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Speaker troubleshooting

gurner

gurner

New Member
Hi Everyone,

I'm new to the forum, so G'day from New Zealand!

I have a problem which I'm struggling to solve.

I have two pairs of speakers, IMF TLS 80 and some homebuilt 3 way speakers.

Both sets of speakers have been working great for the past 2 years, at my wedding my brother in law insisted on having the output on the laptop turned right up and the Amp turned down to mitigate the risk of anyone blowing any speakers by cranking the amp up. About 4 hours in the homebuilt speakers started to sound dull, there was noise, but no clarity, like the music was being played underwater. After swapping the speakers over and about 2 hours in the exact same thing happened to my IMFs. I'm 200% sure it is the way we had the Laptop output/amp volume setup that has caused the issue.

In troubleshooting I've done the following:
Tried a different Amp
Replaced all speaker cables
Removed and tested all driver units with a multimeter (all are fine)
Checked all wiring on crossovers
Visually checked all capacitors
Visually checked all wiring on crossovers and to drivers and pegs.

The only thing I think it can be is something to do with the crossovers, blown capacitor Or somehow a damaged transistor?

The crossovers on the homebuilt speakers are 2 years old, they were not cheap capacitors. The IMF are the originals. (I have a set of replacement caps from falcon acoustics that I was going to put in one day)

I don't have any problem re-building crossovers, but I only want to do this as a last resort because its extremely time consuming and hurts my brain haha :/

The IMF crossover is a maze, whereas my homebuilt is a lot easier for me to visualise.

So before I embark on the lengthy mind task of rebuilding crossovers, what else can I do to test?

Cheers
E
 
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My first thought was that you probably fried the tweeters, but you've tested them. Have you tried a different music source?
 
Welcome to AK!

It happened on both speakers equally? That sounds suspect.

I hope they are still disassembled. Hook up each individual driver to a source and listen. Then listen to the matched pairs to look for any differences. I can’t tell you specifically what you are looking for, but I suspect some dullness or flatness.

Then I’d check out the crossovers. It would be pretty cheap to rebuild them, but I think the LF blocking cap on the tweeter is toasted or at least leaking.
 
I wouldn’t rebuild the full crossover, only the caps, starting with the LF blocking cap then work toward the midrange.
 
Semanon said:
Welcome to AK!

It happened on both speakers equally? That sounds suspect.

I hope they are still disassembled. Hook up each individual driver to a source and listen. Then listen to the matched pairs to look for any differences. I can’t tell you specifically what you are looking for, but I suspect some dullness or flatness.

Then I’d check out the crossovers. It would be pretty cheap to rebuild them, but I think the LF blocking cap on the tweeter is toasted or at least leaking.
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Well there was alcohol involved so it is possible they went separately, but close together
 
Is there any DC on the outputs of the original amp? A few millivolts would be OK, a lot more...not. Check with and without the laptop connected as before.

There could be powerful ultrasonic noise or oscillation from the amp as well (if it has gone bad) but that's harder to test for.

Either condition could have damaged the speakers.

Edit: Again, check with laptop connected also, in case it's the source of oscillation or DC.
 
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gurner said:
at my wedding my brother in law insisted on having the output on the laptop turned right up and the Amp turned down to mitigate the risk of anyone blowing any speakers by cranking the amp up.
Click to expand...

This wouldn't have made any difference. All the speakers care about is the total amount of power they receive, and that's the same for a given volume level, whether you turn the amp volume up or the laptop volume up. For example, if you've got a 100 watt amp, it's almost never sending the full 100 watts. In your listening room you're probably using overall under one watt. In a situation like a wedding, where you're (presumably) playing loud music in a large room, I could see you overdriving the amp and sending it into clipping, which could damage the tweeters. Although you've checked them with a multimeter, it might behoove you to try connecting them (momentarily) directly to the amp with some music playing at a low level. It's possible that the voice coils have been overheated and are now locked up. If you get no sound out of them when they are connected, that's probably what happened.

And welcome to AK.
 

Imf crossover problem

Just acquired these but they are the early version with a slightly different x,over layout to tls 80. No luck from falcon regarding x,over schematic. The problem is no sound output to the tweeter and super tweeter. The crossover have been mucked about with and the tone switch has been removed...
audiokarma.org
 
swechsler said:
This wouldn't have made any difference. All the speakers care about is the total amount of power they receive, and that's the same for a given volume level, whether you turn the amp volume up or the laptop volume up. For example, if you've got a 100 watt amp, it's almost never sending the full 100 watts. In your listening room you're probably using overall under one watt. In a situation like a wedding, where you're (presumably) playing loud music in a large room, I could see you overdriving the amp and sending it into clipping, which could damage the tweeters. Although you've checked them with a multimeter, it might behoove you to try connecting them (momentarily) directly to the amp with some music playing at a low level. It's possible that the voice coils have been overheated and are now locked up. If you get no sound out of them when they are connected, that's probably what happened.

And welcome to AK.
Click to expand...
Will give this a go too, ty
 
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