UK Gospel awards Sound system hire

In the last few weeks we did the sound for the UK Gospel awards, which was held at the London Hilton Metropol Hotel.  Around 20 acts performed, including Ron Kenoly.
On front of house we used Martin W8C wavefront.  Monitors were ASS Spektra SPM12 and SPM15s, and mixing was on a Mackie Onyx 3280.

5 Video screens, including a central LED screen provided an interesting backdrop to the stage.  The event went well, despite several no-shows during the awards presentations!

For PA Hire, please check out our website, at www.soundtruth.co.uk

Green PA Hire

Environmental concerns have risen in profile in the last few years, and few companies or individuals can choose to ignore these completely.  I've read people suggesting that hiring the most efficient speakers (i.e. those that produce the most sound for a given power input) is the most environmentally friendly approach.  This suggestion does not however take into account that efficient boxes (often point source) can sometimes be the heaviest and largest.  Transportation is surely a massive factor if green concerns are paramount.
Line array system can offer a greener option as less equipment is typically required to cover the same number of people.  Of course a lot depends on the exact set-up in question - from an environmental perceptive, less is more, but from a rock'n'roll perspective, MORE is more!

Void Stasys3 Point souce speaker - fantastic sound, but heavy

A 10KW PA system will only use an average of around 2000W, with odd peaks above this.  This of course depends on how hard the system is driven.  But moving this equipment on a 200 mile round trip does have an environmental impact.
The solution, at least in some instances, may be to use firms local to the event where possible.

If you're looking to hire a line array or point source speaker system, have a look at my website, www.soundtruth.co.uk

Sound System for Sean Lock

If you're looking to hire a sound system for a corporate event or a band, have a look at my website here.

A few days ago I did the sound for the comedian Sean Lock at a corporate awards function, which took place at the Park Plaza Riverbank Hotel in London.  A Sennheiser EW300 series microphone was set up, but most of the talking was done from the lectern, equipped with a pair of Audio Technica ES915 mics. Front of house speaker system consisted of 6 HK Audio IL12.1 speakers flown in three way clusters.  An additional 2 boxes where flown over the dance floor.  6 HK Audio Elias subs were positioned under the stage, in order to preserve sight lines.  Front of house mixing was accomplished with a Soundcraft GB4 desk, with Mackie digital outboard.

Sean Lock on stage

The positioning of the subs made for a very clean looking stage area, also with no speaker stands in sight as all the mid / high tops where flown from a 12m truss, parallel with the front of the stage.  There was a certain amount of power alley noticeable during the DJ set, but this was a price worth paying to hide all the subs.

In order to provide maximum gain before feedback, only one of the Audio Technica ES915's was used, the other serving as a hot spare.

Sean Lock proved to be a very entertaining host, although the official photographer might disagree, being the butt of several jokes!

How to use a compressor

This article is taken from my website, which may be of interest if you're looking for PA Hire.

Compression is an essential tool in modern sound engineering. Most commercial recordings will have compression on just about every instrument. In the world of live sound, many amateurs do not correctly understand the best use for compression.

Compression should be used in the first instance to help achieve a sound without harsh or unexpected peaks that cut though and ‘grate’ on ones ears. The human ear is actually more sensitive to these mid-range frequencies. The main culprit here are vocals. This is because vocals have a lot of mid-range frequency content, and because singers (even good singers) often unintentionally vary the distance from their mouth to the microphone, effectively giving their voice even greater dynamic range.

Adding compression limits the dynamic range, evens out the small variation in microphone position, and provides a smoother sound for the audience. You can achieve a similar effect by ‘riding’ the fader on the vocals and listening, but it’s pretty hard work, and the singer can catch you out.

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suggested settings for vocal compression:

• Ratio 3.5:1
• Adjust threshold so the gain reduction is showing 3-9 dB during singing.
• Adjust the limiter so it cuts in only on the peaks, if at all.

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suggested settings for tie clip mic:

• Ratio 8:1
• Adjust threshold so the gain reduction is showing 3dB or less during talking
• Adjust the limiter so it cuts in when the gain reduction gets to 9dB (un-clip the mic and move it closer to your mouth to do this)

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suggested settings for bass guitar, or electric guitar:

• Ratio 2.5:1
• Adjust threshold so the gain reduction is showing 3-6dB during playing

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suggested settings for acoustic guitar:

• Ratio 4:1
• Adjust threshold so the gain reduction is showing 3-6dB during playing
• Set the limiter to cut in when the gain reduction gets to 9dB

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It’s important to remember that using a compressor on an insert will affect the signal sent to the monitors as well. Too much vocal compression may be annoying for an experienced vocalist who expects the monitor to get louder as they approach the mic. Although, in the case of an experienced vocalist, less compression (lower ratio) is normally needed to reign in the sound!

Use of the attack and release controls can change the way the compression behaves. It takes a while to become familiar with the effect of the controls, and with what works and what doesn’t. In most cases, a fairly fast attack and a medium or slow release is the way to go. We would suggest you leave your compressor set on auto if it has this feature, and if not, leave the controls at 12 o’clock!!

Compressors can be used for a variety of other applications, even across a whole mix. This can have un predictable effects – in general it’s best to restrict the use of compression to a few key channels, unless you really know what you’re doing!

How to Prevent Feedback in a PA System

The article below is reproduced from my website, you can find it here:- www.soundtruth.co.uk/soundbasics.shtml

We get asked this all the time, and we're afraid that there is no very short answer (other than “turn it down!”). However, there are steps that can be taken to greatly reduce the risk of feedback. Reduce the risk almost to zero in some circumstances.

• Reduce on stage volumes where possible - then you can reduce monitor gain and hence reduce the possibility of feedback. Prime culprits here are on stage bass guitar amps, and drums... drums being more of a challange to 'turn down'!
• Encourage vocalist to sing really close up to the mic. Not all singers are used to, or like this technique, but from a monitor engineers point of view it works best! A good singer can still pull the mic away a bit for louder syables, words or sections. This tip is especially hand for vocalists that are asking for more in the monitors than you can give them without feedback.
• Eliminate simple causes of feedback – for example a guitar or bass left plugged in, turned up and on a stand. Inexperienced musicians are prone to doing this and need to be educated!
• Make sure your FOH speakers are positioned not to bleed into the microphones.
• Be aware of the pickup pattern of your microphones, and use this to your advantage. Most mics are cardiod, and so are pretty directional. Make sure they are not pointing at monitors or front of house speakers.
• Don’t put unnecessary mics such as the drum overhead into the monitor system.
• Don't use more mics on stage than nessasary. Every time you double the number of mics on stage, you reduce the gain before feedback by 3dB (the system will start to feed back at a perceieved volume about 30% lower than before).
• Use good quality microphones. If you’ve ever used a really cheap mic, you will know how prone they are to feedback and handling noise. Having said this, many people won't find much difference between an £80 microphone and a £350 microphone. Just avoid the cheapo £20 mics and you should be OK.

Shure SM58 Mic, a good industry standard vocal microphone

• Use good quality monitor speakers. Many venues try to save money and buy cheap monitors for the band – this is a shortcut to feedback problems, and a poor stage sound.
• Use good quality FOH speakers. Poor quality FOH speakers can also give feedback problems due to comb filtering and un-even frequency response.
• Hearing loop systems can cause feedback, especially into electric guitar pickups. Solve the problem by removing the guitar from the loop mix, or reducing the loop mix level.
• Follow a standard sound-check procedure (for an example, read running a soundcheck) and make sure to do the FACE / FLAT HAND / CUPPED HAND test, with all the mics ON, both in the monitors and FOH.
• Listen to the feedback and identify the frequency. This can be done with skill – or when an audience is not there, you can ‘sweep’ the mid band EQ and ‘find’ the offending frequency. Cut the frequency by 3dB and the feedback problem will reduce. More cut can be used in some cases, but will of course start to influence the sound of the mic. Low frequency feedback (for example from a tie clip mic), can be reduced by cutting the bass. LF feedback from a kick drum or toms is normally countered using a gate.
• Use a graphic EQ on either the FOH or relevant monitor mix to cut the offending frequency. Some engineers ‘ring out’ a monitor or FOH rig prior to a show. This can result in up to 6dB more gain before feedback. However, the monitors can end up sounding rather dull, as one normally ends up with quite a bit of upper mid-range cut on the EQ (The bands on a normal EQ are not really narrow enough, and end up cutting more frequencies than are required).
• Use a feedback destroyer. In some ways a last resort… the cheaper f/b destroyers such as Behringer can have problems with noise levels. Sabine make better but more expensive models. They use very fine notch filters to cut feedback frequencies and need the system to be ‘rung out’ prior to use in order to work at their best. They should give about another 6dB gain before feedback, without the side effects of graphic EQ or channel EQ.

World's largest photo album- PA System

Last week we supplied a PA System for the Worlds largest photo album.  The record was atempted by Photobox at the Old Truman Brewery in London's Brick Lane.

Worlds largest photo album

Sound coverage was needed for background music, and various anouncments for up to 300 people.  We supplied and installed a pair of Yamaha MSR400 powered speakers, together with a Soundraft E6 mixer and a Sennheiser EW100 series hand held radio microphone.
The photo's on display were superb, and many of them were taken by amature photographers around the UK. The subject was World travel.

The Yamaha speakers were partly conceled behind the pillars

What is loud? Why do I need to know about dB SPL?

Perception of loudness is a complicated subject. Every person will perceive loudness differently, as everyone’s ears are different. In fact, everyone’s ears have a slightly different frequency response.

This is why, in sound engineering circles, there is a need to quantify sound pressure levels to define what is loud, and what is quiet. Or perhaps that should be; what is too loud and what is too quiet. The unit of measurement is the dB SPL (decibel). There are also more accurate measurements of loudness called phons, and subjective loudness, called sones, but these are rarely used and are outside the scope of this course!

For convenience we normally measure dB SPL from the mix position, but it can be useful to measure from other areas such as the front row and the stage.

For those new to dB SPL here is an idea of how different sounds compare in level:-

Recording studio	30dB SPL
Conversational speech	60dB SPL
Noisy office	80dB SPL
Church concert (contempory worship)	95dB SPL
Loud rock concert, front row	120dB SPL
Threshold of pain, average young person	130dB SPL
Concord take-off from runway side	140dB SPL
.357 Magnum handgun, (peak impulse)	165dB SPL
Under a Saturn 5 Rocket on take-off!	194dB SPL

This article was taken from my web site, you can read more about PA Hire and dB SPL here.

Analog vs Digital mixing desks

Firstly, I should say that everything I say here is purely my own opinion ;-) This is a debate that's been running for some time in the live sound and PA Hire world... the relative benefits of analog and digital mixing consoles.
Analog offers familiarity and ease of use, having been around since the dawn of sound re-enforcement, it's what most engineers will have learned their trade on.  Digital offers a brave new world of layers, built in effects and dynamics, and work flows that are completely different to the traditional analog cousins.

Digital has come on in leaps and bounds in recent years.  Interfaces have improved, sample rates improved along with sound quality.  Prices have come down a bit.  Progress in the analog world has been slower, with few manufacturers putting in much R&D into this area any more.

It appears to me that if you've got decent money to spend on a desk (like, over £7000), then digital appears to be the favourite option.  Analog desks in this price bracket tend to be vast and incredibly heavy devices, sometimes needing up to six people to lift them onto a stand. They need a big rack of outboard with them to compete in any sense with a digital board.  Digital desks are for the most part much lighter and easier to handle. They have all the outboard built in, so that's another rack that can be left behind.  Most people agree that the sound of digital desks holds up pretty well too.

The difficult comes when you're spending less money, as the choice of digital desks tends to dry up a bit under £7,000 or $10,000.  You are left with a few 16 or 12 channel offerings like the smaller Yamaha LS9-16 or the O1V-96.  There's a few left field offerings like the Presonus Studiolive as well, but their unusual interface could be perceived as a little bit rider-unfriendly.  If you need 32 channels, as many live sound engineers will, you're a bit stuck.

In the analog realm however there are a good few well respected desks in this price bracket, such as the Allen & Health ML and GL series, and the Soundcraft GB and MH series.  Some of their larger offerings are still pretty heavy, and you do have to wonder how their values will hold up with digital boards getting cheaper.

So perhaps the best decition is to wait untill the prices of digital mixing desks has dropped, and hire a mixing desk should you need one in the meantime!

Me operating a Yamaha M7CL digital desk

Conference PA systems

Yesterday I supplied a small PA system to a conference suite at the MK Dons stadium Hilton in Milton Keynes.  The client needed to project his voice to the back of a large room full of people, without straining his voice.  We used a headset radio mic (Sennheiser EW300 series), connected to a Soundcraft E6 mixer.  Speakers were Yamaha MSR100 powered speakers.
The Yamaha MSR100s are very compact size but produce a remarkable sound quality and volume for a small box.  We had custom covers made for ours as they don't come with a cover.
I was impressed by the size of the stadium and the facilities on offer!

Yamaha MSR100 speakers, great for small conference events

The MK Dons Stadium in Milton Keynes

Subs up for more bass

Getting a good kick drum sound on a gig many engineers would agree, is a factor of how good your subs are.  A pair of 15in drivers is not really going to cut it unless it's a really small gig.  Horn loaded 15s or band pass 15s maybe!  A key fact to consider is this:- to double the perceived volume you'll need to need to more than double the power.  In fact, you'll need around 10 times the power to double the volume (a 10dB increase).  So that's like going from your 1KW system to a 10KW system.
But there is another way... doubling the number of subs will generally increase  your bass output by 6dB.  So let's say you take your 1KW rig, and instead of 1 15 inch sub each side, you put 4 15inch subs each side.  You will have more than doubled the bass output.  For the same power!  I'm assuming your amp will cope here, by the way... It may be asking a lot to go from an 8ohm load per side to a 2ohm load per side with 4 cabs a side connected.  I've blown amps up using them like this in the past.
But what about the mid range and high end?  Yes, you can gain around 3bB each time you double the number of cabs on the high end.  But you'll need to watch out for comb filtering, and lobing.  For small(ish) events, sometimes just pumping up the bass with more cabs can be enough, if you've got good quality tops.

If you are interested in hiring sub-woofers, have a look at my website here: www.soundtruth.co.uk

Tuning for your PA System or Sound System

When setting up a PA system it can be a real challenge to 'tune' your set-up to sound right in any given room.  This particularity applies when you're setting up from scratch with new amps, crossovers, speakers that you've not used previously.  Any given speaker will have a different frequency response, different optimal crossover points, and so on.  Different amps will exhibit different amounts of gain.  And of course, different rooms will have modes, surfaces and reflections to consider.
In these cases it's very hard just to use your ears to set up the system.  After a few minutes of listening, ears can 'adjust' to a particular sound, and your system can end up sounding wrong.  If you have no choice, it's best to take a short break and come and listen again.  But there are other tools out there to help.  One of which is the real time analyser, or RTA.
In basic terms, this is a device, or software application, that splits the sound into different wavelengths, and measures their relative intensity.
The application I tend to use is call True RTA.  It can be installed on a laptop for portable use, but is best used with a good quality condenser or measurement microphone, rather than the built in laptop mic.

True RTA real time analyser

Real time analysers can be used in a live setting for fine tuning a system response.  Playing pink noise through the system provides one method of analysis.  Some programs like True RTA also provide a sweep tone, which can give further insight into the frequency response of the system, and also to some extend the room modes.

True RTA in use on an outdoor festival

If you are interested in fine tuning your PA System, whether in the UK, Africa, or US, please don't hesitate to get in touch with me.  I offer Sound System tuning to churches, schools, colleges, and other music venues.

KT Tunstall rocks at Thelastfestival 2010

Last week we did the sound for KT Tunstall at Thelastfestival, which was put on by CBS for last.fm.  On front of house we used 4 stacks of HK Audio DEACON, monitoring was done with HK Audio Contour CT112 wedges in bi-amp mode, driven by HK digital field controller.
KT's on stage set-up included a bank of effects pedals, including a Akai E2 Headrush loop pedal, and a Korg Kaoss pad.  Four DI boxes where used for the setup, these where Radial Engineering boxes.

KT Tunstall on stage

Due to the bar being positioned at the back of the venue (London's Village Underground), the mixing desk was positioned at the side, but happily still offered a good view of the stage.  The mixer in question was a Soundcraft GB4 32 channel.  Various outboard was used, including a Mackie Quad comp for lead vocals and guitars.
If you have an event coming up, contact me for PA Hire, Lighting hire or other requirements.

Why use one amplifier, when you can use two for double the price?

Of course I'm talking about bi-amping - the method of driving a single two way loudspeaker from two amplifier channels.  Most PA Loudspeakers fall into the the following categories:-

• Passive
• Powered (some manufacturers like Mackie call this Active for some reason)
• Bi-amp / Tri-amp Active

Passive speakers use an internal crossover, and are driven from a single amp channel.  Powered speakers have an amplifier (or sometimes more than one amplifier, and other electronics) built into them.  Bi-amp / Tri-amp active speakers have no crossovers built in, and need a separate amplifier for each driver (woofer / tweeter / horn) inside the speaker.

Back of an envelope - Passive vs Bi-amp design

So what's the big advantage of bi-amp speakers, then?  And is it worth shelling out on double the number of amps to use them?

It's a bit techy but basically passive crossovers sap power from the amplifier. They also have very shallow cross-over slopes of around 12dB per octave. That allows a significant amount of range where both HF and LF drivers are radiating the same sound, which can create comb filtering or other bad effects and phase problems. An active crossover allow for much higher crossover slopes of 24bB per octave or higher, so you're getting less overlap between the drivers.  There is also no loss of power to the internal passive crossover.  You'll gain about 3bB in headroom or output, possibly more in some cases.
When amplifiers are connected directly to the drivers, and not through a passive crossover, they have a greater ability to control the speaker cone, and so reduce the possibility of ringing and other negative phenomenon.
So, maybe it is worth converting your current speakers to bi-amp, and buying more amps and active crossovers?

Alternative to hire - build your own speakers!

I designed and made my first set of loud speakers 23 years ago.  They were vast ugly items that sounded, well, like nothing else I'd ever heard.  But not great. I'd taken a few of the principles I'd read about in books on speaker design, and tried to apply them.  Retrospectively, I should have stuck to a tried and tested design rather than think of something new.

Big, ugly, and loud. Home made speakers.

My second set of speakers where much much better, but still had problems.  I remember I purchased the high frequency drivers, I said to the guy in the shop "Don't I need to use a cross over with these?", and he replied "Naa, don't worry about that, just solder in this capacitor."  No wonder those boxes had such an interesting mid-range 'presence'.
Fast forward to today, I've heard and used a great many different types of loud speaker.  And the time may have come to build another set... after all, there are now a myriad of websites and forums dedicated to loud speaker design and construction.
Of course, cheap loud speaker are much better than they used to be, and you can probably buy a pair for less than the materials required to make one.  So I must think carefully!

The MkII speaker was a huge improvement! 

What is a line array, and why would you want to hire one?

Line array has been a buzz word in the live sound and PA hire industry for a good few years now, ever since the French company L'Accoustics introduced the first concert worthy system in the early 1990's. But what is a line array?
In simple terms, a line array is a set of speakers, designed to create a coherent line source sound, normally for reproduction of live music or speach.  Well, what's so special about that then?
A 'normal' speaker system is typically a point source.  Point sources of sound can be measured to reduce by 6dB for every doubling of distance you move away from them. Therefore if you were 10m away from a speaker and you have a sound pressure of 95dB(A), then you move to 20m away, all things be equal, and in free space outside, you'll have a sound pressure level of 92dB(A). That's because a point source (at least theretically) radiates in all directions.  A vertical line source doesn't and to cut a long story short, the sound level is supposed to fall 3dB for every doubling of distance. It's because sound radiating up and down interferes and cancels.  Yes there is science behind it, but all you need to know is, the sound dispersion pattern of the speakers is more like a slice of cake and less like a football.  And the sound carries further. That's at least part of the theory, but real life factors like absorption of high frequencies by air and the restrictive length of the array it's self arguably limit some of the benefits.  Have a look here for a more detailed discussion on line array theory.
Some argue that point source speakers still sound better, but the bottom line is that the direction of the sound is often better controlled with a line array, and with much less space taken up in the truck.
Take a look at a big festival sound system, and 9 out of 10 times you'll see line arrays in use.

Martin Audio Line array

Bloging on the job

In the PA hire business, there are often time working on a show when one has time to kill... and a few years back a newspaper or magazine was the best remedy.  Now the trend is towards iphones et al.  Yes, I'm talking about Facebook, Myspace, and the blogsphere.

Now its great to keep your mates up to date with the latest Allen & Heath iLive you're using and the jobs your working on.  But posting Facebook updates like "this is the most hateful ***** annoying job I have ever worked on!", surely that crosses the line?

I'm happy to report none of my crew have made such postings.  For quite a while now.  What can I say?  It pays to keep tags on your crews myface pages.

The desk is an Allen & Heath GL2800 by the way

Colour changers, for those that don't like moving head fixtures!

Today I received an SGM Idea 575 Colour changer in the post.  By mistake.  How often does that happen?  So I thought I'd at least take the opertunity to test it before informing the sender.
For those that might not be familiar with this kind of lighting fixture, basically it's a large wash light, capable of switching to any colour instantly.  This is done by the use of CMY colour mixing (that's Cyan, Magenta, and Yellow).  By a combination of any of these, and white of course, almost any colour can be projected.
A lot of these fixture also have a few other features, such as a shutter to enable strobing, an iris for dimming, and a few like this SGM have a beam shaper.
If you aren't a fan of moving fixtures, it's still worth a look at these.  They could be a real time saver in a theatre environment.
I can report that in auto mode this is an amazing light, it lit up the room even with daylight coming in and cycled through it's features. It looks like it has a 'zoom' as well which adds to it's usefulness.
I must admit, I'm reluctant to send it back now!

http://www.sgmtechnologyforlighting.com/prodotti.asp?co_id=1076

SGM 575 Colour changer, received by mistake!!!

If you're thinking of hiring some lights, check this lighting hire page out.

Help, my speakers are blown!

If you've worked with, hired, or used sound systems for long enough, you'll come across this scenario.  In my case, two powered subs came back from a PA hire job not working.  A quick test with a multimeter across the terminals of the drivers and a smell of burning confirmed the worst... basically the voice coils had melted.
This is about the most common reason for a speaker to blow.  In my case, the unsupervised DJ had ran the system into the clip lights all evening.  Even with limiters, this can cause square waves to pass through to your speakers, which is bad for both the voice coils and the speaker cones themselves.
The only remedy in the case of a melted voice coil is to replace the driver.  The cost could be from £20 to £400 depending on the speakers you have.  Of course, more expensive equipment is less likely to sustain this kind of damage, but it can still happen, and it's even more expensive when it does!

Driver from a Yamaha MSR800W sub-woofer

Blown voice coil removed from the driver

Hello world!

Hi, Welcome to the new Sound Truth ltd blog.  I'll try and post occasionally to keep you all up to date with the latest news, developments, equipment, anything PA hire related.

This coming weekend we are supplying two PA systems for the Disney store in Milton Keynes, for the grand opening of their new store.  Should be great!

We'll try and fit a PA System next to the magical castle ;-)