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.

[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.

[Dirk]

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.

Mighty impressive and it works. Um, kinda. I ended up with a response that looks a lot like I had vented a high-Qts driver. Still, the F3 drops from about 38hz to 23hz or so. I just modeled that up:

1. Modeled a sub in Unibox, exported FRD / ZMA.
2. Loaded FRD/ZMA in PCD as a midrange (allowing the series cap). Null driver for the LP & HP.

With the driver I picked, though, I'd need caps the size of garbage cans.

For high-power applications, can you parallel 3 or 4 EE caps?

[Æ]

For high-power applications, can you parallel 3 or 4 EE caps?

Paralleling capacitors will not improve their voltage rating, however, connecting capacitors in series will. Of course you'll end up with the total capacitance being smaller if you do series.

[philiparcario]

Paralleling capacitors will not improve their voltage rating, however, connecting capacitors in series will. Of course you'll end up with the total capacitance being smaller if you do series.

you need to series then parallel it takes a lot of caps if you use the 500uf 100volt ones pe sell. i use polar caps run them in series that turns them into nonpolar. this is a picture of 2 5000uf caps polar and 300volts in series they are 1 2500uf non polar cap with 300volts handling

[philiparcario]

this filter is a overkill version of daryl's idea it uses 60 6 ohm 50 watt resistors that is 1 1 ohm 300 watt resistor and the two caps of 5000uf polar in series to become 1 2500uf cap. this is used with my dayton rss390hf-4 IB. It raises qts from .42 to .52 this is a better IB sub with the higher qts

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

[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]

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?