Pub PA wiring jumble.. HELP!
Hi all, I have just registered to seek help with a 100v PA system installed at my local pub. They have recently moved in and have found a 100v PA, and some wires but nothing is attached!!
I have read up as much as I can find (I deal with IT networks normally) and have the system fully functional with the exception of the zone transformers.. details are...
Several 100v tapped speakers, all with their wires running to the PA in the cellar.
1 main volume variable tapped transformer, 4 positions. This is behind the bar. This has 3 individual wires (1.5mm), 1 brown, 2 blue, returning to the PA.
Under the main volume controller are 3 smaller units of similar design, each with 4 positions. I can not remove the covers as they are 'built around' by a wooden unit. But the wires that appear to go the them are telephone wires!!!
I have been told that the main unit used to control the overall sound and the 3 smaller switches controlled the zones but they are no longer in the circuit and I don't know how to get them back in!
Many thanks for any help or diagrams of suggested wiring you can point me towards.
P.s. I have searched the forum for help, just not sure exactly what to search for.
Pics would tell a lot as there are many manufacturers of installed sound products out there. Shots of the front and back would be great.
So my guess is at least the four control panels under the "main" volume control at the bar originally were remote controls for the main system processor or controller. Phone wire or CAT5 is regularly used for this purpose when no audio is passing through the control panels. It's often either simple analog logic or 232/485 serial data.
Or even just 10V send and return to drive a VCA.
I'm going there later today hopefully and will take pictures of front and back of as much as i can and post back asap.. Cheers.
Went in after work last night to take some photos. I did a bit more poking around while I was there and managed to get the front cover off one of the individual zone switches and have taken a photo of where the wires appear to go.
It's not totally clear as I can only get the right hand one off, but as far as I can work out the small telephone type wire does terminate in the 3 small switches and then loops out through what was used as the master switch.
The only wires I can find in the cellar are the telephone wires. (pic6)
I asked the boss how they were connected before it was 'altered' and it's not clear but he thinks the telephone sized wires were connected in the speaker wire circuit.
Looking at the back of the amp there is no obvious signal level remote type circuit so I think it's just a case of recycling whatever wiring was available to that location, however unsuitable it might be.
Amp currently wired on the 70v circuit through 'choc block connector' and the volume controls behind the bar are not connected. (pic7)
Thanks again for looking and any advice you can offer.. Pictures hopefully attached as requested.
My guess is there originally was one pair of wires that went to the master volume control then split to the three zone volume controls. On the three position terminal block on the master, the outer wires are from tge amp and the center wire goes to the zone volume controls. It looks like they used the phone wire to bypass the master volume control and feed the three zone volume controls directly.
The first thing I would do is restore the original wiring and see if it works. It's possible there was a problem with the master volume and/or zone volume controls.
One more question-
Where do all the other wires in the terminal block at the amp go?
All the "units" are audio transformers with tapped secondary windings all they are used as volume controls (1 master + 3 zones).
Most probably they were initially connected as: amp -> master volume control -> zone volume controls -> speakers. It seems that they had some problems with the master volume control and they bypassed it and connected as: amp -> zone volume control -> speakers. BTW, telephone wires are often used in such installations (this is high voltage, low current circuit).
The information that:
I would connect it like it should be connected (exactly as imix500 says) and while connecting it I would check the correctness of the connections (eg. with continuity tester in a DVM). You can also take any speaker with audio transformer and check first output from the main volume control and then from each zone volume controls (with zone controls most probably the audio transformer is not needed - the volume control already contains the transformer).
The use of a 'main' volume controller seems a little "butter and oil"..... but still OK. I just wonder if they all had one common controller, and the zones were added later....
Wiring for 70 or 100V can easily be done with telephone cable, up to a medium power level, although I would choose something slightly larger cable, .5- .75 sqmm. for anew installation. I take it you know how it works.. - each loudspeaker have it's own transformer, often with different taps to regulate the max power to that unit. The thing to watch out for, is to not exceed the rated level for each level controller. The beauty is of course that speakers can be wired in parallell ( or rather the individual transformer for each speaker).
The brown-blue wires must be the ones going from the amp to the controllers - where the grey ones go you'll have to find out. If you take down a speaker or two, you may find them with open ends, - or other speakers have been used previoulsy.
There's lots of parts for systems like this, and it is usually not very expensvie, unless you gor for very large systems, high quality or high power levels.
This is one example of a 5-way volume unit with common input and 5 zones.
They also have a lot of other stuff for similar use.
Hi all, many thanks for all your help.
With that help and a bit of research, poking and probing I have managed to turn this into a 4 zone control panel.
I eventually had to remove the back of the bar to access the other 2 volume controls and found they had been wired as 2 pairs of zone controllers but both fed from the same source. As I could not trace the wires to one of the pairs I have just joined them all up to the same supply wires, these were brown/blue flex so I believe more than happy to carry the low current.
The telephone wires were connected to the SPK output and they return (changing colour on the way somewhere!!) to the cellar and are then fed out to various rooms.
Connection blocks have been used for this. All returns have been connected to the common return post and.... all seem to work correctly..!
I have had to connect them to the 70v output not the 100v as that was just too loud, even though the speakers have 100v transformers in them and even with the master control on the amp itself turned right down.
A slightly steep learning curve for me, many thanks for all your help. Now to get back to the other side of this bar!!
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