This section includes an assignment i completed for my Sound Reinforcement class, where i was tasked with designing a full live sound system for a hypothetical gig in the college's live room 1/24. I also had to provide a full system diagram, justify my equipment choices, and complete calculations to show that the speaker setup would be loud enough for the room.
Explanation
Mic level inputs in this system will go straight
into one of the 24 "ins" on the stage box, which will then send them
to the 24 corresponding mono channel inputs on the Midas desk. These can then
be compressed if needed using the compressor plugged into the channel inserts,
and effects can be added through the use of the aux 5 and 6 buses. The master
output signal also has a Front of House EQ using a graphic equaliser on the mix
inserts. The left and right master outputs and auxiliary 1-4 outputs are then
carried back to the stage box using the 8 designated "outs", where
the left and right master signals are taken out at line level straight to the
correct sub, and linked to the loudspeaker on top, completing the Front of
House system. The 4 auxiliary outs are taken from the stage box via an XLR
connector and each is plugged into one of the channels of an amp. This then
amplifies the signal to speaker level which can then be taken out of the amps
using speakon connectors and send to the corresponding monitor wedge.
List of Equipment
·
Midas VeniceF 32 Analogue Mixing desk
·
PA - HK Audio Elias PX System - 2 Subwwoofers and 2 Loudspeaker wedges
·
Foldback - 4 Yamaha SM12V passive speaker wedges
·
Amplification - 2 matched dual channel power amplifiers
·
Proel 25m 24in/8out multicore
·
Numerous DI Boxes, XLR cables, Speakon connectors and 1/4" jack
connectors
·
Outboard Effects rack, including compressors, effects processors and
graphic equalisers
Justification
I have put together this system with these
specific components as i believe they would give me enough flexibility and
options to comfortably engineer any size and genre of gig. The VeniceF 32 is a
newer Midas desk, giving me 24 mono mic and line ins, as well as a further 4
stereo mic and line ins should i need them, which should be more than enough
inputs for any band or group. The desk also has 6 auxiliary routing buses,
enough for me to comfortably run effects and a full on stage monitor setup, and
it now also has a built in firewire connection, allowing me to run multitrack
recording or extra effects and plug-ins from a laptop. I have chosen the HK
Audio Elias PX system as it covers a wide dynamic range, 48Hz - 19kHz as a full
system, and it is an active system, meaning it does not require additional
amplifiers, and it gives me more versatility as i could choose to simply use
the loudspeakers for a smaller gig, or i could easily expand my rig using more
active speakers. I have included the Yamaha SM12V's in my system as i know that
they are well reputed as monitor wedges, as they are very well built and
durable, and have a 60Hz - 16kHz frequency response, with good accuracy and
clarity.
I have also done calculations to find expected
SPL levels, and found these to be suitable for the system and venue:
The speaker will be on the stage, sitting on top
of a sub unit, roughly 4-5m above the ground, facing outwards towards the
audience and downwards at a slight 15-20 degree angle
1m from speaker, on axis: 104+10log(400)-20log(1)-0= 130.02dB
10m from speaker, on axis: 104+10log(400)-20log(10)-0= 110.02dB
20m from speaker, on axis: 104+10log(400)-20log(20)-0= 104dB
1m from speaker, off axis: 104+10log(400)-20log(1)-6= 124.02dB
10m from speaker, off axis:
104+10log(400)-20log(10)-6= 104.01dB
20m from speaker, off axis: 104+10log(400)-20log(20)-6= 98db
These calculations show that even at the furthest
20m away from the speaker and in an off axis position, the expected SPL level
will still be 98dB, a very suitable level. However, we must take into account
that the speakers will not always be running at their maximum power level, so
we might expect to see slightly lower SPL levels in a practical situation than
have been calculated here, however i am confident that this system will
adequately cover an area the size of the live room in R1/24
Manufacturer Data Links
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