need Manifold 2 x 18 cabinet plans

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nuconz

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djk said:
The original EV design is a 6th order equalized alignment.

A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).

As we can see, the 6th order alignment is about 7dB more efficient than a sealed box, and 4dB more than a simple ported box.

0.312 is the optimum Qts for 6th order for box size vs efficiency vs bass extension.

If you can give me the T/S parameters on the drivers you're considering I can give you an idea of what can be done with them.
Click to expand...


is this correct - efficiency < 1%?

and, what about a lower f3, say about 20 hz? what size would the box need to be?

thanks.
 
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nuconz

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Joined 2006
djk said:
This is the way I build my manifold boxes, not that much wasted space.

PPSL.jpg


With a pair of 15s it's only about 1 cu ft, the net interior volume is on the order of 8 cu ft, port is tuned to 31hz (low B on a five-string bass).
Click to expand...


pretty cool. do you have the cab dimensions?
 
djk

djk

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Joined 2001
Mine were 36W x 24H x 30D (external with 3/4" plywood).

I use dual 15s with suitable parameters, but there are some 18s that have suitable parameters for this sized box as well.

Looking for an Fs=31hz, Qts=.312, and a Vas around 10 cu ft for this design, otherwise you will have to change the dimensions.
 
Top Shelf

Top Shelf

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Joined 2010
djk said:
It should be clear from the thumbnail sketch that this is a vented design and not isobaric.

If you keep the plenum size as small as possible you can ignore the bandpass action of the plenum and just simulate it as an ordinary vented box.
Click to expand...

Hey djk, did you find any significant response or db advantages to your design over a conventional forward facing double 15"? It is a nice design.
 
djk

djk

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Joined 2001
"did you find any significant response or db advantages to your design over a conventional forward facing double 15"?"

Sorry, there is no such thing as a free lunch.

I use woofers that are suitable for a 6th order vented design, so they are more efficient than a regular 4th order vented system (see post #6). Each box is about 7% efficient, about 101dB/W and 8 ohms, so a stacked pair are 107dB/2.83V/1M, and three are 110dB/2.83V/1M and about a 2.94 ohm (minimum) load. Two per side are adequate for most jobs. One user has twelve cabinets, but I have never heard him use more than eight (four per side).

http://i56.photobucket.com/albums/g196/dkleitsch/CoePA-2009.jpg

" It is a nice design. "

Thanks, I like the clean sound it has compared to a normal forward facing dual driver cabinet.
 
djk

djk

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Joined 2001
I have built many different versions, the one in the above link is -3dB at 31hz (low B on 5-string bass), and the mids run down to 150hz.

If you keep the plenum dimensions small you can have it sound good up to about 400hz (Les Hudson's dual 12 version).

http://www.waveboxes.com/Wave%20G/gi.gif

Most of the stuff I do is for PA so I don't go deeper than about 27hz, but you could go lower with the right drivers and box sizes.
 
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