AR2a/AR3 tweeters interchangeable?

[Mazeppa]

First time poster here from north central AR. I've been enjoying the forum while looking for some specific information, please forgive me if these are "asked and answered" questions that I was unable to locate. I recently came down with the vintage audio bug, did a lot of research, then got to wanting to hear something so it came time to lay some money down and get some stuff. I answered a craigslist ad for some Klipsch KG 4s, they didn't move me but the guy hooked up an AR3 pair and I was ruined. Walked out of there with the 3s, a pair of AR2a (mids & tweeters not working) and a pair of Boston Acoustics A150s. Does this mean I'm a sealed enclosure, acoustic suspension kind of guy? Could be.......

Got home, hooked the 3s up to a Sansui G5500, and they didn't sound right played at low volume. Close check revealed non functional mids. How'd I miss that? Pulled the woofer, pots already jumpered past. Ohmmeter across the mid leads, VC reads open. Haven't got into the other one, but expect to find the same.

On to the 2a pair. Grills still had original staples in them, got them off nearly intact. Pulled the mids assembly for access, yep, much funkiness on the pots. Soldered jumpers past them, tweeters and mids now going strong. Things are looking up! I really like what these speaks deliver. Later I noticed an occassional high frequency pop, sometimes a little sizzle, for short durations which, while yet to seem worse, persists.

Back to the 3s. I'm intrigued by the upgrade kit offered by Carl's Custom. Kinda pricey, so I'm still on the fence. Looking for answers to help me decide which way to go. I'm leaning towards keeping the 2a stock for "AR sound" and hot rodding the 3 w/the Carl's mid/tweeter/crossover kit.

Question 1.: AR2a tweeter(s) trying to fail?

Question 2: Are the tweeters used in the 3 & 2a interchangeable? Google has produced conflicting info on this question.

Question 3: Any feedback from AR-istas who've tried Carl's upgrade to AR3 or AR3a?

[genek]

Question 1.: AR2a tweeter(s) trying to fail?

Question 2: Are the tweeters used in the 3 & 2a interchangeable? Google has produced conflicting info on this question.

Question 3: Any feedback from AR-istas who've tried Carl's upgrade to AR3 or AR3a?

1. No idea.

2. Can't remember which thread it was in, but we recently confirmed that the hard phenolic tweeter of early 2a's and 2ax's was indeed the same nom 4 ohm unit used in the 3. The soft domes used in later 2ax's and 3a's are different impedances, and are not interchangable (I think Carl said you could get decent results putting the 4 ohm unit from the 3a into a 2ax but not the other way around).

3. I've not heard Carl's upgrades in AR speakers, but have heard other speakers that used the same drivers he's using. They sound great on-axis, at the expense of not having the incredible off-axis performance of the AR originals (but then again, the current service replacements don't have it either). I'd guess it's probably more of a personal preference thing than one being "better." As for the cost, if you have a pair of 3's and are contemplating trying to turn them into 3a's using the current service replacement parts, it would cost you around $450 for the mids and tweets and $100 and up for a pair of good preassembled 3-way crossovers. Throw in four rheostats and the midrange enclosure and you're right up to Carl's price, and you still have to do all the running around and ordering for each of the bits because nobody sells them all. If I suddenly found myself in possession of a set of 3 or 3a cabs with no drivers and no crossover, I'd probably be on the phone to Carl right off.

[johnieo]

Question 1.: AR2a tweeter(s) trying to fail?

Question 2: Are the tweeters used in the 3 & 2a interchangeable? Google has produced conflicting info on this question.

Welcome to TCSP - lots of info buried here. If your AR-2ax and AR-3 both have the 1-3/8"-diameter phenolic dome (burnt orange color) tweeter, the units are identical. AR only produced a 4-Ohm version and used it in both speakers. Be careful in pronouncing the tweeter dead. It may have a pulse you have not detected. Its leads are fine aluminum wire. In the AR-2ax they were connected by means of a brass-plated spring binding post. In the AR-3 they were soldered to the tab with an aluminum solder. If broken they are not so easy to rejoin in the AR-3. One way (there are a couple) of rejoining aluminum to copper wire is by means of a small diameter silver-plated crimp connector.

When checking for continuity, first check your meter by shorting the leads :-) Then make contact to the aluminum wires. The potentiometer is in parallel with the tweeter, so one lead must be disconnected to measure the correct resistance of the tweeter coil -- about 2 Ohms. It is possible you have a broken external broken lead, so check carefully and if they are truly open, consider having them restored. If broken internally, Larry LeGace at Vintage AR has had success in reparing these drivers. The AR-3a restore document in the AR section of the Library contains lots of info on cleaning the potentiometers, making an Al-Cu connection, and so on.

Let us know how your restoration proceeds.

Cheers,

[Mazeppa]

Thanks to johnnieo and genek for your replies. I did alot of research in this forum (still working on more useful "search" methodology), and elsewhere via google but remained unsure. All my lurking and looking has led me to believe I can get accurate info here. Y'all also come well recommended from AudioKarma (lots of confidence in them as well), the only other forum I'm a member of.

Looks like I do have spare tweeters (pots also) for the AR2a in the AR3 should I ever need them. Also glad to be made aware that the original AR drivers excel off axis compared to newer offerings.

Check of the afflicted AR3 mid was done w/the tone pot disconneted, probes at the solder joint to the driver, so no chance of reading anything other than the VC. Good tip about shorting leads to check ohmeter, it always amazed me how many of my fellow electricians got fooled by not doing so. Tweeter read 1.98 ohm.

So off I go. The AR2a pair are singing loud and clear, excepting the occassional pop or sizzle, but spare tweeters are on hand if needed. I'll be getting the pots cleaned and back in the circuit ASAP, still have jumpers around them. Also plan to repalce rock wool, which seems to have somehow reduced in volume to leave approx. 1/3 of the internal cab. space open w/polyfill. Have the notion to hang them on the wall like a picture, w/much stouter hardware, of course.

The AR3 cab.s and woofers are just what's needed to experiment with Carl's Supermod. He may be getting a call from me shortly. Will let y'all know how that goes.

Vintage audio, seriously good sounding system, Pioneer SX-D7000 - Boston Acoustics S150 & AR2a - Sony CDP350 and cabling for $365.00. Gotta love it! And there's guys out there doing it for less! Pics will be coming when I figure out how to attach them to a posting.