jbell's set of four tapped horns - Page 16 - diyAudio
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Old 28th March 2010, 03:43 PM   #151
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Default Oliver?

Oliver,

is there any way to force your nifty drawing program to include dimensions/ measurements.

I measured and redrew your diagram on paper and couldn't quite get the 90 degrees you have on a couple of the angles, especially around the top of the box.

Any idea what I am doing wrong?
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Old 28th March 2010, 03:52 PM   #152
tb46 is offline tb46  United States
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Default So much wood to hack

Hi Ben,

That's why Hornresp and AkAbak are such godsends, without them none of this would be happening.

I'm also a great believer in bracing, especially when we are talking about large panels in tapped horns, all the reports sofar indicate the need for extra support. We should keep in mind though, that reportedly screamer hit on a lucky resonant behaviour in his fury box that improved the response measurably.

As to measurements, it would be great to get 10m open field measurements as used by Danley, that is the right way to measure bass enclosures.

Well, have to go to work for a little. Happy wood hacking. :-)

Regards,

P.S.: Yes, I can get the dimensions for you after I'm back from work.
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Old 28th March 2010, 03:56 PM   #153
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Default Testing

In a month or 2, when Summer is here, I can do some testing in a field. Until then, I will do the best I can indoors.

Thanks for helping me out, especially when working.

Sorry to hear you are working on a Sunday!

Ben
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Old 28th March 2010, 04:16 PM   #154
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Default Jeff?

now I've read so many post I know a couple of names here... even found the friendly pro who sent me over to this forum

Jeff,

I see you use much less rounding of corners / use of reflectors than screamer. Oliver's design for 30 x 24 x 48 lies somewhere in between.

Less reflectors or smoothed corners = reduced labour and cost

Were you able to leave your corners at 90 degrees because they are simply cut off on e.g. screamer's build to make space for wheels and handles?

Would his design work if the corners were left on, e.g. for an install where handles are not needed?

As an install, you did not need these... or would your design also improve in some way through messing with the corners with the addition of reflectors? Not sure what would improve if you already have such high sensitivity and linear reproduction, but hey.

This is just for the sake of knowledge and curiousity.

Regards, Ben

Edit. I see internally rounded off corners are known as 'reflectors'!

Last edited by salzburgsoundsystem; 28th March 2010 at 04:34 PM.
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Old 29th March 2010, 02:59 AM   #155
tb46 is offline tb46  United States
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Default Dimensions-Post #151

Hi Ben,

I went through the drawing again, and found no major errors in the angles, etc.. Anyway, I drew the box up in two versions: one w/ the driver wide open into the horn path, and the other with a small driver throat chamber and a coupling port from that chamber into the shortened horn path (shortened L12). The second has a better impulse response in Hornresp. What that means is anybody's guess; screamerusa is quite happy with the sound coming from his furyboxes and the Hornresp impulse response for these is not very good. I'll attach two pdfs with the drawings and a jpg with both Hornresp Input screens. I hope this will help. From the past results others had with these drivers (3015/4015) you should be on the right path.

The 1/2" plywood will require good wood working practices, and lots of bracing to result in a sealed horn path free of leaks. This is very important in tapped horns. Take a look at the AVS thread on Danley's DTS-10 (Danley DTS-10 "Super Spud" DIY kit - AVS Forum) it shows the attention to bracing and sealing the guys at DSL bring to bear. Also, take note of the limited use of damping material.

As to corner reflectors: it seems that they should be used sparingly, and mainly for structural reasons; screamerusa's experiments provide interesting food for thought, and it will take experimenting to optimize the placement and size of corner reflectors. The only thing that is certain about reflectors is that they reduce the internal volume, and that is generally not a good thing.

I hope you will get to build these, and have the opportunity to provide the community with some measurement feedback.

Regards,
Attached Images
File Type: jpg 3015LF_4015LF_dwg_both.jpg (61.4 KB, 509 views)
Attached Files
File Type: pdf 24x48x30_TH_dimensions.pdf (59.7 KB, 151 views)
File Type: pdf 24x48x30_TH_dims_short_S1.pdf (66.1 KB, 128 views)
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Old 29th March 2010, 03:57 AM   #156
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Wow, Oliver. Those are some great drawings.
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Old 29th March 2010, 11:47 AM   #157
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Default Sorry Jim, not sure where iI saw you referred to as Jeff!

mea culpa - mixed up some member names.
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Old 29th March 2010, 11:49 AM   #158
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Quote:
Originally Posted by davygrvy View Post
Wow, Oliver. Those are some great drawings.
I totally agree. You guys couldn't make it any easier for someone hoping to try building a TH!

What kind of sensitivity can we expect from the 24x30x48 TH?
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Old 29th March 2010, 11:51 AM   #159
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On another note - have you seen the Tuba 60. I thought it was a joke, certainly did a double take. And the Tuba 36 is no longer advertised! Looks like someone is aiming to beat the JBELL TH

The drivers and size make it a little to expensive and madly heavy / unwieldy for me, I think tapped horns are going to keep me happy for a while yet!
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Old 29th March 2010, 12:45 PM   #160
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Quote:
Originally Posted by jbell View Post
ben:

As I found out, this tapped horn thing isn't hard to get 80%, or even 90% of the way there... getting that last 10% takes time and effort, and some trial/error. The first dozen inches or so of the path I think has a ton to do with it. Once there, the rest is simple.
Just curious, but have you ever tried folding similar to what I've used for my POC #1? I've seen one reference to similar folding in the Dickason's LDC (under the "Transmission Lines" chapter). I'm about to embark on POC #2 using a larger driver, and I'm just wondering if there's any inherent issues with that type of folding that I need to be aware of.

More about POC #1 at The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction. It's a tapped-pipe, but can be converted to a "horn" by simply moving around the internal dividers.
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