Playing Passive crossover Design.

rinx · 11th October 2009, 02:22 PM

Just very simple question:
-i am using SPL Trace to get driver frequency from graph, but where I can find phase for each frequency point? I do need it further in simluation process?

ps! using SPL trace, it will give me only db and freq., phase is always 0

Pano · 11th October 2009, 03:00 PM

If the plot you are tracing does not include phase, you may be out of luck. Not all plots include the phase. If it does, then use the phase plot function in SPL trace.

You may still be able to get a usable phase plot if your box simulation software will calculate it for you. Unibox will.

rinx · 11th October 2009, 03:31 PM

I will give you and example:
http://www.parts-express.com/pdf/295-366s.pdf

check this second grpah, should I take phase graph from there? (Impedance/phase)

I have Unibox also

5th element · 11th October 2009, 04:29 PM

You have to remember that the phase isn't really absolute, but rather it's a relative quantity. It has to be measured with both your intended drive units on the same baffle from the same microphone position, otherwise it's next to useless.

The phase you're talking about in the datasheet for the RS driver is the electrical phase which is not the same as the acoustic phase.

You'll notice that almost no loudspeaker manufacturer includes the phase response with their frequency response graphs. This is because it isn't really useful unless you know everything about the measurement conditions at the time the measurement was taken.

There are of course ways to simulate and with reasonable accuracy, from what I'm lead to believe, what the phase relationship between two drivers might be.

I believe the process outlined at

http://www.rjbaudio.com/Audiofiles/FRDtools.html

explains how to do this, although I've never tried it for myself.

rinx · 11th October 2009, 05:04 PM

Thats very good! Thanks a lot!
I was actually thinking the same that the phase is relative. I ll probably measure in the future drivets frequency/phase in the proper enclosure and then will play with crossover software. Does that sound good idea?

5th element · 11th October 2009, 06:00 PM

Quote:

Originally Posted by rinx

Thats very good! Thanks a lot!
I was actually thinking the same that the phase is relative. I ll probably measure in the future drivets frequency/phase in the proper enclosure and then will play with crossover software. Does that sound good idea?

That sounds like a very good idea

Michael Chua · 11th October 2009, 09:41 PM

Hi rinx

Phase is generated from the impedance plot. The picture attached is a 2-way that I'm working on right now. Woofer is a Tang Band W5-704S. Tweeter is a HiVi RT1C Planar. 13 Liters Vented Box, Fb=60Hz. Crossover is 12dB/oct. The Impedance is the top plot. Minimum Phase is lower plot. This is electrical phase, not acoustic.

Pano · 11th October 2009, 09:54 PM

Right! Sorry I meant to say trace the impedance. You may be able to derive phase from that.

But measuring the actual drivers you own the box you have is absolutely the best way, for sure. =)

rinx · 13th October 2009, 06:37 AM

Thank You very much guys!

11th October 2009, 02:22 PM	#1
rinx diyAudio Member Join Date: Sep 2007	Playing Passive crossover Design. Just very simple question: -i am using SPL Trace to get driver frequency from graph, but where I can find phase for each frequency point? I do need it further in simluation process? ps! using SPL trace, it will give me only db and freq., phase is always 0

11th October 2009, 04:29 PM	#4
5th element diyAudio Member Join Date: Oct 2002 Location: England	You have to remember that the phase isn't really absolute, but rather it's a relative quantity. It has to be measured with both your intended drive units on the same baffle from the same microphone position, otherwise it's next to useless. The phase you're talking about in the datasheet for the RS driver is the electrical phase which is not the same as the acoustic phase. You'll notice that almost no loudspeaker manufacturer includes the phase response with their frequency response graphs. This is because it isn't really useful unless you know everything about the measurement conditions at the time the measurement was taken. There are of course ways to simulate and with reasonable accuracy, from what I'm lead to believe, what the phase relationship between two drivers might be. I believe the process outlined at http://www.rjbaudio.com/Audiofiles/FRDtools.html explains how to do this, although I've never tried it for myself. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

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11th October 2009, 03:00 PM	#2
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	If the plot you are tracing does not include phase, you may be out of luck. Not all plots include the phase. If it does, then use the phase plot function in SPL trace. You may still be able to get a usable phase plot if your box simulation software will calculate it for you. Unibox will.

11th October 2009, 03:31 PM	#3
rinx diyAudio Member Join Date: Sep 2007	I will give you and example: http://www.parts-express.com/pdf/295-366s.pdf check this second grpah, should I take phase graph from there? (Impedance/phase) I have Unibox also

11th October 2009, 05:04 PM	#5
rinx diyAudio Member Join Date: Sep 2007	Thats very good! Thanks a lot! I was actually thinking the same that the phase is relative. I ll probably measure in the future drivets frequency/phase in the proper enclosure and then will play with crossover software. Does that sound good idea?

11th October 2009, 09:54 PM	#8
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	Right! Sorry I meant to say trace the impedance. You may be able to derive phase from that. But measuring the actual drivers you own the box you have is absolutely the best way, for sure. =)

13th October 2009, 06:37 AM	#9
rinx diyAudio Member Join Date: Sep 2007	Thank You very much guys!

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