[Matt__P]

Ok, its was suggested that these may be good candidates for an OB. Can anyone get me going in the right direction? baffle size , placement, etc. I didnt pay alot for these drivers and they appear to be very well built.
Any help would be much appreciated.

Regards,

matt

Nominal Diameter
12" / 300mm
Impedance
8 Ohms
Frequency Response
60 Hz - 22kHz (-10dB)
Power Capacity (AES standard)
90 Watts
Crossover Frequency
2.7kHz
Dispersion   80°
Sensitivity (SPL)
97dB
Voice Coil Diameter
2" / 51mm
Voice Coil Material
2 Layer Round-Wound Copper
Diaphragm Material   Pure Titanium
Rec. Enclosure Volume
3 cu. ft./ 85 Liters
Net Weight
5.5 kg. / 12 lbs.

MOUNTING INFORMATION

Overall Diameter   12.25" / 311 mm
Baffle Cutout Diameter (front mount)   11" / 279mm
Bolt Circle Diameter    11.58" / 294mm
Overall Depth   7" / 175mm
THIELE-SMALL PARAMETERS

Resonant Frequency (fs)   72 Hz
Impedance (Re)   5.2 ohms
Coil Inductance (Le)   1.5mH
Mechanical Q (Qms)   4.2
Electrical Q (Qes)   .92
Total Q (Qts)   .75
Compliance Equivalent Vol. (Vas)   45 Liters/1.58cu. ft.
Voice Coil Overhang (Xmax)   6.4mm
Reference Efficiency   1.82%
Surface Area Of Cone (Sd)   .055
Pe (max)   100 Watts

[nullspace]

Hi Matt --

Based on the specs, it looks as though regardless of the OB you'll need additional bass support (72hz Fs will do that to you). So, if it were me I'd put in on a flat baffle not much bigger than the driver's circumference and look into adding a subwoofer. Check out the Bastanis for some ideas.

Regards,
John

[Matt__P]

Hi John, thanks for the info.
So since these wont play very low a small baffle is fine?

[nullspace]

That's the direction I would go, meaning I'd also be adding a subwoofer of some sort.

If you don't have access to additional bass support, you'd probably need to make the baffle monstrous to squeeze as much bass as possible out of the setup, because the driver is already limiting the low end to ~80hz.

Regards,
John

[scorpion]

Yes, try a baffle of 44 x 18" mount the coax 34" up in the middle and play. It will hold down to 60 Hz with good output, not bad at all ! 

/Erling

[markC]

I dunno... looking at the posted freq. response it might be a good upper bass and mid candidate, but with a drop of almost 20 db from 1k to 10k it is gonna be tough. Maybe lose the tweet and add a different one?

[Matt__P]

thanks for all the help guys. I received a number of suggestions for baffle size ranging from not much bigger than the driver to 105"x65".
I guess its time to experiment and see what happens!

[MJK]

Simulate! You can run 10 experiments in 5 minutes on the computer and work your way to an optimal solution. Faster and cheaper. Trial and error building is most likely going to end in error.

If you are getting that many different recommendations for baffle size, then you should be wondering about the sources of these recommendation. Did anybody include a prediction of the properties of the response for the baffle size recommended? If not then the recommendation is probably worthless in my opinion. This stuff is not that hard.

[Matt__P]

not that hard for who?....you? Greek to me my friend.
What program can I use to model these for OB?
I'm totally willing to learn and dont expect anyone to do it for me.

[MJK]

John K has an Excel based piece of software or you can look at my OB worksheets. You feed in the T/S parameters, that you provided above, and a geometry for the baffle. Look at the plotted output and iterate to get something that looks good. No magic.

[el`Ol]

FR graph looks like i expected from a 44mm titanium dome.
http://www.jblpro.com/pages/pub/components/2142.pdf
Sorry, I had to say this.
I would make the baffle so big that baffle and driver rolloff fall together and sum up to 18dB, so integrating a sub (with commercially available amplifiers) will be easier. I would go for a ripole sub.

[scorpion]

I might qualify my earlier statment by saying that a baffle with measures 44 x 34" will give a little more even response. In that with you could caculate in wings of your choice of size. No big deal though !

/Erling