Cowen tapped horn modified...

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ampzillason

ampzillason

Member
Joined 2008
Hello,this is original cowen horn folded for 12 inch,,,

gefaltetescowanhornfyk.jpg

I own two C/E/X pa flat to 30Hz with 18inch eighteen sound 18NLW9000 which i like soundwise ,but i found i don`t need the headroom in my hifi system,,,

So eventually i made a test cowen horn and modified bit to fit eighteen sound 15sw 115,yes i did calculations in hornresp but more for

backing up my thoughts,mainly i pushed some wood around and made measurements,,,,

I`M listening the modified sub for half year now and for me it plays well,deep,and enough power for home use :)


Maybee someone can use this info...

so here modified version,,,
DSC_0871.JPG




yes
DSC_0872.JPG





Yes I´m german so only metric :)

here measure of FT30




DSC_0868.JPG
s
brown is 0-meter 20-50Hz (mic direkt horn exit)

blue is 0-meter 20-100Hz ""

cyan is 1-meter 20-50Hz mic 1-meter from horn mouth ground plane


lets see what 15inch cowen modified does

DSC_0867.JPG


same measure

red 20-50Hz 0-meter mic at horn mouth

blue 20-100 0-meter

green 20-50Hz 1-meter mic one meter ground plane


lets compare



DSC_0869.JPG


brown is ft30,red modcowen 20-50Hz mic direkt horn mouth





DSC_0870.JPG




cyan is ft30,green is modcowen mic 1-meter grond plane,yes room modes but comparabel,,,,,







test box modcowen is 18mm chipboard vibrating like hell ft30 is well build lots braces from plywood

so should improve when build right

modcowen is prx:370Liter

ft30 is :595Liter

mod cowen not so bad compared and lud enough for home use,,,

measurements are not spl calibrated,,,

have a nice day
 
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L

LORDSANSUI

Member
Joined 2016
noviygera said:
I tapped horn does not need a high excursion driver,
Click to expand...

No design require this attribute, it's just related to desired performance the user define as target for a single box.

If you need high SPL for lower frequencies you will need high excursion and high cone area (Sd) and also stronger cone depending from what compression ratio you define.

Otherwise, for home use, you can go cheap, as long you adjust the box dimensions to better work for that particular driver, if you respect the driver's work range.

noviygera said:
Can someone suggest a suitable less expensive alternative?
Click to expand...

You can pick up any driver, but, some drivers will work better them other regarding box size, compression ratio and how flat you need it to be. Constrains are the main important thing here, if you have no constrain almost everything can work, if you start to add constrain or target, you start to reduce the options until you find the optimum for your case.

Start looking for drivers with High BL, low Qes and low Le.

Cheap driver will depend also from where you are in the global, but a good global reference is the website below:

https://www.parts-express.com
 
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noviygera

noviygera

Member
Joined 2009
Why low Le?
I am considering for PA use. So tapped horn box, does need high excursions? Even if using the design in the optimal bandwidth, without letting it play below the low cutoff?

Correct me if I’m wrong, but this is unlike a six order bandpass subwoofer box which does not need a higher excursion driver. Rather it needs to have high power handling and a very strong cone
 
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L

LORDSANSUI

Member
Joined 2016
noviygera said:
So tapped horn box, does need high excursions?
Click to expand...

The generic answer is no.

But, it depends from your targets, lower Fs and higher SPL, more excursion you will need. In general to optimize transport and considering high power amplifier, for PA applications some people want to get as much SPL as possible from a single box, so high excursion is desired, check TH18 from xo1c.

My Tapped Horn SS style for 15" has 8,5mm (Fs 40Hz), it's enough for me considering the amplifier I have, higher excursion driver will not help me with my current setup, because I would need to buy more new and more powerfull amplifier or keeping the amplifier I would need to redesign the box to reduce the frequency in order to be able to use the extra excursion.

For people to help you, you need to indicate your constrain/targets.

Sentence wrote by Red Five in AVS forum:

"The important thing to know? Each octave (dividing a given frequency by 2) you descend in frequency will require 4 times the displacement to achieve a given level of output. Let's say when tuned 20Hz a box can hit 88db on 1 watt of power with 1mm of excursion. If we tune the box to 10Hz it would take 4mm of excursion from the woofer to hit 88db. This is an important fact when selecting a Devastator. There are three factors that will come into play. Output, Extension and Cost, those factors will always have to be balanced. You can chose 2, but you cannot get all 3 unless you are in a very small space that gains very well..."

https://www.avsforum.com/threads/the-devastator-index.3094240/
 
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GM

GM

Member
Joined 2003
It was just an example and the first sim I found with a cheap mobile audio woofer and sure there's more brands with them, though with current Covid inflation I assume they will be somewhat higher, but still inexpensive at least here in the USA.
 
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