(btw, it's damping not dampening, "to dampen" would be to get it wet 
)
There's two kinds of damping, cabinet damping and acoustical damping. You're referring to acoustical damping which may or may not be necessary. It can present a larger virtual volume to the driver and/or reduce HF resonance inside the cabinet.
)There's two kinds of damping, cabinet damping and acoustical damping. You're referring to acoustical damping which may or may not be necessary. It can present a larger virtual volume to the driver and/or reduce HF resonance inside the cabinet.
Or an experience thing. Cabinet damping would involve gluing something like tile, asphalt sheets, another layer of wood, bracing or any combination thereof to the inside of the cabinet panels. I've used a combination of bracing, to limit the length of paneling that can vibrate at an undesirable frequency, with asphalt sheets typically used as damping material in car doors. It's generally accepted that having a vibration free enclosure is the ideal and I've heard speakers made from rock that are exactly that and they sounded great. It may have had something to do with superior drivers and crossover too. On the other hand, I've heard speakers (with full-range drivers) where the cabinets were allowed to resonate and blend their sound in with that of the driver making it similar to a musical instrument like a guitar. They have their appeal too. I think that for low-frequency reproduction (like a sub) a well damped cabinet is definitely better.
If you just want to control some HF resonance all you'd probably need is some polyester batting to line the inside of the cabinet with. If you're trying to increase the virtual size of the cabinet then polyester wool (Poly-Fil, Acousti-stuf) would be your choice. In the case of tuning TLs poly-fil is generally used and then it's stuff listen, remove or add, test, until it sounds right to you. As a rule of thumb, you shouldn't have to add more than 2/10th to 3/10th lbs per cubic foot to your enclosure to get the results you want. Some box programs like Martin King's MathCAD worksheet include a stuffing measurement which helps a great deal. Other than that, AFAIK it's stuff and test. An interesting tidbit; Steve Margolis (Seventh Veil) came up with an idea of putting a sand filled sock in the bottom of his cabinets to eliminate standing waves between the top and bottom parallel surfaces (which did work). Later, he removed the sock and put a small amount of poly-fill in the middle of the enclosure. The results were the same.
Timn8ter said:(btw, it's damping not dampening, "to dampen" would be to get it wet
damp·en __ (_P_)__Pronunciation Key__(dmpn)
v. damp·ened, damp·en·ing, damp·ens
v. tr.
1. To make damp.
2. To deaden, restrain, or depress: “trade moves... aimed at dampening protectionist pressures in Congress” (Christian Science Monitor).
3. To soundproof.
damp __ (_P_)__Pronunciation Key__(dmp)
adj. damp·er, damp·est
1. Slightly wet. See Synonyms at wet.
2. Archaic. Dejected.
n.
1. Moisture in the air; humidity.
2. Foul or poisonous gas that sometimes pollutes the air in coal mines.
3. Lowness of spirits; depression.
4. A restraint or check; a discouragement.
Who knew? These were entered as "dampening" and "damping". Notice how damping doesn't even show up as an option?
I was with you Tim.
This comes straight from Google
Anyhoo,
I think the best thing is to "Trial and error it" with the batting. Or is it battening?
Cal
Any real difference between lining (as apposed to stuffing) a sub with batting and lining the sub with "egg crate" foam then?
Do I understand correctly that the result of both would be to attenuate any higher frequencies or harmonics but would not really affect the sub behavior from 80Hz down?
Do I understand correctly that the result of both would be to attenuate any higher frequencies or harmonics but would not really affect the sub behavior from 80Hz down?
Is there a "rule of thumb" as to how much effect stuffing has on increasing the "apparent volume" that the driver thinks is there?
Looks like the effect of stuffing could be interesting for a box that was high Q (relatively small box for a particular driver) to begin with, but not for a low q design.
On a sub box that is already low q, stuffing does not look like it would have much effect. For example a look at a particular .54 Q sub design with F at about 48 only gets a 1 dB increase at 30 if the perceived box size is made twice as big.
Looks like the effect of stuffing could be interesting for a box that was high Q (relatively small box for a particular driver) to begin with, but not for a low q design.
On a sub box that is already low q, stuffing does not look like it would have much effect. For example a look at a particular .54 Q sub design with F at about 48 only gets a 1 dB increase at 30 if the perceived box size is made twice as big.
Here is an interesting link that may prove helpful on the subject of stuffing to manipulate Q:
Polyester Fiberfill Effects on Box Q
Polyester Fiberfill Effects on Box Q
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