Monacor SPH-300KE, loud music, light behind the membrane

[eilon]

Hello,
I had a little accident last night.. I was listening to very loud music with my SPH-300KE and after 2 hours, I saw a short light behind the membrane with a little "plop" sound.. The speaker still works fine, but I would like to know what it was..


Greetings,
Eilon

 

[Galu]

This is my pure guess!

The tinsel wires may have shorted together momentarily as they contacted the aluminium speaker basket where it abuts the magnet, due to overexcursion of the voice coil.

See enlarged photo of the position of the tinsel wires on this Monacor site: MONACOR: SPH-300KE

 

[eilon]

So nothing to worry about?

 

[pdul]

Maybe a good idea to put some insulation between the wires and wires and basket to avoid a repetition.

 

[Galu]

If that really was the cause, I'd worry about the SPL at which you are listening to music!

 

[Mario Pankov]

If that really was the cause, I'd worry about the SPL at which you are listening to music!

These Monacor drivers bottom out easily, unfortunately. They require a small enclosure to prevent this but this limits low frequency performance.

the light behind the membrane is because the weaving of the cone has gaps which are damped with some transparent resin. If you raise the speaker against sunlight (indeed any of the Monacor Kevlar ones) you can see through.

 

[ICG]

These Monacor drivers bottom out easily, unfortunately. They require a small enclosure to prevent this but this limits low frequency performance.

The problem is, a small enclosure would only help if it is a sealed enclosure. If you want to use them in a BR enclosure, you'll have to use a subsonic filter.

the light behind the membrane is because the weaving of the cone has gaps which are damped with some transparent resin. If you raise the speaker against sunlight (indeed any of the Monacor Kevlar ones) you can see through.

If there's a light behind the membrane, it's most likely because of a tweeter or midrange protection circuit (a serial light bulb) in the crossover. After the overload and resulting high impedance of the light bulb it should have returned to normal function.

 

[Galu]

a serial light bulb

A good call, but would that explain the little 'plop' sound?

 

[ICG]

A good call, but would that explain the little 'plop' sound?

That would only explain it under very special circumstances, like the resistance of the bulb would become high at a peak and after cooling down and dropping the impedance therefore again, discharging a capacitor. That's not very likely but it might be an additional interaction with the amplifier. Still not likely but I can't imagine another reason for that right now unless the amps protection or power supply triggered for a brief moment - wich is a lot more likely. I don't claim that to be the definite reason, that's just trying to find a possible explaination.