The Original PA System
When Steve first met Lynn she was singing as one half of the duo Crescent Moon. At that time they were using a small Peavey PA system (which we still use occasionally). This type of PA is typical of the type used for "acts up the corner", in pubs that put on live music. Steve decided that with his experience he could provide them with something better. The main criteria for the PA system was that it should fit in the back of the car; a Fiat Cinquecento.
From the outset it was decided that it should be possible to use the PA for some of the smaller gigs that Grace performed. The basic PA was therefore designed to be used as a two way speaker system to which extra bass cabinets could be added to make a three way system when the full setup was necessary. Although Crescent Moon only used a maximum of six inputs again it was decided that to accommodate the smaller Grace gigs a 16 channel mixing desk would be used.
The loud speakers consist of a bass reflex cabinet with an RCF 10" bass drive unit and a 1" compression driver, also by RCF. The compression driver is mounted on a short axis-symmetrical horn with a tractrix expansion rate. The mouth diameter was chosen to have the same directivity characteristics as the bass unit at the crossover frequency. When additional power is required, a pair of two by 12" bass reflex cabinets are added to the system.
The bass cabinets were designed using a spread sheet program and this was compared with the results from winisd a freeware program available on the internet. The horns profile was designed using another spread sheet, the mould was turned on a lathe and the horns then constructed from fibreglass.
The following list and pictures show the PA as it was in its original form. For information on our current set up go to the page with our current system.
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Just to prove it all goes in 1 CD minidisc player 2 amp rack 3 FX rack 4 mixer 5 PA loudspeakers 6 monitor 7 multicore Stands at right side, bag of cables fits behind speakers and guitar fits on top of equipment |
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Allen & Heath 16chanel Mixwizard |
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FX Rack Ultracurve 8024 Yamaha Rev500 TC CCC multiband compressor Feedback eliminator used as parametric equaliser Autocom compressor/gate At the bottom is a dbx crossover which is in the amplifier rack |
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Amplifier Rack 1
Two RMX 1450 amplifers (these are in the same rack as the crossover) Amplifier Rack 2 Ancient home designed 350W per channel amplifier. Yamaha CP2000 |
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A different shot of the FX rack and
amplifier rack 1 The connectors left to right are mains, 2 speakon connectors for the lower amplifier, 2 speakon connectors for the top amplifier, 2 jack inputs to the crossover, a multipin socket for L/R and monitor returns from FOH, 2 output sockets for linking the crossover to the bass amplifier, 2 output sockets to connect the monitor amplifiers. |
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Loudspeaker loaded with RCF drive units. The horn was built by myself as described here |
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The frequency response of the above loudspeaker measured using a swept sine wave and Spectralab software. |
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The bass cabinets for when using the PA in 3 way mode. Each cabinet uses two 12" Eminence drive units. The silver object on top is a Behringer DI100 |
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The rear of the mixer showing the multipin connectors. The square one is from the stage and the round one connects to the FX rack. The jack socket is connected to a spare cable pair down the multicore and is presently used to give an additional monitor send. |
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The stage box is mounted in the multicore drum. The centre section is a
metal
Quality St box which is fastened to a Fiat Panda rear hub giving
smooth rotation. The sides were laminated using fibreglass and the whole
thing is fixed to a metal A frame. The multipin connector links to the
amplifier rack
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