Driver for AH-160hz horn: cd vs cone?

[bvan]

In dire need of help with my first horn project.

I've settled on a Radian 850PB in an 425hz Azurahorn playing 1k to 10K and with a tweeter above, but I need driver ideas for the 160hz Tractrix horn, to play ±250hz-1k. Budget hopefully < $400/driver. Current production drivers preferred.

I've read of some success with the Radian 950PB used this low (with 4th order XO lets assume), and figure there might(?) be some sense in using fairly tonally matched drivers in the upper bass and midrange horns, but I'm wondering if a 6-10" cone might be a better bet?

On the other hand I like the idea that a cone driver will allow a horn with a shorter axial length which will take up less floor room.

What you guys think vis a vis cones vs CDs at these frequencies? Any brand/model suggestions?

Thanks for any help,

B.D

[SunRa]

A forum member, Angelo, had previously used a 8" Fane Studio midrange for his horn and then switched to a radian 950 PB. He reported a significant increase in detail, dynamics and overall quality.

AV Eikon : finished - Page 2 - Audio Voice Acoustics

The Grande Castine, build around LeCleach horn and with the help of the man behind Musique Concrete, uses the same configuration apparently.

The Cessaro horn as well.

[Lynn Olson]

Is the compression driver being used below its fundamental resonance? (Look at the impedance curve for the driver mounted in a plane-wave tube.)

Power-handling drops like a stone below resonance, and distortion skyrockets - not to mention the hazard of the diaphragm striking the phase plug. Double-check this before committing to the 250 Hz crossover frequency, which is extremely low for a compression driver.

330 to 400 Hz might be a much safer choice, in terms of driver longevity and keeping distortion down.

[ScottG]

Originally Posted by bvan

On the other hand I like the idea that a cone driver will allow a horn with a shorter axial length which will take up less floor room.

What you guys think vis a vis cones vs CDs at these frequencies? Any brand/model suggestions?

Thanks for any help,

B.D

The larger the driver's sd, the greater the "mouth" diameter for loading lower freq.s.

Cones are going to have a larger sd, and as a result will need larger mouths.


Take a look at some of the larger "paging" drivers that are available.. most are pretty cheap, but you can always return product (from a reputable reseller) that doesn't measure well. (..also make sure it doesn't have a voltage transformer.)

Look to partsexpress and MCMelectronics.

Also note that you don't need to fully load the upper freq. response of the driver.. as long as the low-pass is "steep" enough (and low enough) it shouldn't be a problem (..so no super long horns needed).

[bear]

Scott G, that does not seem correct - I could be wrong. but the principle used is usually that the cone is mounted in a position farther down the expansion length, at a point approximately equal to the diameter of the driver... so the mouth does not change.

Lynn, what you say depends much on the driver in question... it's true for most compression drivers...

EV made some large format compression drivers, I am not sure how large the diaphragm was (not having had one apart) but I saw a pile of them at a local surplus store last year, and the OD of the driver itself was on the order of 10" or so... the exit was probably 2"... At one time Community Light & Sound made this monster low Mid compression driver with an 8" aluminum diaphragm... probably you can find info about it somewhere...

_-_-bear

[ScottG]

here are a few:

Midrange Driver Threaded 1 3/8 X 18 Thread 40W RMS | DU-40 (DU40) | Distributed By MCM

Atlas Sound PD60A 60W Compression Driver 16 ohms | Parts-Express.com

This is not rated quite as low, but you can "bypass" the transformer:

Dayton D1075T 75W Driver with 70V Transformer | Parts-Express.com

[ScottG]

Originally Posted by bear

Scott G, that does not seem correct - I could be wrong. but the principle used is usually that the cone is mounted in a position farther down the expansion length, at a point approximately equal to the diameter of the driver... so the mouth does not change.


_-_-bear

It may not be. Horn response should be used.

[Inductor]

Maybe not what you want.
Selenium D250-X 1" Phenolic Horn Driver 1-3/8"-18 TPI | Parts-Express.com
Selenium D408Ti 2" - 400-2K Selenium D408Ti 2" Titanium Horn Driver 4-Bolt | Parts-Express.com
Let's see what you find to play the ±250hz-1k.

[bvan]

Thanks everyone for the ideas, and for the EIGHTEEN SOUND 6ND410 suggestion that was emailed to me.

I'll be investigating them, and the Faital M5N12-80 and P.audio WN-520N that my readings have dug up.

Lynn, I cant find any published impedance curves for the 950pb. Its FR graph shows a gradual lower end roll off without an obvious knee. I found a post by Angelo claiming its resonant freq is 550, and he recons to stay an octave away from it, i.e 1k crossover, but then it appears he later found joy with a 250hz crossover, so although I think 250hz doesnt look good on paper it might be one of those times to trust ones ear instead, or someone elses in this case. Costly compared to the Faital/P.audio if it doesnt work out though...

cheers
B

[56oval]

Hi bvan
Martin from Azura simulated an 8" PHL in the 160hz with a 4" throat .If you PM Enigma on SNA he has the plots .

Cheers