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-   -   Help and advice needed for sports club (http://www.diyaudio.com/forums/pa-systems/224293-help-advice-needed-sports-club.html)

KenHunter 25th November 2012 07:20 PM

Help and advice needed for sports club
 
Hi, my name is Ken and I am a volunteer working for our local volleyball club. We would like to set up a PA system to use in the sports hall so we can announce scores, read out raffle winners etc. As with everything else, funds are tight so I was wondering if I could use a microphone through my old JVC stereo system.

The system is a JVC model DR-E2L AC 240 v 50Hz 170w
it has a headphone jack in the front.
On the reverse there are 4 input sockets under a heading CD/AUX/Phone L and Left and R and Right. my CD player were plugged in to these via some red and white jacks.
There is also a section called Output - Beat Cut DC12v 100mA max. There is a femals style socket here in which I plugged my turntable

I have 2 speakers - model SP-E1BK - it states on the back;
power handling capacity 40w (80w music) - impedence 8 and what looks like a horseshoe - is that ohms?

As you can tell, I am not very knowledgeable so could be easy prey at any local superstores. Is it possible to plug a mic into these system and if so what type of cable should I get and where should I stick it (be polite please) - the headphone socket?

If this is not possible, could anyone recommend a suitable cost effective solution.

Grateful to everyone for reading and responding.

indianajo 26th November 2012 01:18 AM

Well, no. Post 1964 stereo systems didn't have dynamic microphone level inputs. Your CD input could be used to make the receiver function as a power amp, but you would have to buy a mixer to boost a dynamic mike to a 1.6 VAC level. The phono input would cut all the treble off your voice, and accentuate bass noise and clothes/fumbling rumble.
If you can find an electret condensor microphone that will put out 1.6 VAC maximum, to go in the CD input fine, but all the cheap microphones I have are 10000 ohm dynamic mikes. I was reading about electret condensor microphones on wikipedia today. I've never seen one but they have a lot of words about them. No battery required. The expensive non-electret condensor mike I have for music recording has a requirement for 48 v phantom power, which only pro mixers supply. Your best bet is probably to buy a reviled used disco mixer for turntables or CD's or disco system, which has a mike input for the DJ voiceover. These will typically put out 1.6 VAC to a power amp. The mixers for turntables are more obsolete, the CD disco mixers less so, as party DJ's have mostly gone these days to computer sourced music. If you could find a powered disco mixer, it would have the amps built in and you would just use your own speakers.
I liked my $15 used Herald disco mixer because it had great potentiometers and was built of amateur replaceable DIP packages and leaded components. Peavey disco mixers are rare, but they would give you a schematic diagram if you asked. A numark or behringer disco mixer, you better make sure it is working before you buy it, as they are repairable only by factory authorized (ie fixed price) service centers. Numark & Behringer schematic diagrams are copywrited and not available to the amateur. Internal parts on behringer and numark are SMD as far as I know, which take about $500 in tooling to work on. I would suspect them of having custom sized slider potentiometers, also, to make sure you replace the worn out ones with factory parts. Used PA stuff usually has a bad pot or two. Low first price and repeat purchase for failed systems seem to me to be Behringer's marketing philosophy.
The reason I'm droning on about Numark and Behringer, as all the used disco mixers on craigslist here are those brands. Peavey disco mixers are in the catalog, but not available used. the Herald RA88a I stumbled on at a flea market (UK jumble/boot sale). In the UK you might stumble on an old Leak amp which might have the correct input for a dynamic mike (many had 3 inputs), but at 45 years it would probably need considerable maintenance (electrolytic capacitors). I've found several old tube Bogen PA amps, about 13 watts, at the flea market for $15; they have the proper input for a dynamic microphone, but at 50 years they would need a lot of capacitors replaced, also. The bogens have a weird old microphone screw in connector for input which would have to be replaced by an 1/8" phone jack, also. Watch old PA gear you buy used, to make sure it has an 8 ohm (consumer) speaker output. A lot of PA gear had 70 VAC outputs only, which speakers are so expensive you lose the advantage of buying used. The 70 VAC speakers are always abandoned in the building and aren't usually for sale.

DUG 26th November 2012 01:27 AM

Budget solution.

I looked up the DR-E2L and it showed that it has an FM tuner.

Correct me if that is not the case.

What about getting a cheap FM wireless microphone?

Like: Mr. Microphone

Or more modern: Disney hannah montana fm wireless microphone - TheFind

:)

dangus 27th November 2012 01:52 AM

In case you missed my reply to your post in the other forum, I suggested looking for a DVD player that has mic inputs for karaoke. Those are fairly common at thrift stores, and cheap. On the one that I had, the mic board was a separate board with two mic inputs and a reverb effect; the only connections to the rest of the DVD player was the line level audio out and 12V for power, so it wouldn't be hard to mount it in a little box and power it from a wall wart.

chrispenycate 27th November 2012 08:15 PM

Otherwise cassette decks have usually got mic inputs on them, and can generally be persuaded to put them out of the output sockets by a careful choice of buttons (generally rec/pause). And there are lots of them that people haven't got round to throwing away.

Most cheap electret microphones run off one and a half volt batteries (cells, actually), so can't give one point six volts RMS even at 100% distortion. (full square waves) with the FET junction voltage I think about 50-100 mV is about the maximum you could hope for, and you'd have to shout at it pretty loud to get that. (expensive electret condenser microphones often have higher voltage batteries, but that defeats the object of the exercise).

Generally home hifi loudspeakers are not well designed for sound reinforcement – why should they be?– and often fall apart under the strain; either the drivers or, quite often, the boxes. So this is likely to be a temporary solution, or require continuous service.

A mic preamp - no, not a studio quality mic preamp, not a great mic preamp, just something that will get the job done – is a very simple DIY project. 9 volt battery or a wart on the wall power supply, one op amp, a few components- probably less work than repairing a vintage amp. Most of the problems are drilling holes in a metal box, and learning to solder. Even a tone control isn't rocket science, and the components needed are cheap enough that you can blow them up a few times while learning. There's probably a kit for one somewhere, but really it's simple enough not to need one. That way you can choose what you want – a push button to turn the mic on and off? no problem. And if you leave some space in the box, you can improve it later as you find out what's missing.


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