Question Effect of stuffing on Qtc

Mushin

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I'm looking into building a sub, and I don't have a table saw, router etc to make my own box (to a good standard). So I thought something like one of the flat-pack kits would be ideal.

I was looking at the 12" Dayton Ultimax kit on Parts Express. It comes with a 2 cft box, which when I model with the driver in WinISD comes out with a Qtc of 0.80. According to the seller, stuffing the box with 1 lb of fill will give a Qtc of 0.707.

I used WinISD to find that to get a Qtc of 0.707, the effective volume needed would be about 3.5 cft. Could stuffing really lower the Qtc this much? Or is the seller over-stating this? Is there some way of calculating the effect of stuffing on the effective volume and/or Qtc?

On a related note, I've seen comments around the forums of an advanced parameter, Qa, which can be input on WinISD to model the effect of stuffing the box. But I don't have any advanced box settings in WinISD. Was this feature removed?
 
importing an MDF flatpack kit might get pricey on the postage, you can get boxes built here in the UK instead.

which version of winisd do you have? it is in there on the box tab IIRC

apologies for the shameless plug but I have just put this up for sale which might be interest -> For Sale - Dual Infinity 1260w DIY Subwoofer
 
importing an MDF flatpack kit might get pricey on the postage, you can get boxes built here in the UK instead.

which version of winisd do you have? it is in there on the box tab IIRC

apologies for the shameless plug but I have just put this up for sale which might be interest -> For Sale - Dual Infinity 1260w DIY Subwoofer
Thanks for your reply.

Yeah I looked at the postage and it does end up being a bit ridiculous. But I didn't have a clue about getting one made either. How would you go about that? A CNC service?

I'm using v0.44 of WinISD.

No worries about the plug, but it's a bit bigger than I was planning. I have to contend with a smallish living room and of course the missus ;)
 
He's not on here. He's Gordy1948 on ebay. There's also visual.ice on ebay who make enclosures for competitive rates.
 
I don't believe he posts here

He's not on here. He's Gordy1948 on ebay. There's also visual.ice on ebay who make enclosures for competitive rates.

Cheers both - found on ebay.

Out of interest, I set the Qa to 5 for that box in the newer version of WinISD, and it came out with a Qtc 0.758. Should I trust WinISD on this or Parts Express? If I do get a box made, understanding this will help a lot. Thanks.
 
I wouldn't worry about it too much either way, if your model is in the ballpark then that's all you need
 

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