help me tame my BIB subwoofer

[bqc]

I built a pair of BIBs for my FE206s a year ago using dimensions for the FE207 posted at the BIB web site. Now I have moved the FE206's to a pair of Sachikos.
I just ordered a pair of Tang Band W8-704Ps and installed them in my BIBs for sub woofer duty. I use an electronic Xover set at 60Hz. The BIBs are not lined or stuffed. Just a 1 in thick of fiberglass at the folded section of the line. The bass is
overwhelming in my room 13X39X9. Measurement done with a RadioShack SPL
meter showed that the level of sound pressure at 25 Hz and 30 Hz is 10 dB
higher than the level at 40Hz and 50Hz. I would like to even out the response a bit.
Is there a way of stuffing/lining the line that would reduce the response at 25hz
and not affecting the response at 40 and 50Hz?

[bigjppop]

I don't have any advice, but I'd love to see some pictures of a BIB subwoofer.

[chris661]

Set a high pass 12dB/octave at 40Hz. Should bring everything in line.

[italynstylion]

Originally Posted by bigjppop

I don't have any advice, but I'd love to see some pictures of a BIB subwoofer.

Yes...And that tang band is a monster. You mean this one?
Parts-Express.com:*Tang Band W8-740P 8" Subwoofer | subwoofer 8" subwoofer long throw subwoofer tangband tb speakers tangband-41108

[Godzilla]

>>> I just ordered a pair of Tang Band W8-704Ps and installed them in my BIBs for sub woofer duty.

I have the same driver but in a small vented box.

>>> The bass is overwhelming in my room 13X39X9. Measurement done with a RadioShack SPL meter showed that the level of sound pressure at 25 Hz and 30 Hz is 10 dB higher than the level at 40Hz and 50Hz. I would like to even out the response a bit.

That's a big room!

>>> Is there a way of stuffing/lining the line that would reduce the response at 25hz and not affecting the response at 40 and 50Hz?

Yes, this is a 'monster' of an 8" driver for sure! It's making me laugh reading about your situation bc this is not a typical driver you'd use in a BIB... but since you have it let's see if we can make this work. A few questions;

Are you placing both the subwoofer BIBs into corners?

Would you consider using just one BIB sub in a corner playing mono? You can use the other TB driver as a sub in another system or possibly return one for a credit or refund.

Have you tried stuffing with acousta stuff at the bottom of the cabinet? Just wondering bc usually stuffing this way reduces mids coming from the top opening. Never having used a driver capable of such powerful bass in a BIB i can't speak from experience.

Have you tried positioning the BIBs away from corners, maybe at mid wall or in other positions?

Would you consider connecting the BIBs to another amp with along with an equalizer?

I just moved my BIBs (which are smaller than yours) and wish i built them with handles. Had to hug them close to lift and walk with them. LOL. The heavy magnet on the TB driver probably doesn't help!

Godzilla

[MJK]

Originally Posted by bqc

The bass is overwhelming in my room 13X39X9.

If I have done my math right, the first three room modes (half wavelength standing waves) in the 39 ft direction will be at 14.4, 28.8, and 43.2 Hz. In the 13 ft direction the first half wavelength standing wave will be at 43.2 Hz. You are positioning the BIBs at the room corners which should be the most efficient way to generate the bass SPL. It might not be the BIB speaker or the driver, try pulling them out into the room to see if this helps. The room center would be minimum excitation point.

[bqc]

Originally Posted by Godzilla

That's a big room!

Are you placing both the subwoofer BIBs into corners?

Have you tried positioning the BIBs away from corners, maybe at mid wall or in other positions?

I just moved my BIBs (which are smaller than yours) and wish i built them with handles. Had to hug them close to lift and walk with them. LOL. The heavy magnet on the TB driver probably doesn't help!

Godzilla

The room is long because it includes a kitchen at one end, which takes up about 1/3 of the space.

the BIB are laying down horizontally on the floor against the 13' wall, see pictures. I had intended to locate them there, pulling them away from wall boundary will be tough...
To move them around I use hand truck/dolly, I would hurt my back badly if
I tried to lift them way you do Godzilla.
I will try to locate them along the side of the 39' wall
with the opening pointed toward the middle section of the wall instead of the corner and see if that help to tame the peak at 25-30hz. During testing with
1/3 octave warble tone at 25hz, with the volume setting of my 100watt Adcom
amp set on low, the Radio Shack meter register 86 dB or so all around the room.
I think MJK is right, there are room modes that excites the 25Hz range causing it to peak.
I only had that tone on for about couple minutes, but that 's enough to make
me nauseous. The scientific studies are correct: low frequency sound at high SPL can be hazardous to your health

All this dilemma comes from the day that I moved the FE206 into the Sachikos.
I like the Sachikos but miss the low end extension that the FE206 gives in
the BIB. While in the BIB, the FE206 bass extends down to 25hz, not loud, but
tuneful. Now the TB in the same BIB is giving too much bass at 25hz and not enough at 40-50hz to cover where the Sachikos starts dropping off..

May be I should return these TB and save my money and buy the TB
W8-1772 8" Neodymium Full Range... and put them in the Sachiko ?

Parts-Express.com:*Tang Band W8-1772 8" Neodymium Full Range Driver | Tang Band W8-1772 8" Full Range Driver full range tb speakers neodymium driver line array point source midrange home theater computer speaker center channel set tube amplifier

Anybody tries these TB W8-1772 8" Neodymium Full Range in Sachiko?
I know about you should use the driver the Sachiko was designed for in the
Sachiko , but part of DIY is experimenting, right

[peterbrorsson]

Hi,
Stuff them with some fluffy wool in the last section and maybe use just one?
I have tried Peerless bass drivers in my bib's and experienced the same as you. I have about the same room dimensions also..
Good luck!
Peter

[pjanda1]

To tame my BIB's, I finally bought a 10lb box of polyfill at Walmart. I think I ended up with 3ish pounds in the mouth of each one. Some amount will help reduce the LF gain. Buy a big box.

If you need a more adaptable solution to room modes, you might consider using some digital EQ with your subs. The Behringer Feedback Destroyer is a popular choice. Home Theater Shack has some great info about implementing it. You might also consider a DSP unit from miniDSP. Check them out on their forum here.

Though the BIB is a flexible cabinet, it is generally inadvisable to randomly match drivers and boxes. I say that, because unless you've modeled it, I wouldn't toss a TB sub into the Sachikos. There generally isn't a great deal of overlap between enclosures for fullrangers and subwoofers. If you need a dedicated sub, you are probably best off choosing a TB driver and building a tapped horn to match.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

[j.michael droke]

Hi there: Looked-up the BIB site on Zillaspeak and found two diferent versions of the FE206 BIB (L=176-inches and L=140-inches, both have Z=133.875 square inches) The longer one has a shallower roll off from 100hz to 40 hz and the shorter one is flatter from 75 hz down to 40 hz and a steeper roll off thereafter. Which version did you build for the Fe206 (now TB W8-740P)? I'd like to have your problem of taming too much low bass. ...regards, Michael