Sound system for old village hall

In message , cynic writes

If all the speakers are brought back to a common point then maybe the speakers are low impendence, 8 ohm. But, most basic systems over the last 40-50 ++ years would have been 100V line.

I could imagine that yours are 100V and are brought back to one place for zone switching at the amp.

There are numerous amps available for PA such as yours, if it is 100V Ebay is normally full of them. You do need to decide what sort of inputs you are likely to need, line or mic level, do the mics need phantom power etc.

The following will give you an idea as to how 100V line works. The quick test would be to open one of the speaker cabinets and see if it has a transformer in it.

Have fun..........................................

Or connect a 1.5V battery across the leads.

The speakers are probably 100v line and decades old. I cant think what you'd find by googling mfr's names.

Before deciding to spend on a new amp, its worth checking out the sound quality of the speakers. Maybe theyre great, maybe theyre awful and barely work, and would need replacing, upping the ttoal cost and maybe not making it all worthwhile.

Some idea of budget and what you want to do would really help.

NT

A good way round this problem would be to ask for quotes from several companies for a PA System and show them the speakers when they arrive. They may give you loads of info.

I've only got a short memory. I used to know this stuff, didn't need to touch it for years, then when I went back to it this year, everything had shifted.

Now it's modern cheap speakers, and home-built Class T active speakers added to them using modules from China, via eBay. Stuff's unbelievably cheap these days. 100V is IMHO now dead in the water.

If you want brandnames, browse the CPC website as one of the cheapest sources.

Can't you just try hanging a common or garden audio amp on them and have a listen at all?. They might be 100 volt line but I really wonder for such a small installation they'd have bothered with all that?.

If you can take one apart and see if theres anything resembling a transformer in the cabinet if there is then thats very likely to be a

If you can't get inside any makers names at all or a simple ohm meter check might give an indication.

Or post a picture somewhere!......

In message , tony sayer writes

There is next to no difference in price and any idiot can wire them. Trying to match in extra speakers and work out impedances if not 100V would be a disaster waiting to happen.

Measure them with a DVM. If low impedance speakers, you'll get a reading of approx the impedance. Say 4-16 ohms. If 100 volt line, you'll get something very much higher.

You can't just parallel lots of low impedance speakers together and use an ordinary amp. They are designed for two per channel at most. So much easier if 100v line - but you'll need an amp designed for this.

If they are low impedance, they'll work off a domestic amp, so try them out and see what they sound like. If they have no maker's name and spec on them, possibly not good.

In article , Bill scribeth thus

Beg to differ from me 'learned mate but that may be so in recent times but as it sounds as if these have been there since Gilbert Briggs was a lad so perhaps more expensive and specialised in those days;?....

In message , tony sayer writes

That's perfectly OK Sir. I can only remember back the last 40 years or so, therefore I bow to and respect my elders with greater memory range. (age).

:-)

=A0 London SW

I was thinking more on the lines of using an AVO 8 which has been known to produce faint clicking noises from low impedance speakers in the past. At the end of the day I think I am going to have to open one of the cabinets up. Maybe a sharp knife along the corners will allow this without excessive damage to the overlapping paintwork covering cabinet and wall :-( I really hope it is a 100 volt line system as I can get hold of a new amp relatively cheaply.

Sods law says that despite all the asking around in the users of the hall without success someone will say after the situation is resolved "oh yes old harry put those in about 19xx. You should have asked him"

=A0 =A0 London SW

If theyre not 100v line there still shouldnt be anything tricky about using them on a modern amp. It takes a tiny bit more awareness of how to do it is all. I wouldnt open them, if you lack testgear just connect one to a modern hifi amp and see if teh volume output is normal or way down. If the latter, it'll be 100v line. If volume is normal it'll be a low impedance speaker, no transformer

To set up low impedance speakers we'd need to know what resistance they are, how many there are, and some idea of what relative volume you'd like for each.

NT

Come on lets have a few pix posted somewhere;!...

In article , Bill scribeth thus

LOL!....

Back in the day who used to make such gear?. I remember Pamphonic did rather large systems some with amps in the kW range but smaller systems any names anyone?..

EMI Sales & Service Ltd

GEC

Philips - the EL6420, 70W output, 2 x EL34 in push-pull, attractive bakelite case

Whiteley

Pye

Standard Telephones & Cables (microphones)

Cosmocord (microphones)

Trix Electrical (Micorphones)

Reslo Sound (very nice microphones)

Vortexion

Lustraphone

Truvox (loudspeakers)

Grampian Reproducers (amps and speakers)

Communication Systems, Ltd

and of course

TANNOY

A manufacturer of systems popular in schools was Coomber who still exist. Clarke & Smith have died out I think.

Owain

If you have one of those, sell it (even just eBay) and buy a complete replacement system.

That will also measure the resistance - since it needs the battery involved in that to produce the click. But a single cell battery will do the same. However, if you get a reading of about 4-16 ohms, it's likely the speaker is still connected and working. If it is very much higher - many hundreds to low thousands - likely 100v line.

Shouldn't be needed before testing. And running them up to hear what they sound like.

My guess is not. You usually daisy chain 100 volt line - not star as it seems like you have - to save on cable and installation time.

When I had to rewire and install new control gear for an existing disco, faced with rats nest of wires in biscuit tins, I commited what my boss considered was the cardinal sin of hacksawing all the incoming cables off, and then spending a morning with a meter, terminating what definitely seemed to be pairs into a proper DIN terminal block case, and noting down what each pair did.

Apart from a really badly wired cluster using tow fr cables with what transpired to be a completely wrong coloured common neutral wire - I used a live pair of probes to investigate that along with identifying WHICH lights each pair was...that got me to a very stable and documented starting point.

I would suggest the same. Get a portable amp of some sort - say an old tranny radio - and take some leads off the loudspeaker output, apply to each pair in turn, and see what you get.

Ha-ha, I'd be more likely to sell a complete system so I could afford a Reslo!

Not to use, just put in the Display Cabinette and enjoy looking at.

Owain