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RF82 Mk. 1 - No sound from the tweeters


BDS

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Hi. 

 

I´m just got my old RF82 (assuming Mk. 1 as they are roughly 10 years old) speakers out of storage and decided to give them a go again. 

However, I am not able to get any sound out of the tweeters. Both sides are completely dead. The bass elements are working fine.

After switching channels on my amplifier there is no change. 

I am therefore relatively confident that it is not a problem with the amplifier. 

I also tried to remove the jumper and only connect the speaker wire to the tweeter input on the back of the speakers --> no sound at all. 

 

Could it be that both tweeters are blown and have to be replaced?

Am I missing something obvious?

 

I do not have much knowledge about stereo systems. 

 

Thanks for any help. 

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Welcome to the forum

 

It's possible for both to be blown if they have previously been played with the amplifier clipping.  Really, the only way to tell is remove the tweeter wires from the crossover and see if the tweeters measure open with an Ohm meter.

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Thanks for the quick response. 

 

I can acquire a multimeter to test this. 

Is there a good procedure to follow when doing this?

 

I picture something like this:
1. Carefully remove the front cover and try not to disconnect any internal wires. 

--> Am I at risk of messing up the crossover or the bass elements when doing so?

2. Remove the tweeter wires from the crossover and measure the electrical resistance over the tweeter. 

--> Question: Are the wires clipped or soldered on? Or in other words, will I be able to reconnect the wires after measuring with a multimeter?

3. Should be no reading if blown? (broken coil)

4. Reassemble

5. Acquire new tweeters. 

 

Am I missing any important steps, or picturing the procedure incorrectly?

 

Again, 

Thanks. 

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Obviously, you can (should) swap steps 4 and 5 if the tweeter(s) measure either open or "fully closed" (shorted internally - I suppose it's possible for the wire to get hot enough to melt the insulation while remaining intact otherwise, though not so likely in a tweeter). 

 

I'd pull the tweeter only and remove one of the wires from its terminals to check it.  It may be a flattened push-on connector with possibly a little nipple in the middle which requires depressing with a jewelers screwdriver or paper clip, etc. to allow it to release.

 

I don't know specifically what reading it should provide with an ohmmeter, but it should be neither (near-) zero nor infinity.  I'd guess some value in the mid single digits.

 

If the tweeter(s) measure "okay" then go ahead and disconnect all the wires from all the drivers (a snapshot with your phone camera beforehand showing which wire went to which terminal would be prudent) and remove the entire crossover as that's where the problem lies. 

 

Do all this only after you double-check all external connections.

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21 minutes ago, glens said:

I'd pull the tweeter only and remove one of the wires from its terminals to check it.  It may be a flattened push-on connector with possibly a little nipple in the middle which requires depressing with a jewelers screwdriver or paper clip, etc. to allow it to release.

I've never taken an 82 apart but on some of the Reference stuff it's easier to remove either the crossover (behind the terminal cup) or upper woofer to get to the wiring.  Of note: it's easier to remove the drivers when the speaker is laying on it's back.  Normally the drivers are all heavier that you anticipate and easily dropped if the speaker is upright.

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37 minutes ago, BDS said:

I guess both tweeters are dead and need to be replaced, as expected. 

If that's the case then the speakers were over driven.  They're either too small for the space you have them in or they were driven to clipping with too small an amp.  Once you get them up and running, try not to duplicate the scenario that burned them up prior to going in storage.

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I am running the speakers with a Harman/Kardon HK3490 amp.

It offers 240 Watts (2x120), and the speakers have 150 Watts listed as the max. 

 

It is pretty clear that I have limited knowledge about the stereo world, so I will ask the dumb question:

 

The amp has two channels. 

Could it be that if I only use one channel (speakers 1, speakers 2, or speakers 1+2 are possible options on the amp settings) the amplifier is able to output 240 Watts, and therefore blew the tweeters in a careless moment?

Or, is the combined speaker capacity 300 Watts (150 per speaker), meaning that the amp is too weak?

 

Or have I misunderstood the concept completely? 

 

Thanks for your replies. 

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