Where is the throat in this plan? - diyAudio
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Old 8th August 2007, 07:09 PM   #1
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Default Where is the throat in this plan?

Is the throat at right,narrow point of horn or the left that looks like 2nd Segment.The right red circle or the left?

And where is the throat chamber?The volume between the 2 red circles?Or there is not one?

What's the compression ratio here?

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Old 8th August 2007, 07:12 PM   #2
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And of course from what point starts the horn length?The top right or the left?
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Old 8th August 2007, 07:19 PM   #3
AndrewT is online now AndrewT  Scotland
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Hi,
my guess is that the throat is just to the right of the lefthand red symbol. That may be the broken line between 190 & 340.
About 95mm high by 600mm wide. St~570sqcm.
The driver probably has an Sd~1100sqcm
Compression ratio ~2
The compression chamber is the volume inthe wedge shape + the volume in the cone + the volume in the cutout for the driver basket.
The horn length starts at the same point.

Just look again & you can see all the normal features of a horn there.

The horn is VERY short.
The flare rate is VERY fast.
There will be little bass from this horn. Most of the lower bass will come from the big cone as if the horn were not there. The driver probably does not have much bass with that tiny sealed chamber and the high Fs typical of these PA type drivers.

If one wants 40Hz from a horn then it should ideally be about 4m (13ft) long, but can be shortened to about 2.1m (7ft) with some compromise in quality.

The mouth area for a floor loaded horn operating down to 40Hz should be about 2.9sqm (~=31sqft)
Backed up against a wall this can be reduced by half.

Four of those boxes stacked side by side would probably play very well down to 50Hz, but then the four cones take over to produce reducing bass as the horn has a lessening effect. Watch out for exceeding Xmax at 35 to 40Hz.

A word of caution: this is an amateur dabbler speaking.
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Old 8th August 2007, 07:28 PM   #4
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If the Throat is the left then why the throat chamber is a wedge and not rectangular.It seems it plays a role here.
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Old 8th August 2007, 07:47 PM   #5
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Default Well....

I would agree that the throat propper starts where you have shown it I also agree that the wedge section that the driver fires into is a sub part of the throat in that it provides some additional load to the driver prior to the throat proper. The horn length is the full physical length all the way up to the back edge of the driver. From all accounts this is a fine cabinet design. Eminence have a very similar design as do a number of other companies.
This site has a vast collection of cabinet designs. http://photofile.ru/users/tda-audio/182333/.

Out of curiosity why dont you ask Rog Mogale about this cabinet as he is the guy that designed it?
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Old 8th August 2007, 07:50 PM   #6
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I just did this!

Thanks!
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Old 8th August 2007, 07:53 PM   #7
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Default contact Rog at...

www.speakerplans.com. Four of these will do 40 hertz. Efficiency is high and size is reasonable but this is not a deep sub woofer design. A LAB horn will get you down into the twenties with high efficiency but you will still need multiples. Below 20 Hertz sealed or reflex (in that order) are your best bet for reasonable size cabinets.
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Old 8th August 2007, 08:31 PM   #8
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I was looking at that same horn, for it size, but I would like an enclosure design that could go lower for Home theater and only using two cabs not 4 per side...

Does anyone have responce curve for a "super scoop" style horn.
http://photofile.ru/photo/tda-audio/...ge/3269692.jpg

I would think the direct driver would allow lower tones then the other short horn. But still should have better efficency then a sealed or vented enslosure.
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Old 8th August 2007, 08:48 PM   #9
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Quote:
Originally posted by moray james A LAB horn will get you down into the twenties with high efficiency but you will still need multiples. Below 20 Hertz sealed or reflex (in that order) are your best bet for reasonable size cabinets.

This is a lab horn correct?
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Old 8th August 2007, 11:47 PM   #10
Eva is offline Eva  Spain
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For living-room-friendly subwoofer horns see tapped horns.

They are discussed in this thread:
Collaborative Tapped horn project
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