Options in restoring AR-2ax

[MikeW]

Quick question:

Hit a slight snag as the resistor from PE is on backorder until May.

Is there a 'preferred' alternative resistor?

I found this: https://www.mouser.com/ProductDetail/Ohmite/TNP10SC25R0FE?qs=sGAEpiMZZMtG0KNrPCHnjTPAjtLBSopMG9zlno%2fRaPxT80DfEtUMAQ%3d%3d

It's not the standard form factor, but in theory it should do the trick? ¯\_(ツ)_/¯.

They are foil, so inherently non-inductive as I've found it difficult to find resistors that specifically call out weather they are inductive or not.

[lARrybody]

Try these two alternative sources.

http://shopping.na3.netsuite.com/s.nl/c.650256/it.A/id.621/.f?sc=15&category=766

https://www.madisoundspeakerstore.com/wirewound-25-watt/25-ohm-25-watt-wirewound-resistor/

Or I can send you a couple of the Parts Express resisters.  PM me.

[JKent]

You don't need non-inductive (the Daytons that are OOS are not non-inductive). And if you're looking at Mouser, any of these will do: https://www.mouser.com/Passive-Components/Resistors/Wirewound-Resistors/_/N-7fx9f?P=1z0x88bZ1z0z819Z1z0z357Z1z0wt4wZ1z0wn9aZ1z0wn9r&Ns=Pricing|0

Or PM Larry 

 

[MikeW]

Thanks all.  Placed an order and it should be here by the time the rest of the stuff from PE get to me.

With some luck I can sit down and start to work on the speakers in a bit over a week.

[MikeW]

As the parts have started to arrive, and putting the speakers back together will be happening soon I've been doing some reading on the wiring of the L-Pads into the speaker circuit.

I found this schematic pretty helpful:

 

Also noting that the L-Pads align to the older pots as follows:

L-pad #3=Pot #1

L-pad#1=Pot #2

L-pad#2=Pot "B"

My question is, where do the resistors get wired in there?  Is there a picture or schematic?  All I've been able to find is that they are wired across the #1 and #2 L-Pad terminals.  Which then begs the question, are there two per speaker or just one across a specific L-Pad?

[RoyC]

1 hour ago, MikeW said:

Also noting that the L-Pads align to the older pots as follows:

L-pad #3=Pot #1

L-pad#1=Pot #2

L-pad#2=Pot "B"

My question is, where do the resistors get wired in there?  Is there a picture or schematic?  All I've been able to find is that they are wired across the #1 and #2 L-Pad terminals.  Which then begs the question, are there two per speaker or just one across a specific L-Pad?

A 25 ohm resistor is wired across each driver equipped with an 8 ohm L-pad. Page 15 of "Restoring the AR-3a " in the CSP Library shows placement in a schematic.

Roy

[JKent]

I think this is Roy's photo

[MikeW]

Thanks both for the info.  I had been looking at the schematic in the restoration guide and it just didn't click, hence the post.  That picture is not how I would have imagined doing it, but it looks very simple now that I see it.

Unfortunately, it means I'm placing another oder as for some reason I had it in my head that it was only one resistor per speaker.  Oh well.

Thanks again!

[MikeW]

Hi everyone,

I finally have all of my parts in (hopefully) and have been fiddling with the wiring for a little bit now.  A few questions as I'm getting a little confused with the different schematics not really aligning up... mind you this could easily be me.

The picture I posted four posts above of the wiring for the 2ax appears to differ from what I see in the restoration guide.  I got that picture from this thread: 

For example the picture above shows the 6uF capacitor going to the mid driver but the restoration guide shows the 6uF going to the Tweeter and the 4uF going to the mid.  Can someone please confirm?  

Also, the schematic in the restoration guide shows a yellow wire coming from the terminals but I have black for high and green for mid coming from the terminals with yellow a coming from the 'B' pot going to the drivers.

To alleviate my confusion, I've written out the wiring as it was and then how I think each connection should be.  If someone can look over my logic I'd appreciate it.  This writing does not reflect the inclusion of the resistor between the L-Pad 1 and 2 connectors as shown above.

Tweeter:

• Old:   T --> 2_Pot --> Black Wire --> Tweeter
• New: T --> 1_Lpad --> Black Wire --> Tweeter
•  
• Old:   1 --> Capacitor --> 1_Pot
• New: 1 --> 6uF Capacitor --> 3_Lpad
•  
• Old:   B_Pot --> Yellow Wire --> Tweeter
• New: 2_Lpad --> Yellow Wire --> Tweeter

Mid:

• Old:   T --> 2_Pot --> Green Wire --> Mid
• New: T --> 1_Lpad --> Green Wire --> Mid
•  
• Old:   1 --> Capacitor --> 1_Pot
• New: 1 --> 4uF Capacitor --> 3_Lpad
•  
• Old:   B --> Yellow Wire --> Mid
• New: 2_Lpad --> Yellow Wire --> Mid

 

Thanks for any confirmation, clarification or correction of the above!

[MikeW]

So after some additional reading and (mostly) looking at pictures, I think I had it wrong above.

Looks like the picture I posted above was correct and most people have the 4uF going to the Tweeter and the 6uF going to the Mid-Range.  It also seems that AR was not particularly consistent with their wire colors.

So that's how I wired it up.  Tested it at very low volume and sure enough I could hear the Tweeter and Mid-Range drivers.  I put the fiberglass back in, sealed up the woofer and ta-da, a seemingly fully working speaker.  All that is left to do is oil the cabinet and attach the cover, which I intend to do with velcro to make removal easy in the future.

I hooked it up to an Audio Refinement amp (125 W) and pre-amp and it sounded great.  In the short bit of time I was playing it, I could hear it open up a bit so I assume I can expect a bit more of that as everything settles in.

As has been said before, despite the fact that AR says 100 W is sufficient, I can hear how it is a power hungry speaker.  I can't wait to get it into it's final room placement and hooked up to the big Mac (250 W).

I'm including pictures of the final wiring.  If anyone sees anything wrong with what I did, please let me know.

[Cassrat]

MikeW,

Great to hear you are up and running.  I just received my new (old, lol) woofers from eBay...still no luck.  I am thinking it might be my capasitors.  I have seen many people say they almost never go bad.  But mine were stored 30+ in a garage, so I am wondering if that could be the problem.  Anyways, again glad to hear you're playing music again!

Mark

[MikeW]

Mark, I can't speak specifically to the point of the capacitors never going bad.  I replaced mine because there was no reason not to while I was in there and my pots were definitely bad.  As for your specific situation, sorry to hear that things aren't working out for you, though the woofers do not go through a capacitor, but the inductor coil.  I'll let much more knowledgable people weigh in to what might be your issues.  Hopefully you'll be listening to music soon!

[JKent]

Mark,

Old capacitors almost always go bad.

But there are no capacitors in the woofer circuit. There is an inductor, but those don't go bad (it's just a spool of wire).

Have you tested the woofers outside the circuit? Just attach a woofer's leads to an amp's output at LOW volume and you should hear the music.

-Kent

[RoyC]

Mark,

Which thread do you want to discuss your woofer issue in? I've been responding in the one you started.

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/10041-restoration-stopped-at-woofer/&page=2

You are receiving essentially the same information in both threads.

Roy

[MikeW]

Hi all, finally got a chance to wire up the other speaker and play them as a pair.  

Both sound great!  Frankly I'm quite (pleasantly) surprised at the soundstage these speakers put out.  When placed on the same Audio Refinement amp in the same location/room as some Boston Acoustic Lynnfield VR's the AR's fill the room much better (though the Boston's are very detailed so are perfect for home theatre).

Nothing more for me to do other than move them into place and hook them up at home.

I want to sincerely thank everyone here who offered to help and provided (much needed) advice.  I know I really lucked out that all the drivers were in working order and it was just bad caps/pots that were the issue but the electrical was still all new to me so I thanks again.

Cheers all!

[MikeD2]

Just jumping in here as a total (old) novice and a new member.  Thanks to everyone who took time to photo the electronics in the AR-2ax's, as I'm a dunce when it comes to that stuff and need visual confirmation that I'm reading even simple schematics correctly (I am a 75 year-old retired chemist, not an electrical engineer, and all that schematic stuff was always "Greek" to me.)

I am just now ordering restoration parts for my two original-purchase AR-2ax speakers manufactured and purchased by me somewhere back in the late '60's, probably around '68.  I will try to restore this AR-2ax pair before jumping into restoring my venerable AR-3a pair which have been providing only bass for years on a simple home theater setup.  I have ordered new caps and speaker foam for the 2ax's and will go with new L-pads instead of trying to clean the old pots (which I tried to do a couple of years ago with little success on the 2ax's.)  My speakers have been kept in normal living quarters temperature and humidity, so no old garage or basement storage problems.

Does the manufacturing date matter on either the 2ax's or the 3a's in terms of choosing components?  How does one "date" AR speakers and is it necessary, or are techniques applicable to all years/models?

In switching to L-Pads, there are several different links to the 25-ohm resistor.  Does the power rating matter on these (ranges from 10 to 25W)?  And does the tolerance really matter in this application (1% to 10%)?

Sorry for the ignorance, and apologies if these questions have been covered in the hundreds of pages here.

 

[JKent]

Welcome fellow septugenarian?

First, if you haven't done so, download the AR-3a restoration guide. It is relevant to both the 3a and 2ax http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/

Tha manufacturing date only matters insofar as th 3a and 2ax both used cloth surround woofers during early production years, then switched to foam. And early 2ax's used red phenolic dome tweeters like the 2a and the 3. You obviously have later ones with foam surrounds. The photos below show an early pair with cloth surrounds on the left. On these the red dome tweeters were bad so I replaced them with later ones, like the ones in the pair on the right.

For the 25 ohm resistors, 10w is good, and only put them on the mids, not the tweeters. Cheap 5% wirewound are fine. You don't need "audiophile" or "non-inductive".

Please post some pictures and good luck with the project.

Kent

[MikeD2]

Thanks, @JKent.  I need to pull the grille cloth off one of the AR-2ax's and verify that I do have foam speakers -- it has been a couple of years since I had them off.  I did purchased them in late '68 if memory serves me correctly. 

It would be nice if someone would put together a "kit" for these speaker rebuilds.  I have pots and foam enroute along with the caps, but from two different sources, and now a third for the resistors.  Shipping isn't all that much, but it adds up and a nice kit with foam, pots, caps and resistors would be welcome from a common source and a single shipping fee.  But then, I doubt many people are rebuilding them any longer.  Sad, because they are outstanding speakers. 

Checking one of the 2ax speakers, the serial number is FX250128, if that means anything in terms of dating them.

Edit:  I did pull the grille cloth, and the speakers are indeed foam and look like new.  I did order a foam kit so I guess I'll go ahead and replace the foam anyway since I paid for it.  The sealer may be leaking a bit, but pressing gently on the cone doesn't seem to indicate much leakage if any.  Main problem is the pots and caps, I suspect.  They haven't been used in several years and kept protected in a closet, and the pots are scratchy and intermittent as I recall when using them last as rear speakers.  Wife didn't like them in the room so they were relegated to the closet.

A bit OT here, but I'm using a big Sony STR-D 1015 Receiver driving my AR-3a's (bass only at this time) and a JBL center speaker for the entertainment center.  I'm planning on replacing my 5-CD turntable/changer with an inexpensive but good single CD player (need to do some research on that.)  LPs are on a Technics SPL-1200 MK2 turntable with a Shure V15 type III cartridge.  Good stuff.

[MikeD2]

Egg on my face!!

What I thought (without looking for years) was a pair of AR-2ax speakers are really AR-4x speakers.  So I'll change the topic title (if I can) and apply the questions to the 4x.

The AR-4x has a 20 mfd capacitor with the inductor coil strapped on top of it.  So two questions:

Some posts suggest that the 4x cloth surrounds may not need doping.  Mine look good but I did not get the slow return when the cone is pressed so I ordered the dope from Vintage AR.  If anyone sees anything I'm doing wrong here, let me know.

Second, I assume that the same L-pad with 8 ohm resistor works with this speaker as it does with the 3a's.  If not, please yell.

So sorry about the title.  I've had these speakers since 1970 and haven't looked at the back of the speaker for the model number in over 40 years. 

[JKent]

1 hour ago, MikeD2 said:

Second, I assume that the same L-pad with 8 ohm resistor works with this speaker as it does with the 3a's.  If not, please yell.

You can use the same 15 watt 8 ohm L-pad but do not use any resistors.

Suggest you just start a new AR-4x thread.

[MikeD2]

53 minutes ago, JKent said:

You can use the same 15 watt 8 ohm L-pad but do not use any resistors.

Suggest you just start a new AR-4x thread.

Yes, I should do that.  Thanks @JKent

[Chilo61]

Hi Guys,

 

I am new here but have been a AR2ax user on the other side of the pond(UK) for a while now.  I currently try to replace the pots with them. 

I found this on ebay and I wonder if they can be used? 

"Single Turn Resistor 25W 30 Ohm Adjustable Taper Ceramic Disk Rheostat E5U6"

They are cheap Chinese made but it is a simple job so it can't go too badly with the construction, right?

What I concern is the spec if they work at all!

Thanks for your advise in advance.

https://www.ebay.co.uk/itm/174850446088?epid=1390877908&hash=item28b5e61308:g:HxgAAOSw805g97mS

 

[JKent]

Two problems with those: First, they are the wrong value. You need 15 Ohm, those are 30 Ohm. Second, like the expensive Ohmite pots, those are open in the back and you would need to construct some sort of enclosure to keep the fiberglass out.

If you check the For Sale section you'll see some pots I'm selling. https://community.classicspeakerpages.net/topic/13225-potentiometers-for-ar/   PM me if interested. Postage to the UK is $26 USD for the 4 pots you will need.

Kent