Easiest way to protect my compression drivers from overload

[crazyboy]

Power max. 50W Power rms 25W Frequency response 1kHz - 20kHz Voice coil 25mm Dimensions 60mm x 80mmØ Weight 0.57kg

Hi

I'm really trying to find out best way to protect these compression drivers, they are rated 8 ohms but running 2 in parallel so reduced to 4 ohms.

I've Bi-amped the 2 way cabinet and running through an behringer electronic crossover, the amp powering these is as follows

• Modern MOSFET technology
• 480 Watt max achievement at 4 ohms (2 x 160 Watt at 8ohm)
• LED VU meter
• Sturdy 19"steel housing, 2HE (height units)
• Separate volume controls for left and right channels
• Rear located high performance fan

So bearing in mind i have 2 compression drivers on each channel i still need to protect them well from the amp as its saying 240w per channel, please note also this is not rms power.


All help is well appreciated as usual

[Cal Weldon]

They are already protected by the crossover. If you want to back that up you can add a breaker switch, a fuse, a light bulb or a back up capacitor. Is that what you're asking?

The real way to protect them is to keep idiots away from the volume control.

[crazyboy]

so an electronic x-crossover protects them from wattage overload or from clipping, because they are P.A speakers i think it's wise to protect them some how..

If i put a bulb in series will that work, if so what wattage and voltage..

And thanks for reply

[Cal Weldon]

Your xo protects it from LF damage, not clipping. I think you might want one of these from PE

SPEAKER CIRCUIT BREAKERS from Parts Express ship same day and come with 45 day money back guarantee. Free Shipping Available. Order free 10,000 product catalog.

or maybe this

http://www.parts-express.com/pe/show...number=320-225

[Xoc1]

Has your crossover got built in limiters?
I would of thought that if you don,t have limiters in the system then your best option would be to reconnect the compression drivers in series for a nominal 16 ohm load.
This would reduce the output of the amplifier to 80-100w so closer to the power handing of the HF.
If you want to try lightbulbs, Favourites are 12V 21W. 2 wired in series are about right for most 8 ohm drivers. I,m not sure what would be the best combination for you, given that these are fairly low power drivers. Maybe start with 2 wired in series outside the cabinet on your 4 ohm load, so that you can observe the glow as you wind up the power!

[crazyboy]

@Xoc1

No mate i dont think my crossover has a limiter it was the post before which made me say that ..

I know they are protected from lf, but not from wattage overload this is the main reason for my post i will try the 2 x 12v 21w bulbs in series first, as i dont think i quite described it right at the start.

I have 2 speakers on each channel, each cabinet has a 15" 350wrms woofer 8ohms and 1 compression driver of 25 wrms 8ohms and i left the 20w 33r resistor in line for compression driver.

Im more than happy with the woofers, not so happy with the mid / high which is why im here asking help, i was advised to buy selenium but cant find anyone that sells them in uk, does anyone have any knowledge on eminence asd1001 compression driver.

Thanks for your reply's

[doug20]

Why not juse wire a LARGE Cap in series with the driver (First order HP filter)? I do this with all my Compression drivers and ribbons. Buy one that gives you a nice -6dB slope starting around 700Hz.

All my builds are active x-over builds so I always have the cap on the tweeters.

[godfrey]

If you can wire the compression drivers in series (for 16 ohm load) instead of parallel, the combination will be able to handle double the voltage (i.e. amps rated for 4 times the power).

A series capacitor is good for protection too. If the power amp is driven into clipping it can produce DC/very low frequency output, no matter what the electronic crossover's set to.

[crazyboy]

Is there a chart that i can reference for the size cap needed, i know its probably been asked a thousand times..

I thank you all for ya kind response to a complete noob at this

[Xoc1]

If the compression driver is an 8 ohm load a first order (capacitor only) filter with a -3db crossover point at 1khz would be about 20uF, at 2khz the capacitor would be 10uF.
You would probably want a capacitor that was at least able to pass a frequency that was half the frequency that you set your active crossover to. This will ensure that the protection capacitor does not effect the crossover frequency response by too much.
Large plastic capacitors can be expensive, but are cheaper than replacing expensive compression driver diaphrams.
I would connect one capacitor, and 2 light bulbs in series with each tweeter. I would not use the resistor.
My actively driven compression drivers (50W RMS) have a capacitor connected in series, but no light bulbs. But they always have had a limiter between the active crossover and the HF power amp.