Collaborative Tapped horn project - Page 327 - diyAudio
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Old 7th April 2009, 03:42 PM   #3261
MaVo is offline MaVo  Germany
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The mouth is in the plane you look on. I placed it on a wall and sit right in front of the mouth, since my room modes dictate such a strange setup. Cad Drawing:
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Old 7th April 2009, 03:43 PM   #3262
MaVo is offline MaVo  Germany
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Finally, a measurement, mic placed right in the mouth, since everywhere else severe room modes would happen. The input signal was pink noise, with steep filters at 15 and 200hz. Measured with a behringer mic and cheap noname preamp.
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Old 7th April 2009, 06:03 PM   #3263
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Hi Jim,

Thanks for your generous offer. I'll do my part.



Hi MaVo,

Tell us a little more about your TH. We'd like to see some pics. Assuming the view shows x & y, what's the z dimension.
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Old 7th April 2009, 08:22 PM   #3264
MaVo is offline MaVo  Germany
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Your guess is right. Its 160*82*38cm with 15mm walls, great as a bookshelf

What to tell about it? Its a satisfying experience. I planned to make 4 of these and put them together so that one big mouth is formed, but one allready makes more than enough noise (more than 4 of the drivers in small closed boxes - at least at the low end), so maybe i just keep it. I was a bit worried about the high compression ratio. To test this, i pushed maybe 50-100W (guessed by looking at the behringer amp status lights) into it at 18hz sine and with 15-60hz noise, which made several doors in our house rattle, but the cone didnt die of it. Yet, it produces a nice and totally unexpected air stream with large excursions. The driver i use has some noise from its suspension, more on the back side than on the front, but its masked well enough with music playing. Another thing is (i am not sure if it isnt just the "yay i have a big new sub" distortion of the mind), that the bass feels more dynamic compared to the closed box, especially short bursts of low noise, like drum bodies, are fun. Using bracing like you guys told me was definitely worth it. The enclosure is pretty much unaffected by the pressure. I made cross shaped bracing, as is indicated in the second pic. The folding was done in two iterations with volvotreters method. After the first folding, i measured the length, saw that it was about 30cm to short, added those and folded again.

Btw... can someone tell me how to stop my couch from shaking like crazy with the deep tones? Its like having a bass shaker. And i cant move out of the nearfield of it, or my room destroys the response.
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Old 7th April 2009, 11:19 PM   #3265
JLH is offline JLH  United States
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Quote:
Originally posted by MaVo
Its a satisfying experience. I planned to make 4 of these and put them together so that one big mouth is formed, but one allready makes more than enough noise (more than 4 of the drivers in small closed boxes - at least at the low end), so maybe i just keep it. I was a bit worried about the high compression ratio. To test this, i pushed maybe 50-100W (guessed by looking at the behringer amp status lights) into it at 18hz sine and with 15-60hz noise, which made several doors in our house rattle, but the cone didnt die of it. Yet, it produces a nice and totally unexpected air stream with large excursions.

MaVo I'm very happy to hear about your results. I remember not so long ago you, Naudio, CLS and I were all engaged in some very "spirited" exchanges about the very things you wrote today. I was always telling you truth about my experiences with tapped horns. I'm just very happy you built one and can hear and observe the things I was trying to tell you guys about. I think now you can better understand what I was talking about back then. I still laugh about being accused of using a "midrange" driver in a tapped horn and being told it won't work. Well, those tapped horns are still playing quite well in my daughter's room.

http://www.diyaudio.com/forums/showt...36#post1505236

Rgs, JLH
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Old 8th April 2009, 01:06 AM   #3266
tb46 is offline tb46  United States
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Default Post #3259

Hi jbell,

I think you pretty well nailed it with your example. Obviously, you can move the response around a little. I'll attach a 372 Liter version.

Regards,
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Old 8th April 2009, 01:59 PM   #3267
tb46 is offline tb46  United States
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Default Mavo_Beyma_TH

Hi Mavo,

Great data. Did you happen to run an impedance curve, and would you please post it if you did?

Regards,
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Old 10th April 2009, 08:44 AM   #3268
MaVo is offline MaVo  Germany
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No, dont have one.
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Old 12th April 2009, 06:12 AM   #3269
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Thanks for sharing, Mavo.

Anyway, in my own studies, I was wondering how hard it would be to use multiple segments to try to represent a decent exponential flare. It isn't easy, it took several hours but I got lucky and it worked well enough on the first try. As shown it's about 36 x 18 inches. I wouldn't build it like that though, it would be easy enough to move the triangle of dead space way down to the other end and then all the angled boards could be much straighter.

So I'm just wondering if this is too many 180 degree bends. There are several segments in the bendy part that are quite close to 16 inches which puts them way out of the passband, but maybe when added up they could casue problems. Thoughts, please?

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Old 12th April 2009, 10:15 AM   #3270
MaVo is offline MaVo  Germany
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When you make the individual conical segments smaller, this mostly has influence on the higher frequencies. Yet, the higher frequencies will be in trouble in this design, due to the amount of bends.
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