PDA

View Full Version : X-overs and power...



HeatSeeker
08-14-2005, 10:54 PM
Just wondering how is the final ohm load determined in a passive x-over system? Can drivers with different ohm rating be placed in the same x-over system? Also, how is the power distributed? Thanks for any help, I'm kinda new to home audio and trying to build a sound system for my pc (music, games, dvd's)

PV Audio
08-15-2005, 08:54 AM
depending on how you wire it ( you'll probably do parallel..much easier and simpler) you can bank on just averaging the impedances. however, there are impedance spikes so you will either want to utilize a strong impedance eq network or you can put in an l-pad. on my most recent project, i used an l-pad with 6 db of attenuation. i'd ask jim about it cause he helped explain it to me.

HeatSeeker
08-15-2005, 02:40 PM
I have no clue what a lot of that it. Time to get to some reading:)

thylantyr
08-15-2005, 04:45 PM
Just wondering how is the final ohm load determined in a passive x-over system?

If you use a 8 ohm (nominal) tweeter, midrange, woofer {etc} in a loudspeaker
design that uses passive crossovers, then as far as you are concerned
{or the amplifier}, the nominal impedance of your speaker can be considered
8 ohms nominal.

Can drivers with different ohm rating be placed in the same x-over system?

yes, but the frequency of the crossover point changes. To keep the same
crossover frequency you have to redo the calculation for your passive crossover
or accept the different frequency if you keep the same crossover parts.

Also, how is the power distributed?
Each driver will draw a certain amount of power, tweeters being least, woofers
being the most power hungry. The crossover can introduce some power loss
as it may be hungry too. /depends

Thanks for any help, I'm kinda new to home audio and trying to build a sound system for my pc (music, games, dvd's)

Generic response: Build some speakers already engineered, there are plenty of
DIY kits or plans on the web.

HeatSeeker
08-17-2005, 07:44 PM
Each driver will draw a certain amount of power, tweeters being least, woofers
being the most power hungry. The crossover can introduce some power loss
as it may be hungry too. /depends
.

So is there some sort of formula for figuring out how much goes where? Or is it crossover dependent?

PV Audio
08-17-2005, 10:40 PM
So is there some sort of formula for figuring out how much goes where? Or is it crossover dependent?
think of it like a skinny person sitting around with a bunch of fat people. someone throws in a bucket of KFC. fat people rush in a take up most of the chicken while the skinny person takes a lil, or what is left over. something the weight of a 1" square of wax paper does not need alot of power to drive it. large woofers eat amplifier power and this is also why you have powered subwoofers so that you don't rob the main amp of it's duties. another related topic is the classes of amplifiers. you have classes a, b, ab, d, g, h i believe. a is the most inneficeient (spelling?) b is the most effieicnt, a has best sq, b has worst so people use ab for the benefits of both (i have no energy to go in depth of all of the classes so that'll do for right now). most tube amplifiers use class a technology as they provide the cleanest and unadulturated sound, but at the cost of power. a good rule of thumb for class a amps that i have taken up is that for each watt of output, the amp has already lost 4-5 watts in thermal losses (heat).

HeatSeeker
08-17-2005, 11:08 PM
Ah okay, thanks for clearing that up. I always wondered how xovers kept the tweet from getting the same power as a woofer and popping. Thanks! :D

JimJ
08-18-2005, 12:47 AM
you have classes a, b, ab, d, g, h i believe. a is the most inneficeient (spelling?) b is the most effieicnt, a has best sq, b has worst so people use ab for the benefits of both (i have no energy to go in depth of all of the classes so that'll do for right now).

Class C is actually the worst...but it's never used outside of RF applications.

Although that really didn't have anything to do with the original thread topic...:D

analogkid
08-18-2005, 02:40 PM
think of it like a skinny person sitting around with a bunch of fat people. someone throws in a bucket of KFC. fat people rush in a take up most of the chicken while the skinny person takes a lil, or what is left over.

hahahahaha that is the most ridiculous comparison ive ever heard...and the funniest!

PV Audio
08-18-2005, 06:00 PM
Class C is actually the worst...but it's never used outside of RF applications.

Although that really didn't have anything to do with the original thread topic...:D
:eyebrow: are you testing my gangsta?


- Three Six Mafia