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Professional 2.5 KW PA System and all extras for sale


Flash@TMB
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2 x vintage H&H 1200W power amps - 750 each.

Two speaker stacks, each consists of 2 cabs:

top cab

JBL horn

2 x 15" JBL mid drivers

base cab

1 x 18" JBL bass driver

The cabs are carpeted plywood with foam lined heavy steel mesh grills. They are to all intents and purposes indestructable. When errected each stack stands over 6 feet (1.8meters) tall.

The cabs and speaker drivers were recently serviced by Taylored Sound and the system was only used on 6 occasions since.

1500 total for both stacks

3 way active crossover switch with peak limiter - 150

Behringer Virtualiser Pro effects unit - 50

Behringer Composer Pro compressor, limiter, expander, gate unit - 50

Behringer Ultragraph 2 x 32 band graphic equaliser including spectrum analyser with mic and pink noise generator - 250

Yamaha 2 x 24 band graphic equaliser - 100

Spirit 24 channel mixing desk (yes twenty four channels), all preamped with direct outputs and in-outs on all channels. 6 aux ports - 1000

1 x Peavey 100 watts per channel monitor amp

2 x Peavey 100 watt monitor wedges

300 total for both the above

1 x flight case standard rack with wheels - 50

Also:

2 x Seinheiser vocal mics - 50 each

4 x spot mics - 20 each

4 x overhead condenser mics - 20 each

2 x kick drum mics - 20 each

various boom mic stands (very tatty) - 5 each

At 2.5KW this system is more than twice as powerful as that commonly employed by local touring bands. It is large enough to play virtually any bar type venue of up to 100 people.

This PA is ruggedised and of industrial strength. It is a professional system and at a level above anything you'll see in the shops.

If you want to buy the lot then 4000. All cables to wire the above together are included. The only thing not included is mic leads.

Anyone that attended The Moorings Bar in 2003 has probably heard this rig. You'll also see similar JBL stacks installed in several other venues in Aberdeen and elsewhere.

All components deinstalled and available for collection NOW.

Flash

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Power ratings don't indicate volume the same way as they used to. Back in the jurrasic period you got 1K, 2.5K, 5K, 15K rigs etc. Everything was pretty standard and the technology was geared towards dynamics as opposed to quality. Some people still tend to think along those lines.

Also take into account that a 5K rig is NOT 2x as loud as a 2.5K rig! Power requirements increase exponentially with volume. If you draw a graph with volume in dB as the x axis and power as the y axis then the curve will tighten upwards towards the vertical. It actually takes 10x the power to reach 2x the volume! If we just wanted to increase the volume then the easy solution is more speakers as opposed to more power, because more speakers move more air!

Power is simply there to increase the quality of the sound. An amp is rarely outputing anything like full power. So in some ways RMS is more relevevant than peak. Peak power is there to prevent distortion. Distortion will hurt peoples ears far sooner than volume. Distortion makes your ears ring. Distortion also blows speakers. A speaker will happily recieve slightly too much clean power without blowing. Problems occur when you use an amp that's too SMALL for the speakers.

The other consideration is impedance. You need an amp that can deliver clean peak power to speakers. If the amp is rated at 4KW, that probably means 4KW at 4ohms. If the speakers are 16 ohm impedance then (correct me if I'm wrong Ian) the same amp will only be able to deliver 1KW of power to those speakers. So if the speakers have a peak requirement of 4KW then the amp is far too small and will distort when it tries to cough up the speakers peak power requriement, probably damaging or blowing the speaker with 'dirty power'.

Some of the speakers we are using are rated at 16 ohms, considered to be high impedance therefore we need powerful amps.

So the huge power is really about quality rather than volume.

In order to address our volume requirements we are using more speakers than before. This system will have 6 horns, 8 mids, and 4 bass speakers. This breaks down as each main speaker stack has a horn, a high mid, a low mid, and a double bass bin. The double bass bins are located down on the floor underneath the front of the stage. Further down the room we have 2 delay speakers each of those has 2 horns and 2 mids. The bass happily makes it down the room on it's own, its only the high and mid that we have problems with due to the length of the room compared with height of the ceiling.

Another benefit of the high power is that we can run these huge speakers (each horn on the main stack is 50W at 8ohms, more than the total power on a cheap HiFi) at very low volumes. The bass bins are rated at 6KW each!!!This enables our jukebox to output through the PA system instead of installing another set of amps and speakers. 25KW in a bar as small as The Moorings = HiFi quality sound from the PA (obviously it's also high quality kit), and the ability to make very small controlled movements of very large speaker cones, thus undistorted sound at jukebox level volumes.

Another advantage of low distortion is that you can hear the person next to you speaking without them having to shout in your ear. You won't be able to hear someone a metre away though... This means that we can run the jukebox at a relatively high volume still allowing people to talk and order drinks, but keep everyone happy that they can hear the music properly.

Hope this explains.

Flash

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Originally posted by Flash@TMB:

Power ratings don't indicate volume the same way as they used to. Back in the jurrasic period you got 1K, 2.5K, 5K, 15K rigs etc. Everything was pretty standard and the technology was geared towards dynamics as opposed to quality. Some people still tend to think along those lines.

Also take into account that a 5K rig is NOT 2x as loud as a 2.5K rig! Power requirements increase exponentially with volume. If you draw a graph with volume in dB as the x axis and power as the y axis then the curve will tighten upwards towards the vertical. It actually takes 10x the power to reach 2x the volume! If we just wanted to increase the volume then the easy solution is more speakers as opposed to more power, because more speakers move more air!

Power is simply there to increase the quality of the sound. An amp is rarely outputing anything like full power. So in some ways RMS is more relevevant than peak. Peak power is there to prevent distortion. Distortion will hurt peoples ears far sooner than volume. Distortion makes your ears ring. Distortion also blows speakers. A speaker will happily recieve slightly too much clean power without blowing. Problems occur when you use an amp that's too SMALL for the speakers.

The other consideration is impedance. You need an amp that can deliver clean peak power to speakers. If the amp is rated at 4KW, that probably means 4KW at 4ohms. If the speakers are 16 ohm impedance then (correct me if I'm wrong Ian) the same amp will only be able to deliver 1KW of power to those speakers. So if the speakers have a peak requirement of 4KW then the amp is far too small and will distort when it tries to cough up the speakers peak power requriement, probably damaging or blowing the speaker with 'dirty power'.

Some of the speakers we are using are rated at 16 ohms, considered to be high impedance therefore we need powerful amps.

So the huge power is really about quality rather than volume.

In order to address our volume requirements we are using more speakers than before. This system will have 6 horns, 8 mids, and 4 bass speakers. This breaks down as each main speaker stack has a horn, a high mid, a low mid, and a double bass bin. The double bass bins are located down on the floor underneath the front of the stage. Further down the room we have 2 delay speakers each of those has 2 horns and 2 mids. The bass happily makes it down the room on it's own, its only the high and mid that we have problems with due to the length of the room compared with height of the ceiling.

Another benefit of the high power is that we can run these huge speakers (each horn on the main stack is 50W at 8ohms, more than the total power on a cheap HiFi) at very low volumes. The bass bins are rated at 6KW each!!!This enables our jukebox to output through the PA system instead of installing another set of amps and speakers. 25KW in a bar as small as The Moorings = HiFi quality sound from the PA (obviously it's also high quality kit), and the ability to make very small controlled movements of very large speaker cones, thus undistorted sound at jukebox level volumes.

Another advantage of low distortion is that you can hear the person next to you speaking without them having to shout in your ear. You won't be able to hear someone a metre away though... This means that we can run the jukebox at a relatively high volume still allowing people to talk and order drinks, but keep everyone happy that they can hear the music properly.

Hope this explains.

Flash

I'm cool with all that ...... but....... 25K....kinell!!

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Originally posted by Flash@TMB:

The other consideration is impedance. You need an amp that can deliver clean peak power to speakers. If the amp is rated at 4KW, that probably means 4KW at 4ohms. If the speakers are 16 ohm impedance then (correct me if I'm wrong Ian) the same amp will only be able to deliver 1KW of power to those speakers. So if the speakers have a peak requirement of 4KW then the amp is far too small and will distort when it tries to cough up the speakers peak power requriement, probably damaging or blowing the speaker with 'dirty power'.

Some of the speakers we are using are rated at 16 ohms, considered to be high impedance therefore we need powerful amps.

So the huge power is really about quality rather than volume.

Another benefit of the high power is that we can run these huge speakers (each horn on the main stack is 50W at 8ohms, more than the total power on a cheap HiFi) at very low volumes. The bass bins are rated at 6KW each!!!This enables our jukebox to output through the PA system instead of installing another set of amps and speakers. 25KW in a bar as small as The Moorings = HiFi quality sound from the PA (obviously it's also high quality kit), and the ability to make very small controlled movements of very large speaker cones, thus undistorted sound at jukebox level volumes.

Flash

An amp has an output resistor in paralell, so the power/ohmage ratio isn't linear.

The power should be given with the ohmage taken into account.

Equipment is designed to work best at around 0dB. Having too much headroom is almost as bad as having too little.

As a comparison, I use a 5K rig in Drummonds. I can fill the room with that, and it's got a fair bit more air to push around than the Moorings.

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Taking everything into account

Agreed it's not linear but the curve is quite gentle.

25K is the total maximum output of the all channels on all amps into 8ohms. These amps have a mechanism for setting their gain, this means you can limit the headroom you require. My inderstanding is that amps produce the least distortion usually around 1/2 power, using powerful amps and adjusting the gain according to the speaker facilitates use of the broadest cleanest part of the amps power spectrum.

As far as the speakers themselves are concerned the total RMS figure is only 1600 watts per channel. The headroom or peak power figure taking impedance and gain settings into account is 3690 watts per channel, of VERY clean, effortless, and flexible power.

The Funktion One speakers are extremely efficient and most of that power ends up shifting air.

The large number of amps we're using, 6 in total means that every driver has it's own mono, or mono bridged channel with the exception of the double bass bins, where each bin containing a pair of 18" drivers is powered by it's own mono bridged amp; and the delay speakers where 3 drivers are powered by each channel. We're using a total of 16 drivers, 8 mono channels, and 2 mono bridged channels. Using mono channels means that the electronic producing the sound for L & R are entirely separate, so the end result is stereo but with negligible cross talk interference between channels.

The outgoing system had 8 drivers and 4 mono channels.

Flash

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