Drive racks

The drive rack includes all of the system processors that connect between the mixers outputs and the amps inputs. These processors maybe graphic equalizers, compressors, a crossover, limiters and time alignment delay; what the drive rack provides is the ability to tweak the system for better performance and add extra functionality.

Graphic EQ allows for the engineer to ring out the sound system sweeping through different frequency bands pre-gig at a venue. This in turn can help stop feedback through the mics and monitors and help improve the quality of the live sound.

Compressors are used for dynamics of the sound; compressors use ratios between 1:1 and 10:1 and the resulting effect of compression is that the peaks of the signal that are the loudest and generate the most voltage are turned down and the low levels within the signal are turned up; the overall amplitude of the signal can then be increased or decreased using the gain on the compressor. A compressor is ideal for the likes of drums i.e. kick and snare as the drummer may not always play at consistent velocity.

A crossover is a great add on to a sound system, its basic function is to send the low mid and high frequencies to the subs, Mids and horns. This allows for better control and optimization over the sound system. Using a crossover gives the sound system its full potential and allows the system to possibly be driven harder.

A time alignment delay is used when a distributed system in used in a large venue or fill speakers are also used. This processor allows for the signal to be delayed in milliseconds to selected speakers stopping a delay and phasing between the speakers.

The disadvantages of a drive rack are the expensive processors and extra cabling needed for live sound gig although the advantages far out way the disadvantages.

Line arrays and distributed systems

Distributed system speakers, are speakers that are seen at most night clubs and small venues usually placed either side of the stage or throughout the club. These systems may consist of full range cabinets, two way cabinets, three way cabinets or four way systems; containing sub woofers, Mids and horns. Although this system may be good for small gigs they can be used for larger gigs but, they do not work as well as the line array system seen at massive venues and rock concerts. As the distributed system is omni directional it can lose its output power. This is caused by frequencies being absorbed by the crowd and would require fill speakers placed further down the venue to amplify the signal to the audience at the back and would require time alignment delays to sync the speakers output at the same time. A Line array system is a stack of speakers at different frequencies which are connected together at slight angles these are then hoisted high above the crowd and angled down towards the crowd to give better coverage. This allows all frequencies to be projected at the same level and reduces the effects such as muddiness that we may find from a distributed system. Time alignment delays will be used due to the angling of the speakers but not in context compared to a distributed system. Inverse square Law only matters to sound from a point source and relates to how the sound attenuates over distance. In theory as the sound is projected from its source its volume decreases 6db each time the distance the sound as doubled from its source. This is due to the diffusion of sound radiating from the sound source over a spherical area. As the radius of the sphere is doubled, the surface area quadruples. In return this divides the acoustical power by 4.

Finnish gig in the new theatre April 13th 2011

This live sound gig was by far the best I had encountered to date; the college had Finnish bands visiting that were scheduled to perform in the new theatre alongside performers from our college. Myself, Kevin, Marty and Pete were set the task of setting up and engineering the gig as well as Ciaran and Pauric over looking. We had done a test run on the Monday with the road show crew so we knew our channel listing and running order which passed with no problems. When setting up the equipment on stage we ensured that all cables were neatly placed to avoid tripping and danger, due to the new theatre having the wall boxes either side of the stage we thought as a precaution for health and safety that it would be wiser to run a multi-core from the wall box to behind the drum kit. This would be a neater option and decrease the amount of cables running across the stage. Below is a picture of the stage plan for the gig:

The running order and channel list is described below:

Running order

• Health and safety
• The guinea pig (sketch)
• Concrete angel (song/dance peace) left mic/full backline/ except right keys
• Thief (sketch)
• The pet shop
• New born (unmute keys) (WIRELESS MIC!!!!)
• Never miss a beat (song) switch keys/ mute keys
• Beat (sketch) unmute keys
• I know where I’ve been (song)

Channel listing

1. Kick (FP6/1) beta 91
2. Snare top (FP6/2) Sennheizer 604
3. Snare bottom (FP6/3) Sennheizer 604
4. Rack tom 1 (FP6/4) beta 98 ds
5. Rack tom 2 (FP6/5) beta 98 ds
6. Floor tom (FP6/6)  beta 98 ds
7. Hi hats (FP6/7) NT2
8. Overhead (FP6/8) NT2
9. Guitar left (FP7/1) Audix i5
10. Guitar right (FP6/9) beta 58??
11. Bass DI (FP6/10)
12. Right keys Mono DI (FP6/11)
13. Keys left DI (FP7/2)
14. Vocals left (FP7/3) sm58
15. Vocals centre (FP7/4) sm58
16. Vocals right. (FP6/12) sm58

Below are some pictures of set up, engineering and performance from the gig:

Kevin and I took the roll of engineers on the mixer half way through the gig and had the privilege of mixing for the Finnish bands. We really enjoyed this gig as all acts were exceptional on the day although during the gig we did encounter a few problems with guitar levels on stage as they were too quiet which was sorted in-between songs. The area in which I could improve on is to be more vigilant during gigs; keeping an eye on the performers for guitar solos and raising the level for the instrument to sit clearly in the mix. Overall the gig was really enjoyable and passed off with very little problems; videos of the performances can be found on the website address: http://www.wix.com/themanwiththeplan10/livesoundwebsite#!videos

Bound for Boston sound check

My job along with a few of my class mates was to set up and do a sound check for the Bound for Boston gig in Derry. We arrived at the gig around 3.30 and proceeded to set the gear up for the bands to perform later that night, I was unable to attend the gig that night due to travel restrictions so my job was to have the gear ready for the engineer who would be engineering the gig. Paddy, Pete and myself started to set the gear up on stage ensuring that all cables were neatly position to avoid tripping and ensured that all equipment was positioned safely and neatly to avoid accidents or breakages. Below is a stag plan of the set up the equipment;

The channel listing for the gig is also explained below;

1. Kick

2. Snare

3. Hi tom

4. Floor tom

5. Bass DI

6. Guitar L

7. Guitar R

8. Triton keyboard

9. Vox L

11. Vox C

12. Vox R

There were also 3 stage monitors, 1 for the drummer, 1 for the lead singers and 1 for the guitarists.

The reason for the jump in the channel listing is due to a fault within the wall box in the Bound for Boston; connections 10 and 15 are faulty so we avoided using these. Below are some pictures of setup and the sound checking itself:

As you can see from the above pictures from the gig we had some outboard gear that consisted of a; graphic EQ, lexicon effects processor, and two 2 channel compressors.

After setting all the equipment up my first task was to ring out the sound system, this was done by turning all the channels up and raising the gains until the mics and monitors started to feedback. This then allowed me to go threw the frequency band of the graphic EQ and turn each band down until the feedback stopped; this in turn stops feedback when the levels are pushed by the engineer. We used the two channel compressors for; kick, snare and vocals to keep levels in check, overall I really enjoyed ringing out the sound system in the Bound for Boston as it taught me new skills in the frequency spectrum. 

Theatre gig city factory 14/2/2011

This gig consisted of five performance class bands which were;

·         The guess, drummer, bassist,1 guitar and lead vocalist

·         Hammered, drummer, bassist, 2 guitars and lead vocalist

·         5^th Wheel, drummer, bassist, 2 guitars, keyboard and lead vocalist

·         Medium rare, drummer, bassist , 2 guitars and 3 vocalists

·         Progressive darkness, drummer, bassist, 2 guitars and lead singer.

The gear list for this gig was;

·         Drum kit 

·         Behringer bass amp

·         Roland cube 60x guitar

·         Orange tiny terror

·         XLRS 17

·         Mic stands 7

·         Plug board 2

·         Extension reels 2

·         Kettle leads 8

·         Nord keyboard

·         3 The Box MA120 wedge monitors

·         4 DI boxes

The channel list for this gig was;

·         Kick (pg52)

·         Snare top (PG56)

·         Rack 1 mounted tom (PG56)

·         Floor tom (PG56)

·         Bass DI (Mono DI)

·         Electric guitar left (SM57a)

·         Electric guitar right (Audix-i5)

·         Nord keyboard

·         Vocal left (SM58)

·         Vocal Centre (SM58)

·         Vocal right (SM58)

Aux channels

Monitors 1-3

·         1 centre stage

·         2 right stage

·         3 drum monitors

·         5+6 stereo reverb

Below is the stage plan for the theatre gig;

Are first task was to arrange the seating area for the audience, making sure all seats were correctly spaced and safe incase of tripping for health and safety. We then started to set all the gear up ready for the bands to arrive, on stage was a large drum mat and this helped with housekeeping and health safety. Making sure all cables were neatly run under the mat to avoid tripping for the band members and all equipment was secure and neat. After setting the equipment up on stage as a group the next stage was to carry out a sound check before the gig started, we had a few class mates as stage hands and they acted as vocalists to check the levels of the mics. After about half an hour the first band arrived to do the rest of the sound check, so we proceeded in sound checking the guitar amps (mic’d), bass DI, Nord keyboard and the drum kit. After checking all levels we were happy for the bands to proceed although only two of the bands had turned up by this stage and the audience had started to fill the seating area causing some lectures to get frustrated due to bad time keeping from the arranged bands. Finally the rest of the bands arrived and we decided to take turns in groups of two to engineer a band each, myself and Kevin McAleese engineered one of the bands. The problems we encountered during the gig was feedback through the stage monitors due to the band turning the guitar amps up far too loud, we overcome this by sending the stage hands to tell the bands to turn the guitar amps down. Overall the gig went really well although we found we could improve on areas such as more EQ’ing and better monitor mixes. Unfortunately i was only able to get one picture of the gig due to time restrictions.

BRASSERIE GIG WEDNESDAY 1st JUNE

PETER HARKIN AND CO

Myself and Marty Bonner were the engineers for the lunch time gig in the North west regional college brassiere. We arrived at the venue around 11.30am to give ourselves plenty of time to set up the equipment and do a sound check. Our first task was to unpack all the gear and have it ready for the band to arrive, as previously planned the band would require a setup for:

·         2 acoustic guitars.

·         Bass guitar.

·         2 vocals.

·         1 bongo drum.

The gear list required for this setup was:

·         2 extension leads

·         2 multiplugs

·         Soundcraft mixer

·         2 RCF speakers with stands

·         3 DI boxes

·         14 XLR cables (6 of which are spare in case of faulty cables)

·         3 mics, of which were: 1 PG48, 1 Shure SM58, 1 AKG C1000s

·         6 jack leads (3 of which are spare in case of faulty cables)

·         3 mic stands

·         We also had a guitar amp and a bass amp, but these were unneeded as it was an acoustic gig.

We started by unpacking the gear and setting up the speakers, the next stage was to set up the mixer and mic stands and position them so the band had plenty of room. The vocal mics we had available to us were a PG48, a Shure SM58 and an AKG C1000s. We decided to use the SM58 and the PG48 for vocals and the AKG C1000s for the percussion. Being happy with all the equipment positions we then cabled mixer, speakers, mics and DI boxes ready for the band to arrive, below are some pictures:

The channel listing for the instruments were:

1. Left guitar

2. Right guitar

4. Vocal 1

5. Vocal 2

7. Percussion

The reason for channels 3 and 6 being left blank was give space between the channels for mixing as seen in the picture below:

The band was scheduled to arrive at 12.30 but unfortunately didn’t arrive until a 1.15. When they finally arrived we found out that their bass player wouldn’t be coming and also there percussionist plus the brassiere would be closing in 20 minutes. This left us no time to do a thorough sound check; the bass guitar would be swapped for a second acoustic guitar with no pick-up and would need to be mic’d using the PG48. After overcoming these problems we flattened the desk and got the band on the way, changing the channel list to:

1. Guitar left (DI)

2. Guitar right (PG48)

3. Vocal (SM58)

Below is a picture of the band performing;

And below is our stage plan:

The problems we encountered during the performance were the left speaker was not working, we tried changing the XLR cable but their must of been a problem with the speaker or desk. As there was little time to change the speaker we had to carry on with the gig with one speaker. The second problem we encountered was slight feedback through the mics, I overcome this by reducing the bass frequencies on the vocal channel and guitar channels; as bass is omnidirectional I found this helped reduce the amount of feedback. The area I would improve on would be to change the guitar mic (PG48) to the AKG C1000s as I think this would give a better quality to the sound of the guitar. Overall the band performed a couple of nice songs and the gig went well despite a few problems.

Health and Safety

During the stage of setting up the gear we ensured all cables were places neatly to avoid tripping and danger to the band or public. We also ensured that speaker stands were well positioned and safe to everyone in the area.

Experiment on standing waves.

As a group on Monday 1st we carried out an experiment to calculate the standing waves of room 11 in NWRC. Below is a diagram of the dimensions of room 11:

The equation used to calculate standing waves is as follows: 

                                                          Hz = speed of sound (340.29 meters per second)

                                                                  length of room x 2

So to simplify this equation; to find out the fundamental frequency multiply each dimension by 2, then with this number divide it by the speed of sound. So for example using the dimensions in the diagram above these are the results we got using the measurement 7.848 meters: 

                                                                              7.848 x 2 = 15.696

                                                                              340.29 (speed of sound in meters)

                                                                              15.696 = 21.6 Hz (this is the fundamental frequency)

Once we worked out the fundamental we then multiply this by 1,2,3,4,5 and so on until we reach 300Hz. The reason for doing this is to create multiples of the fundamental frequencies that may cause standing waves within the room, we only calculate up too 300Hz because frequencies below 300Hz have enough energy to cause standing waves although frequencies above 300Hz can be dealt with using absorption panels and diffusers. This equation helped us work out the axial modes of room 11.

With our results using the above equation we then played a sine wave at the resulting frequencies, what we noticed was that not all frequencies calculated created standing waves. Although in our group we were working with the measurement 7.848 meters, at certain frequencies we could hear at certain parts of the room  resonant frequencies i.e. the window at the corner of the room resonating.

Standing waves create problems for performers, sound engineers and the audience within a venue! Untreated standing waves will cause certain frequencies to either be increased in amplitude or cancelled due to phase cancellation.  For example the accumulation of in-phase reflections result in a near-doubling of the amplitude, and if the waveform reflects out of phase, the result would cause the reflected frequency to cancel itself (this is known as phase cancellation). All these factors would cause an undesirable sound within a venue for performers and the audience, although we can treat standing waves by either treating the room with absorption panels and diffusers. But in the case of having a venue that cannot be treated with absorption panels and diffusers the best solution is to use a graphic EQ, this will allow the sound engineer to cut the frequencies that are causing the standing waves giving more control over quality sound within a venue.