Concerns

[Frank Kanyak]

It has been about a week since I built my sonosub(http://frank18202.tripod.com/sonosub...ion/index.html). I ran most of the reference material that I have(Titan A.E., Saving Private Ryan, Star Wars TPM, T2 Ultimate Edition, etc.) Mostly impressed by the THX intro from TPM it was scary!!! And everything in T2 was incredible. Now my concern, I live in a bi-level house and my theater is located in the basement family room. For the first time I went to get a drink and I felt everything, and I mean everything vibrate to the point that is this going to damage something??? I then proceeded to sit in my upstairs recliner and during the Pod Race scene (-5 from reference) I felt this very strong sense of energy(bass). It was GREAT!!! All I am powering this is with a 10 year old Technics amp with a built EQ. I have a huge bump in the 50-63 hz region. In the near future I plan on buying a BFD and a Samson s700 or a QSC amp. This kind of bass is unbeleivable.

 

[Ron-P]

I had a 10db peak at 40-45Hz. I completely killed the peak with adding more poly-fill to the sub. My only peak now is 2db at about 60Hz. Before you go and spend money on a BFD and just electronically remove the peak, try tweaking the sub at bit.
Peace Out~

 

[Frank Kanyak]

I have a ported design. Where would be the extra poly-batting help? Along side the inner walls or more around the port? Thanks Ron-P.

 

[Mark Krawiec]

If you have a ported sub, be very careful about adding stuffing.

Will it work to get rid of those pesky room peaks-it sure will, but not in a good way.

If you stuff a ported box you will decrease the Q of that box. Unfortunately, this will have the effect of reducing port output. How much, well you'd have to measure it.

Too much stuffing and you can effectively convert your box to a sealed sub (not quite, but more or less). And if there is no bass output from the port, well, then, you won't have any pesky room modes excited, eh?

A ported box should have the sides lined and maybe, maybe some light stuffing away from the woofer and port (again, without measuring equipment, it's hard to say)

 

[Mark Hayenga]

Do NOT stuff a ported sub, unless you REALLY know what you're doing. I didn't know what to think of the practice until I measured the difference it made. In my case, it shot my port Q to shit (made its output more broad and lower in amplitude) and messed up the boxes loss parameters. Here's the results of the stuffed vs. unstuffed impedance sweep:
http://www.hayenga.com/mark/tempests/tempestcomparo.gif
Red is stuffed, orange unstuffed. Notice the severe change in LF impedance caused by the stuffing.
PS - this was only 50% fill.

 

[Wes Nance]

Do NOT stuff a ported sub, unless you REALLY know what you're doing

Would this hold true for a PR sub as well? Are there sound quality issues with stuffing, as well as the Q of the box? I have a PR sub with a 12" Stryke driver similar to Dayton DVC, and two 15" PR's that tune the box to 21hz. The top and bottom of the box are lined with egg crate foam, but I was going to throw some stuffing in there as well.

Bad idea?

Thanks,

Wes

 

[Greg Monfort]

Yeah, I stuff vent designs regularly to get the vent Q I want, but these are higher Fb drivers, so it's needed to keep them from sounding boomy. For low Fb subs though it's the last thing you normally want to do.

WRT PR designs, I stuff them, but you have to take it into account as it increases the apparent Vb, just as it does a sealed.

GM