Why is crossover calculator spread always fixed?

Jump to Latest
D

deanrantala

Member
Joined 2012
I am working out the potential details of a 3-way loudspeaker, which is as follows:

15 inch woofer (solid response from 30-1000hz)
dual 6 inch mid-bass drivers (solid response from 150-ish to 8000hz
single 1 inch tweeter (solid response from 3000-20k)

Now... without getting to far into the details of crossovers (if possible)....

Why are all the online calculators for xover design LOCKED INTO a "Spread" of "8 (3.0 Octaves)" or "10 (3.4 Octaves)"?

I know, I know... the inductor will be largish.. I got plenty of wire and am not afraid to experiment with Coil64.

For the love of jesus... I want to set the Woofer-midbass and midbass-tweeter points around 200 and 5k. But these calculators only let me choose one or the other.

These midbass drivers really pack a great punch from 200 through 1000.

The Woofer (15 inch) should not HAVE to reproduce frequencies up to 400 and 600hz

Is there a reason why I HAVE to use these pre-selected "spreads"? Is there not a calculator online somewhere that lets me choose my own damn xover points?

Sorry... Just really surprised that after an hour of searching, NOBODY has been bothered by this - nor has anyone asked this question already.

-Dean
 
AllenB

AllenB

diyAudio Moderator
Joined 2008
Paid Member
Do these online calculators figure in the interaction between the two crosses? It's not necessary to have them spread so much, but they may become less accurate when you bring them together. It is better to calculate your own.
 
markbakk

markbakk

Member
Joined 2011
Let me throw in the ‘V/X/B’* word. Put otherwise, skip the online calculators and install a free app that not only enables you to do some networking on your own, but also incorporates the acoustic response of the total system if fed with the right data.

*VituixCAD/XSim/Boxsim and some others ;)
 
  • Like
Reactions: 1 user
mattstat

mattstat

Member
Joined 2009
Adding to what AllenB said, The Great Sound Stereo Speaker Manual states: "in the bandpass circuit, you must make a slight calculation. . . . because the components interact some adjustments should be made to the standard values. . . . In effect, you calculate the values for a slightly narrower band of frequencies than the desired band." It also uses the reciprocal of the ratio of the upper to lower cross points to add to the inductor and subtract from the capacitor standard values. This is a basic method based on nomographs though, and things have progressed since then. As others said, it's now common to use a simulator to get these dialed in (using actual impedance data for the drivers).

Also, the formulas for 3 and 3.4 octave bandpass spreads are included in The Loudspeaker Design Cookbook, so those are pretty well known and likely why you kept seeing those values. It also says: "For other crossover frequency spreads or network types, refer to Bullock and be prepared to do a lot of calculating."
 
Last edited:
  • Like
Reactions: 1 user
Y

YSDR

Member
Joined 2013
Because online xo calcuators are not complex enough for realworld loudspeakers, they give just a very rough guess (because they assume flat frequency and impedance responses that real speakers/drivers usually not have) and they are useless in most cases if you want to build something.
 
Last edited:
  • Like
Reactions: 1 user
Pano

Pano

Administrator
Joined 2004
Paid Member
As said above, online calcs assume flat response and impedance. For much better x-overs with real drivers you should download a calculator that is more flexible and that allows you to input acoustic and impedance measurements.

There are a number of those mentioned here and across the forum.
 
  • Like
Reactions: 1 user
You must log in or register to reply here.
Top Bottom