Collaborative Tapped horn project - Page 112 - diyAudio
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Old 8th February 2008, 08:21 AM   #1111
MaVo is offline MaVo  Germany
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As requested, it looks a bit more peaky in hornresp, it was modeled in akabak before hornresp could do tapped horns. but it worked great as a proof of concept for me.
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Old 8th February 2008, 10:12 AM   #1112
MaVo is offline MaVo  Germany
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Would this sound good up to 200 or even 300hz? The response seems to be very smooth. Is there a reason, not to use it up to its upper acoustic cutoff?

Re is 5, i accidently cut it off. The driver is 18 Sound 15LW1401.
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Old 8th February 2008, 02:28 PM   #1113
MaVo is offline MaVo  Germany
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Partly answering my own question...

There could be a resonance due to the long unfolded straight horn paths. Will the resonance occur at pathlength = wavelength/2 (for example 1 meter of straight horn has a resonance at 344m/s / 2m = 172hz) ?

I am inquiring this, because im currently searching for a woofer, that can cross at least at 130hz, i wouldnt mind 200hz and goes as low as possible.

Tapped horns with rather big mouths and an exponential flare, such as the TH115, seem to be really well damped and usable for higher frequencies.

Parameters of woofers that work in those things are:

qes around 0,3
fs 40-45hz
vas depends on woofer size, around 50 for 12" , around 100 for 15"
qms doesnt matter much

The Beyma 12P1000ND and 15P1200ND are such woofers.

(thanks to cowanaudio for throwing in those woofers and to GM for modelling all those THs, both of it got me thinking about this)
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Old 8th February 2008, 07:25 PM   #1114
kstrain is offline kstrain  Scotland
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Default sawdust time

Quote:
Originally posted by cowanaudio
G'day kstrain
Just do the tapped horn and don't procrastinate. If the design is sound, you'll love the results.

Cheers

William Cowan
Thanks for the advice - procrastinating is exactly what I've been doing. I'm looking at various foldings (and various room locations) before making sawdust - but sawdust I will make!

Ken
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Old 8th February 2008, 07:31 PM   #1115
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In my quest for room gain simulation in AkAbak, i've tried coupling a rectangular enclosure the size of the room to the radiator element at the mouth and then put the measurement point *inside* that box.

It seems that is not possible (keeps complaining radiator is inside a wall), but the resulting SPL plot was somewhat interesting:
it seems I modeled a TH with a huge side-chamber that acts like a low pass -6dB filter.
Does anyone have an idea to find at what freq the room gain starts and if possible how I can implement this at the output stage? So far I can put an inverse active HP filter in the system (ie modifying the amp), but then the excursion graph and max SPL plot is off.


Also, am I the only one who is running into hofman's iron law? By trying to squeeze a TH into the same volume of my bassreflex, there seems to be no gain compared to the current cabinet, even if a TH is a bandpass enclosure? With this I mean that when I model my TH in half space, it has 91dB sensitivity, compared to the 90dB of my BR. Where is the advantage, unless a BR doesn't benefits as much from corner loading as a TH ?

Also, when accidently modeling a rear loaded horn with an average size back chamber, this seemed to be more usefull with room gain than trying to "sculpture" a TH.
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Old 8th February 2008, 08:07 PM   #1116
jnb is offline jnb  Australia
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Is it worth the effort of rounding the bend and flaring the mouth (so it looks like a sax?)
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Old 8th February 2008, 10:06 PM   #1117
MaVo is offline MaVo  Germany
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Quote:
Originally posted by jnb
Is it worth the effort of rounding the bend and flaring the mouth (so it looks like a sax?)
with the wavelengths beeing so long, i doubt that it is beneficial. rounding is important, when the WL is about the internal size of the horn. thats not the case with subs.
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Old 9th February 2008, 02:33 PM   #1118
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New tapped horn. This is the layout. Im going to use two pairs of the drivers in the picture isobaric. two and two face to face, with a metalrod going through the magnets to conect them realy hard and stable.

Click the image to open in full size.
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Old 9th February 2008, 03:18 PM   #1119
MaVo is offline MaVo  Germany
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Can you post more information about the horn and drivers please?
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Old 9th February 2008, 03:36 PM   #1120
djk is offline djk
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Have you modeled isobaric?

I did, and it didn't look good.
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