Why IB Sub?

[Vaughan Odendaal]

I know these Matrix films like the back of my hand, so I'll be more than happy to steer you in the right direction. The chapter that I am referring to is chapter 15 (I have the PAL version).

The first fight scene between Neo and the three agents has some awesome bass in it. When Neo kicks the one agent into the concrete wall, my couch shakes nicely. When Trinity fights the policemen, there are one or two big hits. When she knocks the officier with her helmet, there is a big whollop. You feel very sorry for that guy after that hit.

Now on to the fight sequence of choice. The scene I was referring to is between Neo and 100 Smith's. In that fight scene, there are lots of punchy hits, not particularly deep, but punchy. Each punch and kick should have different timbre.

Further in the fight, things get more and more exciting and the bass reflects in this too. When Neo does a back flip to kick one of the Smiths down, he comes back and does a jumping kick, falls down and then gets back up with a cool sidekick. That sidekick causes my room to pressurize. I can't even imagine what the effect would be like with your IB.

Try it.

Also, further on in the fight there are slow motion parts. Tons of bass in those sequences. Must be at least 5 slow motion sequences. You'll know instantly when you feel it.

When Neo tries to escape the "sea" of Smiths, he uses them as a stepping stone to get away, then all of a sudden, one Smith jumps and knocks him over. That hit knocked me in the chest slightly with my SVS PB10. Also, at the very end of the fight, Neo uses his strength to overcome all those Smiths who've piled on top of him, there is also tremendous deep bass there too.

Also, another great scene that I tested today. Watch the scene in Reloaded towards the end when Neo exists the "construct" and saves Trinity falling. You'll see the door start to melt and there is incredibly bass in that scene.

Neo swooshes in with fire trailing behind him and in my HT, I get this real room pressurizing effect. Excellent test material in my opinion.

--Sincerely,

[khellandros66]

Or you could save up for one those new Fans that does down to 3Hz at something like 120dB @ 200w RMS...

LOL

I would think that four Dayton 15in Titanics would be more then adequate for most rooms.

~Bob

[drumdude]

A good percussion disc is Blue Man Group. they have 2 CD's 'Audio' & 'The Complex' as well as an excellent DVD 'The Complex Rock Tour'. It really shows how quick an IB can be.

[Warmon]

This is probably a total shot in the dark, but could one of you IB'ers give a listen to Joe Sample's "Hippies On A Corner" and "Black & White". If you like piano jazz, there's some really nice bass on these two tracks.

[Avus_M3]

All this talk of IB is making me drool. I must hear one in person!! I am thinking about going with 4 FI IB subs for my 3800 cubic foot room but still have reservations on IB. I msg'd the 2 Sacramento members in here from the google map application for a demo but no response

[WillyD]

I am thinking about going with 4 FI IB subs for my 3800 cubic foot room but still have reservations on IB.

What kind of reservations do you have?

[Avus_M3]

Well, I read and read and am impressed but have never heard an IB in person. It is so alien to me since I am used to building heavy boxes.

[rlammi]

Avus M3, Not sure when I may be able to ,but I have a 4 12's set up only running a behringer a500 to them but they sounds great .I am in the Roseville area .Pm me and we see if we can at least let you hear one ,then there won't be any turning back.
Ron.

[Avus_M3]

rlammi wrote:

Avus M3, Not sure when I may be able to ,but I have a 4 12's set up only running a behringer a500 to them but they sounds great .I am in the Roseville area .Pm me and we see if we can at least let you hear one ,then there won't be any turning back.
Ron.

PM'd!

Thanks for the invite Ron! I'll bring the beer!

[Bigdaddy999]

I have a question about I/B's (which are apparently not "In Basements!")...

If maximizing the baffle size is the key, in effect, then why would a ported sub be designed with 3 or 4" ports as opposed to something much larger, thus making the room itself the baffle? Seems like the point would be to allow the drivers to remain uncompressed. With smaller ports, you trade off compression for "port noise" among other things, so why not make them free-standing in the room and simply have the drivers push free air?

Sorry if this has been discussed to death in the past.

[Chrisbee]

A Helmholtz resonator (reflex subwoofer) requires a specific port area and length to tune a specific enclosure volume to a particular frequency.

In theory one can use an adjacent room as a reflex enclosure and have a huge port tuning that room volume at the desired frequency. The drivers and port would be built into the baffle wall just like any other reflex speaker cabinet. Whether there would be any advantage over an IB would depend entirely on the design. There would be some free output at low frequencies from the port but an IB can manage that well enough on its own with a little help from a BFD. Examples already exist of very Large Low Tuned reflex designs. Rodny's massive double reflex design was a modified IB. He gained some extra bottom end but I think he had to double his amplifier power over the original IB. The enclosures had to be lined to make them airtight which adds to the work and expense compared with an IB. Smaller boxes may colour the sound compared with an IB using the entire rear space.

[SteveCallas]

Chrisbee wrote:

Rodny's massive double reflex design was a modified IB. He gained some extra bottom end but I think he had to double his amplifier power over the original IB. The enclosures had to be lined to make them airtight which adds to the work and expense compared with an IB. Smaller boxes may colour the sound compared with an IB using the entire rear space.

Actually, he gained output without having to add more power, which will always be the case when going from sealed to ported. In total, he gained more solid extension, more headroom, less distortion, less sound spilling over into the rest of his house, and what he and his son found to be better sound quality.

Bigdaddy - why don't more people box off IB space and port them into the HT room you ask? Simply put, I don't know, as they are limiting potential performance by NOT doing that. The only logical explanation I can think of is because it is less work.

[jagman]

Steve,

Please expand on your most recent post. If you can, please put it in perspective with my system. I have a 3000 cubic foot deciated HT. I have a dual Ascendant Audio 18" IB centered above the screen. The attic volume is somewhere around 700 cubic feet. I use a Samson S700 amp (so 350 watts go to each driver) and the subs just reach their excursion limit with full power and a 10Hz signal (WOTW) when they are REQ optimized. I've often thought about converting my sub to LLT, but its not practical in the attic d/t all the support beams and its not practical in the HT because I don't have space for two large enclosures. Wouldn't I need to increase the wattage sent to each sub, too? I have a hard time believing 300 watts x 2 is enough to really push two large excursion 18" drivers.

Thanks in advance.

[SteveCallas]

Since it's come up twice now, let me first clarify that when using the same drivers, a ported application will ALWAYS do more with less power. Sealed implementations, especially when using low end EQ, are the power hogs, not ported.

If you are interested, what you would need to do is essentially close off some of that 700 cubic feet to create an enclosure for the drivers, then add ports. Rodny's sticky thread on this forum is a great walk through of the concept. If you want this additional performance, I can model it and tell you what size I would aim for with the drivers you have.

Whatever you decide, I would upgrade that amp anyway, as 300 per driver is pretty low, and you might very well be losing out on some dynamic peaks in upper bass frequencies.

[NickTF]

If space is limited can you add two more drivers to the IB and a larger pro amp? IB has less space constraints then these box deals. Further, while maybe not as effecient as a ported box, an IB is far more effecient then a sealed box at lower frequencies so consider that when making the IB vs. LLT argument. Good luck either way

I'm sure i'm leaving out put on the table by using an IB vs. a LLT but with four 18s how much more do you crazy people want

[jagman]

Steve...

Thanks for your opinion. I hear you on the power to the subs. My concerned is I've bottomed them twice while watching WOTW. It was a soft bottom that thankfully didn't damage them, but nonetheless it was scary. When playing the specific scene, I started with lower volume and watched the drivers move, then repeated it several times while slowly increasing the volume to a level I thought I wouldn't want to go above. It was just at that level that they bottomed. It's pretty wild looking up into the manifold and litterally seeing two 18" drivers moving 3" peak to peak . If I increase the power, it's only more likely to bottom. The other issue is after EQ, I've never seen the clip light flicker which tells me I have more headroom. Before EQ that happened, but not since. I suppose that if I drop the lower frequencies a little, I could turn the volume up even more and not risk bottoming the drivers. That of course would give me more in the upper bass frequencies. That's probably a good idea. I'd then recheck for clipping, and if that occurs, then I'd get a more powerful amp. I could also have one EQ setting for lower volumes and another for higher volumes. If I'm still unsatisfied, then go for the LLT.

[WmAx]

jagman wrote:

If I increase the power, it's only more likely to bottom. The other issue is after EQ, I've never seen the clip light flicker which tells me I have more headroom. Before EQ that happened, but not since. I suppose that if I drop the lower frequencies a little, I could turn the volume up even more and not risk bottoming the drivers. That of course would give me more in the upper bass frequencies. That's probably a good idea. I'd then recheck for clipping, and if that occurs, then I'd get a more powerful amp. I could also have one EQ setting for lower volumes and another for higher volumes. If I'm still unsatisfied, then go for the LLT.

If feasible and within the budget, a Behringer DCX2496 can be used to protect the drivers. The DCX in addition to a superb EQ and xover system, has dynamic EQs that can be programmed to manipulate specific frequency bands above a user specified threshold. As such, within the normal(known safe) range, the dynamic EQ system would not do anything; it would only take action when specific user specified events take place in order to protect the drivers.

-Chris

[SteveCallas]

jagman wrote:

My concerned is I've bottomed them twice while watching WOTW. It was a soft bottom that thankfully didn't damage them, but nonetheless it was scary.

You'd be immune to bottoming with real media using a LLT with lots more power than that. You are bottoming the IB because there is no resistance in the "enclosure" and the drivers have nothing to relieve them of low end duty. You may not realize it, but you are limiting the performance of your system based on this weak link. If you stick with the IB, I would highly recommend you install a highpass filter between 15-20hz, that way you can actually get more use out of the drivers

[Chrisbee]

It would have been nice if Rodny could share some REW impulse and waterfall comparisons between his IBs and LLTs.

I'd be surprised if the LLT isn't "all over the place" at the bottom end compared with an IB.

At the very least I would imagine far greater coloration unless the LLT enclosures were made into irregular prismatic forms without any parallel surfaces at all. The dimensions of an LLT are ideal for serious coloration in the upper bass.

jagman just needs two more IB drivers in a bigger manifold (or a second manifold) if he wants more output without bottoming.

He may find more power keeps those big cones under better control without overshooting.

Compare the ease of adding an extra manifold with trying to build a huge, irregular LLT box in a forest of roof struts. Or worse: Having them in the room.

[jagman]

Chrissbee

You crack me up. My manifold is centered over my screen, and there is a hot water pipe running along side it, so unfortuneately I don't have the option of adding more drivers. I have thought of adding a rear IB, though, to conform with the Harman white papers. Since the front IB is about twice the distance from the seated position as the potential location for the rear one, I could get a way with one 18" sub in the rear (so no need for a manifold). It might not increase bass output that much, but it would clean it up and decrease the need for EQ (which is obviously beneficial). It might be fun to get a woofer widget to control phase and offer high pass protection, too. That would be a lot easier than adding two massive LLT enclosures. Too many options! I'm going to play with REW this weekend. Regardless, I'm looking forward to getting the woofer widget whenever it is released.

Going up into the attic also give me an excuse to add a small dedicated HVAC system to the room. The HVAC system from the rest of the house has minimal cooling/heating effect in the room.

[SteveCallas]

Chrisbee wrote:

I'd be surprised if the LLT isn't "all over the place" at the bottom end compared with an IB.

At the very least I would imagine far greater coloration unless the LLT enclosures were made into irregular prismatic forms without any parallel surfaces at all. The dimensions of an LLT are ideal for serious coloration in the upper bass.

Where do you come up with this stuff? Facts and existing measurements can be used to show these "audiphile" (cough) stereotypes are either entirely false or non issues.

The scenario that takes place FAR too often is that enthusiasts go from a small, single driver commercial subwoofer to a multiple 15" or 18" driver IB being powered with a beefy pro amp, and the difference is amazing, as it should be. However, the problem is that they then start coming up with all kinds of off the wall reasoning on why the IB sounds better than anything else they've heard, when the simple fact of the matter is that they have increased their displacement by 10x or more, sesitivity by 3x or more, power by 2x or more, and extended their low end FR with EQ, and THAT is why things sound so much better. Sure, I'll give them a thumbs up for creativity in coming up with some of their wacky explanations, but in terms of realistic performance improvements, the writing is on the wall.

Don't take it personally, but the LLT type of design has already proven itself superior in terms of performance vs other implementations on a 1 to 1 driver basis, using a capable driver. Just click on over to Ilkka's measurements page and you can see for yourself.

[willy-be]

SteveCallas wrote:

Don't take it personally, but the LLT type of design has already proven itself superior in terms of performance vs other implementations on a 1 to 1 driver basis, using a capable driver. Just click on over to Ilkka's measurements page and you can see for yourself.

Excuse the n00bie question, but I don't see where Ilkka has does any comparisons between an LLT and an IB. Would you please post a link to that testing?

Aloha,
WB

[SteveCallas]

There is no way to measure an IB outdoors, but luckily an IB is nothing more than a large sealed enclosure. So any of his sealed measurements will do, just don't picture the rolloff on the low end to be as steep with slightly less distortion down low.

The ported TC2000 15" he measured with a 16.5hz tuning is very close to being a LLT - close enough that simple extrapolations can be made.

[willy-be]

Maybe I'm wrong but it looks to me like the IB designs seen in the gallery here really aren't much different than open baffle or dipole speakers. If that's the case you're saying people like Siegfried Linkwitz and others are fundamentally wrong in the way they design speakers?

Aloha,
WB