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-   -   back loaded horn bass frequency phase (http://www.diyaudio.com/forums/full-range/156036-back-loaded-horn-bass-frequency-phase.html)

wicked1 2nd December 2009 05:23 PM

back loaded horn bass frequency phase
 
Do back loaded horns invert the phase of the bass frequencies? I dont know why, but I am having so much trouble pairing a sub to my horns..

When I have the sub xover turned up to 200hz or so, having the phase to 0 is obviously correct. I switch it, and all the mid/bass disappears from my horns. But, I turn the xover down to 80hz or so and bass is a little weak.. I flip the phase switch to 180 and hear MORE bass.. (but.. maybe its canceling some of the lower midbass from my horns and the lower bass is just seeming louder.. I dont know!)

Any advice?

hm 3rd December 2009 11:51 AM

horn + sub
 
Hello,
what kind of Horn,
and what sub do you use,
200 Hz is much to high for a sub.

Pit Hinder 3rd December 2009 12:35 PM

wicked1, I dont always agree with hm (hi there - Hamburg got as lousy weather as Hannover at the moment?) but he is effing right - when using a single sub, 200 Hz is waaaay to high.
Plus, from what you write I suspect your sub Xover only cuts the sub off and leaves the horns to interfere in midbass...your room interacts with both and you get the puzzling results that cause you headache.

MJK 3rd December 2009 12:42 PM

If you look at the following computer simulation

http://www.quarter-wave.com/Back_Doo...er_7_03_09.pdf

starting on page 13 of the pdf file you will see the calulated SPL and phase for a back loaded horn. The driver, mouth, and combined SPL response are all shown.

wicked1 3rd December 2009 01:49 PM

Hey, thanks MJK, actually, I have a pass to d/l your worksheets... This is so simple.. even my grandparents have to pair a sub to their system.. I didn't think I'd need the mathcad :D!
And no, I don't want my sub xovered at 200hz. I'm just trying to figure out the phase for the sub. When it's turned down to 80hz where it needs to be, I just can not tell which way the phase should go.. not at all.. My horns have faded by then, so there's not much frequency to cancel out.
So, I turn up to 200hz for what I would think would be an easier comparison. Which, it seems to be. Like I said in my first post I hear the frequencies getting canceled when the filter is turned up that high.
I'm just confused about why I seem to have the opposite results when I turn the filter back down low.

-Hey! and that mathcad sheet shows what I'm talking about! phase is flipped at just under 100hz and is that way till the low frequencies fade away from the horn!!!!!!!
I guess this is a little more complex than I thought.
Since I'm wanting to xover right where the phase changes, I think no matter what, I'll be canceling something..

well, maybe I'll spend some time modeling my exact speakers (just the fostex bk-16 kit from madisound) and see if it's the same.

Pit Hinder 3rd December 2009 03:07 PM

Martin, Im still somewhat unhappy with your worksheets. I do agree that the laws of physics are the same, but accepting that wavelengths in centimeters do the same slow somersaults as in inches...OK, the flak you got for your TL thing had other reasons, but you never shut up, willya please?:headshot:

MJK 3rd December 2009 03:52 PM

Quote:

Originally Posted by Pit Hinder (Post 2000439)
Martin, Im still somewhat unhappy with your worksheets. I do agree that the laws of physics are the same, but accepting that wavelengths in centimeters do the same slow somersaults as in inches...OK, the flak you got for your TL thing had other reasons, but you never shut up, willya please?:headshot:

Pit I have no idea where your comments are coming from, I don't see much in the way of constructive inputs in your posts. But if I am being asked to shut up maybe it is time to go silent here.

Scottmoose 3rd December 2009 04:07 PM

:confused: I would imagine Pit is kidding with you Martin, but I confess I've missed exactly what -I'm not at my best & brightest today (departmental Christmas night out yesterday...)

Pit Hinder 3rd December 2009 04:12 PM

Martin, that comment goes back to the time when we had contact years and years ago - you got lots of flak because self-appointed gurus got shot to pieces because you applied math and phys instead of smoke and mirrors. As to feet and inches - I still cant think but metric.

Pit Hinder 3rd December 2009 04:31 PM

Scott, I hoped youd know better. Never socialize with people who have got, and will get, on your nerves all the rest of the year. And you ought to be used to academiots...


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