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Multi-Way Conventional loudspeakers with crossovers

Ribbon Unity Horn
Ribbon Unity Horn
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Old 10th October 2018, 04:34 PM   #21
Jack Arnott is offline Jack Arnott  United States
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Quote:
Originally Posted by Patrick Bateman View Post
In my entire life, I've never blown up a conventional tweeter or a compression driver.

The second bit of trickery is that I figured I could extend the bandwidth by getting the efficiency really high and then using a filter to 'flatten out' the bandpass response. Basically flatten out the midrange in the center of it's passband, while leveraging the efficiency of a fairly large array to increase the output at the limits of it's passband.


Hope that makes sense.

TLDR: I'm doing everything thing I can to push the midranges UP, so that I can keep the crossover point as high as possible, to keep the ribbon from blowing itself up.

Thanks for your design intention explanation. Seems to be coming to fruition.
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Old 10th October 2018, 06:58 PM   #22
Patrick Bateman is offline Patrick Bateman  United States
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Basically all of my speakers these days are active-passive hybrids. I use a passive xover for the midrange lowpass and the tweeter highpass, and then I use an active xover for the speaker's highpass and for EQ. This allows me to use a single channel of amplification for the midrange and tweeter, it protects the tweeter from turn-on thumps, and allows me to do fairly basic passive xovers, since I can shape the overall response later.

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Here's the response of the speaker as it is today. This has a 3rd order high pass on the ribbon and a 2nd order low pass on the midranges. The two traces show in-phase and out-of-phase, basically demonstrating that the drivers are pretty well aligned, timewise. (That's what creates the big out-of-phase null.)

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Here's the horizontal polars. Pretty good response I think! One thing that I noticed with my 3D printed speakers is that using a big ol' roundover seems to extend the point at which the directivity collapses.

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Here's the vertical polars. In this measurement, I think you can see why I'm not a big fan of square ribbons - they beam like crazy and they also have off-axis dips. You really have to listen to a big ribbon with your head in a vise. The Fountek NEO CD 3.5H has a horizontal width of 3/4", which gives it really nice horizontal polars. On the flip side, the vertical directivity is narrow. Which is fine for a room, as long as the ribbon is mounted at a reasonable height.

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Here's the impedance of the midrange array with a 2nd order lowpass. I basically did this measurement to make sure the impedance didn't have any dips.
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Old 10th October 2018, 07:01 PM   #23
Patrick Bateman is offline Patrick Bateman  United States
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YouTube

Here's how it sounds today. This is at a much higher volume, and I also filmed it up close to show that the ribbon doesn't seem to be modulated by the midranges. I'm actually shouting over the speaker in the video but you can't hear me at all when I'm close to it!

Also, around the two minute mark, the speaker starts to sound kinda 'boomy' as I walk backwards. That's because I was walking backwards into my garage, so you were starting to hear the concrete walls of the garage coloring the sound.

For comparison's sake, here's a Danley SH50:

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Last edited by Patrick Bateman; 10th October 2018 at 07:07 PM.
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Old 10th October 2018, 07:13 PM   #24
Patrick Bateman is offline Patrick Bateman  United States
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If anyone's curious why there's a dip at 6.8khz, here's the reason:

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The midrange has an out of band peak. I added a 2nd order lowpass, but it looks like I may need to increase that to third order to tame it.

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At 6.8khz the midrange and tweeter are out-of-phase, creating a dip. If you reverse the phase of the tweeter, you can see the dip goes away. But it's replaced by a dip at the xover, which we definitely don't want.

I hate crossovers
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Old 10th October 2018, 09:41 PM   #25
Jack Arnott is offline Jack Arnott  United States
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I don't think it is your crossover, I think something is up in your horn. Crossing the mids down more (steeper slope) will probably help it (the 6.8khz dip). Looking at all of your graphs, something is happening in both the mids and highs at, or about that point, and it gets weirder when when you are off axis, because it gets additive, instead of subtractive when you are off of vertical. How tall is that tweeter? The wavelength that is affected is about 2". Looking at the original post, I don't think this is it, as it happens in your first sweeps, and this was only half way done. Is it the length from your doscs to the tweeter? This might explain why the midrange has the overall bump in this area, as it is reinforcing that frequency in particular, and the nearby frequencies somewhat, and then there are all the harmonics that are cancelling. The HF could be cancelling at this frequency because it hits the dosc exit, then comes back, and cancels when it re-hits the tweeter, out of polarity.

Maybe the distance from your dosc to the tweeter is the same length as the height of the tweeter, so it goes additive instead of subtractive when you are off axis vertically, and goes subtractive when you are on axis, or off axis horizontally.
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Old 10th October 2018, 10:22 PM   #26
Patrick Bateman is offline Patrick Bateman  United States
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That link is restricted

I'll email you my ID and post it if you'd like
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Old 10th October 2018, 10:24 PM   #27
Jack Arnott is offline Jack Arnott  United States
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Can't figure out how to post an image. I have to run, will check my email later.
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Old 10th October 2018, 10:26 PM   #28
Patrick Bateman is offline Patrick Bateman  United States
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Sounds good!
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Old 11th October 2018, 12:31 PM   #29
lowmass is offline lowmass  United States
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Patrick are you planning to enclose the rear of the mids?
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Old 11th October 2018, 01:29 PM   #30
marco_gea is offline marco_gea  Italy
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Quote:
Originally Posted by Patrick Bateman View Post
In a Unity horn, the midrange drivers are firing into a coupling chamber, which rolls off the highs. You get an out-of-band peak, like you would in any bandpass enclosure.

The fix is simple: lowpass the midranges.

The measurement posted here has no crossover whatsoever on the midranges. No highpass, no low pass.
Yeah, I get that. But even so, you'll need a heck of a steep low-pass filter to effectively get rid of those huge peaks. Not a good starting point, IMHO.
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