newbie Q

memphissound · 16th August 2006, 02:23 PM

Hey guys. This question obviously reveals my newbie status.

I'm looking at the different components for 2-way "Pro-sound" enclosures (12 or 15 inch woofers, and compression driver with horn). The woofers are rated at something like 300-500 watts, and the drivers at 30-40 watts. Built with a passive crossover.

Here's my question. How come the driver is rated at aproximately 10% of the power rating of the woofer?

Thanks for your help in understanding.

peace,
memphissound <><

richie00boy · 16th August 2006, 02:26 PM

Because the horns are more efficient you don't need to feed them as much power.

memphissound · 16th August 2006, 02:32 PM

But what about the power that's being fed into the cab? If you're pushing the enclosure with 200 watts (for example) why don't you fry the compression driver? Where is the excess power dissipated? In the L-pad?

Thanks again.

peace,
memphissound <><

planet10 · 16th August 2006, 08:31 PM

it never gets to the tweeter because of the crossover (which will have a pad in it

dave

Cal Weldon · 16th August 2006, 10:10 PM

The big power is used up in driving the lower frequencies to the big woofer cone. It doesn't take a lot of power to move a little compression diaphragm. Therefore the tweeter is able to handle whatever the power is when the woofer is at it's 500 watts. Usually around 10% of that of the woofer. As Dave mentioned, the XO makes sure the low notes don't get to the tweeter.

francis varkey · 17th August 2006, 06:42 AM

I'm sure Cal meant to say 10% goes to Tweeter.

You may refer to the attachment, it shows the percentages involved.
I had saved it from the net some time ago.

richie00boy · 17th August 2006, 08:59 AM

To clarify, a 'pad' refers to an L-pad which attenuates the drive signal.

memphissound · 17th August 2006, 11:36 AM

Muchas gracias,

to everyone for the insight. I had contacted a guy at Eminence who gave me similar input. If anyone is interested his reply was:

"High frequencies are not as abusive as lower frequencies, there's not as much information. You can consider the HF device receives only a percentage of the system power. Some general rules of thumb are from 1.5kHz-2.5kHz the HF device receives 20% of the system power, from 3.5kHz-4.5kHz, 15% and from 5kHz up, 10% (this is assuming you're using at minimum a 12dB/octave slope)."

peace,
memphissound <><

16th August 2006, 02:23 PM	#1
memphissound diyAudio Member Join Date: Aug 2005	newbie Q Hey guys. This question obviously reveals my newbie status. I'm looking at the different components for 2-way "Pro-sound" enclosures (12 or 15 inch woofers, and compression driver with horn). The woofers are rated at something like 300-500 watts, and the drivers at 30-40 watts. Built with a passive crossover. Here's my question. How come the driver is rated at aproximately 10% of the power rating of the woofer? Thanks for your help in understanding. peace, memphissound <><

16th August 2006, 02:26 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Because the horns are more efficient you don't need to feed them as much power. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

16th August 2006, 02:32 PM	#3
memphissound diyAudio Member Join Date: Aug 2005	power? But what about the power that's being fed into the cab? If you're pushing the enclosure with 200 watts (for example) why don't you fry the compression driver? Where is the excess power dissipated? In the L-pad? Thanks again. peace, memphissound <><

16th August 2006, 08:31 PM	#4
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	it never gets to the tweeter because of the crossover (which will have a pad in it dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

16th August 2006, 10:10 PM	#5
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	The big power is used up in driving the lower frequencies to the big woofer cone. It doesn't take a lot of power to move a little compression diaphragm. Therefore the tweeter is able to handle whatever the power is when the woofer is at it's 500 watts. Usually around 10% of that of the woofer. As Dave mentioned, the XO makes sure the low notes don't get to the tweeter. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting


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17th August 2006, 08:59 AM	#7
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	To clarify, a 'pad' refers to an L-pad which attenuates the drive signal. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

17th August 2006, 11:36 AM	#8
memphissound diyAudio Member Join Date: Aug 2005	Thanks... Muchas gracias, to everyone for the insight. I had contacted a guy at Eminence who gave me similar input. If anyone is interested his reply was: "High frequencies are not as abusive as lower frequencies, there's not as much information. You can consider the HF device receives only a percentage of the system power. Some general rules of thumb are from 1.5kHz-2.5kHz the HF device receives 20% of the system power, from 3.5kHz-4.5kHz, 15% and from 5kHz up, 10% (this is assuming you're using at minimum a 12dB/octave slope)." peace, memphissound <><

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