Sign in to follow this  
Followers 0
ironlake

4 ohm speakers

3 posts in this topic

Does anyone know why ar did the 3a,s in 4 ohms. Most transistor amps were just starting out at that time and where not designed for the current draw of 4 ohms. I know that I did not even consider trading up from my ar 2ax to 3as as I had a new fisher TX 300 transistor amp that said 8 ohms only right on the amp so no go on the 3as. I latter traded the 2ax for large advents as I wanted the bass of them and the ax never did enough for bass for me. thanks in advance for any help.

Share this post


Link to post
Share on other sites

Ironlake,

All of the early AR 12-inch speakers were indeed 4-ohm designs. Reason: Ed Villchur selected the Altec Lansing 755A (Western Electric design) for the midrange-tweeter for the original 1954 AR-1, and the 755A—from 1947 until well into the 1960s—was designed as a 4-ohms speaker. Therefore, the AR 12W flat-side woofer was designed to be compatible with the 755A impedance, and it was designed at 4 ohms. By the way, Henry Kloss wound the first AR-1 voice coils by hand on bronze formers.

Since the AR-3, AR-3a, AR-11, AR-10, AR-9 and other AR 12-inch designs used a version of the original woofer, the speakers were all made for 4 ohms. By this time, of course, many new solid-state amplifiers were capable of the high current necessary to safely drive these 4-ohms speakers, so the low impedance was a good thing to drive these low-efficiency, low-Z speakers. For example, side-by-side comparison of an AR-3/3a to a comparable 8-ohm KLH or the 8-ohm Advent Loudspeaker of that period, the AR speakers needed the 3 dB extra amplifier current—for the same voltage input to the amp—just to keep up with the equivalent sound level. The 4-ohm AR-3/3a had about 3 dB lower efficiency than the equivalent 8-ohm KLH/Advent.

The Fisher TX-300 was woefully inadequate to drive something like the AR-3a. It used germanium transistors, and these simply weren't as reliable as the silicon transistors that followed in later designs. The Fisher also was not safe to operate below 8 ohms, and it would surely self-destruct if driven hard into a difficult load like the AR-3 or AR-3a.

You are right that the Advent provided more punch in the bass than the AR-2ax, but the AR-2ax's bass response—though less extended—was nevertheless somewhat flatter than the Advent.

--Tom Tyson

Share this post


Link to post
Share on other sites

Yeh I screwed up as I had a sherwood 40 watt per channel tube amp and sold it so I could get the fisher tx300 with only 36 watts perchannel. It was all about the transistor amps being new on the block and of course I had to be the first one in town to have one. It would have been cheaper to buy the 3as and use the 4 ohm tap on the sherwood and just get new speakers as the sherwood would crank on the axs and the tx would not.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0