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View Full Version : need a graph on how crossovers work



airtas
04-04-2006, 01:12 PM
i have polk db6500 and their crossover point is 4000hz so im assuming anything over 4000 goes to the tweets and anything under to the woofer, correct?


so why is it that it sounds like sometimes sound is coming from both the same sound?


is it for example a vocal might be between 3800-4200? thus its played on both?


any graphs online to show this? im trying to corelate this into a school project as well thx guys

loserpunk
04-04-2006, 05:42 PM
i think what you're talkin about is the actual slopes on the xover.....the xover point is at 4000...but it's not a straight cut off, it's sloped, 12db per octave, 24 db per octave or whatever, so yes, the tweeters and midranges will and are supposed to play the same frequency if it's near the xover point on the xovers.....

Decipha
04-04-2006, 05:58 PM
2 basic components of a crossover

capacitor and coil

coil cuts highs
cap cuts lows

req
04-04-2006, 06:14 PM
http://i2.tinypic.com/szgcbb.gif

as you can see, the tweeter will still play into the high 800hz range, and the midrange will still play into the 9khz range.

these numbers are purely for describing purposes. i do not know if that is the actual angle of the slope @ -12db. i just guessed. it could be less steep, or it could be more steep. i just drew this up in photoshop so you could understand what a crossover does.

so to clarify, as you go lower in frequency PAST the crossover point, your tweeter will be still playing, but for every octave you drop (octave = one halve, for example, an octave below 100hz is 50hz.) the tweeter will be -12db quieter than the "refrence" level of the stereo - aka, the average level of loudness over the ENTIRE frequency band (20hz to 20khz).

its not very complicated, just very hard to describe without a picture :)

hope this helped.


ps, crossover points dont "have to" be crossing at -3db, they NORMALLY do however. if you want a natrual "equalization" at the crossover point, you could move it to -2 to boost those frequencies a litte, or -4 to cut them natrually. normally, the -3 point is where they are on passive crossovers without equalization circuits ect.

pps, the graph i showed you is of a PERFECT pair of speakers that would win you a gold medal at the national SQ competition. actual frequency response of a pair of speakers will vary but should resemble the lines wich are imaginary i remind you :)



*EDIT*

i just realized that the slope of the crossover i put on there is close to exact. a 12db\octave slope would be -12 (for the tweet) @ 2000hz, i randomly drew those lines lawl. and the slope for the midrange is right on 8khz wich is one octave above, so that one is freakin perfect. so the slopes are actually quite accurate and shuold be similar to what you are actually hearing in your car if your xover point is @ 4000hz.