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Amp explosion!

foxwelljsly

foxwelljsly

Me too, I ate one sour too.
Have a Quad 405 with Netaudio boards which I have been using with Kef 104.2s. Listening pretty loud, but not excessively and Today crackling noise, smoke and this happened. Never had this happen to me before. Was listening to a mono album and the other channel is fine. I don't have another amp to test my speakers. Anyone know if that speaker might be toast?

PXL-20220814-100624255.jpg
 
If a driver has fried, there ought to be a significant smell from it.

Other than that, a simple continuity check of any drivers would tell you - very easy to do if the drivers are easily accessed.

Mono albums played using a stereo cart' produce the same signal on each channel, or thereabouts.
 
I hate to say it but I doubt that will be repairable, looks like there is a lot of damage to the pcb
 
killie99 said:
I hate to say it but I doubt that will be repairable, looks like there is a lot of damage to the pcb
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I don't give a monkeys about the amp, my 606 will be back from Amplabs next week. It's my near mint low mileage 104/2's I'm worried about!

A quick inspection indicates no smell from the cabs and no untoward resistance on the mid and bass drivers, so I hope I've got away with this.

The Netaudio boards are supposed to be as good into 4 ohms as the 520 and whilst this happened loud, it was way below what 100w into 4 ohms should sound like.
 
It depends if the tracks are burned out on the other side. Things can usually be put back together with a few wire links.
 
Vinny said:
Mono albums played using a stereo cart' produce the same signal on each channel, or thereabouts.
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Which is why I'm surprised one board got this hot - the other is fine and the heatsink was not hot to the touch, unlike on this channel.
 
The amp boards might well be good for that sort of output but the 405's original heatsinking won't have been designed to dissipate anything like that amount of heat. That could well be your problem.

The board looks like it might go again and it might well have been that burned driver transistor with the small heatsink which started the burnout. Looks like it might have gone short circuit.
 
colasblue said:
The amp boards might well be good for that sort of output but the 405's original heatsinking won't have been designed to dissipate anything like that amount of heat. That could well be your problem.

The board looks like it might go again and it might well have been that burned driver transistor with the small heatsink which started the burnout. Looks like it might have gone short circuit.
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These were running loud, but nothing like that. I notice that the DaDa and Quad boards are fused, whilst these are not.
 
chartz said:
Quite spectacular!
Never seen a Quad module fried like that though.
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It's not a Quad module - it's a NetAudio 405 Mk3 module. Drop-in replacements for the original cards that are supposed to be an improvement.

I'll chase Rob for my 606 next week and wait until that arrives to see if my speakers are toast.
 
foxwelljsly said:
I don't give a monkeys about the amp, my 606 will be back from Amplabs next week. It's my near mint low mileage 104/2's I'm worried about!

A quick inspection indicates no smell from the cabs and no untoward resistance on the mid and bass drivers, so I hope I've got away with this.

The Netaudio boards are supposed to be as good into 4 ohms as the 520 and whilst this happened loud, it was way below what 100w into 4 ohms should sound like.
Click to expand...

You can check your bass drivers, to some extent, by applying at 1.5V battery/cell to the speaker termnals. The driver should move out (and stay there) when the battery is connected + to the red terminal and move inwards when connected the other way round.

The other drivers should be protected from DC by the crossover.
 
Ouch, sorry to see this. If I were closer, I’d loan you my Quad 99 but Kent is a good drive from the West Midlands!

If you can power the amp up with just the working board connected, you could test the speaker on that, but I’d do a continuity check first because if you have a shorted voice coil, you could take out another amp potentially… extremely rare but definitely not impossible, I went out to a bar where I’d got a system installed a few years ago and a DJ had bypassed the limiter (a DBX 266xl has a bypass button which he must have know about), anyway, he’d blown an Ohm bass bin… I was called out to the amp immediately going into protection when powered, but the VC had managed to fail short! The amp had adequate protection and survived thankfully.
 
linnfomaniac83 said:
Ouch, sorry to see this. If I were closer, I’d loan you my Quad 99 but Kent is a good drive from the West Midlands!

If you can power the amp up with just the working board connected, you could test the speaker on that, but I’d do a continuity check first because if you have a shorted voice coil, you could take out another amp potentially… extremely rare but definitely not impossible, I went out to a bar where I’d got a system installed a few years ago and a DJ had bypassed the limiter (a DBX 266xl has a bypass button which he must have know about), anyway, he’d blown an Ohm bass bin… I was called out to the amp immediately going into protection when powered, but the VC had managed to fail short! The amp had adequate protection and survived thankfully.
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The 606 has protection, so should be OK. I also have speaker switching.

This is why it's not a good idea for me to have valve amps. I suspect my 'quite loud' might be someone else's bloody deafening. Amazingly, my hearing got a compete bill of good health recently.
 
S-Man said:
You can check your bass drivers, to some extent, by applying at 1.5V battery/cell to the speaker termnals. The driver should move out (and stay there) when the battery is connected + to the red terminal and move inwards when connected the other way round.

The other drivers should be protected from DC by the crossover.
Click to expand...

In the case of Kef's conjugate load matched crossovers, I wonder if all 5 drivers are protected by the crossover if the amp goes DC?

My office still smells of cordite. :-(
 
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