IB subs?

[ARES24]

I am planning my new HT. The new theater will be acoustically isolated from the rest of the house (concrete bunker style). ~29 x 12.5 x 8 total space to use if I want to use the whole area.
I am looking into the possibility of infinite baffle subs. Now this isn't a true infinite baffle situation as they will not baffle elsewhere. I am thinking about sectioning off 3-4 ft behind the screen an using it to bury the 'infinite' baffle.

I am hoping to take the new theater up a notch. I would like the bass to drop down to 10-15 hz or better. I figure I have all the space I need and 0 WAF to worry about.
I have read that roughly 10x VAS volume still gives you the essence of IB.
I am looking at the Dayton UM18-22 and the Fi IB318.

What are peoples thoughts?

 

[TLS Guy]

I am planning my new HT. The new theater will be acoustically isolated from the rest of the house (concrete bunker style). ~29 x 12.5 x 8 total space to use if I want to use the whole area.
I am looking into the possibility of infinite baffle subs. Now this isn't a true infinite baffle situation as they will not baffle elsewhere. I am thinking about sectioning off 3-4 ft behind the screen an using it to bury the 'infinite' baffle.

I am hoping to take the new theater up a notch. I would like the bass to drop down to 10-15 hz or better. I figure I have all the space I need and 0 WAF to worry about.
I have read that roughly 10x VAS volume still gives you the essence of IB.
I am looking at the Dayton UM18-22 and the Fi IB318.

What are peoples thoughts?

My thoughts are that building an IB speaker system is a really stupid idea.

Again like a sealed speaker you only have loudspeaker cones to couple to the room, which is highly inefficient.

There is no restoring force from the enclosure, so damage over time is to be expected unless you use a lot of drivers.

You need fairly high Qts drivers. Qts will not be lower than driver Qts, therefore the Fi IB318 wil have a poor quality loose sloppy bass.

The Ultimax is better. It has lower Fs and a Qts of 0.5. However cone excursion will be high. You should use at least 4 drivers. Driving the system below fs will give you a lot of distortion.

For what you are doing building an in will TL in that space is absolutely the way to go. You will have really clean natural bass well below 20 Hz with low distortion and require little amp power. Driver excursion will be small as opposed to high on the IB. The fact that it is a pipe will mean it will fill and encircle the room and give very even room coverage. In addition impulse response will be superior and not tend to drive and encourage room resonances.

Your space is crying out for a large TL sub or subs.

Neither of those drivers is suitable for a TL. You need Fs around 20 Hz and Qts as close as possible to 0.35. The drivers you have I think would model well for a TL.

 

[ARES24]

This is why I ask!

Thanks. I might steal one of the drivers for the new ht but I will still be using the other area so I am leaving one behind.
That area will remain an area for gaming and music listening as well as a hosting area.

I am uncertain the exact room dimensions but the size I have said should be close. With that in mind how many subs am I looking at?

 

[TLS Guy]

This is why I ask!

Thanks. I might steal one of the drivers for the new ht but I will still be using the other area so I am leaving one behind.
That area will remain an area for gaming and music listening as well as a hosting area.

I am uncertain the exact room dimensions but the size I have said should be close. With that in mind how many subs am I looking at?

I would start with one. What is this system to be designed for? Two subs might give you more even output. If this is a reference system then two lines tuned half an octave apart gives the best results. Then you have driver support right through the range where drivers struggle. So you can get support from below 20 Hz to 100 Hz.

So you would have one or two lines with the 18''driver and one or two lines with a couple of suitable 8" drivers and cross to mains at 80 to 100 Hz. Sealed speakers are best for the rest so you can make a combined acoustic and electrical fourth order LR filter.

I will soon be building an in wall system for an area in our new home. It will actually be for my wife. It is very potent with sealed mains and center. The mains are two way MTM and the center is a three way with a potent 4"mid covering the whole speech discrimination band. I have designed a TL using a 10" driver as that is all the space I have. It will have decent output down to 30 Hz though.

 

[ARES24]

This system is going to be primarily used for home theater. It will likely be used on occasion for sporting events or other gatherings but those will be a couple/few times a year.

Most if not all of the drivers will be hidden so I was thinking about diy with limited finishing (matte black). I was looking at diysoundgroup.com for the 7. (x) .4 channels. I originally thought about doing er18's all the way around but curious minds explore! Then come back here and beg for wisdom.

The renovation to the house will start in the spring so this particular portion of the project I have a 6-8 month planning stage.

I am thinking about having a rear seating position that will be raised, perhaps with near field subwoofer in it, don't know how that would work....
I am looking to get the 'feel' in the theater.

 

[TLS Guy]

This system is going to be primarily used for home theater. It will likely be used on occasion for sporting events or other gatherings but those will be a couple/few times a year.

Most if not all of the drivers will be hidden so I was thinking about diy with limited finishing (matte black). I was looking at diysoundgroup.com for the 7. (x) .4 channels. I originally thought about doing er18's all the way around but curious minds explore! Then come back here and beg for wisdom.

The renovation to the house will start in the spring so this particular portion of the project I have a 6-8 month planning stage.

I am thinking about having a rear seating position that will be raised, perhaps with near field subwoofer in it, don't know how that would work....
I am looking to get the 'feel' in the theater.

Even one of the subs will give you the "feel". Pipes act differently to other forms of loading and you will find that the bass will distribute well in the room.

My dual TLs, give you the "feel" alright with 4" 10" drivers that are not sub drivers. They vibrate all your internal organs. The bass of TLs though does have a different quality about it. It is much more true to life. This tends to be most evident in the soft deep notes. They are excellent for HT and music.

Anyhow this is the FR and impulse response of my dual TLs.

 

[ARES24]

Very cool.

If I am understanding you correctly, I can use one of my 18" HO sub drivers to run a TL sub and then get a couple of these in a different TL sub to even things out a bit? I picked the Tang Band because the specs looked ok from my 30 seconds of research.

What do you mean by one or two lines? I have been looking at www.diysubwoofers.org and going through some of the design sheets so I think I have an idea but that is even more dangerous then having no idea at all.