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-   -   Optimizing active crossover (http://www.diyaudio.com/forums/multi-way/194848-optimizing-active-crossover.html)

atledreier 18th August 2011 07:06 AM

Optimizing active crossover
 
I've built a proven speaker design, but I am a bit unhappy with my crossover setup so far.

The drivers are two Beyma 15p80nd and a Beyma TPL150H in MTM configuration. Slotport top and bottom on the front baffle.

The original designer recommend a 4th order Linkwitz-Riley 900Hz crossover. I have that set in my DSP (DCX2496), but I can hear the transition is quite muddy.

I have access to REW so I can measure the response, but don't really know how to measure and what information is relevant for crossover design. Any pointers?

jerome69 18th August 2011 09:42 AM

I looked the drivers response....
900Hz is not a good point of crossover... 2kHz seems better.
But 2kHz for a 15", not very a good thing... but can work in your setup.
Do you include baffle step ? Do you include time delay ?
It's better use HOLMIMPULSE or ARTA.

Robert GS 18th August 2011 10:51 AM

I can only agree to what jerome69 write - I wouldn't choose such a low crossover point for the Beyma TPL-150H driver. I am looking at 2-2.5kHz based upon my own measurements:

http://www.groundsound.dk/BeymaTPL-150H.jpg

;) Robert GS

AndrewT 18th August 2011 11:17 AM

Are you running two 15inchers in an MTM format?

You need a midrange driver or maybe two.

pinkmouse 18th August 2011 11:23 AM

Quote:

Originally Posted by atledreier (Post 2676692)
I have access to REW so I can measure the response, but don't really know how to measure and what information is relevant for crossover design. Any pointers?

On and off axis FR, phase and distortion. You're running active, so impedance isn't that much of an issue. Lots of good stuff on the site about the measurement process, so a search should sort you out on that aspect.

However, I agree with the other posters, I think you're trying to push the drivers too far, and a good mid would sort out the problem.

Loren42 18th August 2011 11:43 AM

Quote:

Originally Posted by atledreier (Post 2676692)
I've built a proven speaker design, but I am a bit unhappy with my crossover setup so far.

The drivers are two Beyma 15p80nd and a Beyma TPL150H in MTM configuration. Slotport top and bottom on the front baffle.

The original designer recommend a 4th order Linkwitz-Riley 900Hz crossover. I have that set in my DSP (DCX2496), but I can hear the transition is quite muddy.

I have access to REW so I can measure the response, but don't really know how to measure and what information is relevant for crossover design. Any pointers?

900 Hz is way too low!!!

I am running a Acoustic Elegance TD15H with a Beyma TPL-150. I have mine crossed at 1.2 kHz and that may be a little too low.

Best performance seems to be at and above 2 kHz, but a 15" directivity will be too narrow to match the TPL-150 at that frequency.

The woofers you have selected look like they will play higher up the spectrum, but there is no data on the directivity for the woofer. I can tell from my own measurements that the TPL-150 is a very, very wide directivity driver at 1 kHz and above and my AE speaker starts to get narrow at the same frequency.

I would try setting your crossover at 1.5 kHz if you do not need to play high volumes as a start. At that frequency you can get away with a second order slope or higher. Then you can move that crossover point upward until you get what you like. Bear in mind you will lose directivity in that region.

Lastly, check your TPL-150 polarity with respect to the woofers and the crossover so that there isn't a phase suck out.

atledreier 18th August 2011 12:06 PM

It's the TPL150H, the one with the horn.

The original design is with the two woofers at the bottom, horn on top and two rearfiring ports. That design is very successful with a 900Hz crossover, I've heard it myself in two different setups.

Is there a reason the MTM config is different?

I have the speakers on stands to get the horn at earheight.

atledreier 18th August 2011 12:09 PM

Here is a link for the actual driver specs:

http://profesional.beyma.com/ingles/pdf/TPL150H.pdf

http://profesional.beyma.com/ingles/pdf/15P80Nd.pdf

AndrewT 18th August 2011 01:21 PM

Hi,
try using the DCX to alter the crossover frequency.

Move it up to 1k, 1k1, 1k2, 1k4, 1k7.
For the moment keep the 4P L-R

Audiodidakt 18th August 2011 01:49 PM

You should try to find a transition-area for both drivers where:
a. Directivity off-axis of both drivers are similar, and
b. Where both drivers sound "ok"

just my 2 cents


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