8 15" subs or 4 18" subs?

[mlstrass]

eeyore,

I think I know exactly what you mean as my IB is the same way. I've got 4 Tempests with 790 watts going to them and run em wide open in a 3000^3 room, yet something is lacking. Previous sub was a dual Tempest ported sonosub and I was very happy with it, but got the IB bug.

I've given it a good 6 months to get used to it and have done some tweaking, but with my current set up it just won't cut it. I don't have room or $$$ to add more subs, so an upgrade is out of the question.

What my IB is lacking is "punch" or impact. It gets real low and rattles the house to death, especially in a line array so no cancellation going on. I love it for music as it's as clean and detailed as bass can be, but for movies it just doesn't thrill me.

U-571 is my standard demo movie, the depth charge scene and the old ported sub would literally punch you in the chest and make your pant legs flap in the breeze. Not so with the IB. It gets plenty loud, but doesn't have that impact.

If/when I get the $$$ and figure out where to add more 15's or go to some high excursion 18's I'll try another IB, but for now I've decided to build 2 large ported boxes with 2 Tempests each and stack them in the old IB room, firing through the huge hole in the wall.

I'll sacrafice some musical detail to gain back the missing impact.

[ThomasW]

What my IB is lacking is "punch" or impact

Use EQ and dial in boost between 40Hz and 80Hz, that's where most of the "smack you in the chest" stuff comes from. Experment to get the results you want. With enough excrusion, EQ, and amplifier power one can make an IB sound like any other sub....

[mlstrass]

Thomas,

I tried that with the amp I have. Went up to 6dB of boost between 45-60Hz and it still didn't have that punch.

I'm guessing I need more/better drivers as all I have are 4 Tempests, but don't have the $$$ right now to upgrade.

I will go back to an IB when I have the $$$ to get some serious power and drivers.

[ThomasW]

Try some boost at 80Hz that won't eat up as much of your excursion

[chrisbee]

Didn't I read somewhere quite recently that the "chest thump" occurs at ~160Hz in most men?

Helmholtz resonater or sealed cavity? Mouth open or closed?

160Hz is not even in the full powerband of 99.999% of IBs.

So it's your speakers that cause the chest thump?

[ThomasW]

The chest compression stuff is higher than most believe, I'm not sure about 160Hz though.

I need to fire up the speaker testing rig this weekend for a full range project under development. I'll play around with different frequencies and see what I experience. This isn't an area where I've done much testing since I prefer the really low floor/room rattling frequencies....

[Darren]

I agree that the chest thump is higher up. I have plenty of low end frequency that rattles and shakes things but the chest thumping bass is much higher than a subwoofer outputs. The mains are what should be putting those frequencies out.

[mlstrass]

I would say that "thump" is not the correct word then as I have plenty of big Klipsch Legends that provide that. Kickdrums, etc... all sound amazing. For music the sub was fantastic.

It must be a much lower frequency than 160Hz as I had that effect with my old sub, but didn't with this one. Like the depth charges in U-571. The concussions were almost frightening with the ported sub and more lackluster with the IB.

I will say that it went very low and clean and rattled stuff off the walls continuously, but that really isn't what I was after. For me that didn't add to the viewing/listening experience as it seemed to lack "presence" for lack of a better word. I don't mean overpowering, but I want to feel like I should duck for cover when things are exploding on the screen. ;D

[nolook]

Mistrass.. I'm sure you have heard all this before, but, check and then double check your system.. From top to bottom.. Wiring, line inputs and outputs, terminal connections, phase, and internal programming for ALL your equipment, both inboard and outboard..
I can't tell you how many times I have looked at something and said, Yep, its correct.. Only to find out later that it wasn't.. ??
With all the computer controlled amps and A/V receivers today, it's easy to have something misdirected internally, or set for the wrong values..
I have only 2 18's, line array, powered by an old pro-logic amp.. The 12x18 theater rm is exposed to a 16x25 family rm via a 6' wide opening, and I have no trouble reaching some very respectful levels.. To not be able to do the same with what you have, something must be amiss somewhere ?
Give it another go around, leave nothing unchecked.. Here's hoping you find the problem..

[mlstrass]

I verified polarity on the drives before firing it up, using a 9v battery.

I've tried cranking up the sub level on my receiver and it gets louder and shakes more things, but it doesn't give the sound I want or had with the ported sub.

Also did as Thomas suggested and tried adding boost anywhere from 45-60Hz as that's what my amp offers. No matter where I set it I never got the desired result.

I'm going to "assume" that I just need higher excursion drivers and more power, which I'll get in the future. I can do 4 subs in a manifold through the door when the time comes. For now since I've got the Tempests and amp I'm throwing them in 2 ported boxes. I know they won't be as musical, but I'm at least 75% HT anyway.

And since the subs will fire through the existing line array hole, NO subs in the room, so still a clean install.

If I would have never heard the ported sub I might be happy with the IB, but being able to compare I can tell the difference: IB wins for music, ported wins for HT. And just to clarify for anyone considering building an IB, "MY" set up isn't enough for ME, everyone else who's heard it is amazed. Do NOT let this discourage you from building one.

[jimlowe]

Have you tried a house curve MLStrass?

[ThomasW]

mlstrass said:

eeyore,

I think I know exactly what you mean as my IB is the same way. I've got 4 Tempests with 790 watts going to them and run em wide open in a 3000^3 room, yet something is lacking. Previous sub was a dual Tempest ported sonosub and I was very happy with it, but got the IB bug.

I've given it a good 6 months to get used to it and have done some tweaking, but with my current set up it just won't cut it. I don't have room or $$$ to add more subs, so an upgrade is out of the question.

What my IB is lacking is "punch" or impact. It gets real low and rattles the house to death, especially in a line array so no cancellation going on. I love it for music as it's as clean and detailed as bass can be, but for movies it just doesn't thrill me.

U-571 is my standard demo movie, the depth charge scene and the old ported sub would literally punch you in the chest and make your pant legs flap in the breeze. Not so with the IB. It gets plenty loud, but doesn't have that impact.

If/when I get the $$$ and figure out where to add more 15's or go to some high excursion 18's I'll try another IB, but for now I've decided to build 2 large ported boxes with 2 Tempests each and stack them in the old IB room, firing through the huge hole in the wall.

I'll sacrafice some musical detail to gain back the missing impact.

Unless you post some measurements of the in-room response and have the ability to EQ there's no way we can help.

[mlstrass]

Thanks for the offer Thomas, but the boxes are already built and will go into place as soon as I get back from DC.

I'm going to live with the ported subs until next year when I'll have some spare $$. Then I'll get 4 high excursion drives and a better amp to drive them.

[eeyore]

I have turned the gain all of the way up and have been playing with a house curve.

It is a bit better.

I'm thinking that I may try another amp for more power with headroom.

I know that more power isn't a must but it won't hurt.

If I do add more drivers I will add another amp anyway so buying the amp now shouldn't hurt.

I may like the results and save myself $500+.