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Old 4th June 2014, 12:55 PM   #1
timvan is offline timvan  United Kingdom
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Default Dimensions and Position

Hi all,

I realise from most websites / books that dimensionless guide for a rectangular enclosure is H/W/L - 2.6/1.6/1 following the golden rule. Is there a limit and what are the effects from minimising the width (i.e dimension from front to rear).

Also are there any rules on driver placement within the enclosure

Thanks
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Old 4th June 2014, 01:26 PM   #2
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Some alternative questions
1) why (if...) is an enclosure needed, what's the purpose !?
2)which material should be used ?

Now, answers !!!

1) to hold the loudspeakers, you know, gravity, balance...
The main purpose is to separate front emission from rear emission
Another answer: to maximize efficiency in the given passband
2) It shouldn't allow the sound to pass thru, nor add undesired resonances.

but...
When the air is entrapped in the rear volume, it modifies the movement of the membrane ( which is far less sound proof than the enclosure, guess....).

Of course it always depends on the particular design : which speakers, in which
band they're asked to play.
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Old 4th June 2014, 01:40 PM   #3
timvan is offline timvan  United Kingdom
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I have Dayton Audio ND65-4. 2.5" driver. The enclosure is for a research project and will be used to re-create the noise of a train.

The system needs to produce low frequency sounds (I realise that this size speaker is not ideal for low frequency) with as small enclosure as possible. However they are designed to go in a head rest so trying to be as thin as possible.

It is a sealed enclosure and will fill with pollyfill
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Old 4th June 2014, 01:48 PM   #4
timvan is offline timvan  United Kingdom
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is there any literature you know of detailed thread that explains box dimensions and their effect?
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Old 4th June 2014, 04:42 PM   #5
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Well, search for "golden Ratio" or any name for the particular dimension...
In short, the three dimensions should be not identical or similar for the reason of the wavelenghts, so the box itself scatters the wave...which had already become a chaotic pressure variation.
At this point, given the little diameter of the cone, 2 1/2 inches, the thing becomes tricky , because the phisical construction of the speaker cannot allow big power to be generated - little voice coil (relatively)and little magnet...so no big pressures and difficulty to dispose of the heat.
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Old 13th June 2014, 09:44 PM   #6
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From what I've read about the 'golden rule' for dimensions, it is more of a guide for creating an object that is pleasing to the eye. In other words, objects made with these ratios simply 'look right'. This is commonly used in furniture design.

I am not convinced, for a project such as this, that following the golden rule will make much of a difference. However, keeping the L W & D all different will tend to minimize standing waves inside the enclosure.
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Old 13th June 2014, 09:52 PM   #7
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Quote:
Originally Posted by AcoustatAnswerMan View Post
However, keeping the L W & D all different will tend to minimize standing waves inside the enclosure.
And do not have a dimension an integer multiple of one of the others. Irrational numbers are your friends, but be careful with sqrt(2)

dave
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