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Author Topic: Speakers and enclosures  (Read 4436 times)

Khephre

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Speakers and enclosures
« on: January 12, 2007, 09:30:27 AM »
A request of the budding acoustical engineers amongst us...

I'm installing a bunch of JJC sound modules and a 4" full range speaker. Any suggestions on how to calculate the optimal size/shape speaker enclosure without needing access to every speaker specification under the sun?

Are there any rough rules of thumb for enclosure size/shape?

Given the need to raise a second mortgage to fund the JJC purchase price, I want to ensure that the outcome is as good as possible :D

many tks
Tony

Offline Eddy Matthews

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Speakers and enclosures
« Reply #1 on: January 12, 2007, 08:09:47 PM »
I think that making speaker cabinets is a black art Tony - I'm not sure that the so called experts really know all the answers!

Hopefully someone will prove me wrong and be able to answer your question?
~ Never, ever, argue with an idiot. They'll drag you down to their level and beat you with experience ~

Offline Eddy Matthews

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Speakers and enclosures
« Reply #2 on: January 12, 2007, 08:28:41 PM »
Oooh.... after a quick search on the web, I found this speaker cabinet design software that is free of charge:

http://www.linearteam.dk/

I have no idea if it's any good, but the blurb sounds okay....
~ Never, ever, argue with an idiot. They'll drag you down to their level and beat you with experience ~

Offline derekwarner_decoy

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Speakers and enclosures
« Reply #3 on: January 12, 2007, 11:04:52 PM »
Hi PD's .... so Tony wants a louder  :boom  :music .... for his $

Back in early 2005 I too yearned for more VOLUME from my ACtion Man sound kits [in reality they sounded like a constipated bull frog from 20 paces gently blended in with a  :idea: boiling kettle] for poor old PS Decoy

So I did all of the   :great research  :crash  :hammer  :oops including

1) system Q
2) system free air resonance
3) preferred cut off point @ minus 3dB per octave [steam engine to steam whistle]

Try www.jaycar.com.au or www.jaycar.com.nz, they have five stores  :gift in your southern Islands

I ended up with a 3" X 15 W RMS polypropylene coned driver 80 to 10000 Hz [CW-2103] & a baby KEMO brand IC amplifier #M034 40 W RMS output

So totally disregading the recommended 1.2 litre sealed enclosure, I purchased a few 100mm plastic plumbing pieces [socket, cap & flange & plastic glued them together & mounted the CW-2103 driver]

The reduced volume of say 0.25 litre produced an accoustic suspension of the constipated bull frog & near killed the audio output

Final GUESTIMATED technical modification was a 10 mm diameter hole drilled in the rear plastic enclosure cap to convert the enclosure to a vented style & the result was a tenfold volume increase [the sealed enclosure of such volume killed the actual suspension movement & the free resonant Q of the driver]

Science confirms.... a 4" diameter resonator requires a 4" diameter un impeded free air path to atmosphere [from the resonator face]

Hence the need for higher power amplifiers.... as we cannot expect sound to emanate from cracks in the decking or hull windows  - Derek :roll:
Derek Warner

Honorary Secretary [Retired]
Illawarra Live Steamers Co-op
Australia
www.ils.org.au

Khephre

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Speakers and enclosures
« Reply #4 on: January 13, 2007, 07:47:04 AM »
much appreciated guys - Eddy the LinearTeam software looks very interesting. Their WINISD app is what I need - includes vent diameters and tube length as well Derek so I can produce a vented enclosure.

Now just need the relevant specs from the manufacturer.

Many cheers
best regards
Tony

Offline Eddy Matthews

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Speakers and enclosures
« Reply #5 on: January 13, 2007, 07:53:05 AM »
We're here to help Tony - I just didn't realise I could help!!  :lol:
~ Never, ever, argue with an idiot. They'll drag you down to their level and beat you with experience ~

 

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