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Discussion Starter #1
What level of accuracy is required when tuning a ported cabinet?
Or, asked another way, if my calculated volume is off by a few cubic inches, how much will that affect the tuning/sound of the sub cabinet?
 

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Welcome Zeke,

A few cu in difference won't change the tuning that much. Normally we end with 1 Hz lower than what the design programs tell us.

Why not model with winISD or equivalent?
 

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Discussion Starter #3
I have modeled with WinISD pro. Small changes don't seem to affect the SPL curve dramatically. I just wanted to make sure because everything I've read talks about how much harder a vented box is to tune properly, so I didn't know if that was 'oops, I forgot to calculate the volume of my driver' or 'oops, I cut off an extra inch from my port tube' harder.
 

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You can still post details for review if you want ...
 

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Makes sense - this is the story of my attempt to build my first subwoofer (my first DIY AV component of any sort, really) on a minimal budget, using parts that may never have been intended to match, and limited to the small form factor my wife will approve of.

Basically, I have a Eminence Lab-12 driver and a Klipsch Sub-12 plate amplifier, and no budget to get anything fancier. My current plan is a 20"x20"x20" cube made from .75" MDF, vented and tuned to 25 Hz. The cube, with a double thickness front face, has an internal volume of ~3.51 ft^3. My questions, in no particular order:

1. The Klipsch amp is a bit of an unknown. I don't know if it has a rumble filter / high pass filter, nor whether it has built-in bass boost anywhere. I also don't know whether I need to enclose the amp in its own box - the circuitry is exposed on the back, and I don't know how air-tight the seals are around the gain and low pass filter pots.

2. 3.5 ft. cubed is a bit bigger than the enclosure recommended on the eminence website. I figure, with bracing, amp, driver, and port subtracted, the volume will be "pretty close" to 3.2 feet, but I need to know how close it needs to be, especially for port-measuring purposes. This is where my earlier question comes in - how exact do I need to be before I get far inferior results?

3. Are there any major advantages/disadvantages to a slotted port vs. a round port?
 

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Discussion Starter #10
Well, half of this discussion has just become a purely academic exercise for me, as the seller of the driver just sent a delivery intercept, so I'm back to the planning stages. Anyone have advice for a subwoofer driver that will behave well in a 3-3.5 foot enclosure? Budget is fairly low, since this is an experiment.
 

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CSS SDX10 - $154 shipped - green graph.
CSS SD12 - $183 shipped - pink graph

Just to show you if you upgrade your amp in the future:

The green line with the less output is with the amp you have now - 300 watts with a HPF at 25 hz.
The green line with the higher out put would be a Bash 300 watt amp with a HPF at 18 hz.

The pink line with the less output is the Klipsch amp.
The pink line with the higher out put is 500 watts with a HPF at 18 hz.

sdx.JPG

And here is what can be done with a SD12. Box size increased to 4.5 cu.ft. with the same 500 watts input.

sdx2.JPG
 
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