Unexpected T/S Parameters-Vintage Oxford 15" Drivers

[Kilroy]

I was finally able to get Arta working and test the vintage Oxford/Acoustic Wagner 15" drivers I picked up.
The results weren't what I expected and I guess I need some help figuring out what it all means. ie.. Are they worth any more time and if so, in what sort of enclosure/baffle?

Parameter Value Dim
Fs -- 77.3 Hz
Re -- 7.2 ohms[dc]
Le -- 504.33 uH
L2 -- 1046.4 uH
R2 -- 17.56 ohms
Qt -- 2.6 -
Qes -- 2.99 -
Qms -- 20.27 -
Mms -- 39.26 grams
Rms -- 0.940817 kg/s
Cms -- 0.000108 m/N
Vas -- 6.93 liters
Sd -- 213.82 cm^2
Bl -- 6.780901 Tm
ETA -- 0.1 %
Lp(2.83V/1m) -- 82.7 dB

 

[Flaesh]

at first -

.. 15" drivers ..
Sd -- 213.82 cm^2 ..

must be about 8xx cm^2

 

[Kilroy]

Ha! How'd I miss that?
That's weird... Arta asked for the membrane Diameter in cm... I entered 16.5. So I don't know how that happened.

 

[Kilroy]

I entered 16.5.

Freakin' math.

The RIGHT T/S parameters!

Parameter Value Dim
Fs 77.58 Hz
Re 7.2 ohms[dc]
Le 518.26 uH
L2 1110.59 uH
R2 19.29 ohms
Qt 2.67 -
Qes 3.03 -
Qms 22.02 -
Mms 25.63 grams
Rms 0.56732 kg/s
Cms 0.000164 m/N
Vas 149.17 liters
Sd 804.25 cm^2
Bl 5.444417 Tm
ETA 2.21 %
Lp(2.83V/1m) 96 dB

But now the Vas looks funny?!

 

[Pano]

Vas? You have a Qms of 22! Can that be right? And 39g Mms? That's a light cone for a 15".

 

[Kilroy]

I don't know... This is the lightest driver over all that I've had in my hands over 10"... Maybe even over 8"... It's just not that substantial.
The cone is thin paper.... But that does seem a little on the light side... But if I messed up on the data entry this time, I can't see where.

Upon further examination
They have a very light, flexible cone with a very stiff surround...
I've honestly never seen anything quite like them.

 

[Cal Weldon]

15" with Fs of 78Hz and a Q of 2? Sounds like an old instrument speaker.

 

[Cal Weldon]

You have two threads for the same speaker?

http://www.diyaudio.com/forums/multi-way/176533-acoustic-wagner-drivers.html

 

[Kilroy]

You have two threads for the same speaker?

http://www.diyaudio.com/forums/multi-way/176533-acoustic-wagner-drivers.html

Yep. Sorry about that. I meant to put the T/S parameters in that thread but it slipped my mind.

 

[Kilroy]

15" with Fs of 78Hz and a Q of 2? Sounds like an old instrument speaker.

They do look remarkably similar to the old Hammond Leslie drivers.
They were supposed to have come out of an in wall house installation, but I have my doubts.

 

[godfrey]

Maybe the magnet's lost some strength over the years? A stronger magnet would bring down the Qts and give (even!) higher sensitivity. Less stiff surround would lower the Qts and Fs.

Since you like the sound, maybe it's best to leave well enough alone though. As is, they might be best on an open baffle. That high Q will give a nice lift at the bottom end. Any idea what kind of enclosure was originally used?

 

[Kilroy]

Maybe the magnet's lost some strength over the years? A stronger magnet would bring down the Qts and give (even!) higher sensitivity. Less stiff surround would lower the Qts and Fs.

Since you like the sound, maybe it's best to leave well enough alone though. As is, they might be best on an open baffle. That high Q will give a nice lift at the bottom end. Any idea what kind of enclosure was originally used?

I agree on the magnets. I bet they have lost something.
The sound is very warm and clear... But they need help on the top end. Which is probably why they were coupled with the horns.

They are very sensitive, surprisingly loud, and very directional in free air.

No idea on the enclosure but I have the grills which were identical but separate for the horn and the 15".

 

[Kilroy]

OB it is, I guess

I've been puttering around the internet trying different calculators and modelers and it certainly looks like Godfrey's OB suggestion is really the best suited 'enclosure' for these parameters...

I gotta admit, I'm a little intimidated by the idea of trying to make that sound good. I get boxes... Dipole is kind of new to me but I'm ready to start tweaking a board for sound.

But from what I hear from the speakers, what I see in the other OB threads, and what I've read elsewhere, these old Oxfords are probably best suited for use as a wide rang mid speaker in a 3-Way OB.

Listening to them just sitting by themselves gave me the impression that they sounded surprisingly musical for a big speaker but also had surprisingly little deep bass... And it seems the Arta reinforces that impression.

When doing a 'stepped sine' in Arta, they seem to start to come on around 50Hz... Would it be silly to cross a sub that low?

Judging from the Impedance sweeps attached, do you think I'm on the right track?

Also, I'm wondering if the horn tweet that was originally matched to the woofers, is the right accompaniment for them? I've attached the graph for it as well... Does that tell me anything or do I need to mic the pair?