Got a pair of AR 2ax speakers- Help!
- Thread starter Analogous
- Start date
I really want to hear the story of how you got them 
...is it on the lines of you were walking by in the beach when you stubbed your toe and dug and found the speaker or you were walking in a jungle and found a crashed airplane with these speakers ?
...is it on the lines of you were walking by in the beach when you stubbed your toe and dug and found the speaker or you were walking in a jungle and found a crashed airplane with these speakers ?FlaCharlie
Member
Well I'm a long way from Bangalore and I'm no expert on AR speakers but I do own a few pairs and I can offer some comments.
The tweeter and mid adjustments in these are made with wirewound L-Pads, not common potentiometers. So they probably never felt as smooth as a pot, even when they were new. The connections between the wiper and the wirewound loop get corroded over time and make it even worse. The corrosion is caused by gasses released by the material they used to stuff the cabinets, which is called "rock wool", I think.
If they're working fine (which is unlikely) and the sound isn't cutting out at certain settings the rough feel is not a problem. If they're cutting out and the corrosion isn't too extreme you can pull them out and clean them with a wire brush and some contact cleaner or something.
The back of the cabinets are not removable, which is a pain. You have to remove the woofers and go in through the front in order to pull the L-Pads out and clean them.
I've got a different model (2-way AR 4ax?) set up in a system now and I was able to get them to work at the tweeter setting I like. I don't really care if they cut out at other settings.
As I recall, you can't just replace them with common pots because L-Pads work differently. I don't recall details but maybe someone here knows the technical difference. Something to do with L-Pads presenting a constant impedance regardless of the setting or something???
I've heard that it's not a good idea to replace the rock wool, or whatever it is, with other material as it contributes to the voicing of the speakers. Replacement L-Pads are available if you can't get the originals to behave. I'm not sure of the specs to look for if you go that route.
If you search you should be able to find detailed info on restoration somewhere.
Hope this helps.
The tweeter and mid adjustments in these are made with wirewound L-Pads, not common potentiometers. So they probably never felt as smooth as a pot, even when they were new. The connections between the wiper and the wirewound loop get corroded over time and make it even worse. The corrosion is caused by gasses released by the material they used to stuff the cabinets, which is called "rock wool", I think.
If they're working fine (which is unlikely) and the sound isn't cutting out at certain settings the rough feel is not a problem. If they're cutting out and the corrosion isn't too extreme you can pull them out and clean them with a wire brush and some contact cleaner or something.
The back of the cabinets are not removable, which is a pain. You have to remove the woofers and go in through the front in order to pull the L-Pads out and clean them.
I've got a different model (2-way AR 4ax?) set up in a system now and I was able to get them to work at the tweeter setting I like. I don't really care if they cut out at other settings.
As I recall, you can't just replace them with common pots because L-Pads work differently. I don't recall details but maybe someone here knows the technical difference. Something to do with L-Pads presenting a constant impedance regardless of the setting or something???
I've heard that it's not a good idea to replace the rock wool, or whatever it is, with other material as it contributes to the voicing of the speakers. Replacement L-Pads are available if you can't get the originals to behave. I'm not sure of the specs to look for if you go that route.
If you search you should be able to find detailed info on restoration somewhere.
Hope this helps.
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I wish it was something exciting that led me to this. The story is quite banal. A friend told me these were on sale on OLX and I thought they would be interesting to explore. Well regarded speakers of the time, older than me. What’s not to like?I really want to hear the story of how you got them
i still haven’t had the courage to hook them up for a listen. They are sitting there like a Jurassic object promising a surprise. Time will tell if it’s going to be a good one or not
shafic
Well-Known Member
Nice speakers. They need a good powerful amplifier. I had them very longtime back. Given to a Hyderabad FM as a gift. 
Any suggestions on replacing the potentiometers and caps?Nice speakers. They need a good powerful amplifier. I had them very longtime back. Given to a Hyderabad FM as a gift.
shafic
Well-Known Member
They don't have any potentiometers. They have high frequency and mid frequency switches in the back.
I don't know much about the crossover/ capacitor science.
FM Raghunath of Hyderabad can help in this matter.
Regards
I don't know much about the crossover/ capacitor science.
FM Raghunath of Hyderabad can help in this matter.
Regards
These are knobs that turn just like volume control ones. The second picture above has them - three in a row within the circle.
They feel rough and grate when I turn them. The video link in the post above shows the restoration process but I don’t have the skill or confidence to try this.
shafic
Well-Known Member
Ohh. Ok.
May be they got rusted. Apply WD 40 and try after few hours.
FlaCharlie
Member
As I mentioned earlier, the controls are L-Pads, not pots. The roughness you feel when you rotate them is because the wiper runs across tightly wound wires, not along a carbon track like a typical pot. One control is for mids and one for the tweeters. The three things you see in a row are the connectors. The connectors are labelled 1, 2 and T.
Connector 1 goes to the amp output labelled 0, Neg, Black, or whatever your amp has. Connector 2 goes to the 8 ohm, Pos, or Red.
To run them full range a wire jumper is used to connect Connector 2 and T. Without the jumper the tweeter and perhaps even the midrange driver is disconnected. This allows you to run the woofer only, if you wish.
Here's a close up pic of the back taken from the web. You can see the wire jumper between terminal 2 and T.
As I said, I'm not an expert on all the variations of AR speakers but I've seen some that use a cloth surround on the woofer and others that use foam. If yours has foam it is likely that it's fragile or perhaps even deteriorated to the point that it may come apart when you play it or even touch it. Of course replacement foam is available and if yours is in good shape then someone must have already replaced it at some point. The material used in the original foam on these and other brands (Advents etc) contains an acid which cause the foam to break down eventually. None of the original surrounds will have survived this long. Replacing the foam is not very difficult, I've replaced foam on a few Advents.
If yours have foam, I would suggest you only play them at very low volume at first to see how they stand up.
The ones with the cloth surrounds usually benefit from having some type of pliable sealant applied to the cloth. That's because the original sealant can deteriorate and the air can seep through it. The speakers are designed to be totally sealed and, while they can be used safely with a less than perfect seal, bass response will be much better when they're sealed.
While I don't recall replacing any of the crossover caps in mine, and they do still work reasonably well, I'm sure that rebuilding the crossovers would improve them, perhaps a lot. Any decent quality film cap with the same specs as stock should be fine. I'm not sure what the original caps were though. If they were film then they might still measure fine. If they're electrolytics then you should replace them with films.
Here's a description of the speakers I found online:
The Acoustic Research 2x and 2ax (AR-2x / AR-2ax) are based on the design of the AR-3a, but were marketed as a value product, which means price played a crucial role. Therefore it contains most of the typical elements and ingredients as the high-priced Acoustic Research speakers, but has a slightly lower performance.
AR-2x / AR-2ax Differences:
The AR-2ax is a 3-way acoustic suspension speaker, meaning that its cabinets are completely sealed. The AR-2x is a 2-way acoustic suspension speaker which does not have the 1 3/8 in dome-type super-tweeter of the AR-2ax. According to a press comment, prices in 1971 for these speakers were similar, with the AR-2x being sold for $102 (in walnut) and the AR-2ax being sold at a slightly higher price for $128 (in walnut). The speakers were also available in different cabinets, priced at $89 / $109 for unfinished pine cabinets or $96 / $122 for mahogany/ birch cabinets. However, it seems that different sources have very different prices, not at last because the speakers have been sold for many years and prices decreased over time. As you can see at the Acoustic Research ad above, the AR 2Aax has also been sold for $139.
“The AR-2ax is a lower-cost version of our basic acoustic suspension design. It contains the 254mm woofer and 19 mm hemispherical dome, for very high frequencies, used in the AR-5. The midrange is covered by an 89 mm wide-dispersion cone unit. Separate controls on the back of the AR-2ax permit independent adjustment of the level of the midrange and high-frequency speakers.” (1960/70ies Acoustic Research brochure)
Refoaming the AR-2x and AR-2ax The AR-2 are fabulous speakers and restoring a broken or worn down pair can really pay off. Many of the ARs have foam surrounds that rotted away over the years. Frequently sellers will give them away for very little money, as these speakers were at the lower end of the price range of Acoustic Research models. A refoaming kit can usually be bought for around $30. Replacing the old foams will take around 1 to 2 hours and is not difficult at all! It does not require any particular skill, just a calm hand and a little patience. We tried out several different available foams and recommend to use Parts Express´ 10 inch Surround Kit.

AR-2x and AR-2ax Speaker
Both, AR-2x and AR-2ax share the following specifications (except the 1 3/8″ tweeter):
Drive units: 10 in acoustic suspension woofer, 3 ½ in midrange cone,1 3/8 in mm high frequency hemispherical dome
Crossover: 1400 Hz, 5000 Hz
Impedance: 8 Ohms nominal
Controls: Midrange and high-frequency driver level controls
Amplifier: Up to 100 watts per channel
Size: 13.5 x 24 x 11.5 in
Weight: 36.5 lbs
Woofer resonance: Free air 26 Hz, in enclosure 56 Hz
Volume of enclosure: 38.2 litres (1.35 cu ft)
FlaCharlie
Member
Here's a link to some additional info and restoration tips. It includes pics of the L-Pads that show their wirewound construction. The author says his mids and tweeters weren't working at all and, if you look at the corrosion on the L-Pads you can see why.
The pics refreshed my memory about the crossover. You can see that it's in an enclosed box of sorts. It shows values but not the schematic but I'm sure detailed info is available if you search.
In general, if you come across a vintage speaker whose tweeter or midrange doesn't work don't assume that the driver is blown. More often than not the problem is the crossover (usually a dead electrolytic cap) or the adjustment mechanism, whether it's a pot or L-Pad. If a driver is blown you can usually find replacements if you look.
And don't be afraid to refoam woofers. Many people don't realize that it can be done and just toss them and replace them with "something that will fit in the cabinet" but it will almost never sound right even if it will still "play".
I have a very nice pair of AR 4ax that someone did that to. Replaced the woofer with some cheap "boom - boom" car stereo subwoofer. Ouch. It "plays" and doesn't sound horrible but what a shame.
These are classic speakers that are definitely worth restoring. Hope this helps!
The pics refreshed my memory about the crossover. You can see that it's in an enclosed box of sorts. It shows values but not the schematic but I'm sure detailed info is available if you search.
In general, if you come across a vintage speaker whose tweeter or midrange doesn't work don't assume that the driver is blown. More often than not the problem is the crossover (usually a dead electrolytic cap) or the adjustment mechanism, whether it's a pot or L-Pad. If a driver is blown you can usually find replacements if you look.
And don't be afraid to refoam woofers. Many people don't realize that it can be done and just toss them and replace them with "something that will fit in the cabinet" but it will almost never sound right even if it will still "play".
I have a very nice pair of AR 4ax that someone did that to. Replaced the woofer with some cheap "boom - boom" car stereo subwoofer. Ouch. It "plays" and doesn't sound horrible but what a shame.
These are classic speakers that are definitely worth restoring. Hope this helps!
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Thank you so much @FlaCharlie . This is super helpful.
I will connect and play them today. Hoping they don’t need too much tinkering.
This link is a fantastic step by step guide.
I am feeling much more hopeful that these can be resurrected
Thanks again @FlaCharlie
I am feeling much more hopeful that these can be resurrected
Thanks again @FlaCharlie
square_wave
Well-Known Member
Jeez ! That looks badly maintained. Just curious as to why you picked it up ? Is it a model that holds promise if brought back to life ?
FlaCharlie
Member
There's another site which probably has much more detailed info. Due to forum policy I don't think I'm allowed to link it directly, even though it is not a general audio type forum and I don't think it would be considered "competition" to this site. It is an audio-related forum, though, not a static website. So I assume they will delete this post if they choose.This link is a fantastic step by step guide.
I am feeling much more hopeful that these can be resurrected
Thanks again @FlaCharlie
It's a site that deals with vintage speakers only and only those manufactured in the New England region of the US (NE portion of the country). "New England" type speakers typically used acoustic suspension designs (sealed cabinets) instead of ported or bass reflex types.
So I won't post an actual link . . . but it's called classic speaker pages (eliminate the spaces) and it uses a .net address.
Speakers made by numerous manufacturers are included. They have separate forums for Acoustic Research, Advent, Allison, KLH, ADS, Avid, Bose, Boston Acoustics, Bozak, Cizek, EPI, Genesis Physics, and Snell. Also info on Dahlquist, Dynaco and Rectilinear.
Hope this helps!
It was well regarded at its time.
I briefly tried it and I was surprised at how good it sounded. Very musical and engaging. The sound stage was unremarkable but it’s a speaker that is very enjoyable (all about the musical experience?) I have given it for changing the tone controls and the speaker binding post replacement (banana plugs did not exist in those days I believe)
Thankfully the drivers seem to be in good shape. Waiting eagerly for the maintenance to be done and I can listen to them more.
@square_wave: I think it’s about the “tone”
These vintage speakers are no match for modern speakers in separation, detail retrieval and imaging. If these are important to you don’t even think of getting anything this vintage.
But if you want a beautiful tone and an enjoyable listening experience where you don’t analyse the SQ, then this kind could do it for you, really well.
I now get why there is a whole community dedicated to such special vintage speakers. I guess every era has a few standout speakers that hold their value over time.
By the way I read (and saw pictures); even when new they looked unfinished and rather ugly with the grills off. Apparently AR decided the grills were not to be removed by the user at all
These vintage speakers are no match for modern speakers in separation, detail retrieval and imaging. If these are important to you don’t even think of getting anything this vintage.
But if you want a beautiful tone and an enjoyable listening experience where you don’t analyse the SQ, then this kind could do it for you, really well.
I now get why there is a whole community dedicated to such special vintage speakers. I guess every era has a few standout speakers that hold their value over time.
By the way I read (and saw pictures); even when new they looked unfinished and rather ugly with the grills off. Apparently AR decided the grills were not to be removed by the user at all
square_wave
Well-Known Member
@Analogous , Gotcha. I have always felt that vintage audio products makes sense only if you are able to bring it back to the original technical specs. meaning, it has to electrically and mechanically work as per the original specifications. Is that even possible with a speaker in such a condition ?
A beautiful, well-constructed speaker with class-leading soundstage, imaging and bass that is fast, deep, and precise.
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