Info on AR12c

[Guest]

Does anyone know where I can find the stats on the AR12c speakers? I am looking to restore the set that I have. Any help is appreciated! Thanks.

-Kevin

[Guest Nigel]

Hi Kevin;

My understanding is that the AR12 was to the AR11 as the AR5 was to the AR3a. The only real difference being the 10" versus 12" woofer. There is some question on this matter though, as the document below provides a slightly different story. I have never seen an AR12 to be able to find out.

Nigel

Take a look at: http://www.arsenal.net/speakers/ar/documents/ar90.txt

[Guest]

I got these speakers from my friends dad, he works at Teledyne(not in the AR department when Teledyne owned it). He got these speakers from a friend who worked in another department at Teledyne. I'm hoping to restore these speakers, though they're in very bad condition. This info will help. Thanks!

-Kevin

[Steve F]

The AR-12 was a 10" 3-way speaker in AR's Advanced Development Division product family. It was introduced around 1976, shortly after the 10Pi, 11, and MST.

It used a 2 1/4" cone midrange with ferro-fluid cooling around its voice coil. AR implied that they were the first company to use ferro-fluid in their drivers, although EPI also claims early use around this time. The actual "first" company is somewhat in question.

The AR 10" ADD models (the 12 and 14) had slightly larger enclosure volumes than the previous generation of 10" models (the 2 series and the 5). Actually, the 12 and 14 had the same internal volume as the 11 and 10Pi. This gave the 12 and 14 very slightly deeper bass compared to the 2 and 5, although AR's engineers had to be careful to avoid the possibility of over-excursion in the new 10" models because of the increased cabinet volume. It was a tricky balancing act.

The 12 crossed over to the mid at 700Hz, and then to the tweeter at 4000Hz. AR treated the 12 compared to the 11 in their literature very similarly to the way they used to refer to the 5 compared to the 3a.

The 12 was quite an excellent speaker, and a pair in good working order would be a great set of speakers by anyone's standards.

The 14 (a 10" 2-way with a 1" dome crossing over at 1300Hz) was also an excellent performer and a great value. It was intended to combat the Advents head on, and performance-wise, it succeeded handily. But AR always struggled with their sales/marketing/dealer relations policies, so the 14 never did have the market impact that AR had hoped for.

Steve F.

[tysontom]

>

>It used a 2 1/4" cone midrange with ferro-fluid cooling

>around its voice coil. AR implied that they were the first

>company to use ferro-fluid in their drivers, although EPI

>also claims early use around this time. The actual "first"

>company is somewhat in question.

>

Steve is exactly right here: the AR-12's 2-1/4-inch midrange (1-inch voice coil) was "hung" in ferrofluid. Interestingly, the midrange driver had *no* spider, or inner suspension; only the outer-rim suspension or "skiver" was used. The ferrofluid provided the damping, cooling and "suspension" of the voicecoil. If you ever had to do a complete cone rebuild, it would be tricky indeed. About five years ago I talked with Steve Tatarunis, Audio Products Manager for Ferrofluidics Corporation, and he indicated that their company always had a soft spot for Acoustic Research, "arguably the first manufacturer to use ferrodluids in loudspeakers." However, in 1974 Epicure Products, Inc., (EPI) claimed to have pioneered the use of ferrofluid in their 1-inch, inverted-dome, "acoustic-suspension" tweeter.

>The AR 10" ADD models (the 12 and 14) had slightly larger

>enclosure volumes than the previous generation of 10" models

>(the 2 series and the 5). Actually, the 12 and 14 had the

>same internal volume as the 11 and 10Pi. This gave the 12

>and 14 very slightly deeper bass compared to the 2 and 5,

>although AR's engineers had to be careful to avoid the

>possibility of over-excursion in the new 10" models because

>of the increased cabinet volume. It was a tricky balancing

>act.

>

I agree with Steve here, too. These 10-inch woofers were mounted in a cabinet with the same internal volume as the 12-inch speakers, such as the AR-10Pi and AR-11, and the resonance dropped from 56 Hz. of the AR-2ax/AR-5 down to 52 Hz., giving a bit more deep bass before rolloff. The "Q" of the AR-12 and AR-14 was 1.15, perhaps slightly overdamped. The target for these speakers (particularly the AR-14) was the Advent, known for its AR-3a-like bass response, and AR was determined to improve the low-end of the new 10-inch speakers.

--Tom Tyson