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Author Topic: Wedges & Transfer Function Measurement: Meas. Mic Position?  (Read 16163 times)

Douglas R. Allen

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Re: Wedges & Transfer Function Measurement: Meas. Mic Position?
« Reply #40 on: January 07, 2013, 08:02:06 pm »

Thanks Art and Paul;

The phase of the yamaha in the horn range is of course at the very top or in the + area for most of the horns bandpass area. Where as the woofer section is all in the -side of the screen or bottom for the most part. The phase trace seems to be linear for the most part as well in the horn range. Not going behind in phase as the frequency drops as in the EV speaker.
I wondered if I reversed the polarity would this phase move to the bottom or remain the same just with a problem in the crossover area now. ( I feel this would happen but not sure ) I've measured the yamaha speakers from time to time through the years and they always more or less looked like that.
When I'm building a 2 or 3 way system I'll shoot to have the phase angles to lay on top of each other at the crossover point (s) using delay and using different filter types and slopes to get them to match up. When unmuted they more or less look like the Peavey monitors phase.
Looking at the EV or Yamaha it seems like there should be a problem at the crossover point. Yet there is not. I'm guessing had EV or Yamaha used an all pass filter this could be corrected some what?
A larger part of me thinks that the phase is lagging in time more as the frequency goes lower and it just happens to, for the loss of the correct words, wrap around in the crossover frequency general area with the view I had selected. This seems to be easier to see in the EV trace but not so much with the Yamaha one.  Thanks for the tip Paul on changing the view. I'll try this next time

To sum it up I'm trying to get a better handle reading measurements like these as they come up.
The way I see it now the EV and Yamaha just happen to have not as good phase response as the peavey though out thier frequency range but wanted to see if there is another way to look at it.
Thanks for any input;

Douglas R. Allen
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Art Welter

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Re: Wedges & Transfer Function Measurement: Meas. Mic Position?
« Reply #41 on: January 07, 2013, 09:33:11 pm »

Thanks Art and Paul;

The phase of the yamaha in the horn range is of course at the very top or in the + area for most of the horns bandpass area. Where as the woofer section is all in the -side of the screen or bottom for the most part. The phase trace seems to be linear for the most part as well in the horn range. Not going behind in phase as the frequency drops as in the EV speaker.
I wondered if I reversed the polarity would this phase move to the bottom or remain the same just with a problem in the crossover area now. ( I feel this would happen but not sure ) I've measured the yamaha speakers from time to time through the years and they always more or less looked like that.

Douglas,

Paul's tip is helpful, I have reposted the Mackie 1502HD, DSL SH100, and WS8H so you can see the phase response a bit better.
You can see that it is typical for all ported speakers phase to invert towards the port frequency.
It is also typical for phase to generally trend down from low to high, the Peavey is a bit odd in the "up and down" trace.

If you reverse the polarity of a loudspeaker, the phase trace will still look the same, but will be rotated 180 degrees.

The phase traces you posted all look to be OK in the crossover region, but all use different filters to achieve those results.
The phase traces of the speakers I posted all look a bit better, and again, each used very different filters and transducers- there are many different ways to skin the phase cat.

Art
« Last Edit: January 07, 2013, 09:38:36 pm by Art Welter »
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Re: Wedges & Transfer Function Measurement: Meas. Mic Position?
« Reply #41 on: January 07, 2013, 09:33:11 pm »


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