Omni- TL WITH 8" AN, possible practical?

[carl bailey]

Hi Guys,
First post.
Am looking into building a Omni- TL design to use the 8" Audio Nirvana driver. Thinking of using the Audio Nirvana 8" firing up from an approx 1m triangular with heavily radiused corners (when viewed from above) case with sides approx 12" across. That design should easily give me 2m in line length to play with.
Basically envisage the 8" driver mounted at the top, firing up, in the center of the top of the speaker with a tube from the bottom of the 8" driver and sealed to it with the tube then going to within a few inches of the bottom of the speaker case and then returning to exit around the outside of the 8" driver.
Is having the open end exiting around the circumference of the driver a good/bad idea?
How would adding an extra sub to the bottom of this design change the property's of the TL?

I'll do a few sketches and upload later. Just wanted to get things started. Sure you know how it is when inspiration strikes. Just have to got on with it
Carl


OK Quick photoshop mock-up but hope my ramblings make more sense now.
Speakers will be Active, Bi-amped using a 60w rms per channel into 8ohm T-amp.

[GM]

The 'folded' TL is a variation of one of the original bass reflex patent designs, so a good plan IMO. I don't see the 'sub' in the bottom turning out well though since it will tend to audibly modulate the 'mains'.

GM

[carl bailey]

since it will tend to audibly modulate the 'mains'.

Can you explain, How is this different to a bass and mid in an ported or sealed case? is that because of the the fact that they are orientated directly at each other?

[chrisb]

Originally Posted by carl bailey

Can you explain, How is this different to a bass and mid in an ported or sealed case? is that because of the the fact that they are orientated directly at each other?

No, even in a vented enclosure the internal pressure by back wave of low frequency driver will be more than substantial enough to modulate other drivers in the enclosure - for example, otherwise PRs wouldn't work.
I doubt you'll find many well executed multi-ways (other than OB) that don't isolate the mid-range/tweeters or use sealed back drivers for the latter

[GM]

What Chris said plus the woofer would be end loading the pipe opposite the mains, amplifying the modulation, so a 'tail wagging the dog' scenario. Now if you sealed off the mains, then the TL plus floor loading would create a 6th order band-pass [BP]. Get the design/damping right and you might have something without the need for an electrical XO, but this will be no trivial pursuit.

GM

[carl bailey]

Now if you sealed off the mains, then the TL plus floor loading would create a 6th order band-pass [BP]. Get the design/damping right and you might have something without the need for an electrical XO, but this will be no trivial pursuit.

Was,nt looking for a trivial project, no fun unless it,s a challenge! What you said about the poss of no xover is exactly what im after.
Right so need a woofer to compliment that AN driver. Preferably 8" or10" and budget not exotic i,m afraid. Once sub is settled on i can work out volumes needed and get on with the case,s

Hope it,s ok linking to an image on another site, could,nt copy/paste specs.

Any input is appreciated. Not built any speakers for 20 years so am right out of the loop and have a big learning curve ahead.

Thanks guys, looking forward to more input.



.

[PJN]

I think that there was a project some years back where someone built a omni speaker using the 8" Pioneer full range driver in an tall octaganal enclosure. Try searching for it, it might give you some insights into your new build.

PJN