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Multi-Way Conventional loudspeakers with crossovers

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Old 18th August 2011, 01:58 PM   #11
sreten is offline sreten  United Kingdom
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Hi,

You might have some phasing issues as your high pass is 4th order
L/R + the driver rolloff at around 1KHz, try reversing tweeter phase.

rgds, sreten.
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Old 18th August 2011, 02:27 PM   #12
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Quote:
Originally Posted by atledreier View Post
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.
You may copy the successful setup ie the crossover ?

900Hz can work with a passive crossover, not with a regular active crossover. It is possible with active but complicated at 900Hz. The crossover will not be full LR4. The 15" is done to work till 5kHz This is shocking for a lot of people. I also heard a 15" could be fullrange, till 20kHz.
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Old 18th August 2011, 02:55 PM   #13
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My initial 900Hz crossover was a copy of one of the successful builds.

I tried raising the crossover to 1,2kHz, and that cleaned up the midrange, but introduced a little harshness that I imagine will become fatiguing in the long run. I better get REW out and do some measurements so I know what I'm doing.

Any particular measurements I want to look at besides FR?
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Old 18th August 2011, 06:53 PM   #14
_Wim_ is offline _Wim_  Belgium
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If by FR you mean polars, then no. But as explained by others, your main goal will be to match directivity at the crossover point, and the only good way to do that, is by making polars....
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Old 18th August 2011, 06:58 PM   #15
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by atledreier View Post
I tried raising the crossover to 1,2kHz, and that cleaned up the midrange, but introduced a little harshness
That "harshness" could be a break up mode, or could be a peak in the frequency response.
If a peak then you can notch it out using the DCX. You need to identify the frequency of the peak and the height of the peak and the width of the peak, so that you can tell DCX what correction to apply to the signal.
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Old 18th August 2011, 07:05 PM   #16
Loren42 is offline Loren42  United States
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Quote:
Originally Posted by jerome69 View Post
You may copy the successful setup ie the crossover ?

900Hz can work with a passive crossover, not with a regular active crossover. It is possible with active but complicated at 900Hz. The crossover will not be full LR4. The 15" is done to work till 5kHz This is shocking for a lot of people. I also heard a 15" could be fullrange, till 20kHz.
No 15" will match the directivity of the TPL-150 or TP-150H (doesn't matter) at 1 kHz and up.

The woofer may have a great response on-axis, but physics will intervene at some point due to the size of the radiating surface.

Discontinuity of the power distribution will result above 1 kHz. What that means is the SPL on axis response will be fine, but the power distributed off-axis will peter out until the TPL-150 takes over above the crossover point.

If you look at the polar plot you will see a narrow waistline at the crossover point if it is too high because there is nothing the woofer contributes to the off-axis response.
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Old 18th August 2011, 07:13 PM   #17
Loren42 is offline Loren42  United States
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Quote:
Originally Posted by atledreier View Post
My initial 900Hz crossover was a copy of one of the successful builds.

I tried raising the crossover to 1,2kHz, and that cleaned up the midrange, but introduced a little harshness that I imagine will become fatiguing in the long run. I better get REW out and do some measurements so I know what I'm doing.

Any particular measurements I want to look at besides FR?
You need to get on-axis and off-axis horizontal response to find out what is happening.

That TPL-150H spews a lot of sound out 90 degrees of the horn mouth, by design. That sound is what you hear reflected off surfaces of the room. If the woofer does not match the TPL-150H at the crossover point you actually hear a slight null or suck out at that point.

Also, measurements will determine how the box and placement of the drivers in the box interact and impact the frequency response. This includes diffraction artifacts inherent with the enclosure.

Be forewarned, getting reliable measurements is not an easy task. I have often stated that a DIY Audio forum dedicated to measurements would be a good thing for builders.
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Old 18th August 2011, 08:36 PM   #18
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I'm planning a baffle wall. Will that help or complicate things any?
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Old 18th August 2011, 08:50 PM   #19
Loren42 is offline Loren42  United States
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Quote:
Originally Posted by atledreier View Post
I'm planning a baffle wall. Will that help or complicate things any?
You are mounting the cabinet flush with the wall?
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Old 19th August 2011, 06:38 AM   #20
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With such an MTM configuration don't forget to try an odd-order Butterworth crossover !
Both your on-axis response and your power response might profit.

Regards

Charles
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