AR 2-ax

[powerglide]

2 hours ago, RTally said:

The fines will be attracted to the magnets in the drivers

All the drivers have been removed now but great point. On further inspection the lacquer needs to be completely stripped back, it has lost its nourishment and degraded back to a brittle coating that should sand off quite easily. I wasn't planning on going that far as they look quite presentable. Finishes have come a long way in 40 years, I have a spray booth and will probably go with a clear satin two pack poly, it will have the same gloss level as original but super hard, probably won't need a wax for ten years. 

 

[powerglide]

1 hour ago, Giorgio AR said:

here's how I solved with a masonite crossover panel that was deformed and useless due to moisture.

Great work Giorgio, it's a shame some many great speakers ended up in landfill 

[powerglide]

Progress.....

So with the drivers out I unearthed the reason for the "fresh" tweeter blobs @ra.ra was referring to, both tweeters have been replaced back in 83, still fairly old but sounded clean to me, will reassess with new caps and better amplification.

 

Crossover panels removed and I will make matching new ones, without the hackouts 

 

Found this photo from a build by another member which makes everything seem a little simpler, as I don't really know what I'm doing with that big box

more evidence to support that the speakers not an original pair, while sanding the boxes back to the raw veneer and raw timber trims the finishes acted quite different, one powdered up and had a stain in it that required scrapping from the corners while the other finish just seem to melt away with a heavier residue.

The solid timber trim was not a full bead with rebates either side, just a 10mm tounge that they groove into the veneered board, makes sense, it's an easy and cheep way to do it. Anyway one set of tounges was really pale, was on the set that had colour in the finish. I've used a lot of American Walnut and have come across some with yellow sapwood streaks that would normally be rejected. These beads are a constant yellow it is possible they are Walnut, they have the same cell structure but looks more like some kind of Maple to me.

I stained the affending beads with some Teak stain and kept repeating until I thought it would be right, hard to judge as the veneer is raw and will change colour tenfold when sealed compared to the solid timber.

 

Had a few corners to reconstruct and a couple of bad repairs from the factory to redo 

 

 

 

Sprayed a couple of undercoats of 25% gloss Acid Catalyst Lacquer 

 

Happy with stain the match and the overall finish

 

Need a rub back and another two top coats in the morning before the temperature rises, 40 deg C. down here today 

 

 

 

 

 

 

 

[JKent]

Beautiful professional work! You set the standard for us all.

The light wood “may” be poplar or sapwood.

Are the big boxes you mention the caps? If so just toss them.  You can salvage some of the wire.

Kent

[powerglide]

Thanks Kent, 

yes the old caps, I'm all over it now after seeing a few pics of other members upgrades, I think the photo I posted was one of yours? I like the heat shrink and will be doing the same. Getting some caps tomorrow and hopefully my bass surrounds turn up before Christmas. 

Only thing I'm missing are the volume pots or L pads, what's the difference? 

Oh, and new terminals if I'm going that way

 

[lARrybody]

When I first started restoring AR speakers I did a couple pairs of 2ax's by wiring two Dayton 3uf polys in parallel and a 4uf and inserting them back into the empty wax block and filling it with siliconized house caulk. I was into keeping everything original looking, by cleaning and repairing the original type  pots and keeping the original screw terminals. Nowadays I no longer keep the original pots and just replace them with something new. I have also just left the wax block in place and placed the new caps to the side. The main thing in my opinion is to make sure the speakers are as air tight as possible. Your restoration is coming along great. Make sure we get to see the new crossover boards installed. 

 

[ra.ra]

18 hours ago, powerglide said:

Found this photo from a build by another member...

Hey, those are my 2ax speakers which were re-built almost 7-1/2 years ago! Thx for sharing. Not sure what happened to my post (now showing up as blank  ?) from last Wednesday, but your progress since then is very impressive. My previous comments were meant to state that classic AR speakers were generally not sold as "pairs", and that the several minor differences that you have uncovered should not be considered particularly unusual. Most likely, these two speakers were assembled during different batch runs several weeks apart, and the minor differentiations simply reflect components which were obtained from different sources. I was a bit surprised to see two different materials used for cabinet stuffing, but that multi-colored material was found in many Euro AR's and is original. For the sake of consistency, my inclination would probably be to replace both speakers with new fiberglass, which according to AR assembly drawing for the 2ax, should be 27 ounces per cabinet.

You are receiving plenty of good advice here, and your cabinet refinishing work looks terrific. No expert here, but I've often thought that the walnut veneer found on the Euro-produced cabinets has distinct differences from the walnut cabinets manufactured in the U.S. - - - could this simply reflect the distinctions between American Walnut and English Walnut species? 

[JKent]

20 hours ago, powerglide said:

Only thing I'm missing are the volume pots or L pads, what's the difference? 

I don’t really know the difference. A pot is a variable resistor. An L pad is 2 rheostats, one in series and one in parallel. ?‍♂️ It’s all Greek to me. In practical terms it doesn’t matter. L pads are cheaper and seem to last longer.

I’m away from my home computer but hope another member will post pictures and instructions on how to wire an L pad and resistor 

Kent

[Aadams]

Even if your pots seem to be exceptional after 40 years LPads with resistors are better path.

Look at the March 25 posts in this thread.  Because you are working completely outside of the cabinet you can easily copy the tidy version by RoyC.

 

[RoyC]

13 hours ago, JKent said:

I don’t really know the difference. A pot is a variable resistor. An L pad is 2 rheostats, one in series and one in parallel. ?‍♂️ It’s all Greek to me. In practical terms it doesn’t matter. L pads are cheaper and seem to last longer.

They are both types of rheostats, and they both control the output of a driver by providing varying amounts of series and parallel resistance. (There is also something called a "fixed" L-pad, which is a simple circuit comprised of a series resistor and parallel resistor, which provides non-variable modification of a driver's output.)

For our purposes both types of controls provide the same function. Technically speaking, a variable L-pad is a bit more sophisticated than the AR potentiometer because it uses two variable resistor elements instead of one. It works quite well as is, but for more authentic restorations the addition of a 25 ohm parallel resistor to the parallel leg (between L-pad terminals "1" and "2") can make an 8 ohm L-pad act more like the AR pot at the most often used settings...the benefit of which is most noticeable when used with midrange drivers.

There is alot of nonsense being said about the L-pad approach in a current Ebay listing for a new imported pot replacement. While the item being sold is not bad, the scare sales tactic is false. I have seen many melted/burned out original AR pots in AR speakers, and no burned out L-pads to date. I also provide some services to Ebay's "Vintage_AR" (Larry Lagace) who has sold well over 1000 15 watt, 8 ohm L-pads (sourced from Parts Express and Madisound) for use in AR speakers. Other than a few defective ones out of the box, he has never received a report of a burned out L-pad.

Roy

[powerglide]

Thanks for the info lads

I can't find any compatible L Pads over here although I have been looking for 16 ohms - 25 watts. I'll look for the ones mentioned, if I can't get any here, and have to order from the US I guess the 25w resistor route sounds the way to go? 

Surrounds never showed up so I rubbed the boxes back and gave them another 2 hits of flat, looking superb. Progress will slow now with Christmas and waiting on parts 

 

 

[powerglide]

On 12/22/2019 at 9:05 AM, lARrybody said:

When I first started restoring AR speakers I did a couple pairs of 2ax's by wiring two Dayton 3uf polys in parallel

I just finished some boxes for a speaker nut and he gave me some components for the crossovers, not sure what brand they are but I will be utilising 2's and 4's in parallel for the mids 

[JKent]

The L pads you want are 8 ohm 15 watts.

Power ratings of L-pads differ from pots. Sometimes there are Russian 25w 15 ohm pots on ebay but I only see one now. 

Looks like you scored some Russian paper-in-oil caps. Nice. 

Try ebay for the L-pads. They’re all made in China or Taiwan anyway.

Kent

[powerglide]

5 hours ago, JKent said:

The L pads you want are 8 ohm 15 watts.

And these can be used with or without the 25w resistor? 

[JKent]

Follow Roy’s advice. Use the resistors on the mids. Not necessarily needed on the tweeters.

Don’t mix up ohms and watts (I did that first time around).

25 OHM, 10 watt resistors 

[lARrybody]

If you are using 1/8 in.thick crossover boards you will want the 8 ohm 15 watt mono L-pads with the 3/8in shafts. The 1 in shafts will work, but the 3/8 in shafts are a much better fit. I have made this mistake myself before.

[powerglide]

Rats, just ordered the 1" 

PE guaranteed delivery 2nd Jan

I was going to use the majority of the old wiring, but the guy who gave me the caps said I should start again. What gauge should I be using and any specific configuration better? 

Alan 

 

 

[JKent]

You can make a spacer to put between the bodies of the pots and the back of the Masonite so the shafts won’t protrude too far.

Best wire is tinned stranded 18 gauge, sometimes called marine grade.

Nothing wrong with using the old wire where you can. It’s color coded which is nice. 

[powerglide]

Managed to cancel and re order the 3/8" shafts

22 ohm resistors were the closest they stock,

Jantzen Audio 22.00 Ohm 10 Watt Audio-Grade Superes Resistor

Will these be OK 

[Aadams]

12 minutes ago, powerglide said:

22 ohm resistors were the closest they stock,

I made the same mistake but had I known what I was doing at the time I would have found this one. They no longer stock the 5% but there is a 1% for just a bit more.

https://www.parts-express.com/dayton-audio-dnr-25-25-ohm-10w-precision-audio-grade-resistor--004-25?gclid=EAIaIQobChMI_-ui6rbT5gIVTfDACh0EGgfoEAQYAiABEgLDxPD_BwE

 

[JKent]

Roy has experimented with resistors extensively so he’s the expert on this but I ‘d say the 22 ohms are fine

[ra.ra]

I like using the thin green resistors made by Jantzen, Mundorf, and Lynk, and because of their length and ample lead wires, my own preference would be to install it directly to the backside of the driver and solder in place. Not sure who provided this diagram, but the attached schematic clearly shows how the added resistor could be located either at the L-pad or on the driver.  

[RoyC]

powerglide,

A 22 ohm resistor takes it back out of the realm of electrically "original".  You may find it attenuates the driver a bit too much. The proper Dayton 25 ohm resistor recommended in the PE link provided by Aadams is in stock!

I prefer the 1" shaft L-pad. It is very easily adjustable to the proper length, and allows for any crossover wiring to be run under the L-pad body if necessary. Either version will work just fine.

The resistor difference is more significant than the L-pad shaft if authenticity is one of your goals.

Roy

[JKent]

So of course  I defer to Roy on this but shipping from PE to Oz is an issue.

They MUST sell plain ol’ wirewound resistors down under. You don’t need so-called Audio Grade or non-inductive.

[genek]

I'd start here:  https://au.mouser.com/