I'm looking for some expert advice from the makers of the drivers.

 

About 2 years ago I purchased 2 18IBs.  I built a IB sub in the ceiling and about 2 months later I sold the house and moved.  Before moving I pulled my 18s from the ceiling and now they are sitting in my closet.

 

The big problem is my new home is not conducive to the IB design (no basement, flat roof).

 

So, the question is can I use the IB drivers in a sonotube design?  If not, why not?  If I did, although it may not be ideal, what should I expect?

 

Any light you can shed is much appreciated.

 

Richard

I believe for IB you simply need ten times the VAS of the driver. I'm intoxicated so it might be the wrong T/S parameter but a supppper big sealed enclosure, perhaps stuffed to shit would work.

Correct me if i'm wrong, but i've come across that a few times in a few years.

Pretty simple. Calculate the volume of the sonotube and model the subs in that enclosure volume to see if you'd be happy with the response. The only issue with using IB subs in a sealed enclosure volume that is around or less than Vas is that the Q will rise to something higher than most listeners desire and the low frequency response will roll off higher compared to if they were IB. Also there will typically be a hump in the response where most IB drivers will model pretty well flat anechoic. No way to predict how much worse the Q, peak and low end will be without modeling them in the proposed volume. Worst case scenario you sell the IB subs and buy something more suitable.

Is this for home audio or home theater? Big difference in requirements that will affect the decision.

Have you thought about an isobaric alignment ?  about 9 cubes would do 

Have you thought about an isobaric alignment ?  about 9 cubes would do 

 

isobaric would just cut the vas in half and he would take a hit to efficiency. still probably better off selling the subs and buy something else i would think. flipping a pair of ib3 should be pretty easy. 

 

might be worth modeling just the sake of demonstration... 

Edited January 5, 201411 yr by lithium

Guys, thanks for posting!

 

For a point of clarification the Sonotube is a ported design.  I downloaded a program, Sonosub, that had a Fi Q18 as a default driver and it had a suggested total volume of 260 liters.  I tried to paste in a pic, but was not successful.

 

The other parameters the program suggests are:

 

Tuning Freq - 15.6hz

Inside diameter of Tuber - 22inches

Port Diameter - 6inches

Port Length - 30inches

Endcap to Endcap Height - 48.7inches

 

Of course the height and diameter can be changed to meet the Volume requirements.

 

A couple of more generic questions.  Is there a book that I could read that clearly explains the driver parameters and their effects on real world performance?  Such as Vas, Q, etc.  Impious you seem to have a handle on them.

 

The other question, Impious, you mentioned running a simulation on the design.  Is there software that would make that easy, and free ?

 

 Again, thanks Guys...

BTW, no need to answer on the Software.  I googled.  Starting to play with WinISD now.

BTW, no need to answer on the Software.  I googled.  Starting to play with WinISD now.

 

That is what most use on here and if you have questions they can help you.

Do not use the IB drivers in a ported enclosure. The response will be terrible. That is not at all what they were designed for.

If you are wanting to go ported then most definitely sell the IB drivers and purchase something else.

Impious,

 

Off topic but I like your signature.  Recently out of the closet on religion.  Thanks!

Have you thought about an isobaric alignment ?  about 9 cubes would do 

 

isobaric would just cut the vas in half and he would take a hit to efficiency. still probably better off selling the subs and buy something else i would think. flipping a pair of ib3 should be pretty easy. 

 

might be worth modeling just the sake of demonstration... 

 

I've had good luck with Iso but that was an SPL setup. 

I too would sell what you have and buy something else. Really should only be out the shipping that way and the results will be far better. Model both in WinISD and you will quickly want to change drivers

The question above about Home Theater or music should really be answered as well. The "design" you have is tuned low for movies, but IMO for that purpose could be even tuned lower (driver dependent of course) at the same time it is tuned lower than necessary for music.

With a Large, Low tuned box/tube you will also need a SSF if you are to watch movies playing through it. Some of the audio content on film these days is absurdly low and can rapidly damage drivers otherwise. For music it probably isn't a concern unless you find the 11 on the volume knob regularly.

Guys, thanks for posting!

 

For a point of clarification the Sonotube is a ported design.  I downloaded a program, Sonosub, that had a Fi Q18 as a default driver and it had a suggested total volume of 260 liters.  I tried to paste in a pic, but was not successful.

 

The other parameters the program suggests are:

 

Tuning Freq - 15.6hz

Inside diameter of Tuber - 22inches

Port Diameter - 6inches

Port Length - 30inches

Endcap to Endcap Height - 48.7inches

 

Of course the height and diameter can be changed to meet the Volume requirements.

 

A couple of more generic questions.  Is there a book that I could read that clearly explains the driver parameters and their effects on real world performance?  Such as Vas, Q, etc.  Impious you seem to have a handle on them.

 

The other question, Impious, you mentioned running a simulation on the design.  Is there software that would make that easy, and free ?

 

 Again, thanks Guys...

I missed the question on the book....Loudspeaker Design Cookbook is pretty much the bible in this hobby. It's boring as hell to read, but it's a must if you are serious about learning the technical side of the hobby.