Vintage Carlsbro alpha pa speakers

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   Hello and thank you for letting in on this forum.

I have some Carlsbro alpha vintage speakers.
Forgive me if my technical terms are wrong as I'm new to this.

I have a bass speaker, a mid-range speaker, and a tweeter.

there's very little sound coming from the midrange and the tweeters on both speakers.
Could this be the diaphragms in the speakers (  part number cp16 cp25) all the crossover system. Part number not known.
if it's one or the other or both I would like to repair them and where can I get some from.
I can take photos if needs be.
Kind regards

Simmark

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Simmark Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 11 June 2020 Location: Norfolk uk Status: Offline Points: 4	Post Options Post Reply Quote Simmark Report Post Thanks(0) Quote Reply Topic: Vintage Carlsbro alpha pa speakers Posted: 11 June 2020 at 3:11pm
	Hello and thank you for letting in on this forum. I have some Carlsbro alpha vintage speakers. Forgive me if my technical terms are wrong as I'm new to this. I have a bass speaker, a mid-range speaker, and a tweeter. there's very little sound coming from the midrange and the tweeters on both speakers. Could this be the diaphragms in the speakers ( part number cp16 cp25) all the crossover system. Part number not known. if it's one or the other or both I would like to repair them and where can I get some from. I can take photos if needs be. Kind regards Simmark

studio45 Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864	Post Options Post Reply Quote studio45 Report Post Thanks(0) Quote Reply Posted: 11 June 2020 at 3:22pm
	Hi mate welcome to the forum :) It is quite likely to be the diaphragms. But they are old speakers, and most likely have electrolytic capacitors in the crossover - these tend to dry out and fail after 10-20 years. To find out what's wrong, you will need a continuity tester. Easiest thing to get is a cheap multimeter. Use this to check whether the coils on the diaphragms still have continuity, and are not shorted. For an "8 ohm" speaker you should measure 5-6 ohms resistance, for a "4 ohm" speaker about 3 ohms resistance. If the diaphragms are OK according to the meter, then you will need to look at the crossover. If you can see any components that look burnt or exploded to the eye, those will need to be replaced. Test each coil, resistor and capacitor individually with the meter - coils should have very low resistance, resistors should be whatever is printed on them, capacitors should measure open circuit (infinite resistance) or if your meter has a capacitor test function, as printed on them. If the diaphragms and crossover components all measure OK, but there is still no sound, the only other thing to check is the physical condition of the diaphragms - to do this you have to disassemble the drivers. The diaphragm should be intact, shiny, and not dented, torn, holed or misshapen. The magnetic gap where the coil sits also needs to be free of dirt and debris. Hopefully one of these procedures reveals the problem :)
	Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA

Simmark Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 11 June 2020 Location: Norfolk uk Status: Offline Points: 4	Post Options Post Reply Quote Simmark Report Post Thanks(0) Quote Reply Posted: 11 June 2020 at 3:50pm
	Thanks for your reply on this. I've checked with a multimeter and yes the tweeter reads 7 ohms and the mid was 6 ohms. The diaphragms are dented . The coils 'if that's the right term' look in good condition but dull in colour.' not shiny new' And the date on one is 1979. Wow! I will check the capacitors when I get home. I'll let you know how I get on.

Digbethdave Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 16 November 2018 Status: Offline Points: 406	Post Options Post Reply Quote Digbethdave Report Post Thanks(0) Quote Reply Posted: 11 June 2020 at 6:53pm
	Bung some photos up, I've got some old carlsboro catalogues

Simmark Members Profile Send Private Message Find Members Posts Add to Buddy List New Member Joined: 11 June 2020 Location: Norfolk uk Status: Offline Points: 4	Post Options Post Reply Quote Simmark Report Post Thanks(0) Quote Reply Posted: 11 June 2020 at 7:35pm
	I'm new to this forum . So how do add photos?

DMorison Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 14 March 2007 Location: Aberdeen Status: Offline Points: 1649	Post Options Post Reply Quote DMorison Report Post Thanks(0) Quote Reply Posted: 12 June 2020 at 1:06pm
	Simplest is to host externally on imgur/imgbb/whatever you find easiest and paste the bbcode for the images into your post. You can upload to the forum, (though you may need to make more posts to unlock that) but it compresses images reducing clarity in the process.