How to choose active XO freq? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th May 2003, 10:25 AM   #1
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
Default How to choose active XO freq?

Having been inspired by Rod Elliots article on Bi-amping I have decided I am going to build an active crossover for my Mission 703e s. The only problem is I don't know what crossover frequency to use. Does anyone know where I might find such information? Or if there is a way of calculating it?


Any info is much appreciated

jnxw2
  Reply With Quote
Old 15th May 2003, 11:25 AM   #2
Raka is offline Raka  Europe
diyAudio Member
 
Raka's Avatar
 
Join Date: Aug 2002
Location: Close to Oistrakh
Default Good question

Hi,

I think you are doing a good thing.
Is not difficult. Are they two ways?
You should find out which is the crossover point based on the crossover parts and impedance of the drivers.
Would be even better if you could measure the drivers, that would be very good, because then you could choose the trade-offs and not the original designer.
Any info about the speaker?
Which filter do you plan to use?

My modest knowledge is at your service

BTW the esp article is very inspiring
__________________
What is beyond the speaker?
  Reply With Quote
Old 15th May 2003, 11:30 AM   #3
diyAudio Member
 
Andypairo's Avatar
 
Join Date: Sep 2002
Location: near Milano , Italy
The starting point can be the present XO frequency set by the passive crossover, anyway bi-amplification implies that you open your speaker and bring outside speaker terminals directly, completely eliminating the passive xover; if the speakers allow bi-wiring you can take advantage of the double terminals, otherwisa you need to find a solution.

Cheers

Andrea
  Reply With Quote
Old 15th May 2003, 12:50 PM   #4
MadMax is offline MadMax  New Zealand
diyAudio Member
 
Join Date: May 2003
Location: South Otago
You can use a sine wave generater like in winisd the xo point is when output is even from both drivers, this will give you a starting point then use your ears and wot test equpment youve got. Take your time and do a few times write things down as you go. good luck Max.
  Reply With Quote
Old 15th May 2003, 01:09 PM   #5
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
In fact I made a mistake they are not 703e but 773e s
The cones are approximatly 10.5cm or 4in in diameter. I am not sure though if they recieve the same signal or if one does mid and the other does bass??
The speakers have two sets of terminals and I have already taken the passive XO out to have a look, unfortunatly the value of the inductors isnt marked on it. I dont have my digital camera with me but i should be able to post a picture of it tomorrow if that would help.

cheers

jnxw2
Attached Images
File Type: jpg 773e.jpg (50.9 KB, 303 views)
  Reply With Quote
Old 15th May 2003, 01:23 PM   #6
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Default hold on there

when you start from scratch you usually have some semblance of the response curve of the driver from the manufacturer -- I did say "semblance" since the conditions are often ideal which isn't what you will experience at home.

One thing which I have been thinking of doing is a "State Variable" filter using digital pots to set the low pass, band pass and high pass filters -- one could adjust the performance on the fly by adjusting the digital potentiometers.

Analog Devices has one such design on the PDF for their dual 8-bit DAC, but, of course, you could use a digital pot from Analog, Dallas (Maxim) etc.
  Reply With Quote
Old 15th May 2003, 01:38 PM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Don't try to second guess a good designer. The electrical crossover may not be (probably will not be) a simple, symmetrical function. Get in there and measure the electrical transfer function of the crossover at each of the driver terminals, then design the electronic crossover to duplicate it. Otherwise, you'll end up with a speaker that sounds different but almost certainly NOT better.
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  Reply With Quote
Old 15th May 2003, 01:48 PM   #8
diyAudio Member
 
Join Date: Sep 2002
Location: London, UK
im pretty new to this, is there an easy way to measure the electrical transfer function of the crossover with a DMM and sinewave generator?

jnxw2
  Reply With Quote
Old 15th May 2003, 02:27 PM   #9
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
If your DMM has a spec'd frequency response that's flat out to 10kHz or so, then it's a piece of cake (though a bit tedious)- feed the signal generator to your amp, adjust the volume to something reasonable (not too loud, not too quiet, something on the order of a couple of volts), then measure the voltage at each driver terminal at a number of frequency points. Plot the results for each driver on a log-log graph, and you'll have a good idea of what the crossover will have to do.

If your DMM is not spec'd to be flat over the audio range, borrow an oscilloscope or an AC voltmeter. Or get serious and use some MLS or FFT software and do it with your computer. This will give you MUCH faster and cleaner results.

Keep saying this mantra: "Electrical crossover transfer functions are not the same as acoustic crossover transfer functions."
__________________
The more you pay for it, the less inclined you are to doubt it.- George Smiley
  Reply With Quote
Old 15th May 2003, 02:57 PM   #10
Raka is offline Raka  Europe
diyAudio Member
 
Raka's Avatar
 
Join Date: Aug 2002
Location: Close to Oistrakh
I strongly recommend the speakerworkshop, I think would be perfect for you.
Then, your task will be easier.
__________________
What is beyond the speaker?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Active 3-ways with solen active loudspeaker module soundemon Multi-Way 14 19th March 2009 11:17 AM
Behringer DCX2496 I want to try active biamping using it as the active xover. georgehifi Digital Line Level 3 15th August 2006 07:46 AM
Hi-freq Active Crossover Needed HipoFutura Solid State 6 30th July 2006 08:22 PM
TL freq response bigwill Subwoofers 6 13th July 2005 07:02 PM
XVR1 active crossover, discrete active stage promitheus Pass Labs 18 22nd July 2002 01:29 AM


New To Site? Need Help?

All times are GMT. The time now is 10:22 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2