AR 2ax serial numbers, different weight..?

[Guest ARtwox]

Hello,

I'm new to this forum - it seems like a great place to be for a vintage AR owner (:-)

Just bought a pair of AR 2ax, serial numbers 237748 & 226579 - just one previous owner since new.

I hooked them up yesterday and have been playing then non-stop (well...almost) - they sound great!

Using a Scott 299 integrated tube amp to drive them.

They sounded so good, that I wanted to find out more about them and ended up here - been reading through posts etc. etc. looking all over the place.

A couple of questions; was it common for the serial numbers to differ that much for 2 speakers sold as a pair?

When can these have been made please?

Do these have the Alnico woofers or not, and if not, do those make a significant diference to the sound?

Oddly enough, one speaker weighs 16.3 kg (35.7 lbs), wheras the other weighs in at 16.5 kg (36.1 lbs)...go figure; anybody have an idea how this can be so?

These are in excellent condition, bar a few water marks on top of one of them (flowerpot?) - they have obviously not been tampered with in any way by the look of it, but still they are possible some 30+ years old; is there anything I should consider replacing - they sound great, but I know xover caps have been mentioned?

Not original stands, but I plan to get a par of those, I've senn that at least one Seller on eBay offers them.

I thoroughly enjoy the way these speakers play/portray all sorts of music - full bodied, with good bass, proper mids and nice highs!

Forgot to mention that I'm in sunny Sweden :-)

Peter

[Guest matty g]

Hi Peter -

It's not unusual to have a wide spread in the serial numbers even though they may have been purchased as a pair. I don't know if the numbering system is different for units produced in other countries, but usually the serial number is preceded by the prefix "AX" on that model (at least all of the ones I have seen). I've got a set with the serials AX151022 and AX151017, and the rubber date stamps on the drivers indicate July 1970. They have ceramic woofers which AR started using in 1969 (I think?). Other forum members are very well versed in the AR numbering system and can tell you what the serial indicates. If you want to know if they are the ceramic or alnico, shine a flashlight through the grill fabric and look at the woofer surround edge. If it is a doped fabric surround, that is the older alnico unit...foam indicates newer ceramic magnet type.

While you are looking in there, pay close attention to the condition of the surrounds. The foam type often rot and crumble without immediatley sounding bad, and using them like this can damage the woofer permanentley. If they are rotted, don't panic...you can replace the surrounds yourself along with the caps (always a good idea) and the pots can be cleaned to eliminate dead spots. If you're not comfortable with changing the surrounds, they can be sent out and re-done for not much money - if they're even bad in the first place. I'm not sure if the amount of insulation changed in the span between the two serial numbers, or if that's enough to change the weight of the whole system. You may want to check and make sure that they both are the original AR drivers, as sometimes people see rotted surrounds and foolishly replace the drivers with generic ones.

They are a great sounding speaker especially when driven with equipment of that Scott's caliber and vintage.

Hope this helps

Matt

[Guest ARtwox]

Hi Matt,

Thanks!

I just managed to remove the grilles, without destroying anything... ;-)

These are indeed the later woofers. The surrounds on one of them had a small tear which I temporarily repaired (so I can go on playing them until I can have new surrounds fitted).

When I eventually remove the woofers; what about replacing those crossover caps? If so, then what best with?

About the surrounds; read in a thread here that JBL 125a surrounds were a good match for the AR-2ax woofer.

Anyway - these are great speakers.

[Guest matty g]

Hi -

Yes I believe Roy C. posted about the superior JBL surrounds which will fit the 2ax and 5 woofers, excellent advice from Roy as usual. As for what caps to use, well that's all very subjective. Many many posts on that one. Some prefer non polarized electrolytics like the ones originally used, some prefer poly caps, Solen, Kimbercap,Sprague, etc. The best advice I can give you is to read through some of the postings and try to sort out the pro's & con's. The npe's are nice but may have longevity issues (although the ones in there are 40+ years old and are working relativley well, we assume)...film caps may need very slight resistors in line to match the inherent resistance in an npe, but they last and are supposedly more stable. Then there's the issue of how a given cap sounds, how long it takes to "burn in" and so forth.

Anyway, it's probably a good idea to replace them with something, as an out of spec cap can most certainly blow out a tweeter or a mid, and I think we can all agree on that.

You are not going to want to hear this, but DON'T continue using them with patched up surrounds. If the cone goes out of kilter (which it most likely will) the voice coil will start rubbing the pole piece and damage will result, and that's no fun! Besides that, the accoustic seal of the cabinet is compromised when the surround is bad, and that can not only damage the woofer by not providing it with the accoustic suspenion (which made these speakers so famous and well loved in the first place) it can also make them sound bad. Replace the surrounds and you'll be even happier with them, and they'll last for years to come.

Hope this helps

Matt

[dynaco_dan]

Hi there;

As a thought, what if, instead of using one capacitor, use two, half the value of the orginal cap, in parallel.

If one cap becomes defective, open for example, the reduced capacitance will now make for a higher crossover, rather than lower.

Or not.

[Guest matty g]

Peter -

My appologies to you and to all CSP members for this inaccurate post. Reading Mitch's post and Brad's reply shook loose some once known but long forgotten facts. The 1970 - 1974 (please tell me I at least have THAT right)alnico "slug" magnet woofers that were used in the 2ax system completely slipped my mind. Just because a 2ax woofer has a stamped frame and a foam surround doesn't mean that it is a ceramic version, so the only true way to tell is to remove the woofer and look at the magnet structure. The alnico "slug" magnets are the type with an open bracket surrounding the magnet, the open sides of the bracket usually wrapped with tape. The ceramic version has a round magnet with the ring around the circumference of it (if I am not mistaken). The info for the older version (doped fabric surround and aluminum frame) still holds true - at least I remembered that much!

The mid on the ceramic version looks the same, but I think the imp. has changed. The coil on the "slug" version changed to a #7 (from a #5 used in the early 2a and 2ax) and the tweeter on them changed from the older orange "fried egg" tweeter to the new black dome version.

I hope this inaccuracy hasn't caused you any problems as far as ordering parts or made you think any differently about your loudspeakers. There are people on this sight with an incredible wealth of knowledge about all aspects of these great systems and they are willing to give you accurate information to the last detail. Hopefully I can someday know half as much as these great folks!

Matt

ps - please speak up if you see any inaccuracies....it's important to get the facts right.

If you want to know if they are the

>ceramic or alnico, shine a flashlight through the grill fabric

>and look at the woofer surround edge. If it is a doped fabric

>surround, that is the older alnico unit...foam indicates newer

>ceramic magnet type.