sealed damping?

[rogerb]

What can be done to lower the "boom" on a sealed woofer? Will adding more stuffing work?

[Dirk]

To a point. Generally, you can go up to about 1lb per cubic foot of volume. After which point, it will seem to suck the life from the sound.

Is this a sub, or a woofer in a cabinet?

[Todd G.]

What Dirk said, plus, try getting the speaker away from room boundaries. With a woofer that usually means raising it off the floor and away from corners.

[gmilitano]

adding stuffing makes the box appear larger. There is a good comparison table in the Loudspeaker Design Cookbook (Table 1.21). 1lb/ft3 of fiberglass is a good number, but in some cases double that worked better, so there is no hard and fast number.

[philiparcario]

if it is a sub cross lower if possible.
/ 80hz
/ stuff it with fiberglass or polyfill
/ play it softer
/ all the above factors may be the problem.
how about letting us know what driver is causing the problem

[philiparcario]

one more thing if you need a 5 cu ft box and used a 2 cu ft box you will not get rid of the boom completely. the 5cu ft vs 2 cu ft are just an example

[nbuk]

Do a little research on Aperiodic Damping and see if your woofer might be good for this.
I am no expert on the subject, but I have been trying to solve "BOOM" problems myself, and getting positive results experimenting with home made vents.
If you think this may help your problem, you could build a rough test enclosure so you don't have to make holes in your good stuff, but even then, if your enclosure is WAY too small. this will not help.

[daryl]

Measurements are definitive in diagnosing such problems.

It could be crossover related or could be Qtc is too high.

If it is that Qtc is too high then using series capacitance to transform the system to third-order-sealed is superior to stuffing or aperiodic damping.

A capacitor will remove the peak above Ftc, boost bass below Ftc extending bass response lower and finally reduce cone excursion below the systems passband which now extends lower.

Third order sealed systems use smaller enclosures than second order sealed or ported fourth order systems.

Can you tell us which driver and/or it's specs and Vb?

[nbuk]

Measurements are definitive in diagnosing such problems.

It could be crossover related or could be Qtc is too high.

If it is that Qtc is too high then using series capacitance to transform the system to third-order-sealed is superior to stuffing or aperiodic damping.

A capacitor will remove the peak above Ftc, boost bass below Ftc extending bass response lower and finally reduce cone excursion below the systems passband which is now lower.

Can you tell us the which driver and/or it's specs and Vb?

Now that is interesting stuff from a clever chap !.
Daryl. I may send you some of my problems later, if you would be so kind.

[Todd G.]

Daryl is smarter than most any kid his age. (see picture) A lot of us used to think that his dad (in the background) was really doing the typing, but he said that his dad didn't even care for techi things. Daryl's been posting here since he was 4 years old, and even back then he was smarter than most.

[WmAx]

What can be done to lower the "boom" on a sealed woofer? Will adding more stuffing work?

If you have available a parametric equalizer - this can be used to compensate for the issue perfectly.

If you need a passive solution, here is one....

If you have a box that is seriously too small, then you can completely remove the boom with proper stuffing. The stuffing is high density mineral or rock wool board or fiberglass board. High density means 6 to 8 pounds per cubic foot. Owens-Corning 705 is correct, for example. The rock and mineral high density is much lower in cost and will perform the same. This material is standard mineral wool or fiberglass, but it is compressed and a glue is added so that the material stays compressed. It is rather stiff - it can stand on it's own in a shape. Simply add enough material until the response is smoothed as desired. The acoustic co-efficient of this material is so high that it can literally remove the ability of the box to act as an effective acoustic resonator. However, be warned that this will also cause the low frequency extension to be penalized substantially. Take for example a 6.5" sealed woofer in a 0.3 cubic foot box that should be in a 0.8 cubic foot box; the result is a notable peak in it's lower band. Let's say it's F3 is 80Hz in this 0.3 cubic foot enclosure. If you added 4" of this material to all walls, leaving only a few inches empty, behind the driver, then the result would be no peak, and a F3 around 105-115Hz. Obviously, this is only an example and you would scale the amount of material and relative F3 change according to the actual situation.

-Chris

[rogerb]

To a point. Generally, you can go up to about 1lb per cubic foot of volume. After which point, it will seem to suck the life from the sound.

Is this a sub, or a woofer in a cabinet?

This is the the Wayne J's Veritas version with dual 10" woofs (Dayton classics).

[rogerb]

Measurements are definitive in diagnosing such problems.

It could be crossover related or could be Qtc is too high.

If it is that Qtc is too high then using series capacitance to transform the system to third-order-sealed is superior to stuffing or aperiodic damping.

A capacitor will remove the peak above Ftc, boost bass below Ftc extending bass response lower and finally reduce cone excursion below the systems passband which now extends lower.

Third order sealed systems use smaller enclosures than second order sealed or ported fourth order systems.

Can you tell us which driver and/or it's specs and Vb?

the drivers are the Dayton classic 10" in a sealed cabinet.

[mike1234]

I knew a guy who packed so much stuffing in his subwoofer enclosure that it decreased the box volume to practically zero. Yes, he compacted the suffing so tightly that he may as well have been using bricks.

You can completely fill the box just don't compact it. If it's still boomy then either replace the driver or build a bigger box.

[rogerb]

What Dirk said, plus, try getting the speaker away from room boundaries. With a woofer that usually means raising it off the floor and away from corners.

Well you might have something there; The speakers are somewhat in a corner, 2 feet out, toed in with the woofer about 10 inches off the floor. I might try placing the speakers closer to the room center, away from the corner.

[rogerb]

To a point. Generally, you can go up to about 1lb per cubic foot of volume. After which point, it will seem to suck the life from the sound.

Is this a sub, or a woofer in a cabinet?

This is the Veritas by Wayne J (dual 10" woofs)

[Todd G.]

This is the Veritas by Wayne J (dual 10" woofs)

I have a pair of the Veritas, and they should not be boomy at all. Assuming that your xover is correct, I would suggest getting them out of the corner. Two feet out as you stated in another post wouldn't seem to be bad, but 4-5 feet would be better, with several feet behind them to the back wall.

FWIW, my Veritas are stuffed with about 4# of polyfill each.

BTW, how do you like my Veritas center?

[Dirk]

Todd, that is awesome. Way to break out of the square box.

[rogerb]

Thanks for all the good replies.
I moved the boxes out of the corners but it didn't make much diff. These speakers are Wayne J's Veritas design right down to the last detail.

I am thinking that I need to "slightly" add stuffing to maybe "fine tune" them. But I don't want to loose too much bass. Further opinions??

Guys, ANOTHER detail that I have noticed is what I believe is a midrange harshness when driven slightly more than moderate. That is of course is the Dayton dome mid. I'm thinking that what I am hearing is the "digital" sound that audiophiles complain about from cd's. OR is this just because the domes have yet to "break in" ? Any opinions ??

As always THANKS for input.

[philiparcario]

add stuffing and wait for 50 to 100 hrs of play time with different cd's dvds. then decide on changes.