AR 2ax "old" tweeters with "new" crossovers?

[Guest Islands Innovation]

Hi Folks,

I am restoring a pair of AR 2ax that my dad gave me. He bought them new around 1971. These are the "new" style AR 2ax, serial numbers 163168 & 162508.

Both original tweeters are the 3/4" soft dome type, and both VC's are open.

A couple years ago I bought what I thought were replacement tweeters, but they ended up being the "old" style orange phenolic hard dome tweeters. They measure about 5.4 ohms DCR. Much bigger magnets.

My question is will I see any problems using these older tweeters with the newer crossovers? I appears from the AR 2ax write up in the library (nice job on that...very helpful) that the crossover point was changed from 7500 with the old tweeters to 5000 with the new ones. Can these older tweeters handle the lower crossover point?

Are these tweeters comparible in performance to the newer soft dome versions? They seem like they would have been a lot more expensive to manufacture.

I am planning to replace the caps and clean and/or replace the pots (hopefully just clean). The original caps are the combo 4 and 6 uF. I'm wondering if I should use a little smaller cap for the tweeters? If so, any suggestions on what size to use? Solen has a 3.9, 3.3, and 3.0 uF listed on Parts Express.

For the midrange, I'm thinking either the 5.6 or 6.2 uF Solens listed. Any thoughts on that?

I saw a few threads on the issue of non-nominal caps, but could not draw a conclusion either way...

Thanks!

Jeff Maling

[Shacky]

I have heard of folks on AudioKarma using the early tweeter with later crossover and liking it. I've been putting together an early and late model and doing a lot of reading - but I am far from an autority on this mater.

My first thought is that the resistance of the tweeter driver itself is part of the crossover - as both moels use the sames capacitor values for mid and tweeter crossover. Therefore I think using the earlier tweeter will change the crossover point (not sure if it will be higher or lower) regardless of whether or not they can handle lower crossover designed into later model.

Good news is that the older tweeter is well sought after so if you wanted to you can probably trade with someone or sell yours and buy correct tweeters.

Shacky

[charger3834]

Shacky is correct on the crossover issue. The capacitor values are the same on both the "old" and the "new" models. The crossover is determined by the tweeter resistance. The only crossover difference between the "new" and the "old" version would be the inductor coil value. "Old" AR-2ax's used a "number 5" inductor, while almost all "new" 2ax's used the "number 7." The only exceptions were the earliest "new" versions built around 1970.

I also agree with Shacky that the best system performance will be achieved by getting the newer 3/4" tweeter.

Both the 1-3/8" fried egg tweeter and the 3/4" tweeter, have very flat power response on axis to beyond 20,000 HZ. The 3/4" has better off axis response. In other words, it has better dispersion and acoustic energy response. It is also somewhat more efficient.

[charger3834]

Jeff,

By the way, thanks for your comments on my 2ax write up. Guys like you were always my intended audience.

[Guest Islands Innovation]

Thanks for the helpful comments and advice!

I've been thinking I really should get the correct tweeters, so I'll start looking and see if I can score a pair for a reasonable price. In the mean time, I'll hook up the "old" tweeters and get back in action.

Mine do have the number 7 inductor coils. They have the stamped steel 10" woofers, which also need some work (rotted surround on the one original I have). Working on a plan for those too...

I just ordered a set of new Solen caps (3.9uF and 6.2uF), and have had good luck so far cleaning and dielectric-greasing the pots, so I am on my way as far as getting the cabinet internals buttoned up.

I'm looking at some options for grille cloth, and I've been practicing my cabinet finishing skills on a set of AR 4x's, so hopefully I will have a nice sounding and looking set of restored AR 2ax's after some time off around the holidays.

I grew up with these speakers in my parents living room. We are having our first child in January, so they will have their chance to do the same. I bet it won't be long before they find those pots and wonder, like I did, if they will get in trouble for turning them (Dad never noticed)!

Thanks again, Jeff

[Shacky]

You will be pleasantly surprised at how well the sound of these great spekers holds up in todays market. I think they are perfectly suited to both LP's and CD's. They were designed to play LP's and they take the edge off of potentially harsh CD's making them very listenable without fatigue.

My 2AX's are the older set. At first I wasn't sure if I liked them as they are not bright like many new speakers. But then I was drawn into that beautiful AR sound. That's why back then 1 out of evey 3 speakers sold was AR!