Isobaric ob?

[hollowboy]

to get maximum bass within a certain height [...]i could have double the woofers for any given height

A folded frame is the way to pack many drivers into a small frontal area.

Subwoofer Origami

Another way to maximise output for a given baffle size is to get the largest excursion drivers you can afford. Good luck

 

[GBOGH]

Like these?
Peerless by Tymphany STW-350F-188PR01-04 15" High Power Subwoofer,
I think audible air from the back of these may be present.
If that's not the case yeew 4 per cabinet, then 4 morel 10s in each love minidsp

 

[scottjoplin]

So it might look this, will a curved slot hurt? Best low fq in this would be say 4 15s or 18s, or a double bank of smaller one like 12 8s?

At 40 Hz and below the shape won't make a difference. You are in the room mode region and position is everything, it would be best if they were in separate cabinets that you could position independently of the main speakers

 

[Toaster]

Google Trans-fi Audio and take a look at Vic's OB bass system. He's also discussed it and the development of his speaker systems recently on the Lenco Heaven forum. I've heard the version using 15" drive units and it worked really well. It's.The best OB bass system I've heard. He's since changed out the drivers for 18" ones to add more headroom. This is a compound system using face-to-face drivers attached to each other and suspended from a compact frame. There's no baffles, and despite the size of the drivers, it's less dominating than you'd think, because it isn't very tall.

 

[GBOGH]

Thanks scottjoplin, for your insite.
Thanks toaster,
What a fantastic idea something so different yet seamingly so pure.
Lol back to the drawing board and down a new rabbit hole.

 

[Octavia]

Thanks for the Trans-fi link, mirrors my experience only I went with slot loaded 18" pairs inspired by Nelson Pass's idea. Some might remember the old Celestion 6000 system. Old ideas become new again.

 

[planet10]

The main use of isobarik is to halve the volume of the box. An OB has no box, isobarik makes no sense… use them as hollowboy suggested.

dave

 

[hollowboy]

Like these?
Peerless by Tymphany STW-350F-188PR01-04 15" High Power Subwoofer,

Those are probably fine, but over priced for the application - you don't need a woofer that can handle thousands of watts.

For OB use, most drivers will hit maximum movement well before they approach their power limits.

EDIT - to clarify "to maximise output for a given baffle size is to get the largest excursion drivers you can afford"

excursion = driver surface area multiplied by Xmax.

 

[GBOGH]

Planet ten,
Thanks for posting, going down the trans hifi rabbit hole have changed my plans alot, if you do look at his ob page he details the numerous stages of his development and ends with two woffers face to face in an infinite baffel minimalist frame, not technically isobaric but tell me what to call it and i will, other drivers to complete the full frequency.
Hollow boy,
Thanks again for your input, since reading the trans fi page i have decided to do something different two nice 18s mounted face to face with a slight space between then maybe 2, 8"inch tang band 1808 fr and a nice ribbon to finish, no curves, no array.

 

[adason]

dave is right...isobaric and open baffle makes no sense
but you would not be the first to use it, I have seen it done before, just can't find the pic

 

[adason]

found it!

 

[Octavia]

Interesting look. Slot loading is of course different from isobaric. Nelson gave a good description.

 

[scottjoplin]

That would give a perfect on axis null

 

[adason]

remember Helsinki gradient?

 

[adason]

Interesting look. Slot loading is of course different from isobaric. Nelson gave a good description.

no one is talking about slob
what I posted is isobaric ob

 

[Octavia]

Actually I was talking about slot loading but ok. And Gradient was damn nice the time I heard them at one of the Audio Shows.

 

[adason]

Ok...

Agreed, Gradient Helsinki is fine speaker.