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Multi-Way Conventional loudspeakers with crossovers

Suitable midrange cone, for bandpass mid in Unity horn.
Suitable midrange cone, for bandpass mid in Unity horn.
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Old 11th February 2019, 10:13 PM   #2231
njones is offline njones  United States
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Originally Posted by Patrick Bateman View Post
In the Danley SH50, the midrange taps are 3/4" in diam, and they're located 3.5" from the throat.

In the Waslo Cosyne, the midrange taps are 5/8" in diam, and they're located 2" from the throat.

I haven't used hornresp to simulate a Unity horn in ages, basically I just copy the Danley geometry. I have to bring the taps in a bit closer because I am crossing over higher than Danley is.

In my experience, the only way you can really screw up the midrange taps is if you put the mids way too far away. If you're off by an inch or half an inch, it's not the end of the world.

Click the image to open in full size.

Here's an example of how you can screw it up.

In the Unity horn that's on the left, the gap from the throat to the midrange taps is about five inches. That's not an impossible gap; for instance Sound Physics Labs sold a Unity horn that used a BMS compression driver and an 8" woofer, named the "SPL Runt."

The reason that it didn't work for me was threefold:

1) I was using a tiny little BMS 4540ND compression drive. A big gap requires a low xover, and the 4540ND couldn't do it.

2) I was using a "hifi" midrange that didn't have a low QES. For instance, the SPL Runt used a prosound woofer, with a low QES, and the low QES allows you to play the midrange higher. (See page one of this thread.)

3) It's easier to cross over lower with a narrow beamwidth horn. For instance, a 90x90 horn is "working" 4x as hard as a 45x45 horn, because the pattern is wider.

So basically I'd painted myself into a corner. My beamwidth, compression driver, and midrange were all wrong. I trashed the project.

TLDR: do what Danley does
Thanks for the explanation, Patrick.

I get how one can screw up the ports, and I have tried many variations as well. When you are measuring the distance of the ports from the throat (and does this mean the flange where the compression driver mounts), are you measuring from the central axis or diagonally on the horn wall?

It is difficult on a 60x90 horn to get 5" mids that far back. I cut them down to be squarish which helped, but things start dropping right before 1000hz which is making me cross over the compression driver lower than what I would think is optimal. Since Danley's is a 50x50 horn doesn't that factor in? Bill mentioned having the ports separated too far horizontally does weird things to the polar response so I was trying to avoid that.
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Old 11th February 2019, 10:52 PM   #2232
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by njones View Post
Thanks for the explanation, Patrick.

I get how one can screw up the ports, and I have tried many variations as well. When you are measuring the distance of the ports from the throat (and does this mean the flange where the compression driver mounts), are you measuring from the central axis or diagonally on the horn wall?
I took a tape measure and measured the distance from the bug screen on the compression driver to the midrange tap.

This isn't the ideal way to do it, you SHOULD measured from the CENTER of the horn all the way to the diaphragm.

But in my case, it was just one of those things I wanted to measure when I rented those SH50s, so I've followed the same procedure with other ones.

Quote:
Originally Posted by njones View Post
It is difficult on a 60x90 horn to get 5" mids that far back. I cut them down to be squarish which helped, but things start dropping right before 1000hz which is making me cross over the compression driver lower than what I would think is optimal. Since Danley's is a 50x50 horn doesn't that factor in? Bill mentioned having the ports separated too far horizontally does weird things to the polar response so I was trying to avoid that.
If your midranges are rolling off below 1500hz you're going to have a hard time making the design work. I can get my mids to play to about 2khz using conventional midrange taps, like Bill and Tom use. With the crazy looking midrange taps on my 3D printed horns, I can get them to play all the way to 10khz! But there IS a dip caused by the reflection.

I'd say as a general rule it's harder to get a wide angle waveguide to work as a Unity horn than a narrow one. Most the of the Danley horns are 60x40, 50x50, etc.

You CAN make the wider angles works, but having a 3D printer helps a whole lot. Being able to get the mids within millimeters of the compression driver is nice.
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Old 12th February 2019, 12:50 AM   #2233
chrapladm is offline chrapladm  Australia
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PB was 2000hz an easy exercise to achieve?

I ask because I am hoping to finally start my build in the coming months. I have Celestion closed back mids 4"but just want to have as high as possible as an option. I am still going to attempt to do a SH with the TPL200. Its what I have now so most likely will just copy the DSL way for the mid taps and go from there. I am sure I will learn a lot after building a proto.

Dont have a lot of measuring equipment or anything else that is fancy. SO I will just do what I can, have fun and hope for the best. I love the TPL's and have never heard anything that sounded as good to my ear. AND thats why I am attempting the TPL SH.
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Old 12th February 2019, 03:29 AM   #2234
njones is offline njones  United States
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Originally Posted by Patrick Bateman View Post
Why are the ports so long?

I like using super long ports, but I'm 3D printing the chambers so I can "cheat" a little. If you're just drilling a hole into plywood, a 4" long port won't work
They were frustrums so very short, like 3/16". I was referring to the slot length and width which was in the corner of the horn, for the woofer.
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Old 12th February 2019, 03:42 AM   #2235
njones is offline njones  United States
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Quote:
Originally Posted by Patrick Bateman View Post
I took a tape measure and measured the distance from the bug screen on the compression driver to the midrange tap.

This isn't the ideal way to do it, you SHOULD measured from the CENTER of the horn all the way to the diaphragm.

But in my case, it was just one of those things I wanted to measure when I rented those SH50s, so I've followed the same procedure with other ones.



If your midranges are rolling off below 1500hz you're going to have a hard time making the design work. I can get my mids to play to about 2khz using conventional midrange taps, like Bill and Tom use. With the crazy looking midrange taps on my 3D printed horns, I can get them to play all the way to 10khz! But there IS a dip caused by the reflection.

I'd say as a general rule it's harder to get a wide angle waveguide to work as a Unity horn than a narrow one. Most the of the Danley horns are 60x40, 50x50, etc.

You CAN make the wider angles works, but having a 3D printer helps a whole lot. Being able to get the mids within millimeters of the compression driver is nice.
I think they worked ok up to 1khz with help from the compression driver. Just hoping to get a little bit more out of them. I think filling some of the chamber volume with circles will help. I routed out some crescent shaped circles out of 1/4" MDF with a bevel bit and glued them down, and plan on shaping with some Bondo to get the cone angle better as it's not 45 degrees.
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Old 12th February 2019, 04:37 AM   #2236
GM is offline GM  United States
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Originally Posted by njones View Post
When you are measuring the distance of the ports from the throat (and does this mean the flange where the compression driver mounts), are you measuring from the central axis or diagonally on the horn wall?
The acoustic center of a compression driver basically sets on the phase plug so measure on axis from this point to locate the mid driver ports. The actual ideal driver location is found by measuring its acoustic center at the XO point, then lining it up to the port centerline, though with differing panel slope angles, use the shorter distance.

GM
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Old 13th February 2019, 02:38 PM   #2237
njones is offline njones  United States
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Originally Posted by chrapladm View Post
PB was 2000hz an easy exercise to achieve?

I ask because I am hoping to finally start my build in the coming months. I have Celestion closed back mids 4"but just want to have as high as possible as an option. I am still going to attempt to do a SH with the TPL200. Its what I have now so most likely will just copy the DSL way for the mid taps and go from there. I am sure I will learn a lot after building a proto.

Dont have a lot of measuring equipment or anything else that is fancy. SO I will just do what I can, have fun and hope for the best. I love the TPL's and have never heard anything that sounded as good to my ear. AND thats why I am attempting the TPL SH.
That TPL200 looks really cool. Is the built in waveguide removable? You might need to do that to get the mids mounted close enough. If you designed the horn with a vertical rectangular throat matching the stock waveguide you could mount pairs of mids on the vertical sides and get them much closer to the tweeter.
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Old 13th February 2019, 02:41 PM   #2238
njones is offline njones  United States
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Originally Posted by njones View Post
That TPL200 looks really cool. Is the built in waveguide removable? You might need to do that to get the mids mounted close enough. If you designed the horn with a vertical rectangular throat matching the stock waveguide you could mount pairs of mids on the vertical sides and get them much closer to the tweeter.
Which also might be more challenging to get the angles and cuts right since Bill's spreadsheet does not account for a non-square throat, AFAIK.
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Old 13th February 2019, 02:59 PM   #2239
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by chrapladm View Post
PB was 2000hz an easy exercise to achieve?

I ask because I am hoping to finally start my build in the coming months. I have Celestion closed back mids 4"but just want to have as high as possible as an option. I am still going to attempt to do a SH with the TPL200. Its what I have now so most likely will just copy the DSL way for the mid taps and go from there. I am sure I will learn a lot after building a proto.

Dont have a lot of measuring equipment or anything else that is fancy. SO I will just do what I can, have fun and hope for the best. I love the TPL's and have never heard anything that sounded as good to my ear. AND thats why I am attempting the TPL SH.
Here's the response of my Gento midranges on a 3D printed waveguide:

Click the image to open in full size.

Click the image to open in full size.


Looks like they made it to 1800hz
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Old 13th February 2019, 03:07 PM   #2240
njones is offline njones  United States
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Originally Posted by GM View Post
The acoustic center of a compression driver basically sets on the phase plug so measure on axis from this point to locate the mid driver ports. The actual ideal driver location is found by measuring its acoustic center at the XO point, then lining it up to the port centerline, though with differing panel slope angles, use the shorter distance.

GM
I'm stuck with the port locations at this point due to physical mounting limitations. I got them as close in as possible while still allowing a gap between the frustrum port near the edge of the mid cone/surround. I ended up settling with 5/8" ports, as I have tried 3/4" as well as 1/2" and this seems to be a happy medium.

For the woofer ports I chose 1-1/2" slot port, 2-5/8" length (with a frustrum, so actual port depth is 1/4") This size ends up being 20% of the cone area so a 5:1 compression ratio. The 3/4"x4" slot ports worked ok but the frequency response was peaky so hoping this works better.

I'll post a pic later showing the port modification and filler "phase plugs".
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