What the "PHASE" is going on????? :S - diyAudio
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Old 29th September 2011, 12:39 AM   #1
endrek is offline endrek  Spain
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Default What the "PHASE" is going on????? :S

well..... i just build this :

221L Bass Reflex box with Fane Colossus 18XB
140 L aprox. Bass Reflex box with Double 12'' (Beyma 12MI100) + CD (Beyma CD755Nd)+ Horn (TD595)+ Filter (Beyma FD212, Fc 1,2KHz).

The sub hasn't got a filter in it, so i use my dBx DriveRack to filter it, and the other signal i send it to the Top box with a HPF.

picture of the speakers:
green line XOVER LPF 100HZ // pink line XOVER LPF 125Hz // red line Top FRF HPF 100Hz
Click the image to open in full size.
well the problem is, i'm newbie and i don't know much about "phases" of speakers and what to do with them... So i just start trying...inverting phases and see what happends......
but then i realise...i'm measuring FRF(Frequency Response Functions), not Phase Functions,....hmmmm

First of all, How do i measure this phase functions?!??!
Second, what is the normal thing to invert? the compresion driver?? the 12''s(MF)??? The sub??

well... i did my lttle experiment with the TOP box, and first inverted the polarity of the 12''s from the Top Box, and measured the FRF.
green the measured Top box without inverting polarities, Red measured Top box with 12''s inverted
Click the image to open in full size.
Well....Now that i "think" that the Top box has reached a balance between "flat response" and losses.... i put it all together... and measure,

Click the image to open in full size.


is it ok what i am doing??? Because i'm just guessing.... Can someone explain this newbie what to do??What's the procedure to phase the speakers????& etc...

WHAT THE PHASE IS GOING ON!!????

pd: any site good to look? thread? whateverrrrr?????

thx for your helppp!!!!!
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Old 29th September 2011, 05:06 AM   #2
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Hi endrek;

It looks like you do good work, those look great!

What measurement system are you using? Is it capable of impulse response and phase measurement?

In the first graph it looks like the big dip or notch in the frequency response is at the crossover point of the filter network yes? Were it me I would drive the 18 and 12's so that posative voltage gives outward cone motion (non inverted) and switch the polarity on the compression driver to which way minimizes the 1.2kHz notch, you will have to measure it both ways.

As for getting the best phase response, since the 12's and compression driver are on a passive network, you only have time control of where the 18 and 12's overlap. The small dip in the response where the 18 and 12's integrate looks like it could use a little help.

How is your system set up? Is everything run through the DriveRack?
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Old 30th September 2011, 11:58 PM   #3
endrek is offline endrek  Spain
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Join Date: Sep 2010
LabPulse, a really old hardware from a friend university, where he lets me go inside the anechoich chamber to make measures but i'm a newbie... hehe

everything through driverack, I BP 20-140 to the sub and HP >125 to the Tops.
I have 2 american audio , V4001 and V5001
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