Smoking B&Ws Help?!

Turbo Dragon

Active Member
Hi All,

Tonight I started to smell something funny in my flat, couldnt figure it out for ages.

Then I noticed that one of my B&W 601 S2s had faint whisps of smoke coming out of it :eek:

Quickly powered everything off and disconnected and my tweeter ring appears to have melted and it was red hot on the speaker connections. The amp always seems quite warm and didn't seem any different tonight when I felt it :rolleyes:

They are being driven by an Onkyo A-5VL that is roughly 12 months old, normally it is being fed my my PC via optical, I wasnt listening to anything at the time but it (and my PC) were powered on as usual.

I have had the speakers for years and they have been powered by several amps without problem.

Is this likely to be the speakers at fault or the amp and how can you check, don't really want to hook the left one up to test if its the amplifier output :confused:


Any thoughts greatly appreciated....... :lease:
 

LargeStyle

Standard Member
I'm definitely no expert on speaker and amp technology, but it at a guestimate, I'd say that it's the individual speaker at fault, but I could be completely wrong!

In fact, I'm only writing here really just to state that I've read a hell of a lot on this forum that B&W's after-sales service is well-beyond expectation, so if you haven't done so already, perhaps try to contact them directly. They should at least advise you on what's actually happened, and how to fix it (if possible).
 

Turbo Dragon

Active Member
I have spoken to B&W and you are right, i've dealt with them before- there customer service is excellent.

Problem is that the inspection fee is 75 quid. I can buy a second hand set on the bay for less than that.

There engineers said that they doubt it is the speaker as they are passive and at the time were inactive. Spoke to Superfi who i bought my amp from, they said bring it back and they will inspect it to try and figure out what's wrong.

I'm thinking its a transformer in the amp gone wobbly, if it is the amp at fault i'm going to have an interesting discussion with Onkyo about the damage caused. (and the risk that it could have caused a fire in my flat!)
 
B&W service is top notch. I had some 804's that had developed a fault with a tweeter. It was within warrenty so they just replaced the whole speaker! Can't fault them.
 

Turbo Dragon

Active Member
Ok. Got my amp back with no fault found.

So to summarise one speaker melted, amp is fine, I'm now thinking that there must have been a problem with my sound card?!

Is it possible that the speakers crossover went faulty and caused the meltdown?

Any other thoughts greatly appreciated.....
 

scottthehat

Distinguished Member
to me it sounds more of an amp problem, asyou said you was notlistening to anything at the time(you havent over driven the speakers) and i cant see a faulty sound card causing the problem, post some pics up of the melting.
the only time i have had a problem with smoking speakers was when my sherwood amp soulder shorted and desided to max the volume whilst i was down stairs, man the stunk and the smoke was terrible, speakers are still going now and sound like they did when i first got them.
 
I'm pretty sure its going to be something to do with your amp. I wouldn't be able to say exactly what it is but the chances of a set of idle speakers heating up and melting a component is very unlikely.

I would be wary about getting another set of speakers before finding out whats caused the fault.

How did they test your amp? By plugging it in and trying to re-create the problem for about 5 minutes?
 

BlueWizard

Distinguished Member
I wonder if they checked the output of the amp for DC voltage. It could be one of the coupling capacitors broke down. If there is DC voltage then current will flow even if there is no sound. It would be like connecting a battery to the speaker.

Now it is possible that the voice coil on the tweeter has been wearing over time, and just the right combination of time and temperature caused the insulation on the voice coil to break down and short the coil. Though I would have expected that to shut down the amp, though it could have only been a partial short rather than a complete dead short.

As other have said, I would be reluctant to connect a the speakers until I had some sense of what the problem was.

There is a slim chance that something went wrong in the speaker crossover, though I don't see how that could cause this problem. I could see the tweeter blowing while you were playing it, but not sitting idle.

Very confusing I must confess.

If you have a voltmeter, you could try disconnecting the tweeter, and connecting the speaker to the amp. Then with the volt meter set to DC on a range the covers, say, 25v or up to 50v, and place it on the output of the amp. If you measure any DC voltage then there is a problem with the amp. Note the DC voltage if it is present could be either positive or negative.

Still something of a mystery though.

Steve/bluewizard
 

Turbo Dragon

Active Member
I will be picking amp up today/tomorrow. When I dropped it off with Superfi they hooked up another set of speakers to it and it was fine, I think that can rule out the DC output, unless it is a transient issue?!

Will definatley get a meter across it before I hook it up again, in theory what would happen if my soundcard had gone faulty and sent out very very (inaudible) high frequency audio on one channel, to my amp (via spdif).

Would this have been been amplified enough to cause the meltdown or would any freqs have been rejected during the chain?
 

Seriously Ltd

Distinguished Member
AVForums Sponsor
BlueWizard said:
I wonder if they checked the output of the amp for DC voltage. It could be one of the coupling capacitors broke down. If there is DC voltage then current will flow even if there is no sound. It would be like connecting a battery to the speaker.

Now it is possible that the voice coil on the tweeter has been wearing over time, and just the right combination of time and temperature caused the insulation on the voice coil to break down and short the coil. Though I would have expected that to shut down the amp, though it could have only been a partial short rather than a complete dead short.

As other have said, I would be reluctant to connect a the speakers until I had some sense of what the problem was.

There is a slim chance that something went wrong in the speaker crossover, though I don't see how that could cause this problem. I could see the tweeter blowing while you were playing it, but not sitting idle.

Very confusing I must confess.

If you have a voltmeter, you could try disconnecting the tweeter, and connecting the speaker to the amp. Then with the volt meter set to DC on a range the covers, say, 25v or up to 50v, and place it on the output of the amp. If you measure any DC voltage then there is a problem with the amp. Note the DC voltage if it is present could be either positive or negative.

Still something of a mystery though.

Steve/bluewizard

Very strange. As an operational firefighter I am too at a loss I can only guess that maybe something became live in the amp and ran a current through the speaker cable. No idea if that could happen just a theory as I have come across weird causes of fire with electrical equipment. I cannot see it being your speakers at all.
You do need to get to the bottom of this though for obvious reasons.
 

Turbo Dragon

Active Member
Right, so i've got my amp back reported fully tested and no fault found.

The only thing I can think of is that my soundcard in my PC has sent out some really high frequency and I've not heard it and its melted my crossover. Which would suggest the soundcard has gone faulty?!

Currently i've connected it up with a pair of old rubbish satellite seakers from a dead TV, see if it causes any problems if I leave it powered on but not in use.

Is it possible that spurious audio from my PC could have caused this? My soundcard has never been 100% 'clean' and seems to pick up noise from inside my PC (mousewheel clicks etc.) but thats common in a lot of internal soundcards ?!
 

swiftpete

Distinguished Member
I've never heard of this happening before. I wouldnt trust the amp check, when I read the post that said amp is being checked I immediately though they won't find a fault.
I think your speakers are haunted, you need to get the ghostbusters in.
If I were you I'd just get new kit.
 

daniel1111

Standard Member
I would not trust the amp check either. If there was a problem they most likely fixed it already without letting you know. Reason? Depending on what country you are in that could cause trouble for them, as you could sue them for the potential danger caused.

And I would say 95% it was the amp. Your speakers are passive, like the B&W engineers said. It takes energy to heat and melt. The only part in your chain that delivers this energy is your amp. Of course the crossover could have gone faulty, but that would be most likely due to overload, again caused by the amp.
The other 5% would be the soundcard theory that you have, but I honestly doubt it would be sufficient to cause melting.

So what I would do now, is bring the amp to some technician I trust and have it thoroughly checked. Also check if there are replaced parts to be found. If so, you have got your cause.
 

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