Speakerplans.com Homepage
Forum Home Forum Home > General > General Forum
  New Posts New Posts RSS Feed - Passive crossover advice
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Passive crossover advice

 Post Reply Post Reply Page  <12
Author
Message
RobinMatrix View Drop Down
Young Croc
Young Croc


Joined: 23 August 2013
Location: Monmouth
Status: Offline
Points: 553
Post Options Post Options   Thanks (0) Thanks(0)   Quote RobinMatrix Quote  Post ReplyReply Direct Link To This Post Posted: 15 February 2020 at 12:07pm
I use somethign very similar to Xsim,  with response and impedance sweeps captured out of REW and the results are incredibly accurate.

Being able to adjust component values and see the actual reponse curves and impedance curves vary is incredibly useful.  I don't think it is possible to relaibly produce a crossover design without software like this ... unless you have eithre lots of time, or lots of luck.

What I always find fascinating is how well they work ... if you take a good impedance sweep and a good reposnse measurement and leave the measuring mic setup and then make a crossover up and re-sweep the speaker ... if you don't change the mic position and re-sweep it, the response curve will *exactly* overlay the prediction ... right down to the smallest details and bumps.  I supposes its not that surprising, it's just electronics, but it is amazing to see.

The thing I use is no longer avaialable, but it looks very similar in functionality to Xsim,  I'd be surprised if it wasnt the same author.
Matrix Amplification Limited ::http://pa.matrixamplification.com/"
Back to Top
ceharden View Drop Down
The 10,000 Points Club
The 10,000 Points Club
Avatar

Joined: 05 June 2005
Location: Southampton
Status: Offline
Points: 11526
Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 15 February 2020 at 1:05pm
You have to be careful not to fall into the trap of trying to EQ or Align out a feature of your measurement environment.  Not many people have access to chambers to do their measurements in so you have to make do.

I think one of the most difficult issues is that you can't time align with a passive crossover.  On the one I've just done I was fairly lucky that I could put the crossover point at the equivalent of a half wavelength of the offset, flip the polarity and get an approximation of 'in-phase'.  However crossovers being a long way from brick walls you still get some interaction and octave or so either side.

I could also have made my life easier by doing a proper impedance compensation network on both drivers but I didn't want to end up with a design the size of an A4 sheet that wouldn't fit in the cab!  Managed to adjust the values in the filter sufficiently to get a good approximation.

Back to Top
odc04r View Drop Down
Old Croc
Old Croc
Avatar

Joined: 12 July 2006
Location: Sarfampton
Status: Offline
Points: 5264
Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 15 February 2020 at 7:48pm
Originally posted by RobinMatrix RobinMatrix wrote:

I use somethign very similar to Xsim,  with response and impedance sweeps captured out of REW and the results are incredibly accurate.

Being able to adjust component values and see the actual reponse curves and impedance curves vary is incredibly useful.  I don't think it is possible to relaibly produce a crossover design without software like this ... unless you have eithre lots of time, or lots of luck.

What I always find fascinating is how well they work ... if you take a good impedance sweep and a good reposnse measurement and leave the measuring mic setup and then make a crossover up and re-sweep the speaker ... if you don't change the mic position and re-sweep it, the response curve will *exactly* overlay the prediction ... right down to the smallest details and bumps.  I supposes its not that surprising, it's just electronics, but it is amazing to see.

The thing I use is no longer avaialable, but it looks very similar in functionality to Xsim,  I'd be surprised if it wasnt the same author.


On the few times I've made a passive xover, LTSpice and REW did me well. LTSpice takes a bit of getting used to of course but once you're in parametric component sweeps are possible.

Next level would be doing it in something like Scilab/Octave?Matlab where you could use regression to compute a nominally flat bandwidth whilst varying components. But I suspect this would fall foul of real life not being as well behaved as measurements. Still, be interesting to try on day.

For full nerd points, simulate your entire enclosure after the xover in spice by converting the enclosure model into its electrical analog, and congratulations you have basically re-programmed an Akbak script. Maybe when I am retired.
Back to Top
 Post Reply Post Reply Page  <12
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.117 seconds.