Phase *PIC*

[chadg]

http://chadgray.info/speakers/PhaseDifference.jpg

Provided Link: http://chadgray.info/


Hello, It has been a while. Life got really busy this summer, but I have last minute christmas speaker building to do and have a question on my phase.

This is the RS150 + RS28 in a ported box.

I dont understand phase very well, and wanted to ask if this phase looked ok?

It is the blue trace in the bottom graph. Ignore the top graph.

Does anyone have an example of "Good" phase on a two way speaker?

Happy Holidays!

[curt_c]

http://www.geocities.com/cc00541/TritrixMTMph.gif

Provided Link: TriTrixMTM (http://www.geocities.com/cc00541/Tritrix_pg_1.html)


> Hello, It has been a while. Life got really
> busy this summer, but I have last minute
> christmas speaker building to do and have a
> question on my phase.

> This is the RS150 + RS28 in a ported box.

> I dont understand phase very well, and
> wanted to ask if this phase looked ok?

> It is the blue trace in the bottom graph.
> Ignore the top graph.

> Does anyone have an example of
> "Good" phase on a two way speaker?

I can't tell much from the summed phase. The individual phase responses of the woofer and tweeter should overlay each other through the crossover region. The plot below is of my TriTrixMTM design:

C

[chadg]

Provided Link: http://chadgray.info


Thanks Curt, i did do this throughout my design process. I kept the phase lined up for the tweeter/woofer responses.

In Soundeasy you can optimize for the total system taking into consideration the driver spacing and that is where my graph comes from.

[curt_c]

> In Soundeasy you can optimize for the total
> system taking into consideration the driver
> spacing and that is where my graph comes
> from.

So, what did you optimize in the ‘total system’? Frequency response, I assume. If the individual driver phase still track, I’d say you are OK. The changes in phase rotation starting at 300 Hz up to about 6K seems curious though…

C

[chadg]

> So, what did you optimize in the ‘total
> system’? Frequency response, I assume. If
> the individual driver phase still track, I’d
> say you are OK. The changes in phase
> rotation starting at 300 Hz up to about 6K
> seems curious though…

I optimized for aplitude only (no phase). I turned on all of the woofers crossover parts and optimized. Then i turned them off and only turned on the tweeters crossover parts and optimized those. Then i turned on all of the parts in the crossover and optimized again.

This gave me a nice flat SPL response like you see in the picture.

The phase from 40 - 7k use to be a pretty straight shot down.

After the optimization that i did above my phase line started going up from the 300 - 6k range like you mentioned.

that is what peaked my interest and resulted in the question.

The crossover is 4th order LR.

[curt_c]

Depending on how far off your response was before optimization, the phase could have changed significantly. Can you go back now and look at the individual phase plots? How close do your current acoustic transfer functions follow the ideal 4th order LR or whatever you chose...
C