Jump to content
The Classic Speaker Pages Discussion Forums
David Cutter

AR 2ax Advice Please

Recommended Posts

AR 2ax Advice Please

I bought a nice pair of AR 2ax recently for $200. Early 1969 model with fabric woofer surrounds etc...All drivers appear to work OK. 

Cabinets are overall very good, not much visible wear.  
The pots were gritty sounding so I removed the woofers and gave them a Deoxit treatment. They turn easier now, and I believe one of the tweeter pots may still actually function. 

I am using a Marantz 2270 receiver, and my music source is currently Tidal and Apple Music via a 2018 Mac mini.

They sound quite good to me as they are. However, I have noticed  harshness in the upper-mid frequencies on vocals and piano on some recordings. I have done a lot of research on recapping and cleaning/replacing the pots, and am totally prepared to take the plunge.

MY QUESTION: Should I just go ahead and fully service them, or just take care of the pots first and listen to the results, or recap first and see? Or...Leave them original as they are?

What should I listen for to know what to do? What kind of improvements should I expect to hear? Should I try to clean the original pots first before opting for replacement L-pads?

Any advice/comments would be greatly appreciated. Thanks in advance.

Share this post


Link to post
Share on other sites

David

Welcome.

Do the cabinets have the correct drivers?  The cloth woofers indicate a probable driver configuration.  If you remove the grills and supply photos of the front so we can see the drivers it will be helpful. Also any photos of the interior when you removed the woofers.  There is plenty of help here.  

Out of curiosity what device serves as the interface between the Mac and the Marantz?

Adams

 

Share this post


Link to post
Share on other sites

Thanks... tried to upload photos several times, but keep getting an error (200) message from the website. Do they restrict new members from posting pics here? 

They are the correct round alnico magnet woofers. AR switched to foam surrounds in the early 70s I believe. I connect from the Mac to the receiver via a 3.5 mm jack to RCA cable. 

Share this post


Link to post
Share on other sites

There are photo size restrictions on all of us but they are quite liberal. Screen captures and snips work well.   Are you the first person to ever attempt a repair on these speakers?  Are they original?  Which tweeter do you have?  Did you open the pots to clean them or did you squirt juice through holes?  Have you listened close up to determine in which driver the harshness appears?  On the back, remove the wire jumper from the T terminal and play woofers only.  Do you still  hear the sound?   Be sure to replace the jumper.

Have you downloaded the Restoration guide?

Are all of the drivers operating in both speakers?  If they are working properly the 2ax provides a smooth balanced sound.   Photos will be most helpful.

Share this post


Link to post
Share on other sites

I agree that photos would be helpful and I would like to share. I tried different browsers Mac and PC and I see the upload  progress bar, but get the same error message each time about a problem processing. I messaged the site moderator earlier about the issue.

All drivers work and all components inside and out appear original. No visible signs of previous repairs.

I just squirted cleaner in the holes in the pots and turned them for a while. They rotate more smoothly now. I know a proper cleaning will require removing and opening them up.

Just bought an Audioquest Dragonfly DAC on eBay yesterday. The harshness I hear could be digital noise   ???  The external DAC should make things sound smoother.

Share this post


Link to post
Share on other sites

If your photos are on a PC, use the snipping tool to grab the piece you want then copy and paste it into your post.   This problem is unlikely to be related DACS and more likely to be a Pot problem. I too am all digital, meaning no vinyl or tape.

 

Share this post


Link to post
Share on other sites

 I use a PC at work...Your solution solved the problem! Thanks 

image.png.5f83933c6fe5da9109f832e433950583.pngimage.png.83bf30acceb5e7bfada3a989ac7987dc.pngimage.png.431e6ddf350851388d9c870c1e3134ed.png

Share this post


Link to post
Share on other sites

Those are fine examples.  The drivers are correct.  Those woofers have a tendency to come unglued at the spider and between the woofer frame and masonite rim where the cloth roll attaches.  

 

Assuming the "harshness: is not coming from your amp. 

My suggestion is

1. Isolate the woofers by removing the jumper from the T terminal to check if you still hear the harsh sound to which you refer.

2. clean or replace the pots first but also check the woofers closely for detached areas after they are removed.  Look at the 3a restoration guide.  You can open the pots for inspection without cutting the wires.  If they are not too bad they can be cleaned sufficiently to test at least and maybe for adequate long term use.

3. The tweeter crossover is around 5000hz.  They are not easy to hear when they are working and easy to miss when they aren't.  If you hear them next to a pair 2ax with properly working tweeters the difference is obvious.

This is to get you started.  If you want new caps and pots there is a bit more effort but the good news is now that you have photos the real 2ax experts will be coming along soon.   Report your progress.

Adams

 

Share this post


Link to post
Share on other sites

Welcome David!

Those look really nice and should give a lot of listening pleasure.

Definitely replace the caps. It's cheap, easy and those wax blocks have probably drifted over the las half century. You "can" replace the pots with L-pads. There are instructions somewhere in these pages. Some members prefer cleaning the pots to keep everything original but they will require cleaning again in a few years.

When everything is sealed up with new foam gasket tape from PE, do the 3-finger push test on the woofer. If it returns slowly, great. If it springs right back you'll need some of RoyC's cloth surround goo.

Regarding the photos. you want to resize pics to about 100Kb or so. There are probably many ways to do it. I use Photoshop Elements on my Mac. Go to Image > Resize > Image Size. Resize the pic to about 6" on the longer side, adjust the Resolution to about 100 and save the pic with a Quality level of about 8. That should give you an image in the ballpark of 100Kb that can be easily uploaded to this site.

-Kent

Share this post


Link to post
Share on other sites

Very grateful for all of the fantastic advice.

I ordered new caps from PE and plan to attempt cleaning the pots w/o cutting the wires. I'm concerned about the confined interior space however.

The previous owner told me he had to re-glue part of the surround on one of the woofers. Looks OK to me.

Maybe the Marantz has an issue? I'm actually planning to take it to my hifi guy in Savannah, GA. One channel does intermittently cut out at low volume. 

Couldn't I use plumbers putty to seal the woofers? 

I just re-connected my vintage Infinity Qb's to compare for a couple of days. I like them, they may be considered more of a Rock speaker...Perhaps a less revealing, more forgiving design. The Emit tweeters are nice.

Share this post


Link to post
Share on other sites
37 minutes ago, David Cutter said:

I'm concerned about the confined interior space however.

Internal cleaning can be done easily with a dremel tool and buffer pad.  If you don't have a dremel use q tips.  Serious cleaning for seriously bad pots has to be done externally but if you remove them you might as well go back with lpads IMO.  You can also purchase good used pots from some CSP members.

Do not use plumbers putty.  Use Mortite or Duct seal.    I prefer Mortite because it can be applied in exact lengths and variable widths right off the roll.  Duct seal must be shaped by hand. 

A lot people like the Parts Express foam seal tape.

Adams

 

 

Share this post


Link to post
Share on other sites
2 hours ago, Aadams said:

 

Do not use plumbers putty.  Use Mortite or Duct seal.    I prefer Mortite because it can be applied in exact lengths and variable widths right off the roll.  Duct seal must be shaped by hand. 

I have a Dremel in the house somewhere. Which head should I use? Just ordered the Mortite from Amazon. Gonna get started on the pots this weekend. Is it easy to pry loose the panel the crossover is mounted on?

Thanks

 

2 hours ago, Aadams said:

 

 

Share this post


Link to post
Share on other sites
38 minutes ago, David Cutter said:

Which head should I use?

Use one of the felt polishing wheels. 

40 minutes ago, David Cutter said:

Is it easy to pry loose the panel the crossover is mounted on?

Don't do this? There is no need unless you are parting out the speakers.  Everything can be done through the woofer hole.   http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9246-ar-5-and-2ax/   image.png.017fc0c169950196e5624c8265935fd3.pngJust cut the wires at the cap block and install your new caps.  You can leave the old wax cap in place.

 

 

Share this post


Link to post
Share on other sites

Thanks again. The woofers have six mounting bolts. I noticed that each speaker has one bolt that does not tighten.

Do you know of a way to remedy an apparently stripped screw hole in the baffle? 

Share this post


Link to post
Share on other sites

I am not sure exactly how those woofers fasten but I doubt the threads are stripped.  Both topic and remedy have been discussed on this forum.  When you get the woofers out supply a photo of the problem holes and someone who knows will comment.  

EDIT:  This link discusses your problem.   You have plywood baffles not particle board.  You may just have a loose fastener on the backside of the baffle.

 

Share this post


Link to post
Share on other sites

One interesting thing...The serial numbers are close together in the 22000 range, but the finishes don't match very well when they are side by side. One is noticeably darker.

I know that in 1969 speakers were not always sold as matched pairs, and that stereophonic sound was not widespread yet. So often people just bought one for their current mono system, and bought a second one later when they upgraded to stereo.

Share this post


Link to post
Share on other sites
1 hour ago, David Cutter said:

...each speaker has one bolt that does not tighten....

Aadams has most likely identified your problem - - it sounds like one T-nut in each speaker has lost its grip and is now spinning in place, and that linked thread is a very good reference. The plywood is generally better at maintaining its integrity than particle board, but it is a real PITA any time this situation arises. You'll need to proceed carefully in order to not damage any drivers. One suggestion might be to use a pair of needle-nose vise grips on the offending screw head, and to exert some slight pulling force on the grips while trying to turn the screw - - this will sometimes secure the nut long enough to allow the threads to begin to disengage.

As an added measure to avoid this situation in the future, anytime I have a cabinet open, I always apply a smear of two-part epoxy over the backside of the T-nut to bond it to the front panel material.

  

epoxy 1.jpg

Share this post


Link to post
Share on other sites

Thanks ra.ra.

The bolt comes out easily with a pull. It won't tighten when you insert it into the hole a turn. It just goes around. Perhaps the nut is loose as you suggested, or missing. I'll check it. 

Share this post


Link to post
Share on other sites

"I know that in 1969 speakers were not always sold as matched pairs, and that stereophonic sound was not widespread yet. So often people just bought one for their current mono system, and bought a second one later when they upgraded to stereo."

This is incorrect. Stereo was introduced in 1958 and was an immediate success. Part of the reason that AR had such market dominance in the mid-60's (over a 30% market share in 1965) is that with AR speakers, a listener could easily fit two compact speakers into a living room and enjoy deeper, better bass than from a single older-design bass-reflex speaker.

By 1969, there were virtually no mono systems at all. Everything was 2-channel/2-speaker stereo.

Share this post


Link to post
Share on other sites

 

1 hour ago, Steve F said:

Stereo was introduced in 1958 and was an immediate success.

Thread drift alert!!!!!!!!!!! The OP is clearly not as OLD  experienced as some here and innocently provided a hook for a possible thread hijack on a topic which does nothing to get his speakers repaired. 

Adams

Share this post


Link to post
Share on other sites
On 5/9/2019 at 2:32 PM, David Cutter said:

No visible signs of previous repairs.

I just squirted cleaner in the holes in the pots and turned them for a while. They rotate more smoothly now. I know a proper cleaning will require removing and opening them up.

 

On 5/9/2019 at 3:16 PM, David Cutter said:

 

image.png.431e6ddf350851388d9c870c1e3134ed.png

Hi David,

Examining the crossover photo you posted, the pots seem to have been bypassed (not in the correct way) by the previous owner. The photo is not so clear to see all the wirings precisely.

When bypassing these 16 Ohm pots, the 16 Ohm resistance should be left in parallel with the respective driver (tweeter or midrange) otherwise the crossover network (in this case a 4 uF and 6 uF capacitor for the tweeter and midrange respectively) will be loaded by a different impedance and this will change the frequency cutoff and shift the crossover points in comparison with those of the original design.  

Obviosly,  bypassing the pots (even if carried out in the correct way) does not allow to decrease and adjust the tweeter and midrange volume any longer and this could be a problem.

Attached you can see the normal pot wiring, the early AR 2ax schematic and the correct and incorrect way of bypassing pots.

Luigi

potentiometer-wiring.thumb.jpg.7dbf9aec8215ce2368435b7a6c98407b.jpg

 

 

 

crossover-1-series.jpg.c549cd9fa22fe873170de2eeb94aa84a.jpg

 

 

crossover-1-series_pots_bypassed.jpg.1ec57e34529a7147ff30ed38db2c5ca7.jpg

 

 

 

crossover-1-series_pots_incorrectly_bypassed.jpg.e294757fa33de8bd9ab01c9dc63c9310.jpg

Share this post


Link to post
Share on other sites

Well spotted by a trained expert eye! Who knows how many previous owners these had...

I will have a closer look at the insides this weekend. I'm not experienced reading electrical schematics, but I am interested in learning. They appear logical and probably elementary to an experienced person, but to a novice it's like a new language.

Thanks very much for your interest in my project.

Share this post


Link to post
Share on other sites

Update:

I see now that previous owner cut pot wires to connector 1 and B. The inside contacts are pretty bad and I have tried a few different techniques to clean them up.

Deoxit, Dremel buffer, fine sandpaper, metal polish, elbow grease....

The brown oxidation is difficult to get off. Any ideas? 

See pics. 

IMG_0807.jpg

pot-inside1.jpg

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×