Burning smell from speaker cab
 

So tonight I played a quick set with a new band at a show, about 15 minutes long. I was using an Ampeg V4 through an SWR 6x10 with the volume at around noon when I started smelling something like an electrical component burning. I haven't had any time to really investigate but I was able to determine that the smell was definitely not coming from the V4. The cab wasn't farting out and all the cones were still moving together. I was getting some distortion from the amp and had the tweeter set at about 10 o'clock on the back of the cab, I was thinking that maybe that was what I was smelling. Any possibilities thats what it was? Or suggestions on where to start investigating this? I probably won't be able to dive in until tomorrow night at the earliest, maybe not even until Monday, so some good tips on where to start and what to look for would be appreciated.

And the magic smoke escapes...

Check all the wiring. It might be from the tweeter Lpad or the xover.

We all know electronic equipment runs on smoke,
because when it escapes things stop running.

What's up with the slight distortion?
hopefully not the amp going unstable and producing ultrasonic high frequencies and cooking the tweeter HP capacitor or limiter resistor :-(

There are ususlly two things that happen, what you have noticed is the result,
and the cause may need to be investigated too.

If the speakers seem OK, then you may have been lucky (for the speaker), but get the amp checked.

Distortion means you were hitting the cab with a lot of highs. That's what happens during amp clipping. So I'd agree that either the crossover or the L-pad or both were running hot. Maybe even an overheating tweeter voice coil. Maybe all 3.

^^^^^^^ Were you running a clean sound or a bit of overdrive/distortion?? If so, tweeters do not like this! You'll kill them quick!

Now that it has cooled down, rotate the L-pad and feel/listen for crunching in the area where the control was set when you smelled the burning. If it's crunchy, your L-pad was burning and if you keep running it that hard, the L-pad will fail. It usually turns into a fuse when it fails and it can't cause any damage if it does this but it will need to be replaced.

However, it would be good if you would post the control settings on the amp and any effects you use regularly- anything that can increase the signal level makes a difference in the level where the amp is over-driven, when it starts to distort and what the speakers are being fed. You may even hear crunchy sounds from the 10" drivers- if you do, it's possible that at least one voice coil was damaged.

You had this in 15 minutes? Take a whiff directly from the tweeter- if it's a horn, stick your nose into the horn and if you smell this, you're cooking the tweeter and you might want to put a dome light in series, if it doesn't already have one (if the tweeter is burning, I would say it doesn't).

Also, if you crank the snot out of the rig, don't just shut it off when you're done, turn it down and play, to let the voice coils cool down. Some voice coil formers become a bit more flexible when they're really hot and if the coil cools rapidly, the former can warp, causing it to change shape enough that the coil will rub on the magnet and/or top plate. The gap between the pole piece and outer diameter of the magnet/top plate isn't large and if the former warps, it's cross-section becomes somewhat elliptical, which doesn't fit in a circle. If you let it cool down more slowly, the chance of this is reduced.

I love the smell of an electrical component burning in the morning. Smells like... victory!

My votes on the cabs L-pad.

The L-pad on my SWR Goliath II literally burst into flames at a gig. I by-passed it and ended up using that cab without the tweeter for several more years.

Guys...he was OBVIOUSLY underpowering that huge cabinet with that low-wattage tube amp. Although, it was pumping out TUBE watts instead of your regular SS watts, so that may be impossible since they are completely opposite things. It probably distorted because he didn't give the bass waves time to develop after coming out of the cabinet...need a good 20-50ft to let that occur properly ;)

ok /ExtremeSarcasm


In all seriousness, I'd check the crossovers

LOL. I almost thought......but, no one could hold all those beliefs at the same time.....well....almost no one.

Oh believe me, if you glean through some of "those threads" you will see some repeat offenders in there who ascribe to all of the above lol.

The amp is fine. The slight distortion is what normally happens when you crank a 100w all tube amp.

If it is the L-pad for the tweeter I'll probably just take it out of the circuit, I don't need much high end, I can get what I need with just a little treble boost without it.

Also thanks for all the replies, they're along the lines of what I was thinking, it's nice to have it agreed on though.

I was running my bass directly into the head, no effects, a little mid boost at 300hz.

I find it strange that it happened with this band, considering that with my main band I use an SVTII with the same cab running at about 1 or 2 o'clock (yeah, we're really loud) into the same cab, with a decent treble boost and lots of distortion from an Aguilar Agro pedal and I've never smelled anything. But I guess that sure wasn't helping anything either.

"Those" twits got two good threads shut down this week because they get uppity about being put straight.

It's better to filter highs with Eq pre the amp for SS amps at least. Reduces the workload on the L-pad.