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David Cutter

AR 2ax Crossover Tweeter Issue...Need Advice Please

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I started a thread a few days ago describing my foray into refurbishing the crossover in my 1965 AR 2ax speakers. 

I received lots of excellent help and advice, which I am grateful for. I bought all of the parts, tools, and misc items and followed the recommended schematic. After connecting everything back up, I am disappointed to find that the tweeter is not working. I have checked the wiring over and everything looks like it's correct...But perhaps more experienced eyeball will see the issue.

Troubleshooting advice please?? Here are some pics of what I did. Thank you in advance. 

xover1.jpg

xover2.jpg

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5 minutes ago, David Cutter said:

After connecting everything back up, I am disappointed to find that the tweeter is not working.

Do you mean one tweeter is not working or neither tweeter is working?

 

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I'm on the first speaker. Haven't started the 2nd one yet. 

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It looks right to me but you need to wait for others. 

Do you feel comfortable putting a signal directly on the front wire tweeter terminals?  If so you can quickly check for function.

Did you by any chance trim off a piece of this coil wire before you reconnected? image.png.d9e546134c219973a266dbbdb441567a.png

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10 minutes ago, Aadams said:

 

Do you feel comfortable putting a signal directly on the front wire tweeter terminals?  If so you can quickly check for function.

Yes, I did try it with alligator clips. The midrange made sound, but I did not detect sound from the tweeter.

 

 Did you by any chance trim off a piece of this coil wire before you reconnected?

I did not trim anything with that wire. I left the loop on and paired it with the blue wire from the capacitors. Why?

image.png.d9e546134c219973a266dbbdb441567a.png

 

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26 minutes ago, David Cutter said:

tors. Why?

Because it has a transparent non conductive coating that must be scrapped off if you use a new section.

To be clear:  You connected clips to these points and could not hear the tweeter?

image.png.a44bfd3cdeb2fff0372dc48bf2b9e2b2.png

 

 

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24 minutes ago, Aadams said:

To be clear:  You connected clips to these points and could not hear the tweeter?

That is correct. The midrange made sound, but I could not detect sound from the tweeter.

I thought the tweeters worked previously. Is it possible the tweeter is not functioning? Is there a reliable test I can try to check? Hmmmm.

 

 

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I just discovered the problem...Somehow the thin wire that runs up the front is disconnected. Did not notice until I checked it with my finger and adjusted my lighting angle.

Solution???

tweet.jpg

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That one is tricky and is out of my league.  I think soldering is practically out of the question.  I have seen pictures of new copper wire crimped to the old wire but I have not done it.  I am sure this thread is being watched by someone who has a solution short of a tweeter rebuild.

Meanwhile you could connect the clips to the two leads check for tweeter operation, then move on the the other speaker cabinet.

Aadams

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See page 20 of Restoring the AR-3a

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7 hours ago, JKent said:

See page 20 of Restoring the AR-3a

Thanks for that advice...Now where can I get a silver-plated butt connector for 24 gauge wire??? I've been looking without luck.

This will be a very delicate/challenging operation. The wire is as thin and wispy as cotton thread and not easy to manipulate with middle-aged men's fingers and eyesight. I've got a small piece of electrical tape temporally holding them together for now and the tweeter is working.

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Whatever you try, even if you fail, won't be fatal if you are careful not to damage the tweeter body or dome.   You have repair, rebuild and replacement options.

 

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3 hours ago, Aadams said:

Whatever you try, even if you fail, won't be fatal if you are careful not to damage the tweeter body or dome.   You have repair, rebuild and replacement options.

 Not sure how the wire was cut. I have been very careful to avoid touching and protecting the tweeter. Thanks again. I'm going to get started on the second speaker tonight. 

 

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Yeah David, I feel your pain. Those tinsel leads are maddening. They are way too brittle and break easily. When I refurbished an early pair like yours I ended up replacing the tweeters (which were both dead) with later 2ax tweets. So I have NO experience repairing the aluminum tinsel leads.

Those crimps were John O'Hanlon's recommendation. John is no longer active on the CSP. This is just speculation but maybe you could make your own crimp from very thin aluminum tubing, sold at hobby shops.

There such a thing as aluminum solder but I understand it is very tricky to use. There is also, as mentioned in the resto manual, "conductive glue".

Bill LeGall http://www.millersound.net/contact-bill-legall-millersound.html is known for repairing woofers but it may be worth a call to ask if he can repair the leads on your tweeters.

Good luck. The early 2a's are really beautiful speakers and worth repairing.

Kent

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You may already know this but JIC , you can purchase Argentium silver crimps from jewelry hobby suppliers but I haven't seen 24 gauge.   The price is not onerous. I don't know why tin coated base metal would not work.

Adams

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Agree with Adams. Some other options:

  1. Contact CSP member RoyC to repair the leads
  2. Contact CSP member Chris1This1 to repair the leads
  3. Install Hi-Vi tweeters with inductors as described in Restoring the AR-3a. You can always sell the old tweets (even with a broken lead) on ebay.

-Kent

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Many thanks JKent and Aadams for your advice on this project.

The electrical tape is working ok, holding the wires together and I'll leave it alone for now. I read in another thread on this forum that a single strand of copper speaker wire can be used to patch the connection. I will look into it.

I completed the 2nd speaker in a fraction of the time that it took the 1st one. I made some better decisions the second time around that I feel I should duplicate on the first. So I will go back in and redo a few things with the wiring. The most noticeable thing I did was remove the blue plastic insulators. See photo.

I'm very pleased with how they sound and notice that their tone is much brighter now with the new caps and pots. Is the midrange or tweeter that sounds a bit shrill? I have to adjust the working pots now...

Question: What should I use as a replacement for the flimsy thin fabric that goes behind the woofer, that is supposed to keep the insulation away from the cone? 

 

xover2ax.jpg

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Glad things are working out. Looks good.

Yes--you should be able to use a single strand of copper. Be sure to tin it.  

The blue plastic insulator is a wire nut. It's meant to splice 2 wires. So if you soldered them there's no need for the nut.

Things sound brighter because of the crap pots that were in there. If you don't feel you get enough modulation with the pots install a 25 ohm 10w resistor on the Mid pot (refer to the AR-3a resto guide).

And speaking of the guide, in there John suggests 28-count crinoline to replace the crumbling paper Kimpac. However, Roy made a brilliant (IMHO) recommendation for my current 3a restoration: Low loft poly batting from Walmart. A crib-size piece is under $4, in the fabric dept.

Good luck.

Kent

PS. This stuff: https://www.walmart.com/ip/Morning-Glory-Low-Loft-Batting-1-Each/19397503 or from JoAnn's https://www.joann.com/poly-fil-low-loft-bonded-polyester-batting-crib-size-45inx60in/7145667.html

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3 hours ago, JKent said:

 

And speaking of the guide, in there John suggests 28-count crinoline to replace the crumbling paper Kimpac. However, Roy made a brilliant (IMHO) recommendation for my current 3a restoration: Low loft poly batting from Walmart. A crib-size piece is under $4, in the fabric dept.

Good luck.

Kent

PS. This stuff: https://www.walmart.com/ip/Morning-Glory-Low-Loft-Batting-1-Each/19397503 or from JoAnn's https://www.joann.com/poly-fil-low-loft-bonded-polyester-batting-crib-size-45inx60in/7145667.html

Interesting...I have some old speaker grill fabric. Do you think that would work?

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58 minutes ago, David Cutter said:

I have some old speaker grill fabric. Do you think that would work?

I usually make every attempt to re-use the original material unless it is substantially tattered, but regular kitchen cheesecloth will even work in a pinch and it is very flexible and form-fitting. If you plan to replace the original stuffing with new long-strand FG, this issue may be somewhat less relevant if your woofers have screen segments covering the voids in the woofer basket. 

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I have used cheesecloth from the grocery store with success.

d14d51Ll.jpg

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Well...This morning I finished/tidied up the crossover business on both boxes. Experienced some frustration screwing in the woofer bolts as a total of three T-nuts decided to pop out whilst inserting the bolts. Had to glue them in and wait. They sound great...Very happy. My first time trying something like this. Couldn't have done it as well without the helpful people here. 

Next step is changing the dirty, discolored grill cloth. I've seen suggestions for replacement material that I will explore. I'm considering adding a pull tab to the grills to make removing them easier. Has anyone tried this?

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3 hours ago, David Cutter said:

I'm considering adding a pull tab to the grills to make removing them easier. Has anyone tried this?

All the time. Here is a pair of 2ax's with the little pull tab made out of white satin ribbon. 

IjwVLr8h.jpg

The grills are held in place with six 1/2 in round wafer magnets countersunk into the speaker baffle and six into the grill frame.

89GPl8jh.jpg

I know it's been said many times here, but you cannot get anything more authentic than the 18 count lambswool linen grill covering  available from 123 stitch.com  I used the shere black grill cloth from parts express first just because I didn't want to see the grill cutouts.

 

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4 hours ago, lARrybody said:

 

All the time. Here is a pair of 2ax's with the little pull tab made out of white satin ribbon. 

The grills are held in place with six 1/2 in round wafer magnets countersunk into the speaker baffle and six into the grill frame.

I know it's been said many times here, but you cannot get anything more authentic than the 18 count lambswool linen grill covering  available from 123 stitch.com  I used the shere black grill cloth from parts express first just because I didn't want to see the grill cutouts.

 

Excellent solutions!...I read that someone painted the grill frame black to hide the cutouts.

Magnets sound better than Velcro. Thanks.

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