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Imp. for automotive applications (Read 13648 times)
John in CR
Ex Member



Re: Imp. for automotive applications
Reply #30 - 05/05/06 at 21:20:19
 
Don't waste your wood and time.   There's not enough air volume for the wave to fully develop into a wave, so much of it will just stay as a pressure front not a sound wave.  A horn needs to couple to the environment it is in to function properly.  In this case there will be much more audible bass outside the van than inside.  With the tremendous cabin gain inside a vehicle, there are much easier and smaller ways to get big bass in a car.  A single high excursion 12" or 15" can give you more bass than your ears can handle in a well designed BR.  If all you want to do is ride around disturbing the neighborhood, then go for it.  If someone shoots you, at least you'll know why.
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« Last Edit: 05/05/06 at 21:22:14 by John in CR »  
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Jet-Lee
Ex Member



Re: Imp. for automotive applications
Reply #31 - 05/05/06 at 21:22:22
 
Horn Segments
Cross-sectional Area

Length = 109.675in (11.056ft)
Throat = 245in^2 (1.7ft^2)
Mouth = 1656in^2 (11.5ft^2)


S1
length = 21in
throat = 245in^2
mouth = 720in^2

S2
length = 37.675in
throat = 720in^2
mouth = 1152in^2

S3
length = 51in
throat = 1152in^2
mouth = 1656in^2

Using two of these(sharing ~15ft^3):
Quote:
Specifications:
This woofer is designed to work best in the following enclosures:

A small, sealed enclosure with an internal volume of 1.25 cubic feet (1.25-1.75 cu/ft acceptable)
A ported enclosure with an internal volume of 2.0 cubic feet (1.5-2.0 cu/ft acceptable) with a 4" diameter x 10.75" long port
RFP4412 Size 12 inch Type Woofer Voice coil Configuration
Single Material
Aluminum Description
2.5 4-Layer Cone Material Paper
FIBERlock Frame Material Frame
Stamped Material
Steel Surround Material Foam Description

BART Spider Crossover Specifications:
Power handling(RMS) - 200 Watts
Power handling(Peak) - 400 Watts
Impedance - 4 Ohms
Sensitivity - 88 db
Vas - 3.05
Fs - 28
Qes - .510
Qms - 6.237
Qts - .472
Xmax - 12.954
Revc - 3.69
Levc - 4.48

Dimensions:
Depth Bottom mount - 5.8125 in.
Cutout - 11.125 in.
Displacement - 146.88 cu in.

Enclosure:
Sealed box:
Recommended volume - 1.25(Cubic Feet), 35.40(Liters)
Ported box - Recommended volume - 2.00(Cubic Feet), 56.64(Liters)


This is just a quick sketch with somewhat rounded numbers.

Would it do anything?? Methinks not, but curious none-the-less.
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« Last Edit: 05/05/06 at 21:24:49 by Jet-Lee »  
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bassboy
Ex Member



Re: Imp. for automotive applications
Reply #32 - 05/05/06 at 22:21:37
 
This is all just meaningless speculation until we find out how a large horn works in a very small enclosure.  John may be very right about the horn needing a relatively large area to couple to.  I would not be inclined to argue with him unless I tried and got favorable results with the imperial in a van.

Jet - I am not using hornresp to model horns.  I use the tractrix calculator or exponential calculator on the single driver website for a quick and dirty idea of what the horn is going to look like.  All you need to know is the throat area and lowest frequency desired.  Model in eighth space (corner loading) and it will numerically plot the horn flare in about 5 seconds.
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bassboy
Ex Member



Re: Imp. for automotive applications
Reply #33 - 05/05/06 at 22:30:10
 
Hornresp is a more versatile tool, as you can model whatever you want.  The horn flare calculators will only show you the ideal expansion for ideal response.  If you stray from the plan the results are unpredictable.  Hornresp can take these deviations into consideration but it is a much more cumbersome and slow process.  (But probably worth it in the later stages of design)
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Jet-Lee
Ex Member



Re: Imp. for automotive applications
Reply #34 - 05/05/06 at 23:27:23
 
I didn't know there was anything other than HornResp, and it's like greek to me (I think I understand Greek better).

Where's this tractrix calculator?
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bassboy
Ex Member



Re: Imp. for automotive applications
Reply #35 - 05/06/06 at 02:13:52
 
Start here.

http://melhuish.org/audio/horn.html

Read the whole horn section and the calculators are the last things in the section you need.  You can check the last pages in the section but they are just driver specific recommendations.

You only input 4 parameters, but it's metric.  Throat area, flare frequency (lowest effective frequency), size factor (8 for cornerhorn), and desired width of cabinet.

It outputs 4 columns of information.  The only ones I look at are distance from throat (length) and area, which is the cross sectional area.

This is the fastest and easiest way to model an ideal expansion rate.  (Remember that variations from the plotted design are at your own risk.  This makes no accomodations for shortened horns, hard bends or inaccuracies within the horn, bad room placement, etc., hornresp is better for that)

Use the theory you read on the previous few pages to design a loading scheme to couple to the throat.

If you want more good sources, just ask, I got lots of good articles on theory.
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« Last Edit: 05/06/06 at 02:16:39 by bassboy »  
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Steve Deckert
Administrator
*****


If the 1st watt
sucks why continue?

Posts: 2425
Re: Imp. for automotive applications
Reply #36 - 05/06/06 at 14:26:35
 
The only way any Imperial is going to work in a van is if you cut the floor of the van out and fire the entire enclosure down onto the street.
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bassboy
Ex Member



Re: Imp. for automotive applications
Reply #37 - 05/06/06 at 16:34:21
 
Well it looks like Gex was right all along and I was wrong again (I kinda thought it was gonna work).  But it saved me the work of actually trying it out, so even if I'm wrong I'm still happy.

Stick to the WO and be happy, it's more than enough for me, anyway.  (In a vehicle)

Don't give up on the horn theory though, Jet, one more trick up your sleeve isn't going to hurt, just leave the big horns in the house.
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Jet-Lee
Ex Member



Re: Imp. for automotive applications
Reply #38 - 05/07/06 at 03:15:58
 
I respect Steve's post, but am still going to make an attempt, at some point.

I'm one of those people that touches the stove after being to it's hot. I learn from experience, not example.
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gexter
Ex Member



Re: Imp. for automotive applications
Reply #39 - 05/08/06 at 02:31:59
 
It depends on how many times you touch a hot stove before you learn!
third degree burns are not for everyone.

heh heh could not resist. Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley Smiley

pulling your leg Jet!  :)
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DaveCan
Ex Member



Re: Imp. for automotive applications
Reply #40 - 05/08/06 at 06:15:22
 
 Why not just put a motor and some wheels on an Imperial?, now that would be something  ;D   Dave Smiley
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« Last Edit: 05/08/06 at 06:24:00 by DaveCan »  
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Jet-Lee
Ex Member



Re: Imp. for automotive applications
Reply #41 - 05/08/06 at 06:17:36
 
[quote author=gexter  link=1145468358/30#39 date=1147051919]It depends on how many times you touch a hot stove before you learn!
third degree burns are not for everyone.
:) [/quote]
I dunno. I've lost quite a few hairs. I made $20 walking barefoot across a fire in shorts, at Pismo. Some of the hair is still missing after 2 years.
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60ndown
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Re: Imp. for automotive applications
Reply #42 - 05/08/06 at 14:52:34
 
[quote author=Jet-Lee  link=1145468358/30#41 date=1147065456]
I dunno. I've lost quite a few hairs. I made $20 walking barefoot across a fire in shorts, at Pismo. Some of the hair is still missing after 2 years. [/quote]

$20 for an injury you can still identify 2 years later? and i thought you were smart jet Roll Eyes  was alcohol involved Grin
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Jet-Lee
Ex Member



Re: Imp. for automotive applications
Reply #43 - 05/08/06 at 15:16:53
 
[quote author=60ndown  link=1145468358/30#42 date=1147096354]

$20 for an injury you can still identify 2 years later? and i thought you were smart jet Roll Eyes  was alcohol involved Grin [/quote]
The $20 was just a bonus, I do it anyways. Embarrassed

Oh yes, alcohol had a BIG role in it! Cheesy

Anyone got $20? I'm goin' campin' this weekend. Kiss
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gexter
Ex Member



Re: Imp. for automotive applications
Reply #44 - 05/09/06 at 00:37:27
 
LOL
your a true adventurer Jet. and the scars to prove it. Smiley
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