Hi all, I'm making a 13" x 13" x ~15" ID subwoofer using the 8 in. Dayton Shield DVC 8"
With a slot port and amp all calculated, the question I couldn't answer myself was, what could I use for lining, I'm considering this for foam, and Polyfill for stuffing (I already have polyfill, I'm not changing that) Would I use foam, polyfill, or both.
Would it be effective to line the walls with just polyfill (cheapest for me) or is it really that much better to add the foam? Or even better for the foam and polyfill? (The Port would have netting at the end of course) Thanks for all your guy's help,
Matt
With a slot port and amp all calculated, the question I couldn't answer myself was, what could I use for lining, I'm considering this for foam, and Polyfill for stuffing (I already have polyfill, I'm not changing that) Would I use foam, polyfill, or both.
Would it be effective to line the walls with just polyfill (cheapest for me) or is it really that much better to add the foam? Or even better for the foam and polyfill? (The Port would have netting at the end of course) Thanks for all your guy's help,
Matt
Only add fill to a vented enclosure if the response is boomy, fill damps resonance at all frequencies and isn't just for mid-range standing wave control.
If your design has the vent extending the bass response adding fill will reduce the low bass, just use the acoustic foam on the walls (Foam carpet underlay works quite well too, lot cheaper)
If your design has the vent extending the bass response adding fill will reduce the low bass, just use the acoustic foam on the walls (Foam carpet underlay works quite well too, lot cheaper)
I don't often build BRs, but my understanding is that you just want to line the walls -- in a BR sub it actually shouldn't make all that much difference if you stuff it or not.
dave
dave
planet10 said:
grab a vented enclosure, measure the drivers impedance and spl at the tuning frequency, stuff the enclosure, then measure impedance and spl again, it's not a small difference.
To put it another way, if stuffing made little difference in a BR, then it would make little difference in a T-line...
Volenti said:
I didn't phrase that very well... a BR should have no stuffing except maybe some on the walls (to help kill high frequency reflections). At the frequencies that a sub produces the purpose of the wall lining is defeated because the wavelengths of interest don't see the lining.
If you stuff a BR completely it is no longer really a BR but tending towards an aperiodic enclousure. The impedance peaks should decrease, move around abit, and the 1st derivative of the impedance curve will become much smoother. The Q in the bass will go down -- and in general, i find them more musically satisfting than a BR.
dave
You need stuffing if longest internal measurement approaches 1/4 wavelength of the highest frequency within the speaker passband. For a longest internal dimension of 15 inches that frequency is 226 Hz, so stuffing or lining is not necessary here. If the woofer was being run full range then fully lining or stuffing of the box would be required.
BR? sorry, but what does that mean?
And, thanks guys, no stuffing or lining it is. I just saved 15 bucks, put me down to 90 bucks for the whole project, I love this hobby 🙂
And, thanks guys, no stuffing or lining it is. I just saved 15 bucks, put me down to 90 bucks for the whole project, I love this hobby 🙂
😀 I have to concur with VOLENTI .... is right in a bass reflex sub like you are building you should only line the walls , for which ordinary 1 in plain foam or a little thicker is adequte if you want to kill the bass by all means fill it lightly with fibrefill , this is not a tqwt or a tl for which it is almost mandatory
cheers TC
cheers TC- Status
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