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AR-2ax tweeter is confusing me!


Ericus Rex
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Hello All!

New member here. I saved a 1973 pair of 2ax's from my neighbor's trash pile a couple of years ago.  I'm just now getting to their restoration.  Standard stuff; surrounds, caps, pot cleaning.  I plugged up the first speaker, prior to full reassembly, and I'm getting nothing from the tweeter.  It tests at 6.8 ohms (at pot end of hook-up wires, desoldered from pot) so I thought it was ok.  Suspected the pot, of course, even though I cleaned all the contacts inside and out and it was working fine. I bypassed the pot with a jumper (keeping the caps in tweeter line) and still nothing.  Removed and retested the tweeter this morning (thinking I may have messed up something during restoration) and it still tests at 6.8 ohms.  To rule out caps/crossover, I connected another speaker to the tweeter pot and I'm getting signal.  So the problem appears to be my tweeter.  Or am I missing something here?

Can a tweeter be bad and still test at 6.8 ohms?  I thought tweeter failures would result in either 0 or infinite ohms on the multimeter.

*scratching my head*

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Welcome ER

Sorry no one has answered yet. I'm a bit stumped too. Think I'd try connecting a source directly to the tweeter terminals (at low volume) and see if anything plays.

Kent

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Hey!  Thanks for the response, Kent.

I've done a lot of reading and experimenting since my posting.  The most likely answer to my question came from a friend who used to be in the stereo business.  He said the tweeter parts have likely stiffened/hardened with age with no compromise to the voice coil wiring.  Sounds logical to me; no/low output but still testing fine.

I did isolate the tweeters and mids after posting by taking the pots out of the circuit (had to make sure they weren't the culprit!) and jumpering my new caps directly to each individual driver.  One tweeter was VERY faint, the other only slightly louder but still way more quiet than the mids.  New tweeters have been ordered.

 

Thanks again!

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From what I have both read and experienced first hand, it’s not unusual for the 2-ax tweeters to go bad. Most of them are over 50 years old. My tweeters produced no sound after I purchased a pair of 2-ax’s last year.

What color are the domes on the tweeter, brown or black? The brown domed tweeters can be rebuilt at this site:

https://www.ebay.com/itm/193473033903?hash=item2d0be436af:g:fRcAAOSwCNpaw-sP

I’m not sure if anyone offers a service to rebuild the tweeters with black domes.

The other option is to replace the tweeters with a non-AR aftermarket tweeter with similar sound, which is what I did since my tweeters were black domed. It’s a little less expensive to go this route, and it’s documented in this thread from the Classic Speaker Pages site. You have to get half way through the thread before it talks about the replacement tweeters, but the beginning is instructive if you plan on reworking or replacing the L-pads:

 


Good luck, and don’t hesitate to come back to this site if you need help! I got much needed assistance here.

 

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Thanks everybody!

 

I have the black-domed tweets.  Is there anything that can be done to resurrect them?

 

I've read all the links posted here and elsewhere on the 2ax tweeters.  I have ordered the HiVi + 0.05mH inductor from Madisound.  Scheduled to arrive today!!!  I've got the guts all cleaned and back in, with the 'right' amount of new fiberglass, new cheesecloth and the woofers are back in.  Just waiting on the tweeters.  Then, when I have some more time I'll address refreshing the veneer (not too bad, but will require more time than I have at the moment).

 

Thanks again!!!

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2 hours ago, Aadams said:

Yes.  They should be rebuilt in pairs. Msg @royc or @chris1this1. 

Will do!  Thanks!

 

The tweeters came in!  I'm wondering what everyone did about the holes.  My original tweeters had 3, quite large, machine screws securing each of them; basically the next size up from what holds the mids and woofers (12-24 maybe?). The original screws don't fit the holes in the new tweeters.  Does everyone drill open the three holes in each of the tweeters? Or should I replace the screws and T-bolts with a thinner screw.  And what to do about the extra holes in each tweeter?  I'm inclined to mask off the domes and drill the three holes open to somewhat keep the original look and just leave the extra three holes be.  Let me know if this is foolish.

 

Thanks!

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In my AR-3a's I used 6 wood screws. I think they're the deep thread black ones from PE. Others have drilled out the holes in the tweeter and used machine screws that fit the T-nuts but the holes end up being on the very edge of the tweeter face plate, so you need to use washers too.

HiVi and AR11 copy.jpg

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I got the HiVi Q1R + 0.05 mH coil tweeters in using jkent’s wood screw method. The speakers sound quite “dark.”  I’ve got the tweeter level maxed and the mid level low. I’ve never owned AR speakers before. Is this their ‘sound?’  Were they voiced to tame early ‘70’s transistors?

 

Now the whole speaker has me scratching my head and not just the tweeters, lol!

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1 hour ago, Ericus Rex said:

Were they voiced to tame early ‘70’s transistors?

No

1 hour ago, Ericus Rex said:

Is this their ‘sound?

No

The Hivi mod attempts to mimic the original tweeter by rolling off at just below 5000 hz. The tweeter in these speakers reproduces only sparkly bits, cymbals and high harmonics, zero musical notes.  The 2ax mid driver, if working properly, doubles the tweeter as far as it physically can.  The solution should be to increase the mid and tweeter controls to max and begin adjusting from there.

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1 hour ago, Aadams said:

 

Did you reinstall the jumper wire between 2 and T?

Yes.  (changed it with 20 gauge solid copper wire, actually, but same difference)

Got a question here that may help things.  Do you guys listen to your 2ax's with the tone controls of your amps flat?  Or do you find that you 'bump' up the treble just a tad (or a lot)?  I'm listening to these through a DIY tube integrated I made using 13EM7 tubes.  This amp has no tone controls and these speakers make me wish it did.  How do you guys shape you sound with your tone controls?

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4 hours ago, Ericus Rex said:

Yes.  (changed it with 20 gauge solid copper wire, actually, but same difference)

Got a question here that may help things.  Do you guys listen to your 2ax's with the tone controls of your amps flat?  Or do you find that you 'bump' up the treble just a tad (or a lot)?  I'm listening to these through a DIY tube integrated I made using 13EM7 tubes.  This amp has no tone controls and these speakers make me wish it did.  How do you guys shape you sound with your tone controls?

It is not at all unusual for owners of earlier AR models to liberally use treble/high frequency controls.

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11 hours ago, JKent said:

Didn’t you replace the pots? If so, cut those jumpers 

I cleaned and lubed the contacts, then reassembled. I wanted to keep these as original as possible (but functioning properly).

 

7 hours ago, RoyC said:

It is not at all unusual for owners of earlier AR models to liberally use treble/high frequency controls.

I think we've found the problem I'm having with these speakers!  I haven't had tone controls in my system in 25 years!  But now the question I have to answer for myself is 'what am I going to do about it?'

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5 hours ago, Ericus Rex said:

I cleaned and lubed the contacts, then reassembled. I wanted to keep these as original as possible (but functioning properly).

 

I think we've found the problem I'm having with these speakers!  I haven't had tone controls in my system in 25 years!  But now the question I have to answer for myself is 'what am I going to do about it?'

My mistake. I was looking at Norman’s photo with the inappropriate jumper

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