Choosing midbass drivers

Waldodamon · Post by **Waldodamon** » Thu Apr 20, 2006 7:22 pm

Part 3? Bring it on, this is awesome!

tomcat · Post by **tomcat** » Thu Apr 20, 2006 7:27 pm

Part 3?!?!

I'm still working on understanding part 1.

While this is great stuff

it may take me awhile to get it all.

Waldodamon · Post by **Waldodamon** » Thu Apr 20, 2006 7:32 pm

Well, thanks to Ryan and a couple other intelligent members still left at CAF, I have a better understanding of how octave slopes work. The graphs I am still learning how to read, lol, but it'll all sink in....

Jonathan · Post by **Jonathan** » Thu Apr 20, 2006 8:08 pm

I'll do part 3 tomorrow or the day after. I've got a big ass barbecue pit I've got to finish building before my wife takes a sledgehammer to it

"Why don't you just go get a nice gas grill?"

Part of the homebuilding tradition for me, I used to have BBQs every weekend when I lived in Texas.

Please post any questions you have so far so we don't lose you along the way.

Robert Wollenberg · Post by **Robert Wollenberg** » Thu Apr 20, 2006 8:56 pm

Sweet ... this is what keeps me coming to work every day. I had my hopes up last night when I went home that something good was going to be waiting for me and here it is. :) I get the feeling I might be doing some rearanging of my setup.

I'll save all my questions until I can read the completed writeup. :)

car1990 · Post by **car1990** » Sun Apr 23, 2006 11:18 pm

Awesome stuff!!! Jonathan.

It just so happen that I have the Seas Lotus Reference woofer in my car, I do not really notice (or maybe I don't know what to look for???) those distortions by running Lotus Reference active and x-over Ref woofer (RW165) at 1.625KHz @ -18db and Ref tweeter (RT25F) at 2.5Khz @ -12db. Maybe I should try parametric equlized at 4KHz or 5 KHz to see if that will make a big difference.

Post by **GlassWolf** » Mon Apr 24, 2006 1:57 am

Waldodamon wrote:Well, thanks to Ryan and a couple other intelligent members still left at CAF, I have a better understanding of how octave slopes work. The graphs I am still learning how to read, lol, but it'll all sink in....

ww.bcae1.com has some great info on crossovers and slopes (Q factor)
Simply put, understand that an octave is half, or double the frequency of your starting point. 40Hz is one octave above 20Hz. 80Hz is one octave above 40Hz and two octaves above 20Hz. Same works in the opposite direction.

The slope of a crossover determines how quickly above or below the starting frequency (crossover point) the sound will diminish in volume as you get farther away (in octaves) from that crossover point. The "steeper" the slope, the faster the sound will "roll off" or get quieter as to move away from the XO point.

That's really the gist of a crossover slope.

speakers naturally roll off at about 12dB (decibels) per octave. If you cross over a speaker above it's natural roll off point, you can use a steeper or shallower slope crossover for a more sudden, or gradual decrease in volume respectively, as the speakers "roll off" to meet the speakers you use to cover the octave range above or below the speakers being crossed over.

typically subs only require a filter to blow higher frequencies (except with ported boxes, where a subsonic filter is used to protect the subs)
midrange speakers are crossed over to block both very high and very low frequencies, and tweeters are filtered so that no midrange or low frequencies reach them.

Post by **GlassWolf** » Mon Apr 24, 2006 1:59 am

P.S.

Waldodamon wrote:Well, thanks to Ryan and the couple other intelligent members still left at CAF.

grammatically fixed.
*grin*

John, Guide has been transposed to the FAQ section.

Jonathan · Post by **Jonathan** » Mon Apr 24, 2006 4:38 pm

car1990 wrote:Awesome stuff!!! Jonathan.

It just so happen that I have the Seas Lotus Reference woofer in my car, I do not really notice (or maybe I don't know what to look for???) those distortions by running Lotus Reference active and x-over Ref woofer (RW165) at 1.625KHz @ -18db and Ref tweeter (RT25F) at 2.5Khz @ -12db. Maybe I should try parametric equlized at 4KHz or 5 KHz to see if that will make a big difference.

If the woofers are off axis, it's likely that the breakup really isn't going to show up due to the falling off axis response by that point. Keep in mind the distortion will still be there as well as the effect upon the rest of the frequency range. Most car doors are nearly 60 degrees off axis, by that ~4.5k breakup the response has fallen off dramatically anyway. If you really wanted to hear the breakup, you could put your head on axis with the drivers and turn off the LPF. They aren't that hard to tune, especially in a car. Welcome to the forum, BTW.

As far as the next tutorial, please be patient with me guys :) I've been putting in a lot of overtime lately. I'm working on it when I get the time.

car1990 · Post by **car1990** » Wed Apr 26, 2006 1:16 am

My woofers are off-axis at car doors, I guess that's why I don't notice the distortions. I did para EQ at 4KHz (Q=7, Gain=-4db) but the impact is not significant though. Anyway will be adding Lotus RM110 midrange to go 3-way active in the future when I get tired of 2-way active, so distortion of Lotus RW165 at that frequency range will be even less noticeable.