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Old 11th August 2008, 11:21 AM   #1
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Default jbell's set of four tapped horns

Jim,

I'll trust you're joining the forum now and can tell us about your tapped horn project for live sound. I expect details! hehe without fear of getting the hammer.
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Old 11th August 2008, 06:43 PM   #2
contour is offline contour  Netherlands
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That is a 15" Eminence driver isn't it? That must be some very big cabinet. Perhaps a little more bracing in the hornmouth could be used?

I bet these are much better then those Tuba 36 horns :-)

Best regards,

Walt
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Old 11th August 2008, 07:40 PM   #3
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Default A bit more info

A few details, until Jim gets here and shares his side of the story.

Jim emailed me about the potential for a tapped horn design to cover 40 Hz up, and already had 3015's from another attempt that did not work.

I looked up the specs for a 3015LF and simmed a TH sub that made the numbers Jim needed, he took the ball and ran from there. I wish I could turn a hornresp output into reality as fast as Jim did.

He built a simple up/back prototype to test the design. When that worked out, he worked up a simple folding topology and tweaked the design to better fit the space he had and be much more plywood-friendly.

Initial email to the testing of four finished cabinets in a week, including a prototype tested in 2 days. Did you do anything else???

My hat's off to ya Jim. Excellent work.
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Old 11th August 2008, 07:40 PM   #4
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Yes, the cabinets are large (approx 36"X46"X24"). This is a built-in install, so transportability was a secondary concern.

Drivers are Eminence 3015LF's.

These cabinets are not -13dB @ 40 Hz relative to 100 Hz.

Certainly they have a limited bandwidth (things do get ugly above 200 Hz), but they were designed for a purpose that takes the limited bandwidth into account.
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Old 11th August 2008, 07:40 PM   #5
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We aren't here to diss on the T36.. we're here to talk about Jim's new TH cabs in a place not subject to thread deletion
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Old 11th August 2008, 07:50 PM   #6
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Here's some more photos. I was going to wait for Jim, but think I'll jump the gun

Click the image to open in full size.
original test cab. He says he burned it, but didn't roast any weenies.

Click the image to open in full size.
That shows the fold he used.

Click the image to open in full size.
Here's a setup where Jim was wondering about phase steering patterns
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Old 11th August 2008, 08:07 PM   #7
contour is offline contour  Netherlands
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Well they look very nice,

As I have said sometimes before, a tapped horn with the driver in the mouth is in fact very close to a normal back loaded horn (also known as 'Scoop') you can run them both in Hornresp and probably see very little difference.

I am wondering how these ones will sound compared to Rog Mogdales 'SuperScooper' loaded with an 18".

Best regards,

Walt
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Old 11th August 2008, 09:03 PM   #8
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Was just commenting that the Hornresp simulation and Jim's measurements indicate that these are basically flat (outdoors, groundplane measurements) from 40 to over 100 Hz (which is the range Jim was looking for).

I'm sure Jim could provide more detail with respect to what he needed and how he measured them.

If I recall, efficiency was measured at ~102 dB, 1W/1M for a single, the set of four measured at 114 dB 20V/10 M, at 40 Hz.

They may look similar to a scoop, but they model and perform quite differently. The scoops I am familiar with do not have a sufficient horn path length to reach as low as these do.
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Old 12th August 2008, 08:41 AM   #9
contour is offline contour  Netherlands
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I didn't mean these would perform the same as a normal 'Scoop'. Size, areas and hornlength are different so performance will not be the same. That should be clear

What I meant was, that when you use Hornresp and simulate JBells design as a Tapped Horn, or as a normal Back loaded horn, you will get about the same response curves.

This is because at the mouth of a horn, the pressure is very low (almost ambient pressure) so when the cone is in the mouth for LF performance this is not much different form the cone above the mouth.

Best regards,

Walt
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Old 12th August 2008, 03:58 PM   #10
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@ contour

I have looked at the Super Scooper design since your post - it is quite different from the simple short-path scoop bins I have seen in the past. Indeed - a long-path back-loaded horn and a tapped horn such as this may be far more similar than I realized.

Ahhh, the more I learn, the more I find to learn......

Thank you.
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