Hi all.A very Happy New Year!
I know this topic has been discussed to death but has anyone definitive proof that stuffing or lining the insides of subwoofers both sealed and ported actually benefits?
If so,with what type of material and how.
TIA.
I know this topic has been discussed to death but has anyone definitive proof that stuffing or lining the insides of subwoofers both sealed and ported actually benefits?
If so,with what type of material and how.
TIA.
There are people on here who could write entire books on this subject. When you say benefit, what is your goal?
Data-Bass: Subwoofer Measurements
Data-Bass: Subwoofer Measurements
Sealed: Make box 5% small and stuff to the desired measured Q. Not only do you tune the Q, but you reduce the harmonics being reflected back out. Maybe a dB less distortion, but every dB helps.
Actually anything less than Qtc of .7 is great. Does not hurt to line but I found not really much help. I say that having sticky fingers from just installing "boom mat" on all the surfaces of my BP-4 sub build as I was getting too much above cutoff out the port. I normally only built sealed subs, so it is a bit of a learning experience.
I think the fad of imported long hair wool has finally gone away. The slippery poly pillow stuffing is suggested as not as good an the non-sticky stuff sold by speaker parts suppers. For sealed, fiber glass or rock wool is fine. I tried some denim insulation and found little difference. When stuffing a sealed cabinets, it is the Q that matters, not the material so much.
Ported. More differing views. Normally just lined, but light stuffing can sometimes help with damping harmonics. Ported, never use FG or rock wool. Health risk.
Actually anything less than Qtc of .7 is great. Does not hurt to line but I found not really much help. I say that having sticky fingers from just installing "boom mat" on all the surfaces of my BP-4 sub build as I was getting too much above cutoff out the port. I normally only built sealed subs, so it is a bit of a learning experience.
I think the fad of imported long hair wool has finally gone away. The slippery poly pillow stuffing is suggested as not as good an the non-sticky stuff sold by speaker parts suppers. For sealed, fiber glass or rock wool is fine. I tried some denim insulation and found little difference. When stuffing a sealed cabinets, it is the Q that matters, not the material so much.
Ported. More differing views. Normally just lined, but light stuffing can sometimes help with damping harmonics. Ported, never use FG or rock wool. Health risk.
17 foot pipe sub 12-230 Hz ±5dB
The charts in post #2 related to a labyrinth sub are pretty clear about the effects of stuffing here. TL and BR have a great deal in common even if adherents resist the notion.
B.
Ah yes that would be nice. So MANY opinions but so LITTLE data, rather like the "woofer break in" topic. Tom Nousaine did some measurements:
https://www.ranger5g.com/forum/attachments/box-builder-fill-er-up-pdf.35156/
And Vance Dickason did quite an investigation in his wondrous Loudspeaker Cookbook which annoyingly I can't find in my garage right now.
My current state of thought about this is:
- Some people say that data shows stuffing the box doesn't work. I say SHOW ME THE DAMN DATA or I won't believe you.
- Stuffing can absorb sound from the rear of the woofer.
- Stuffing can dampen panel vibration...but not well and there are better products for this
- Stuffing can dampen internal acoustic resonances of the box. This is best done away from panels because AT the panels the air is not moving.
This leaves it that probably boxes should have multi layers of stuff for best total effect, which is my recollectino of what Vance found.
Anecdotally, I once fixed up my best friend's indecisive husband's old speakers while he decided what to buy. I cross-braced, coated with anti-vibration goop, and stuffed them well. The transformation was so amazing he has now for 17 years refused to sell them.
Again, this can only be answered by what kind of box. Sealed? Ported? TL? each is different. Stuffing, i.e. a material that provides both resistance to air flow and a longer path will have differing results in different cabinet designs. Making an overall generalization without cabinet design is, well flat naïve.
If you were referring to my post on Q, you need to read up on the differences between transient response and frequency response. A high Q system equalized into submission will sound quite different from a low Q system. Just as a low Q system rolled off too high and boosted to response is likely to exceed X-max very early. You can change the electrical Q by filtering (Linkwitz) but not the mechanical Q.
Lower Q subs tend to blend with room gain better as well as better transient response. But, you have to be careful of excursion. I have concluded that ALL speakers should have a HP filter for protection. Do the modeling.