Wharfedale cross over bulb

[makarunga]

My wharfedale speakers went dead and on checking realized that the cross over fuse (hf protection bulb) blew. I can not get this anywhere in Kenya. Does anyone know what alternative I could use to replace this fuse?

Cheers

[aidso]

what wattage is the HF driver?

[makarunga]

what wattage is the HF driver?

 

you mean the speaker? I have a lx 15 (400 watts)

[johndenim]

Have a look on the blown bulb, it may have the wattage written on it.

 

Please note this is for the HF only, as you say the speaker died, do you mean the whole cab or just the HF?

The thing to look at is, why did it blow in the first instance?

You could easily replace the bulb, but it may go again.

 

I would suggest you have overdriven the cabs, causing the fuse to blow.

[KevinE]

They are these???

 

http://vitalitylighting.com/images/MiniatureRigidLoop.jpg

 

If so, it's 12V 10W, the rating is by a coloured dot at one end and should be double checked with your lighting supplier in Kenya.

 

They are essentially an american auto bulb.

[makarunga]

Thanks a lot man. You sorted me out and was able to purchase these in town

Cheers

Mike

[johndenim]

Glad you are sorted mike.

 

However there could be a chance that it could go again.

A side note.

 

As this is essentially a 10w lamp, does anyone have any explanation as to why the HF driver

would run OK with this in line?

I.e, this cab may (wild stab in the dark) have a 50-100w HF horn, but it has a 10w protective fuse.

 

As in.

12 Volts (E) .83 Amps (I) 14.4 Ohms ® Power 10 (Watts)

 

Or have I got the wrong end of the stick?

[bruce]

I.e, this cab may (wild stab in the dark) have a 50-100w HF horn, but it has a 10w protective fuse.

 

Or have I got the wrong end of the stick?

 

You've got the wrong end of the stick :)

 

Fuses are not rated in watts - they are current limiting devices. Rated in amps.

 

And the lamp doesn't just act as a fuse.

 

That particular lamp will blow at just over 1 amp. So you're limiting the current thru the horn to that. No doubt that value is carefully calculated based on the impedance of the horn, and the amplifier output voltage. Or maybe they just picked a lamp off the shelf ;)

 

The interesting feature of using a lamp is that its resistance varies with temperature. As it heats up, it's resistance increases. So effectively it acts as a simple limiter - if the power is increased too much, the lamp "lights", thus increasing it's resistance, thus limiting the current, thus protecting the driver a little.

[johndenim]

Interesting.....

 

Yes, I understand that the fuse or lamp dissipates the hf voltage and or current?

So as in this instance the bulb has blown, the OP has driven the cabs too hard?

[Sound In Gloucestershire]

yep its a protective thing, hes over driven the speakers, usually on this level of speaker, the horns blow very easily, so the bulb blows instead!

[KevinE]

The last batch I supplied was because the vocalist had wandered too far in front of his speakers and let them squeal for nearly half a second!