Just caught my speaker on fire!

[Wolf]

Re: Just caught my speaker on fire!

C

Yah- I likey!!! I've used them quite a bit.
Wolf

[[email protected]]

Re: Just caught my speaker on fire!

would just elavating off the board be enough? in what situation should they be of higher wattage? do they make tiny onboard extinguisher systems for queen lovers?
his guitar player wasn't half bad either.

[tomzarbo]

Re: Just caught my speaker on fire!

I'm curious...

What would have happened if neither you, nor your wife saw the smoke?
Could there have been an actual fire?, or would there have been a disconnect on that part of the circuit which would have been obviously audiable?

Was the ribbon driver okay?

Also, I must say... that's pretty cool!

TomZ

[dano]

Go

Whats the proper way to calculate the power dispensation of resisters in crossovers? Also are fuses or light bubs a good Idea for speakers designed for high power.
________
SUZUKI RGV250 SPECIFICATIONS

[Face]

Re: Just caught my speaker on fire!

Were the resistors covered in hot glue?

[Jim Holtz]

Re: Just caught my speaker on fire!

Wow! I was playing my Queen Live in Montreal DVD tonight on my Mini Statements. I was playing at pretty high volume and kept bumping up the volume, but really being careful to stay below distortion levels. About a half hour into the DVD my daughter worked her way front row. I'm kind of smiling getting a kick out of it right behind her. We hear what sounded like the woofer bottom out. Kind of surprised me because it wasn't bass heavy. We look at each other so I turn it down a couple notches. My wife is out on the deck watching through the slider and comes running in and says there is smoke coming out of your speaker. I look at her like yeah right. So I walk up to the speaker to see what she is talking about and sure enough I smell smoke from the ribbon. Everything is still playing. I backed the volume way down and all the drivers sound fine. After about 10 minutes I put my hand on the back of the speaker and its warm. This can't be good. So I pull one of the woofers out. Unbelievable there was no sign of distortion at all. I can't believe I could get something that hot and not even know it.

Hi Dave,

WOW! That is amazing! I've never heard of a crossover getting that hot before. Curt, as always, came to the rescue with excellent advice. I'll have to think about this for future builds. Considering the low cost of resistors, paralleling might be a very good idea as a standard design upgrade for systems that will be cranked very hard.

I'm glad that the Mini's didn't suffer any other damage.

Jim

[markk]

Re: Just caught my speaker on fire!

It does bring up a good point. Usually only a modest effort is put into power handling. Usually we think that our speakers are limited by excursion. But that's not always the case. I took a quick look at the schematic and it does look like the 4 ohm shunt resistor is going to dissapate the bulk of power in that midrange circuit. The shunt resistor/driver combo has more than half the voltage drop, and the shunt resistor valus is less than the impedance of the 1337. It's a bit hard to guess, but it's not unreasonable to think the bulk of the power is going to the mid circuit.

Not a problem normally, but definitely a problem under a high output scenario. Using 2 or 4 series, or parallel or both to distribute the power load is a good idea.

Just makes you want to go completely active....:eek:

[danklugherz]

Re: Just caught my speaker on fire!

Wow Dave, that had to put the scare into you! Have you checked the other XO? I can't recall ever hearing of this happening before. Maybe you should mount a fire extinguisher to your speaker cabs. :D

[davepellegrene]

Re: Just caught my speaker on fire!

I will say again I don't think this was a flaw in the design as much as a noob building a poorly ventilated crossover. Yes there was hot glue on them. As Curt said it was the resistor in the shunt circuit. It was tight against the board and also had foam over top of it. The resistor doesn't appear damaged on the outside but I assume it gave out. I am thinking the driver my daughter and I heard bottom out may have been the mid. Being the noob I am I'm going to take a stab at saying this would be the resistor to attenuate the mid and when it went out it wasn't attenuating the mid any longer so they were getting full power.

When I pulled the driver the board started to glow when it got air so it may have ignited eventually had we not pulled it. I do have smoke detectors on all levels and fire extinguishers threw out the house. I may have to start keeping one next to me when I want to jam to my Queen DVD from now on. I am assuming it was a combination of the foam against the resistor and resistor against the board with to much hot glue on them.

I will probably order the resistors Ben and Curt suggested. They will only cost $12 to replace. I am going to pull all the furniture foam out of them and go with the stiff fiberglass like I have been putting in my later builds. I can tell a difference in sound so now would be a good time to do this. I am going to pull all the other boards and raise the resistors and make sure they get plenty of air around them.

I may go ahead and double up the ones on the other boards as well. I am assuming this could happen on the tweeter and woofer circuits too? Am I correct in saying this happened in the shunt circuit because it was sending the power away from the driver instead of though it? So any resistors in series with the tweeter mid should be fine?

I can say the Mini's will crank and sound very clean doing so. As a matter of fact I probably could have kept on playing them til they caught fire. :D:eek: As far as I could tell last night all the drivers were still playing fine when I lowered the volume and listened to each one separately.

Now everybody in my family can stop saying were are you going to put those after there built. Now I know. They will be back ups if I need them while my other speakers are getting worked on.

Dave

[davepellegrene]

Re: Just caught my speaker on fire!

Wow Dave, that had to put the scare into you! Have you checked the other XO? I can't recall ever hearing of this happening before. Maybe you should mount a fire extinguisher to your speaker cabs. :D

My wife keeps walking by me shacking her head. What can I say sometimes I like lots of beer and loud music. At least I'm not on the road crashing into stuff. She also said the same thing. You should have pulled the other one apart to make sure you weren't going to burn down the house, but in a some what sarcastic voice.

Dave

[LouC]

Re: Just caught my speaker on fire!

This kind of failure probably required a "perfect storm" with Freddie Mercury at the eye! ;)

I had a similar experience with an intermediate version of a 3 way crossover (melted the hot glue off the board and blistered my finger). I reported it here and was told that I must be mistaken and must have miswired the crossover.

Now I double check my boards outside the boxes at high volumes for an hour or so. Any resistor that even gets warm is doubled. The only times I've found issues:

• Padding mid ranges in 3 ways - particularly when padding closer to the amp
• L-Pad shunt resistors on midrange drivers

It makes sense though. A shunt resistor's job is to dump power before it gets to the driver. Mid drivers are usually getting more power. Unless there's a component ahead of it that dumps/blocks some of it, padding resistors could take a lot of watts. If I use padding resistors, I often put them in lead wires (rather than on the board). Easier to change later, and better heat dissipation.

I've never found any problems on tweeter circuits. I've never used any kind of padding or direct shunt on a woofer. (Bad JuJu)

[MSaturn]

Re: Just caught my speaker on fire!

Badass.

[ravo2000]

Re: Just caught my speaker on fire!

Freddy could have set the world on fire with that beautiful voice if only he could have stayed with us a little longer... nice to see he still has that affect from the great beyond. Someone aso mentioned his guitarist... Brian May... another monster among men in the music world. I'm going to listen to some Queen right now.

This is a great thread... I'm sorry to hear about the speaker, but glad everyone is ok. Just think of the story you have to tell from now on... just don't sell it to J. Peterman like Kramer did with his stories... you'll want to tell this one for years!


Johnny Ravo

[billcurrier]

Re: Just caught my speaker on fire!

Your cabinets look very nice from the little I could see of them.

[davepellegrene]

Re: Just caught my speaker on fire!

The good side of it I have been to a Queen concert many years ago and I can say I was there again last night. That was the closest I have ever been, with any system I have ever had, of recreating a concert feel. The 52" plasma helps in the recreation as well. The down side is I didn't get to watch/ listen to the best part as the concert ramps up through the whole DVD. The few times I have watched it I have never had any amp left at the end. This was the first watch with my QSC GX3 with the Mini's and two subs. I can't wait for the replay. The amp wasn't even warm and I had it set two notches back from full.

Interestingly I was listening in 2 channel and when I tried surround sound it seemed to bring the volume down. Not sure why that would happen but it did sound better in 2 channel.

That does make sense about the shunt in the mid needing addressed . There is no restriction on the woofers so it would bottom out first, but wouldn't the tweeter shunt have the same concerns as the mid if it is attenuated as much as the mid?
Dave