Dual 8" tapped horn = TH-SPUD - Page 5 - diyAudio
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Old 1st April 2009, 07:29 PM   #41
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I tried to remove some stuffing with the following results:

Click the image to open in full size.

Click the image to open in full size.

I think I will try to remove some more stuffing. But not today as I already unscrewed and rescrewed the 48 screws on the sides, and that is enough for one evening.
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Old 2nd April 2009, 07:13 PM   #42
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So today I removed some more stuffing inside. It seems the stuffing has quite a large effect and needs some carefull tuning.


Click the image to open in full size.

I also did a quick distortion measurement at I guess around 2Vrms. If I find some more time I will do some more detailled measurements. But it looks already promising:

Click the image to open in full size.
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Old 2nd April 2009, 09:48 PM   #43
myn is offline myn  United States
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It's amazing how much effect that stuffing has on the freq response.


Hows it handle the power? Any Max SPL graphs?
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Old 4th April 2009, 11:53 PM   #44
zora is offline zora  United States
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I've been thinking of building this clone and wondered if anyone has an opinion on bracing? I believe that I read on build threads that a few people felt that the long panels might benefit from some additional bracing. Any thoughts?


BTW, I was wondering if anyone had measurements that are more clear than the copy of the blueprint that has been posted? I am having trouble reading some of the measurements and wondered if there was a set of exact measurements floating around.

JP
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Old 6th April 2009, 04:12 PM   #45
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I didn't try any high power into It. Its now just connected to my 70W receiver. Even with this it makes more than enough noise, on low frequencies even enough airflow :-)

I'm not able to do an absolute spl measurement right now as I have no real reference.

This box is already quite braced and very heavy. I might add some bracing later in the area where the drivers tap in the horn and near the mouth.
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Old 6th April 2009, 05:42 PM   #46
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Thanks for the very informative writeup. Excellent work.

I do have a stuffing question -

When I completed my recent tapped horn, I lined only the throat end of the horn path and achieved a relatively smooth frequency response that was quite similar to what Hornresp predicted, though down a few dB (which may be my microphone or measurement technique).

Your initial measurements showed a significant dip, then you provided updated measurements taken after you removed some stuffing. The change in the frequency response is significant. In post 28 of this thread, the entire path length of the horn is lined with what appears to be polyester batting. Where did you remove the stuffing from to cause the changes in frequency response?

Thanks.
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Old 6th April 2009, 05:53 PM   #47
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littlemike,

Below a picture on what stuffing is still in the horn now. This gives the respons as in post #42

Click the image to open in full size.

If I find some time I will try with even less. I'm not sure if it would be best to remove more around the throath or the mouth.
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Old 6th April 2009, 10:24 PM   #48
myn is offline myn  United States
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Quote:
Originally posted by geitmans
I didn't try any high power into It. Its now just connected to my 70W receiver. Even with this it makes more than enough noise, on low frequencies even enough airflow :-)

I'm not able to do an absolute spl measurement right now as I have no real reference.


I'd love to know what this thing does with some decent power.

When you do a sweep with your 70w receiver cranked, whats your SPL meter read?
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Old 6th April 2009, 11:24 PM   #49
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Thanks for the photo, that helps. I only stuffed the throat of the sub that I built, fortunately I was pleased with the results. I had to be - I sealed it up tight and left myself no way to change it.

If it were me, I'd probably leave the throat area and remove the fill from the mouth side. I'm sure that others may have different feedback for you though.

Thanks again for documenting and sharing your project.
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Old 6th April 2009, 11:27 PM   #50
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@ myn

This design should reach over 110 dB before it runs out of excursion.

Corner loading will help considerably.
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