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Old 22nd May 2004, 04:28 AM   #1
cave is offline cave  United States
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Location: michigan
Default tumult subwoofer

I just ordered a 15" tumult driver today from acoustic visions and now my next step is the enclosure. I'm thinking about ordering a precut 3cb ft sealed cabinet from parts express. This is my first diy project so any input or suggestion will be appreciated because I really have no idea what I'm doing. Oh yeah do you guys think a samson s2000 would have plenty of juice to power to tumults?
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Old 22nd May 2004, 06:42 PM   #2
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Location: Toronto, ON, Canada
Well, do you have any woodworking tools? If not, do you have any good friends that do?

Oh, and 1000W is definitely enough for a Tumult.
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Old 23rd May 2004, 12:45 AM   #3
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Take a look at the suggested enclosure types for the Tumult on the Adire website.

There are a few designs suggested, both ported and sealed with varying SPL levels and extension.
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Old 23rd May 2004, 01:16 AM   #4
cave is offline cave  United States
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Well it sounds like a 3cuft encloser will do the job from what I've read. Now my other question is the wiring. Is it as easy as running wires from the driver to the binding posts then from the amp to the posts? I've no idea but I think it will be fun. Oh yeah I've read something about a linkwitz thing a majig used in a sealed tumult sub but I couldn't find what its used for. I also was wondering how you would think a sealed tumult would compare to my pc-ulta svs sub. Thanks
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Old 24th May 2004, 03:00 AM   #5
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Is it as easy as running wires from the driver to the binding posts then from the amp to the posts?
it depends if its DVC or SVC..you have a few extra options if its DVC

\You dont want to cook your amp..

Oh yeah I've read something about a linkwitz thing a majig used in a sealed tumult sub but I couldn't find what its used for
its basically a filter taht increases bass output( www.linkwitzlab.com),kind of fills in the sealed box bass response to be ok-its a way of having low SPL with high power requirements and tiny box.

Hoffmans iron law
-small box
choose 2
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Old 24th May 2004, 03:23 AM   #6
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A Linkwitz transform filter is basically a circuit that boosts the low-frequency output of a sealed subwoofer. This approach requires more power than would normally be needed (depending on the amount of equalization), and the subwoofer driver must have relatively high excursion.


"Hoffman's Iron Law": One of the most fundamental design principles that the new DIY speaker builder must learn is generally known as "Hoffman's Iron Law". First formulated back in the early 1960's by Anthony Hoffman (the H in KLH), Hoffman's Iron Law is a mathematical formula that was later refined by Thiele and Small, whose work now forms the basis of all modern loudspeaker design. Hoffman's Iron Law states that the efficiency of a woofer system is directly proportional to its cabinet volume and the cube of its cutoff frequency (the lowest frequency it can usefully reproduce). The obvious implication is that to reduce the cutoff frequency by a factor of two, e.g. from 40 Hz to 20 Hz, while still retaining the same system efficiency, you need to increase the enclosure volume by 23=8 times! In other words, to reproduce ever lower frequencies at the same output level you need an extremely large box! However, box size isn't the only variable… You can continue to use a small box by accepting a much lower efficiency. In order to retain the same sound pressure level (SPL, meaured in dB's), though, this requires both a very large amplifier and a driver that can handle a lot of power and move a lot of air (requiring high excursions). Furthermore, it must be able to do so with minimal distortion. This is exacerbated by power compression, a phenomenon where the power heating of the driver's voice coil results in a non-linear relationship (read "distortion") between the electrical power in and the acoustical power out. Another variable not often mentioned is bandwidth… You can provide the perception of violating Hoffman's Iron Law by using a bandpass design, which can provide a lot of bass primarily across a very limited bandwidth. In all too many bandpass designs, the impressive bass is produced around a single frequency. This is often referred to as "one-note bass". It can rattle the furniture and impress your friends, and may even be OK for sound effects in action movies, but don't expect too much accuracy when listening to music with a lot of low bass content. Summarizing, Low-frequency capability, box size, and efficiency form the three key aspects of system design. To increase any of the three, you have to give up something from the other two, with box size being the most sensitive. The often unpopular bottom line is therefore to plan on using the largest box you can comfortably live with. This partially explains the popularity of subwoofers, which can be both large and hidden from view, and often include their own built-in high power amplifier.
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Old 24th May 2004, 03:43 AM   #7
rotgg is offline rotgg  United States
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i have one in a sealed box i think my box is a little shy of 3 cubes i was not that happy with it untill i crossed it at 40hz now it realy shines i had it at 80hz and it didnt sound near as good
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Old 24th May 2004, 10:06 AM   #8
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For the Linkwitz Transform see here:

Rod Elliot's Project - http://sound.westhost.com/project71.htm

The speadsheet - http://sound.westhost.com/linkxfrm.zip

The other spreadsheet I have found - http://www.pvconsultants.com/audio/eq/linktran.htm
If it aint broke, don't fix it. If it is broke, fix it.
If you can't fix it, take it apart and see how it "worked".
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