I'm sorry but i can't find the right
dimensions of Pi-BR for Eminence 12LT...

Could you send me, please, a right
dimension of the box and of the BR ?

What's also the f3 for this dessign ?

Thanks a lot,
O'tor

Unfortunately not. Its not Delta 12LF. It Is Beta 12LT used
in Thorsten Afterburner project. There was a post from you
in another forum about a Pi-align for this driver,
and i just can't find the details.

Thanks in advance,

O'Tor

Vas = 4.81 cubic feet
Fts = 45Hz
Qts = 0.51

And these correspond to PiAlign values of:

Vad = 4.81 cubic feet
Frd = 45Hz
Qd = 2.0 (1/Qts)

PiAlign recommends a bass reflex cabinet of 2.4 cubic feet tuned to 33.75Hz and having Q of 1.5. It recommends doing this using a 2.5" diameter port that's 2.75" long, which is very close to a perfect match - corresponding to Frd of 34.0Hz and Q of 1.56. Without any volume displacements, it is suggesting the cabinet be 24" x 16" x 11", but after consideration of the volume displaced by the speaker driver and the wood thickness, I'd expect your cabinet's outside dimensions to be closer to 26" x 18" x 14". And while these cabinet dimensions can be off a half inch or so, be sure the port dimensions are "right on the money." You must have inside dimensions of 2.5" diameter and 2.75" long for the design to be optimal.

I built Thorsten's Afterburner but am now going to try the Beta12LT in a PI cabinet.

Thorsten used an Extended Bass Shelf alignment (EBS) which is in the oposite direction compared to Wayne's alignment. It should make a nice comparison.

Do you have the Rat Shack tweet? I found them too bright--could be too sensitive or the 1st order crossover isn't attenuating quickly enough so there's too much overlap at 8-10kHz.

I'm going try a piezo tweet with a second order crossover.

Good luck and please let us know how it goes,
Cheers,
Jeff

> I built Thorsten's Afterburner but am now going to try the Beta12LT
> in a PI cabinet.

From my side, I was inspired by reviews about hammer dynamic
super12. I haven't possibility to hear it, so i decided first
to build afterburners for having an idea how 12" FR performs.

what's your opinion ? Can you compare it with something I
know ;-), let say FE103 or 40-1354 or FE208s....

what's also your amplifier ?

> Do you have the Rat Shack tweet? I found them too bright--could be
> too sensitive or the 1st order crossover isn't attenuating quickly
> enough so there's too much overlap at 8-10kHz.
> I'm going try a piezo tweet with a second order crossover.

Thanks for your advice, i haven't possibility to buy RS tweeter
here so I had the same idea as you - Motorola piezo. Which one
is your favorite ?

And, what about adding a low-pass and zobel for beta12tl same as
used in super12 ? This could be a solution to clarify the 10k region.

> Good luck and please let us know how it goes,
> Cheers,
> Jeff

thanks, I will do

O'Tor

> PiAlign recommends a bass reflex cabinet of 2.4 cubic feet tuned to
> 33.75Hz and having Q of 1.5. It recommends doing this using a 2.5"
> diameter port that's 2.75" long, which is very close to a perfect
> match - corresponding to Frd of 34.0Hz and Q of 1.56.

I just verified this calculs and unfortunately this doesn't work
for me. In your whitepaper for the port calculation I read:

Fre = 1/(2*pi)*(Ap/(Ve*Lc))^(1/2)

If Dp=2.5 and Lp=2.75, then Lc= 4.87,
if Dp=2.5 then Ap=pi*(Dp/2)^2 = 4.91,
and then for Ve=2.4 i have
Fre = 0.10312
and not 33.75 Hz as you said.
(Qe = 1.54 with no problem)

What's wrong ?

Thanks in advance,

O'Tor