AR2AX restoration

[dxho]

I've been looking for a second set of 2s for some time now. Well, I found some cheap ones on CL, and now I know why. Looks like there are two tweeters and a mid blown. Other than buying used speakers, what's the latest recommendation for replacement?

the woofer surrounds also need replacement. I found this:

http://cgi.ebay.com/AR2ax-Speaker-Foam-Rep...1713.m153.l1262

or http://preview.tinyurl.com/6h3pte

I've read some conversation about the relative firmness of the surrounds, and I'm wondering if anyone knows about those above. Or if anyone knows of a recommended source.

There is some definite difference in firmness between the two now. The 'good' one seems too rigid. The 'bad' one is much less firm, and I don't think that's just because it's rotted.

Even though the boxes are close in serial number- 263218 and 263295, they look different where the speakers mount. The front plate is recessed on one of them.

.

[genek]

I've been looking for a second set of 2s for some time now. Well, I found some cheap ones on CL, and now I know why. Looks like there are two tweeters and a mid blown. Other than buying used speakers, what's the latest recommendation for replacement?

If you look at the various threads on AR-3a tweeter replacements, most of the issues are the same, since the 3 and early 2ax's used the same tweeter and the 3a and later 2ax's were the same except for the impedance . There aren't nearly as many discussions going on about mids, so I presume the AB Techservices replacement mids haven't given many people headaches. But if you do decide to go with one of those, I would replace both speakers in a pair. Differences that are slight enough not be noticed when one driver replaces another can be much more noticeable when you have old and new side-by-side in the same pair.

[dxho]

I unhooked the drivers, and fortunately they all test good. Woofers were 8.2 and 9.5 ohms, mids 8.2 and 9.3, tweets at 5.9 and 6.1. Assuming the wiring is good, and several speakers weren't working, that points to XO problems? I'll dig into them shortly.

Still, much better than I expected

[genek]

I unhooked the drivers, and fortunately they all test good. Woofers were 8.2 and 9.5 ohms, mids 8.2 and 9.3, tweets at 5.9 and 6.1. Assuming the wiring is good, and several speakers weren't working, that points to XO problems? I'll dig into them shortly.

Number one on my list of suspects would be the mid and tweeter level controls, then the crossover caps.

[JKent]

Number one on my list of suspects would be the mid and tweeter level controls, then the crossover caps.

I sound like a broken record, and I swear I don't get a kickback, but I've been very satisfied with the VERY complete kits and friendly advice from MSound:

http://www.citlink.net/~msound/

I would bet money that your level control pots are corroded. Consult the excellent AR3a restoration manual in the Library section for info on restoring the pots (and MUCH other valuable advice). You can also use L-pads, which work very well. They are available with complete instructions from ebay seller vintage-ar, or buy them from Madisound or Parts Express. While you are at it, buy new caps: One 4uF and one 6uF per speaker. If you order from PE Daytons are good and fairly economical. If you go with Madisound try Carli mylars for the best bang for the buck, or Solens.

Be sure to study that AR3a booklet--lots of good restoration advice and info there applies to the 2ax. Also ask here for help.

Hope the cabinets are good. If they don't require patching, try Howard's Restor-a-Finish. No sanding, easy to use, looks great.

New grille cloth can be fairly inexpensive Irish Linen from Michael's Craft Stores (not bad) or really nice linen from 1-2-3 stitch (more expensive. Again, check the restoration book).

btw--vintage ar sells some very nice reproduction logo plates.

I've restored 2 pair of 2ax's with help from the good folks here. My 1st pair are shown in the AR setion of the Library here:

http://www.classicspeakerpages.net/library...res_from_jkent/

And below is a shot of my second 2ax restoration, with those cool cast aluminum frame woofers. Next poject is a nice pair of mahogany-finished AR2a's (btw--any members have an opion on whether to replace the 2a mids to upgade them to 2ax?)

Good luck with your project!

Kent

[dxho]

Looks like the pots are serviceable. They cleaned up with tuner cleaner to a usable point. I'm going to do the woofer surrounds and button them back up for the moment. I'd like to see how they sound in their present state before undertaking restoration.

My crossover networks (at least the one I checked) were wired a little different than the schematic in the library. There's a green wire on each pot from the center wiper (yellow) wire to the capacitor side of the rheostat. Here's the diagram:

[RoyC]

Looks like the pots are serviceable. They cleaned up with tuner cleaner to a usable point. I'm going to do the woofer surrounds and button them back up for the moment. I'd like to see how they sound in their present state before undertaking restoration.

My crossover networks (at least the one I checked) were wired a little different than the schematic in the library. There's a green wire on each pot from the center wiper (yellow) wire to the capacitor side of the rheostat. Here's the diagram:

Your pots appear to have been partially by-passed with those extra green wires. They will not function as level controls as shown in your schematic, but will act as if turned to full "increase". Since corrosion typically only affects that part of the pot, jumpers like your green wires can be used to set the pot to the maximum position.

Roy

[dxho]

Your pots appear to have been partially by-passed with those extra green wires. They will not function as level controls as shown in your schematic, but will act as if turned to full "increase". Since corrosion typically only affects that part of the pot, jumpers like your green wires can be used to set the pot to the maximum position.

Roy

I measured the circuits after cleaning the pots. Usual range was from as low as 2 ohms to upper teens or 20.

After I hooked everything back up, they seem to work right (I've never heard 2AXs). I could turn the mids way too bright or too soft. The tweeters needed to be all the way bright.

[dxho]

Here are some more pictures.

[RoyC]

I measured the circuits after cleaning the pots. Usual range was from as low as 2 ohms to upper teens or 20.

After I hooked everything back up, they seem to work right (I've never heard 2AXs). I could turn the mids way too bright or too soft. The tweeters needed to be all the way bright.

Just measured some pots...

The non-functioning control I mentioned above, fixed at max setting, only occurs when a badly corroded wiper is not working, and the pot is wired as shown in your schematic. When the pots are not corroded and are working properly, as yours seem to be, your wiring arrangement provides only variable parallel resistance (no series resistance) to the drivers. Attenuation characteristics would be different than typically wired AR pots, and the crossover frequencies would change to a greater degree as they are turned down. It seems the main effect would be to allow for greater output from the tweeter and mid.

The question is whether they were wired with those green jumpers at the factory. From your photos, it appears they could have been.

Interesting...Thanks for sharing the info.

Roy

[dynaco_dan]

Hi there,

I see that the tweeter has a larger recess compared to the the other.

The front baffle board may have been routered out for AR-2A's or newest AR-2AX's with the 1 3/8" tweeter, they had the larger and deeper magnet system.

Vern

[onplane]

The question is whether they were wired with those green jumpers at the factory. From your photos, it appears they could have been.

Interesting...Thanks for sharing the info.

Roy

I totally agree with my friend, Roy. Those green "jumper" wires are a very bad idea!

If a child were to turn those controls so that the mid and tweeter were full off, you would have the full power of your amp going into those caps!

I mean, if you like that "magic white smoke", this would be the way to do it.

The correct way to wire the pot by-pass is shown below. The key is to isolate the pot wiper.

Hope this helps ...

Regards,

Jerry

[dxho]

Okay, just going by the schematic in the library, it looks like I would only have to eliminate the small green wire(s). Your suggestion looks like it would cut the rheostat(s) out of the circuit(s) entirely.

[onplane]

Your suggestion looks like it would cut the rheostat(s) out of the circuit(s) entirely.

Exactly, Ken!

The whole idea of a "by-pass" is to eliminate the corroded pots which severely limit current from getting to the drivers.

Now, if your pots are NOT corroded (and given their age that would be a big surprise), there would be no reason for the "by-pass".

Hope this helps ...

Regards,

Jerry

[dxho]

Yes, the pots are functional, so I'll probably leave them wired in (and cut the small green wires). That (and two boxes full of good drivers) was definitely a pleasant surprise.

Thanks, all.

[genek]

It seems the main effect would be to allow for greater output from the tweeter and mid.

The question is whether they were wired with those green jumpers at the factory. From your photos, it appears they could have been.

If these boxes started out with the 4 ohm hard phenolic dome tweeter, rewiring the pots might have been an attempt to increase tweeter output after switching to an 8 ohm tweeter. Doesn't explain why the mids would have gotten the same treatment though. Or does the fact that they measure 20 ohms at one end of their range suggest that maybe it was an attempt to comensate for a batch of pots that came in with the wrong values?

[RoyC]

If these boxes started out with the 4 ohm hard phenolic dome tweeter, rewiring the pots might have been an attempt to increase tweeter output after switching to an 8 ohm tweeter. Doesn't explain why the mids would have gotten the same treatment though. Or does the fact that they measure 20 ohms at one end of their range suggest that maybe it was an attempt to compensate for a batch of pots that came in with the wrong values?

I've been wondering about the same things, Gene....and we also need to remember that the midrange of the later 2ax's had a higher impedance of 9+/- ohms. The original mids measure 6+/- ohms. Some of those can be found with 3 ohms in series glued to their magnets, presumably for a transition period to the 9 ohm version. It wouldn't be the first time AR changed something on the fly.

Roy

[onplane]

It wouldn't be the first time AR changed something on the fly.

Roy

Hi, Roy!

Do you really think AR would have sold this set with this wiring? Seems way too risky for a relatively conservative company.

I mean, if anyone (a child for instance) turned the pots full off, you'd have a net load on the amp of a 10 mfd cap!!!???

Regards,

Jerry

[genek]

Do you really think AR would have sold this set with this wiring?

Although the jumper wires are green, they are also much thinner than the rest of the wiring in the photos of the crossover. If this had been done at the factory, I would have expected them to be cut from the same wire being used to wire in the rest of the crossover. My guess is somebody tried to bypass the pots and just got it wrong.

[RoyC]

Hi, Roy!

Do you really think AR would have sold this set with this wiring? Seems way too risky for a relatively conservative company.

I mean, if anyone (a child for instance) turned the pots full off, you'd have a net load on the amp of a 10 mfd cap!!!???

Regards,

Jerry

Hey Jerry!

I agree with you (and Gene). It seems very unlikely they would have been wired that way at the factory...

Roy

[genek]

It seems very unlikely they would have been wired that way at the factory...

I guess the next question is, what happens to the sound of the speakers when dxho cuts those wires?

[dxho]

I guess the next question is, what happens to the sound of the speakers when dxho cuts those wires?

I might have gotten around to that today, except that McPeak Sound sent the wrong surrounds. So I guess we'll know sometime next week, eh?

[dxho]

I haven't tinkered with the XOs and probably won't for a while, but I did get the new surrounds on.

And I'm reminded again why I bothered. The ARs just sound so sweet compared to everything else I have, even with old caps and mis-wired pots. They are smooth from top to bottom (and reach the tops and bottoms), unlike my KLHs, HKs, etc. It's that old-time religion all over again

[dxho]

I guess the next question is, what happens to the sound of the speakers when dxho cuts those wires?

It tames down the mids and highs a bit, even after new Solen caps. The wire wasn't soldered, and it was only on the one speaker.

Since new caps, the speakers are more closely matched (though one tweeter (w/jumper) sounds a shade weak compared to the other). It did open the sound up, especially the mids, and cleaned up a little muddiness.

On the other hand, I renewed caps in an AR-2, and couldn't hear any difference in it and its original twin.

I may reinstall the original, bullet-proof cap pack But I'll let these age a bit, too, before I start yanking things again.