home made system

[Harry Fisher]

hi folks!

i have made an amp that puts out 400W peak Iv made the speaker cabinet and it sounds great!

but i need to know how to protect a 60W tweeter from this power, will a passive crossover do this??

i need some help please!!
many thanks

harry

 

[Iain McNeill]

Depending on your crossover frequency and any padding to match sensitivities the answer could well be yes.

It is common for tweeters to be more sensitive than woofers requiring a resistor in series (or resistive L-pad) This will reduce the power delivered to the tweeter.

If you are crossing over above 3KHz then the total power to the tweeter is small and you'll be OK.

Bottom line is it all depends how loud you turn it up. The worst thing for tweeters is the amp clipping as this converts all the LF energy for the woofer to HF energy to the tweeter.

Keep the volume down to start and monitor the AC voltage on the tweeter terminals with a good AC voltmeter. power=V^2/R. so for an 8ohm tweeter you don't want to see levels hitting 22Vrms

edit: by good I mean a voltmeter with 20KHz bandwidth - not all are.

 

[Harry Fisher]

i am planing to use a 3.5 Khz crossover with a tweeter of range 3.5Khz-20Khz and a bass driver of range 40hz-3Khz would this be suitable??

so the crossover should protect the tweeter from the high power imput?? 400W

many thanks
harry

 

[Iain McNeill]

Bottom line is it all depends how loud you turn it up.

At sane listening levels you should be OK. Typically, you need 20dB headroom to handle peaks so your 400W amplifier is good for 40W continuous programme. You don't say if the tweeter is 60W ave or 60Wpk or what kind of music or room you use it in. If this is for a nightclub or party sound system then I would say you could quite easily blow this tweeter.

Best way is to measure, then you know.


edit: it also depends on the order of the crossover. A 4th order will offer better protection than a 1st order.

 

[Harry Fisher]

its primetaly for playing very loud! party system thing

what would you suggest to protect the tweeter instead??

 

[Cal Weldon]

It helps if you know at what frequency and XO slope gave the tweeter a 60W rating in the first place. Do you have any info on it? For example if it's rated at 2.5khz 2nd order and you go 3.5khz 4th order with 6 dB of padding, you might have no problem.

 

[Iain McNeill]

You need to do some engineering then. Break out the paper and calculator

A well designed XO will provide the protection you need.