that more of the setup work is displaced to a time well before the performers get to site. When I run shows I like to provide the drum kits and backline as it makes everything run much smoother on the day. This also means that our sound engineers have plenty of time to get the sound perfect. Extra time spent aligning microphones and tuning drum kits can make a huge difference to the quality of performance. We have an excellent stock of guitar amplification and drum kits that are suitable for international touring acts. These are immaculately maintained and setup by our sound engineers, many of whom are experienced musicians. Typically we aim to provide house kit for low prices to encourage clients to book this with SXS rather than getting musicians bringing their own. It is also worth seeing if the performers can offer some cost savings by not bringing their own drum kit and guitar amplification.


A rider is a document that a performer provides to outline their requirements for their performance. These range hugely in detail and style. I have worked with some US acts whose riders are 50+ pages and go into a very high level of detail with every aspect of their performance, food, backstage dressing rooms, transport, type of drinks, spec of hotel rooms etc. Other riders are a simple one-page document with a stage plan (layout of where each performer stands) and overview technical requirements. Many performers (especially semi-professional or those working in small venues) do not have riders. It is important to remember that riders are generally written with a certain type of show in mind. Sometimes I get given riders that have been written with a stadium performance in mind, but the event the performer is working on may be much smaller. In these cases the best thing to do is get an experienced production manager to speak directly with the performer's management or technical team to establish what is actually required. I have had conversations that are quite amusing for both parties, as in some cases the equipment specified on the rider would not physically fit into the venue! In other cases the performer's rider is far too basic for the show they are working on. In these cases the production designer should design a solution for the event which will invariably exceed the performer's expectations. This is a much more common occurrence for our team. The main thing to remember is that riders are almost always a set of guidelines and a basis for understanding the needs of performers. This means that there is usually flexibility from both performer and production designer. It is vital that open communication takes place between production designer and performer. While there generally is flexibility with riders, it is important to understand that there are often certain non-negotiables - i.e. things which the performer must have with absolutely no substitutions. These can include but are not limited to:
  • Certain models of sound or lighting control desks (often performers have their shows pre-programmed for a specific piece of equipment).
  • Certain models of backline such as guitar amps - as this is crucial to the sound of the performer.
  • A certain size of stage because of set or other equipment that needs to fit on it.
  • A certain quality of sound system (although there can be some flexibility on specific manufacturers as there are several main brands that all offer comparable quality).
  • It is wise to get a copy of a performer’s rider before booking them. This is because they may have very specific requirements that could present considerable costs to the event organiser. All production managers are happy to speak with your acts in advance of booking to ensure that a suitable technical specification is being provided.

    Scheduling the event

    The performance schedule is the most important document for stage management. The purpose is to show everyone what is happening, when it is happening and what each party needs to do to make it happen. The performance schedule should be a table with the vertical axis showing times and the horizontal showing what happens at each point.
    The column headings should include, as a minimum:
  • Start time
  • Duration
  • Performer
  • Stage manager
  • Stage hands
  • Sound
  • Light
  • You may also include other specialist areas where applicable such as video, special effects, backline technicians, dressing room etc. For each section of this running order write any relevant details that each party needs to know.

    Stage Safety

    A stage is a potentially dangerous workplace and as such needs to be treated carefully. Stage design and risk assessments are an in depth field of production management which requires considerable knowledge of statute and good practice as well as years of experience. As such it is beyond the scope of this article. However I will list a few top-line considerations below:
  • Stage height - do you need handrails, or a drop stage?
  • Light levels - have you got adequate work light in the backstage area?
  • Is the stage and roof structure sound and suitable for the environment?
  • Backstage tidiness - is the backstage area tidy and free from trip hazards or other items that could cause injury?
  • Public access - consider how easy it would be for a member of the audience to get onstage. You may identify needs for specialist barriers, or to make the stage suitable for public access (there are various statutes and building codes relating to raised platforms, ramps and steps)

  • On the Night

    By the time the event takes place all the hard work should have been done and the show itself should be a smooth and enjoyable experience.
    As long as everyone knows what they are doing and the planning has been done well the show should run smoothly. The exact chain of command will vary depending on the event, but as a basic outline the following are essential:
  • Stage manager to oversee everything and make sure the schedule is adhered to.
  • Production manager to oversee the technical aspects of the show and manage the sound and lighting technicians

  • Things to think about

    The following is a checklist of things that should be considered for a live event.
  • When the performer can gain access to the venue
  • Parking for performers
  • Access to venue, especially if there are large items
  • Storage of performer equipment
  • When sound checks take place
  • What order sound checks are being done in
  • Stage layout, especially if there are multiple performers
  • Any items that bands are sharing
  • Sound desk settings between each band (this is much easier now, as SXS use digital sound desks which allow for instant recall of settings)
  • Dressing rooms
  • How long each performer is performing for
  • What is happening between performers? Are you having pre-recorded music? If so, who is providing the music and in what format? E.g. will it be on a CD or USB stick?
  • Will have you a DJ, or other form of entertainment between acts? If so, what are their requirements in terms of space, staging, tech etc?
  • Food for performers and the production team and when this will be scheduled
  • Drinks for performers and production team
  • Water on stage
  • Towels on stage
  • How much time is available for bands to get off stage and the next one to get back on?
  • What happens if other parts of the event run over schedule and how this will affect the performances
  • Accommodation for performers

  • Final Notes

    As you will have learnt from this article, most of the work with stage management is done in advance. It is all about communication, managing expectations and organisation. Get this right and stage management can be a very fun and enjoyable role to have.

    Read more at www.sxsevents.co.uk
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Headsets Explained

'Headset' is probably the most overused and misunderstood phrase in modern production.  The phrase can mean different things to different people, companies and countries. 

We have seen many instances where minor mis-understandings have occured.  As such this article has been drafted to give clarity to all the different types of headsets and associated equipment.  All headset related items in proposals from SXS have a link to this page.
The names given below are what the SXS team use and are intended to remove any ambiguity when communicating what is required or being provided.  Phrases other than these should be avoided.

Radio Performer Headset

This is a device that a performer/presenter wears on their head to allow for their voice to be fed into a sound system to that audience members can hear them.  These are typically used in conjunction with a radio belt-pack system.  The devices we use are very thin and skin-coloured to reduce the visibility on stage.  Michael McIntyre uses these for his comedy roadshow.  Larger and thicker versions were used by 80s and 90s pop stars such as Madonna and Britney Spears, although we do not use these anymore for aesthetic reasons.

Show Comms Headsets - Wired

'Show Comms' refers to the specialist communications systems we use for "calling" shows.  These systems allow for both listening and talking at the same time.  These headsets are "closed cup" which means they fully cover your ear to reduce ambient noise.  These come in single-muff and double-muff versions.  These headsets are attached to a beltpack controller which is in turn physically wired into the rest of the system.  Due to the cabling required these devices limit mobility so are best suited to static technicians and managers.  SXS primarily use Tecpro and Altair equipment for this.  Wired show comms are very affordable to hire.

Show Comms Headsets - Wireless

These are exactly the same as Show Comms Headsets except that the beltpack is wireless.  These are compatible with each other.  This means that the user can move around freely, so are best suited to front-of-house managers, stage managers etc.  These devices allow both listening and talking at the same.  SXS use Altair equipment for this purpose.  Wireless show comms are considerably more expensive to hire than wired ones, so it is best to only use wireless where essential if your show is on a budget.

Presenter Talkback

Watch a TV talkshow or news show and you will see that the lead presenters generally wear a small ear piece.  This allows the show producer to speak to the presenter to update them on the progress of the show.  This can be done using an "in-ear monitoring" system (see below).  SXS typically uses wireless show comm systems for this though.  The reason for this is that we give the presenter the ability to communicate back to the producer very easily.  We have specially modified ear-pieces for this purpose.

In-Ear Monitors

Watch any modern pop-music performance and you will likely see the lead performers wearing what look like ear-plugs.  These are actually very small earphones that allow them to hear the rest of their band and themselves (known as "foldback" or "monitoring").  This system has a transmitter controlled by a sound engineer which transmits to a small belt pack on the performer.  The earphones (generally referred to as "in ears" in the UK) are plugged into the beltpack.  SXS use Sennheiser in-ear monitoring systems which are considered some of the best in the world.

2-way radio headsets

Imagine a walkie-talkie.  Now imagine what an airline pilot wears.  That is a 2-way radio headset setup.  A very important factor to consider with 2-way radios is that if one person is transmitting their voice no one else is able to.  This means that 2-way radios are only suitable for occasional site communication.  Although many people use these for "calling" a show we feel they are unsuitable in most cases.  SXS use Motorola 2-way radios for site communication as these are very reliable and durable.

2-way radio covert pieces

These are 2-way radio which can either recieve or transmit, but not both at the same time.  Covert earpieces are used a lot by security personnel as they are discreet and can be operated easily without large equipment.  This can be good for catering managers and other people walking through an event space.

SXS have large stocks of all of the above available to all clients.  SXS also hold their own radio frequency licenses for the above.

Sound Delay Explained

Delay of audio is one of the main design considerations for any audio application.  The concept is important in applications where multiple speakers are used through an audience area or venue.  The concepts also applies to stage layout, microphone placement and loudspeaker design
This article will explain the concept and the main environments to which sound delay tactics apply.

What is sound delay?

Sound takes time to travel.  This means that we hear things after they have happened.  Sometimes we notice this and other times we do not.  Sound delay is the time between when something happens and when we hear it.
A good example of this is lightning and thunder.  We see lightning immediately but it takes longer for thunder to reach us.  Another example is during very large concerts where the audience’s response to music may have a delayed effect. For example everyone jumping on a beat can give a quick “wave” effect as people further down the arena hear the sound.

How fast is sound?

Sound travels at a speed of 340 metres per second (760 miles per hour). This is subject to small changes depending upon air density, temperature and humidity.  The table below shows speed comparisons which helps us to understand relative speed:

Fastest bird flight (Peregrine Falcon) - 68 Mph
Boeing A380 cruising speed - 587 Mph
Speed of sound - 760 Mph
Land Speed record (Thrust SSC by Andy Green) – 763 Mph
Concorde cruising speed 1354Mph
F14 Fighter Jet max speed – 1544 Mph
Speed of Light – 670,616,629 Mph

So while sound does travel quickly, the speed is one we can comprehend and visualise.

Why does this matter for live events?

Imagine yourself standing at one end of a football pitch.  At the other end there is music being played from a speaker. On a quiet day you can hear the music and, although it sounds distant, you can hear what is playing quite clearly.

Imagine that another speaker is setup at the halfway line and playing the same music.  What would the music sound like?  You would hear the music twice, as one sound source will reach your ears followed quickly by the other.
The delay will be approximately 1/6 of a second.  This will make the music much harder to hear (in the audio industry we call this “reduced intelligibility”).  Now imagine two more speakers are added at different distances down the football pitch.  Now you are hearing the music four times but at slightly different times (we call this “offset”).  Consequently, the sound will become poor or “muddy”.  If this was the spoken word as opposed to music it would become hard to hear or to understand.

So sound delay can cause an issue and render a sound system almost useless.

Why Not just use one big speaker?

This is a very good question and there is merit in this practice.  If we just had one very big speaker we might not need many smaller ones and all the issues that go with time delay are gone.  

The reason that this is not done is because of coverage. 
Image this giant speaker sitting on the ground at one end of the football pitch.  Now imagine how loud it would need to be to give the person at the end of the football pitch a good volume.  If you were standing next to that speaker it would be extremely loud.  Anyone living nearby would certainly not appreciate this super-loud speaker blaring away.

Instead we use distributed speakers.  This means many speakers are placed throughout the audience area. As they are spaced out, the audience will be closer to the sound which means they do not need to be as loud therefore enabling the audience members to enjoy the sound at a comfortable volume.

So how are delay speakers used?

Return now to the football field example of four speakers.  To counter the problem of lots of sound sources reaching you at different times we add a delay to each speaker.  This means that the sound comes out of each speaker a little later than the first speaker.  How much later depends upon how far it is from the first speaker.  We call this process “delaying back”.

The sound then travels down the pitch and, as the sound from the first speaker reaches the next speaker, then the second speaker makes the same sound and therefore adds this to the sound field.

The effect of this is that each speaker is almost indistinguishable from the other sound sources.  The result is that the audience hears clear, accurate and precise audio.
A real world use of this method could be an indoor concert.  We may be using a large main sound system, such as a Martin Audio Line Array.  But it may also be necessary to have additional smaller loudspeakers further down the event space and under a balcony to provide even sound coverage.  In such a case these smaller speakers would have time delay applied to align them with the main sound source

In speaker design

Audio delay is also a very important concept in loudspeaker design, although the delay effects are much more subtle than in multi-speaker arrangement.

If the components (such as woofers and tweeters) within a loudspeaker are not in line with each other (common in most speakers) the sound will arrive with the listener at different times.  This means that high frequencies may be heard earlier/later than low frequencies.  Although the time delay is minute, it is enough to “colour” the sound.
To counter this aberration, the individual components within a sound system may be “time aligned” to the component that is furthest from the listener.  This way the sound at all frequencies is emanating at exactly the right time.  This time alignment is done using sound delay equipment as part of the sound system’s Signal Processing System.

Few people can distinguish a specific delay from one speaker component to the next but most people can tell that a correctly time aligned system sounds better than one that is not.

This practice is commonplace within professional audio but is rare in the semi-professional and hi-fi fields of audio.  In our company we use time delays for all 2-way, 3-way and 4-way active systems.

How is time delaying done?

Every loudspeaker component we use is controlled by a Digital Signal processor (DSP).  These devices have an array of control functionality of which one is time delay.  We are able to time-align loudspeaker components individually, as well as entire sections of an audio system.

In cases where it is necessary to time-delay microphones (such as in orchestral sound reinforcement) delay equipment is inserted into the sound desk.

HD Vision Mixing and Formats

In recent years there has been considerable development in video formats which has resulted in high-quality, flexible systems.  Most notably with advent of HD video.  This article has been written to give a basic overview of the main terms and concepts associated with this.

What has changed?

Only a decade ago most video was Standard Definition - less than half the resolution of modern High Definition.  High Definition relates primarily to the resolution (number of pixels) displayed - more pixels generally means a clearer image.  However there is more to it than than that, just having a lot of pixels does not mean the images is good.  More important is how little noise there is and how broad the dynamic range of the image - these two factors are arguably more important than resolution, especially on smaller screen.
HD video tends to be transmitted in digital format, as opposed to analogue, which means a more accurate image reproduction and less noise and inteference.

What is Dynamic Range?

Dynamic range refers to the depth of tones and colours - it can be likened to how much range in contrast is available and how many steps there are within this range.  High dynamic range is important as it gives a more realistic image with more drama.


These are three different main digital transmission systems.  Here is a basic overview:

SDI - "Serial Digital Inteface"  - this is a broadcast grade transmission system which is currently used for commercial video - you will not see it on the back of your TV any time soon.  SDI allows for HD video over long distances and is the standard for top-tier production and broadcast companies.
HDMI - "High Definition Multimedia Inteface" - this is a consumer-grade HD video and sound transmission system.  It provides very good video and audio quality on a simple and cheap connector.  However cable distances are limited to no more than 10m - as such it cannot be used as a primary transmission system for production purposes.  You will see HDMI connectors on most modern consumer video equipment.  We do use HDMI as an attachment method to screens and laptop but the signal is immediately converted to SDI.
DVI - "Digital Visual Inteface" generally speaking DVI is a connector that carries digital video.  HDMI signals actually carry a DVI signal (but not always).  DVI is common on the back of computers but seems to be getting replaced with HDMI these days.

What equipment do SXS have? 

We hold a considerable stock of broadcast grade HD video equipment. Our primary transmission format is HD-SDI which is for professional applications only. This format allows for long cable runs and full HD video. We also hold BlackMagic Design broadcast vision mixers, Blackmagic SDI converters and Van Damme SDI (BNC) cabling.We are very proud of this equipment as it allows a level of video quality on par with HD broadcasters, which we feel that is the level of quality that guests and delegates are now expecting.

Friday, 14 February 2014

Active, Passive, and Bi-Amped Speakers Explained

This article has been drafted to clarify one of the most widely and incorrectly used phrases in audio today - 'Active'.

Parts of a sound System

First let’s define the parts of a sound system:

Amplifier - the electronic device that changes a small signal to make it more powerful

Crossover - the electronic device which splits an audio signal into separate frequency ranges – such as high frequencies (treble) and low frequencies (bass)

Driver - the component within a loudspeaker of which there may be several.  These are sometimes referred to as “woofers” and “tweeters”

Loudspeaker - the box from which the sound comes from.  These can include one of more drivers and numerous electronics


In audio theory, active means that a crossover (the “active crossover”) exists before the amplifier.  This means that multiple amplifiers are needed to power different frequency ranges.   A system could be “2-way active”, “3-way active” or “4-way active” (5-way systems are rare but do exist).  This refers to how many bands the audio signal is split into, therefore each requiring a different amplifier channel.

Active crossovers are usually part of a Digital Signal Processing (DSP) unit and are commonly stored in racks with the amplifiers, although this does vary from company to company.


Passive means that a crossover (the “passive crossover”) exists between the amplifier and drivers.  Such a system could be “2-way passive”, “3-way passive” etc., which refers to how many bands the already-amplified signal is divided and fed into each driver.  Passive crossovers are typically circuit board mounted within the loudspeaker and have components such as resistors, capacitors, and transformers

Self-Powered Speakers

This means that the loudspeaker has the amplifier(s) within it to make it work.

What about “active” speakers?

People refer to products such as Mackie SRM450s, JBL Eons and RCF Art500A as “active” speakers because the amplifiers are built into the speaker.

In these examples the products do have “active” electronics as they have separate amplifiers for the low frequency and high frequency drivers.  The fact that the amplifiers are within the loudspeakers does not make them “active”

The correct phrase for these products is “2-way active self-powered”.

So people use the word “active” when they actually mean “self-powered” – which are different concepts.

Am I being pedantic?

No I am not.  The reason is that there are many self-powered speakers that are passive.  The distinction is important as it suggests a level of electronic complexity and audio quality.

Active and Passive

Some sound systems can be both active and passive.  For example an active crossover may split the signal into sub bass and full range.  The sub-bass signal then goes into a dedicated amplifier and then into a sub-bass speaker – this element is “active”.  The full range signal may then go into another amplifier which powers a loudspeaker which in turn contains a passive crossover and two drivers.  This example has both active and passive elements.  A good definition of this system would be “a passive 2-way system with a separate active sub bass element”.

Active vs. Passive

As with any field of technical engineering, each concept has pros and cons – neither is “better” or “worse” but each has situations for which it is appropriate.

Active systems allow each amplifier to only work on a specific frequency range.  This can be of benefit as a high current drain on a sub-bass will have no impact on the power and clarity for the high-frequencies. Active also breaks up the power requirements of a system which can allow for greater overall power performance in larger applications.  This can also help to increase “headroom” (spare power which helps achieve a cleaner sound).  Headroom is a concept that is very important to us as this is what helps create sound with big impact but without distorting or being painful.

As each element is controlled separately a greater level of project-specific customisation of each element is possible without colouring the sound.  This is important for larger audio applications where high performance is required.

The downside to active systems is that they require considerable processing equipment, many more amplifiers, more complex cabling and distribution networks.  This makes them significantly more expensive. Most professional concert systems contain active elements.

Passive systems tend to allow for lower maximum power levels due to fundamental limitations within the electronics of the passive crossover networks (although these limitations have reduced considerably in recent years).  Passive systems require less processing and fewer amplifiers which make them cheaper but less flexible.

Modern concert sound systems (including the Martin W8LM and D&B Q1 systems) can run in passive or active mode as they have highly sophisticated passive crossover networks which present minimal performance limitations.

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Gobos Explained

Sounds like a clown, but it actually goes inside a light!
A gobo is a metal or glass disc that fits inside a lighting fixture and allows for the projection of the image on that disc.

There are two main types of gobos. The first is metal. This is simply a piece of high-temperature metal that has had sections laser-cut out of it to make a shape. Think of a stencil that you might have made in art class at school, but much more accurate and much smaller. Because of the makeup of metal gobos, perfect circles are not possible, as they must have a join at some point.

The second type is a glass gobo. These allow for significantly more detail and allow for circles and other shapes. Glass gobos can have multiple layers that allow for multiple colours. Glass gobos are more expensive than metal ones.

Once designed and manufactured, the gobo is placed into a lighting fixture. Where there is a lack of metal or etching the light will pass through and project onto a surface.

Gobos can be placed into a range of light fixtures from moving lights to generic lights.

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How to Write a Creative Brief


In essence a brief is a way of communicating what you know that you need.  Briefs are rarely a definitive list of specifications but written more like a musing or a set of items outlining "what I know" and "what I think", mixed with relevant documents.  Briefs are used in law, creative industries, technical fields and construction, although they may not always be called briefs.


Briefs are ideally suited to situations when the requirement from a contractor (the person or company hoping to fulfil the brief) is difficult to define or uncertain.  Briefs are also suitable when the client (the person purchasing the products or services) knows less about the product than the person or business they are buying it from.  For example if a business needs a new website they will outline what they know they need for certain as well as items they believe they need, but are flexible on.  This brief will then be given to a design expert who may present new ideas, challenge parts of the brief or come back to the client and help them refine their brief.

In events briefs are particularly useful as often clients know some parts of their needs but others are less clear.   Clients will often know what outcomes they want from the project and they may also know what some of the key inputs to this are.  However they will

I personally find that clients all too often come to me with a list of specific inputs (the items or work to be done for a project) rather than outlining what they are trying to achieve from their project.  In most technical and creative businesses it is important to see past the requests for specific inputs and instead understand the objectives of the project.  For example a lot of clients often come to me asking for 4d projection mapping onto a building.  Following consultation with them it is often the case that what they really want is a means by which to make a brand message go viral; 4d projection mapping was just one idea they had but they are very open to new ideas.  In such a case other projection options, water screens, interactive content and experiential activations are often more appropriate, effective and cost-effective.

A simpler example is when clients approach us with a specific list of technical equipment they wish to use.  It is often the case that the list is incorrect, incomplete and based on legacy activity.  In such a case it is important to understand the project needs and "rebuild" the specification based on that understanding.


A specification is a specific list of what needs to be done, the parameters by which it should be done and often how it is to be done.  These items are sometimes called "input specifications" as they are the building blocks of the project.

A brief is an outline of what outcomes are required from a project.  Briefs generally invite dialogue, collaboration and even disruption to establish the right outcomes.  In the case of a brief, different providers may approach it differently.

It is often the case that after discussing a project with multiple specialists a brief becomes a specification and vice versa.

Specifications are very useful when quotes are needed from multiple contractors for comparative purposes; known as a "tender".  This can be a dangerous approach though as, if the specification is incorrect or inappropriate, later variations may be required which can be costly.  Having worked on many public-sector tenders I see this all too often and my approach is to contact the client and help refine the specification.  It has been my experience that many public bodies are not open to this dialogue which can result in overpriced and inappropriate solutions that fail to deliver on the key outputs.  At SXS we have a commitment to presenting solutions that are going to work and within a clear and transparent pricing structure - as such we frequently step down from doing public sector jobs. We see that winning them can only be done by knowingly quoting for unsuitable solutions to as to fulfil the specification or be "competitive".

The downside of a brief is that different possible contractors are likely to come up with different solutions to fulfilling the brief which can be very hard to assess quality and value on.


Discussion is good and should always be part of establishing relationships with new contractors or partners.  However to give a contractor a brief verbally puts people on the spot a little too much, which can prevent them from having the time to think through the brief.  A written brief gives the contractor a chance to speak to colleagues, do background research and think about a project on a wider basis.  Often a brief is just used as an efficient way of getting a conversation going.


The below is a structure that will be a useful starting point.  Items marked with an asterisk (*) are considered essential.

- Background* -  why the need has come about which will help contractors understand the motivations behind the event
- Parties involved - outlining the who the parties involved in a project are.  This could include client, site details, legacy contractors, authorities, beneficiaries and stakeholder groups
- Past projects - it is helpful to understand where a client has come from and what successes and challenges they have faced
- Outputs* - what the client is hoping to achieve from the project
- Thoughts* - what the client believe may be appropriate solutions, but are open to discussion
- What matters* - outline the factors that are most important to the client; speed?  Cost?  quality?  stakeholder management?  Innovation?  Environmental? Flexibility?  
- Creative communication - mood boards, pintrest pages and montages are a great way of communicating ideas to a contractor


In my career I have both received and written briefs for everything from making a custom desk, to developing bespoke software, to producing major European public-funded events. Below are some of the things I have seen done which are a really good idea to do, or not to do:
- Casual pre-qualify -  phone up contractors you are considering on including and find out if they are interested - this will help to avoid wasting peoples time
- Pre-qualify - a client should understand in their own mind the kind of contractors they are looking for - search for contractors that are within these parameters before sending out your brief.  Recommendations and examples of previous work are a good way of doing this.
- Avoid wasting people's time -  if too many briefs are sent out that do not convert into business contractors will start to lose interest in a client
- Ask contractors what they would like to see on the brief - this will help a client produce a brief that inspires and excites possible contractors
- Do not use smug or arrogant language -  I recently had a local authority phone me to ask why they did not have a single response for a tender/brief they sent out to us and many of our competitors.  The reason I explained was because the language and tone of the tender demonstrated a dis-interest in collaboration and an attitude that suggested that they already had someone in place
- Create a mood-board - include images, swatches or samples to communicate what is in your mind

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