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AR2 one is less clear than the other


arcticfox
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I just acquired a couple of AR2 speakers (I knew nothing about them at the time but they looked interesting enough) and while they sound good, one of the speakers doesn't sound as clear (more muffled) than the other. Like the "tweeters" aren't tweeting enough or something. It's not as noticeable when listening to both at a distance but when up close I could tell they're different. After perusing these forums it looks like the issue is likely the potentiometer and I'm looking for suggestions/confirmation that I'm suspecting the correct issue. Strangely these speakers, while being the same model, are made a bit different and after researching a bit it looks like it's due to speakers not being sold as pairs at the time. One speaker is unfinished pine and the other is finished (on only 3 sides) but unsure of the veneer. They're clearly designed to be placed on their side, not upright. The problem speaker is the one on the right in the photo, the unfinished pine with a skinnier pot knob and two papers on the back. I've turned the pot a pit to help but it's not enough to make them sound the same. Luckily the problem speaker is also the easiest to remove the cover from as it's just a tight friction fit. The woofer foam still looks good, not cracked. I haven't looked at the other speaker as the cover is not friction fit, likely glued in place and much harder to remove.

 

Getting into it looks like a chore, there's thick black goop surrounding the woofer, I haven't bothered unscrewing anything yet. If I'm able to get it sounding better I'll likely refinish the cabinets and "attempt" to match the colors even though it's different wood. Probably a gel stain. 

On a side note, are there any "tweeter only" speakers? I'm considering putting a couple tweeters on the top of the speakers. I currently have some cheap channel master speakers hooked up and music sounds better when both sets of speakers are running because the dark brown speakers fill in the gaps of higher frequencies that the AR2s don't. 

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My first ARs were this model, and after many years of attempting to wake up
the stock configuration (original tweeters only make to about 13khz), I converted
them to AR-2x. This was a factory option from about 1964.

It's just the AR-2ax midrange in an adapter plate that you'll probably have to make.
The crossover doesn't need modification, though I would renew the capacitor(s).
Even the metal caps didn't hold up to the years. The sound is satisfactory to me now.

Hard to tell the difference in cabinet color from your photos.

installed-2.JPG

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Does the problem speaker have any highs at all? If so, do the highs cut in and out when you turn the pot?

If there are highs, but they are just "less," one of the two tweeters may have gone out.

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Welcome arcticfox.

I have some fresh experience with these as I was gifted a similar pair of AR-2's last month. Both are in unfinished pine, with one having a slightly lower serial # than yours (B18023).

The serial numbers on your speakers indicate that the earlier unit (B18877) was made around 1958, and that the later unit, with the AR Guarantee, was made after 1961.

The pots on the earlier speakers tend to age well, and both of mine are problem free. You indicated that you're having a problem with the later speaker, and the pot stem looks like that used on the newer Aetna Pollock pots that tend to corrode more easily.

Since the grill on the problem speaker is just a friction fit, you could remove it and check to make sure that both mid-tweeters are operating. You could also remove either the woofer or the mid-tweeters, and clean the pot if needed.

The front of both of your speakers look the same, so I'll guess that the earlier speaker is in a lacquered birch cabinet. AR had two grill styles for the AR-2, one for the mahogany cabinets, and one for 'other finishes' (unfinished pine, birch).

Also, use care when working with the grill cloth. Replacement cloth is very rare!

AR-2 grill cloths.jpg

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32 minutes ago, genek said:

Does the problem speaker have any highs at all? If so, do the highs cut in and out when you turn the pot?

If there are highs, but they are just "less," one of the two tweeters may have gone out.

It does have highs, when the wire connecting "2" and "T" are disconnected, the highs drop out. The highs do cut in and out when the pot is turned, and to answer your other question, even when they cut "in" at the highest tweeter setting for the pot, they still aren't as clear and high. It's hard to tell if one has gone out or not as both are next to each other. 

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13 minutes ago, JeffS said:

Welcome arcticfox.

I have some fresh experience with these as I was gifted a similar pair of AR-2's last month. Both are in unfinished pine, with one having a slightly lower serial # than yours (B18023).

The serial numbers on your speakers indicate that the earlier unit (B18877) was made around 1958, and that the later unit, with the AR Guarantee, was made after 1961.

The pots on the earlier speakers tend to age well, and both of mine are problem free. You indicated that you're having a problem with the later speaker, and the pot stem looks like that used on the newer Aetna Pollock pots that tend to corrode more easily.

Since the grill on the problem speaker is just a friction fit, you could remove it and check to make sure that both mid-tweeters are operating. You could also remove either the woofer or the mid-tweeters, and clean the pot if needed.

The front of both of your speakers look the same, so I'll guess that the earlier speaker is in a lacquered birch cabinet. AR had two grill styles for the AR-2, one for the mahogany cabinets, and one for 'other finishes' (unfinished pine, birch).

Also, use care when working with the grill cloth. Replacement cloth is very rare!

AR-2 grill cloths.jpg

Is there a way to test the tweeters? It's a bit hard to discern if both work as they're next to each other. What would be a good way remove the speakers? I unscrewed the rectangular plate housing the tweeters but it still won't budge. 

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28 minutes ago, arcticfox said:

Is there a way to test the tweeters? It's a bit hard to discern if both work as they're next to each other. What would be a good way remove the speakers? I unscrewed the rectangular plate housing the tweeters but it still won't budge. 

Two things you could try are:

Very lightly rest the tip of a finger on the dustcap while playing. Do you feel the vibration on one but not the other?

Also, you could try removing the individual tweeters. If successful, disconnect the wires and hook each one directly to your speaker wire and play at a low volume to check for operation. This may require de-soldering the wires to each driver, which would add difficulty.

Take care as the cones on these drivers can be torn easily.

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Hey Arcticfox

To answer one of your questions, you can add external supertweeters. Back in the day Microstatic made some specifically for the AR and KLH speakers. They're pretty cool but lately they have gone up in price on ebay so another option is to find some other brand external supertweeters or make your own. Making your own isn't hard. You just need a tweeter and a capacitor (2uF works but you could experiment. If you want to get fancy you can add an L-pad. Set it on top and wire in parallel with the AR-2.

Here's a thread on some I cobbled together: 

Or.... Parts Express has a range of piezo horn tweeters starting at 0.98 each (!) that don't require a capacitor and you could just set on top of the cabinet "naked". If you like the sound you could fancy it up.

btw, if you find you need one or 2 new pots PM me regarding new replacements. Or you can replace the pots with inexpensive L-pads.

To test the speakers use a paper towel or toilet paper tube and use it as a stethoscope (or use a stethoscope). That way you can listen to one driver at a time,

Kent

MicroStatic copyg.jpg

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PS: Some more random thoughts:

Your woofers don't have foam surrounds. They're treated cloth. You may want some of Roy's sealant to improve bass response or it may not be necessary.

Your speakers probably have oil filled capacitors. Best to leave them alone.

Those tweeters are 5" Carbonneau full-range radio speakers and yes, the speakers were designed to be lain on their sides and the angled tweeters were designed to give wide dispersion. If one of yours does turn out to be bad check ebay. They show up from time to time and aren't expensive. Recently pairs sold for under $20.

Be sure to download "Restoring the AR-3a". Much of the information is relevant to your speakers, such as how to remove the woofers. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

 

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1 hour ago, JeffS said:

Two things you could try are:

Very lightly rest the tip of a finger on the dustcap while playing. Do you feel the vibration on one but not the other?

Also, you could try removing the individual tweeters. If successful, disconnect the wires and hook each one directly to your speaker wire and play at a low volume to check for operation. This may require de-soldering the wires to each driver, which would add difficulty.

Take care as the cones on these drivers can be torn easily.

2 hours ago, genek said:

Does the problem speaker have any highs at all? If so, do the highs cut in and out when you turn the pot?

If there are highs, but they are just "less," one of the two tweeters may have gone out.

I didn't detect any vibration so decided to remove the tweeters and test them. Desoldering is not my specialty and with the way they wrapped the wires I decided to cut them as close as possible to where they intersect in the cabinet leaving enough length to resolder later. One of the tweeters tests at 3.2ohms and the other is 3.3ohms. 

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1 minute ago, arcticfox said:

One of the tweeters tests at 3.2ohms and the other is 3.3ohms. 

Sounds about right. 

 

1 hour ago, JeffS said:

Also, you could try removing the individual tweeters. If successful, disconnect the wires and hook each one directly to your speaker wire and play at a low volume to check for operation. This may require de-soldering the wires to each driver, which would add difficulty.

Take care as the cones on these drivers can be torn easily.

Give it a try.

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28 minutes ago, JKent said:

Sounds about right. 

 

Give it a try.

I see, I hooked them up and one of them sounded considerable quieter and thin. I'm assuming finding a replacement would be hard?

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52 minutes ago, JKent said:

If one of yours does turn out to be bad check ebay. They show up from time to time and aren't expensive. Recently pairs sold for under $20.

Check out ebay items 165617525765, 134165175997, 134167834405, 134158439711

Those have all ended but that's what you want. I don't see any right now but keep looking.

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11 minutes ago, JKent said:

If one of yours does turn out to be bad check ebay. They show up from time to time and aren't expensive. Recently pairs sold for under $20.

I'll keep a lookout for some then. Thanks

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Here's a pair. A little over-priced but "or best offer" so maybe you can do better

eBay item number:

115458998867

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11 minutes ago, JKent said:

Here's a pair. A little over-priced but "or best offer" so maybe you can do better

eBay item number:

115458998867

Yeah, I noticed those. They're more expensive than what I paid for the speakers heh. I'll look into it.

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Are you sure your tweeters are properly connected via the rear terminals in your "bad" AR2?  The photo is not clear enough to be visible on this computer.

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25 minutes ago, Martin said:

Are you sure your tweeters are properly connected via the rear terminals in your "bad" AR2?  The photo is not clear enough to be visible on this computer.

Bit of a moot point as I've already figured out the problem. In any case, yes they're wired correctly. 

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The dual mid/high range units do come up for sale at reasonable prices ever so often. Just be careful with them for the cones are paper thin. DxHo has a viable option. AR supplied these tweeter kits to many AR2 and AR2a owners. This would make your speakers into AR2x's. A major upgrade in frequency response and dispersion. 

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I too have a set of AR2's that are completely original. The grills have never been off. They do sound fine, but the addition of a exterior tweeter would help them out a lot.

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 Good luck on getting them sounding right again.

 

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I might actually be able to repair the tweeter. I examined it a bit more and noticed the spider has become unglued on one side from the metal support and luckily it's still glued to the cone. If I level it out while it's playing, it comes back to life. 

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The fix worked out! It was quiet the hassle getting it clamped in the right areas but after the glue dried it played like it should. I know I need to clean or replace the pot at some point as I have to turn it all the way for the tweeters to sound about the same as the other speaker but that's a project for later. My next project is to refinish it, I'm debating to either attempt to get the colors to match or just stain them different colors and embrace the different veneers. It looks like on the "3 sides" finished speaker, the unfinished wood is different :(

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The finished cabinet on the left in the last photo is birch.

Although you don't have a matched pair, birch and pine are two of the rarer AR cabinet types. Changing either will reduce their values. Both seem to be in good condition from your photos, so my advice would be to clean them, apply a light coat of uncolored wax, place them correctly (horizontal and raised up off the floor to ear level so your view is mostly the edge banding on the front faces), then just sit back and listen to the music.

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