MikeW Posted March 11, 2018 Report Share Posted March 11, 2018 Hi all, I've been browsing the forum for some time and figured it's time to take the plunge and introduce myself. I have recently come into possession of a pair of AR-2ax speakers and am looking at my options and what needs doing to get these speakers working properly. With my apologies as this topic has been discussed extensively, I did not want to jump onto the thread that (as of this first post) is very close to the top of the board, to not confuse the answers to what may (or may not) be different questions. My father purchased these speakers new at a store on the Upper East Side of Manhattan in 1968 or 1969 (the serial numbers are separated by 16). The speakers were paired with a Fisher 400-T (which I also have) and have lived in continuous use at various locations with my parents ever since. About 2 years ago they moved into a new apartment and purchased some new smaller bookshelf speakers to fit in the new space, at which time the AR's went into storage at our cabin where they have been patiently waiting wrapped in bubble wrap. A few days ago, I finally unwrapped them, hooked them up and got very little. A bit depressing as I do not remember the speakers having issues before they were put away but I haven't lived at 'home' for a while at this point. Obviously the reason that I'm here is that I'd like to get these speakers back to working order so I can take them home and hook them up to my McIntosh MC2255 and C33. After reading as much as I could quickly find a few observations: 1) The cabinets and grills are in great shape. The cabinets need a little wood oil (BLO or similar) to bring them back but there are no large scratches or marks. 2) The woofers appear to be in decent shape. They 'glide' back when pushed in and appear to make decent bass and vocals. It's quiet, but hard to tell if normal or not given #3. 3) The mids and highs are effectively not there. I can play with the controls in the back (horrible grinding noises) and get the tweeter to come on but very quietly. I don't think I can hear the mid at all. I've attached pictures of both speakers. My first question would be (difficult as it may be), based on the photos, is there something I'm missing about the condition at first glance? I'm trying to figure out if this is something I should tackle myself or would it be easier to find a repair shop in the NYC area (or within a day drive) or just forget the idea of using them altogether. Secondly, based on my reading it is likely that I need to remove and clean or replace my pots and possibly replace the capacitors? At which point I have to ask, how hard/easy is this to do? Reading the forums always make it seem easier than it actually is. And here's the caveat. I'm great at following directions, but not the greatest diagnostician. Thanks in advance for any assistance! Quote Link to comment Share on other sites More sharing options...
Cassrat Posted March 11, 2018 Report Share Posted March 11, 2018 Hi Mike, and to all here. I'm Mark. Wow, almost the same thing here. Been following this forum for weeks, and decided yesterday to create an account. I have the exact speakers. There Alnico magnet is stamped May 22, 1968. Mine were in a garage 30+ years (free). Tweeters worked, mids didn't. Was able to clean pots in place, as they looked new, and those two drivers are functioning. I'm stuck at the woofer. It still won't play. Same problem with the other side. I would like to follow your restoration, and keep my questions separate (I don't want to highjack your restoration thread). I would like to get mine playing (not going for perfection), for their 50th anniversary. With that, wishing you the best for your restoration!!! Mark Quote Link to comment Share on other sites More sharing options...
JKent Posted March 11, 2018 Report Share Posted March 11, 2018 Welcome Mike and Mark! The AR-2ax is a wonderful speaker and yours, Mike look great! 12 hours ago, MikeW said: based on my reading it is likely that I need to remove and clean or replace my pots and possibly replace the capacitors? At which point I have to ask, how hard/easy is this to do? Yes. The pots are bad (the "horrible grinding noise") and the capacitors are more than half a century old and unless they are the oil-filled cans found in the 2a they are wax blocks and will be way out of spec. Please download and read the AR-3a restoration booklet pinned to the beginning of the AR section. The 2ax was one step down from the 3a, produced at the same time, and much of the info there will apply. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/ The pots "may" be able to be cleaned and used, or you can switch them out for L-pads. The capacitors are fairly easily replaced. Do you have a soldering iron and know how to use it? Finding a good repair shop can be dicey. We've seen classic speakers in these pages that have been mutilated and ruined by "reputable" repair shops. If you want to drive to NJ I can recommend Bristol Electronics in Ho-Ho-Kus. Tim works on electronics (he's an authorized Mac repair center btw) but he may be willing to take on your speakers. Mark--similar advice. Download the 3a rest guide. Both woofers being out is curious. First check the terminals in the back and make sure there is a jumper (short piece of metal or wire) from T to 2. If that's missing it would explain the problem. Maybe something got knocked loose or mis-wired when you did the pots? Did you replace the caps? There is an extensive discussion in this thread (one of MANY) and the 2nd post shows what your terminals should look like (and this is one sad story of a "pro" screwing up some beautiful classic speakers). Good luck to both on VERY worthwhile projects. Ask questions and we'll answer! -Kent Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 11, 2018 Author Report Share Posted March 11, 2018 Hi Kent, Thanks for the quick reply! I had been reading the restoration guide (actually downloaded it ~2 years ago when I first started weighing my options. In re-reading my post above I decided to start playing with the speakers and the Fisher. I wired one speaker up at a time and started playing with all settings to try and bing back some echoic memory and see if I could recreate what I thought these speakers sounded like. While I believe I had to turn the volume up a bit more than I remembered, I realize that when I was using this stereo more often I was likely turning up the treble and getting most of that from the woofer. So the speakers have likely needed attention for quite some time. With that said, I decided to open the speakers up and see what I have in front of me. I am optimistic that given that I know the full history of these speakers and they have almost exclusively been used reasonably in conditioned space that I just need some basic restoration and that the bones (drivers) are all still in working order. While I did not test the woofer, as I said, it seems to produce nice sound and there does not appear to be any internal damage. I couldn't quite make out the date on the magnet. Looked like 12.27.1968 but the faded red stamp on shiny brass is hard to make out. I am going to try and do this job while removing as little as possible so here is where I stand. The woofer is removed and placed aside. I did not remove the wires, just put the woofer out of the way. I removed the shroud just below the woofer and enough fiberglass to access the controls and have them removed. Will report back. And welcome Mark. Good luck with your project not the other side of the coin! I look forward to following along. Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 12, 2018 Author Report Share Posted March 12, 2018 So I got the pots off and took them apart. The High pot seemed to clean up pretty well but the mid looks to have been eaten away in the center. Thoughts? Is this workable, or time to replace? TIA High Before High After Mid before Mid after Quote Link to comment Share on other sites More sharing options...
dxho Posted March 12, 2018 Report Share Posted March 12, 2018 Spin that center disc 90° on the mid pot, it might be usable. Position the corrosion opposite the ends of the wire. Quote Link to comment Share on other sites More sharing options...
JKent Posted March 12, 2018 Report Share Posted March 12, 2018 Or use cheap, reliable L-pads from Parts Express, Madisound, Erseaudio..... Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 12, 2018 Author Report Share Posted March 12, 2018 12 hours ago, dxho said: Spin that center disc 90° on the mid pot, it might be usable. Position the corrosion opposite the ends of the wire. How would you recommend doing so? They don't just spin freely, or even with a solid push with a screwdriver. Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 12, 2018 Author Report Share Posted March 12, 2018 10 hours ago, JKent said: Or use cheap, reliable L-pads from Parts Express, Madisound, Erseaudio..... As I've been doing my initial reading over the past few weeks I've been looking at my different options in case the pots do need replacement. Per the AR-3 restoration guide, the options seem to be the Ohmite RHS-15R and various L-pots. It appears that the Ohmite's are the preferred (but more expensive) option. Is there a performance difference between the two that might justify the price difference? Wondering if one can one mix and match? As in, if I have good pots I can reuse those while putting in an Ohmite unit in the same or different speaker and expect the same performance? Or to expect uniform performance, I should use the the same (originals, Ohmite or L-pads) across both speakers? PS: kicking myself as in reading 'sarals' thread, I didn't even think about doing what she did and try to repair the pots in the speaker. I easily could have at least inspected before I desoldered the wires. Quote Link to comment Share on other sites More sharing options...
JKent Posted March 12, 2018 Report Share Posted March 12, 2018 The resto guide may be dated. Ohmites are ridiculously expensive and are not sealed, so you have to put them in an enclosure. I used Ohmites in my 3a's and even though I only paid $7 each for them at the time they were a royal pain and not worth it. The L-pads are cheap and easy to install. Just be sure to wire them correctly. FWIW, ebay seller "vintage AR" sells plain ol' L-pads (for $15 each as opposed to Erse's $3.50 ea) and writes this in his ad: Superior to the original control which AR used earlier and was eventually utilized in the AR-3a Limited. It is heavy duty, has finer turns for better set-ability, is ventilated for heat removal and has excellent contact life. All controls on all early model AR speakers were the same, both the High Range and the Mid Range. We use these in all AR speaker restorations. We have been using and selling these for over 15 years and have never had to replace one. Personally, I would not "mix and match". You can buy 4 L-pads, plus resistors for the mids, and sell the old pots on ebay. -Kent Quote Link to comment Share on other sites More sharing options...
dxho Posted March 12, 2018 Report Share Posted March 12, 2018 5 hours ago, MikeW said: How would you recommend doing so? They don't just spin freely, or even with a solid push with a screwdriver. Depends on your toolbox and attention span :-) I'd probably escalate tactics until I got it turned or broke it/ proved I couldn't turn it. Nothing to lose, really. Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 13, 2018 Author Report Share Posted March 13, 2018 11 hours ago, JKent said: The resto ...-Kent 6 hours ago, dxho said: Depends on your toolbox and attention span :-) I'd probably escalate tactics until I got it turned or broke it/ proved I couldn't turn it. Nothing to lose, really. Thanks both for the information. I got a chance to take apart the other speaker and these pots looked to be in worse shape. While the High pot shined up nicely, there is pitting and some metal was removed. The Mid is very pitted and appears quite corroded even after polishing with a Dremel wire wheel. Given this information, I'm tempted to go the L-pad route. So I put together my shopping list: 2 x Dayton Audio DNR-25 25 Ohm 10W Precision Audio Grade Resistor 2 x Dayton Audio PMPC-6.2 6.2uF 250V Precision Audio Capacitor 2 x Dayton Audio PMPC-4.0 4.0uF 250V Precision Audio Capacitor 2 x Acoustic Research, AR Speaker Level Control (from Vintage-AR) or 2 x Parts Express Speaker L-Pad Attenuator 15W Mono 3/8" Shaft 8 Ohm and 2 x Acoustic Research Speaker Cabinet Sealer (from Vintage-AR) Am I missing anything to put the speakers back together? And do you think there is any difference between the L-pads offered by Vintage-AR versus the ones offered at Parts Express? Other than about $10/unit. High Mid Quote Link to comment Share on other sites More sharing options...
JKent Posted March 13, 2018 Report Share Posted March 13, 2018 The PE L-pads are EXACTLY the same as the ones sold by Vintage AR. Save your money, especially since you have a PE order anyway. Also--the gaskets or sealers sold by PE are as good or better than the duct seal sold by Vintage AR. I like the "Parts Express Speaker Gasketing Tape 1/8" x 3/8" x 50 ft. Roll" or "Parts Express 12" Speaker Sealing Caulk Box of 72 Pcs". I see the PE speaker caulk is out of stock. This will work: https://www.amazon.com/Gardner-Bender-DS-110N-Duct-Seal/dp/B00689V41G/ref=sr_1_2?ie=UTF8&qid=1520911355&sr=8-2&keywords=duct+seal also available at Lowes https://www.lowes.com/pd/Gardner-Bender-16-oz-Duct-Seal/4595233 or Home Despot or your local hardware store. I'm pretty sure this is the stuff Vintage AR sells--just cut into smaller chunks. -Kent Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 13, 2018 Author Report Share Posted March 13, 2018 Follow-up questions before I place the order. While I recognize that I'm not going the 100% OEM route, my plan is to keep the capacitor box in place and just unsolder or cut the wires leaving as much wire attached to the box as possible. Then putting them aside. This is just for looks and "the ability to go back to stock". Something left over from my automotive hobby. Question 1: How does one mount the capacitors/protect from the stuffing giving a little air space? Most builds/guides show a mounting bracket but I was looking last night and couldn't find one to purchase so I assume most people just make one up from other parts. Question 2: What gauge and material wire is used internally? I'm going to need some additional for the resistor and capacitors. TIA! Quote Link to comment Share on other sites More sharing options...
JKent Posted March 13, 2018 Report Share Posted March 13, 2018 15 minutes ago, MikeW said: While I recognize that I'm not going the 100% OEM route, my plan is to keep the capacitor box in place and just unsolder or cut the wires leaving as much wire attached to the box as possible. Then putting them aside. This is just for looks and "the ability to go back to stock". Something left over from my automotive hobby. Good idea 15 minutes ago, MikeW said: How does one mount the capacitors/protect from the stuffing giving a little air space? Air is not much of an issue. You can attach them with an adhesive like Goop. Avoid hot melt wax--the high heat is bad for the caps. One neat way is to use ny-ties and a mounting block. 15 minutes ago, MikeW said: What gauge and material wire is used internally? 18 AWG. Tinned wire (aka marine grade) is best. Pic below is an AR-4x with wax block capacitor left in place and new caps mounted with a ny-tie on a mounting block. Keep us posted! Kent Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 13, 2018 Report Share Posted March 13, 2018 I agree 100% with everything Kent has advised. Crusty corrosion on pots' wiping surfaces always has pits under it. There is no rational argument relating to sound to retain them in pitted condition no matter how shiny you can make them. Toss them or sell them to someone who just has to have original AR shafts sticking out the back of the cabinet. Btw, referring to an earlier post in this thread, the pot's center disk cannot be rotated. It is solidly riveted in place and not worth the effort. Roy Quote Link to comment Share on other sites More sharing options...
ra.ra Posted March 13, 2018 Report Share Posted March 13, 2018 On 3/12/2018 at 10:45 AM, MikeW said: How would you recommend doing so? They don't just spin freely..... Looks like you are leaning towards new L-pads, but I'll throw this out anyway. I have no experience trying this, but in order to try to salvage the disk by rotating (or replacing) it, one would need to drill out the rivet completely and re-install with a new fastener such as a tiny screw and nut. Sounds like a lot of fussy work, but if the wipers are in good shape, it might be possible to salvage the original pots. Edit: I see that Roy posted at the precise same time as me, and also confirmed the original solid rivet connection and the amount of work involved with this process. To be clear, the image I posted was cribbed from a Korean source that is re-habbing the original A-P pots - - they have stamped out new spring wipers and they use brand new disks. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 13, 2018 Report Share Posted March 13, 2018 1 hour ago, ra.ra said: Looks like you are leaning towards new L-pads, but I'll throw this out anyway. I have no experience trying this, but in order to try to salvage the disk by rotating (or replacing) it, one would need to drill out the rivet completely and re-install with a new fastener such as a tiny screw and nut. Sounds like a lot of fussy work, but if the wipers are in good shape, it might be possible to salvage the original pots. Hi Robert! Of course I just posted not to bother with the riveted disk. ...but, based on the photo in your post, it appears it may be worth the effort if there is a very good disk to work with. Roy Quote Link to comment Share on other sites More sharing options...
thornev Posted March 13, 2018 Report Share Posted March 13, 2018 That curly spring-like thing in the white half of the pot against which the wiper moves, if the spring is bent at any point, is that bad and requires a replacement? Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 13, 2018 Report Share Posted March 13, 2018 2 hours ago, thornev said: That curly spring-like thing in the white half of the pot against which the wiper moves, if the spring is bent at any point, is that bad and requires a replacement? That is the resistor (nichrome wire)...the heart of the pot. It can sometimes be deformed, but it doesn't usually cause sound issues. It is also not prone to the corrosion found in other areas of the pot. Roy Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 13, 2018 Author Report Share Posted March 13, 2018 Thanks all! While I am going to keep the pots, in case I want to go back to factory, at which point I would fully rebuild, at this time I'll just go the L-pot route. Seems like there is no benefit (functional, ease of DIY or sound quality) to restoring the pots past originality which I'm loosing anyway. I have now placed the order and have to wait a bit (some things were out of stock and won't be in until the 23rd. I will update as things progress. Thank you all for the assistance to this point (and in advance for a few weeks from now). Quote Link to comment Share on other sites More sharing options...
thornev Posted March 14, 2018 Report Share Posted March 14, 2018 And thank you to everyone from me too as I've been reading this thread and learning while I repair/replace my 2Ax controls. Quote Link to comment Share on other sites More sharing options...
dxho Posted March 14, 2018 Report Share Posted March 14, 2018 13 hours ago, ra.ra said: Looks like you are leaning towards new L-pads, but I'll throw this out anyway. I have no experience trying this, but in order to try to salvage the disk by rotating (or replacing) it, one would need to drill out the rivet completely and re-install with a new fastener such as a tiny screw and nut. Sounds like a lot of fussy work, but if the wipers are in good shape, it might be possible to salvage the original pots. these work nicely: https://www.ebay.com/itm/8pcs-Antique-Brass-Plated-Brass-Base-Center-Hole-Round-Disc-14mm-1871C-U-299/401173375672?hash=item5d67cbeab8:g:WPQAAOSwPYZU9htH Quote Link to comment Share on other sites More sharing options...
lARrybody Posted March 14, 2018 Report Share Posted March 14, 2018 20 hours ago, JKent said: 20 hours ago, MikeW said: While I recognize that I'm not going the 100% OEM route, my plan is to keep the capacitor box in place and just unsolder or cut the wires leaving as much wire attached to the box as possible. Then putting them aside. This is just for looks and "the ability to go back to stock". Something left over from my automotive hobby. Good idea 20 hours ago, MikeW said: How does one mount the capacitors/protect from the stuffing giving a little air space? Air is not much of an issue. You can attach them with an adhesive like Goop. Avoid hot melt wax--the high heat is bad for the caps. One neat way is to use ny-ties and a mounting block. 20 hours ago, MikeW said: What gauge and material wire is used internally? 18 AWG. Tinned wire (aka marine grade) is best. A lot of people here are aware of how I like to hide the new caps inside the wax box, but not always. Here is a picture of some 2a's where I left the original cap box and mounted the new caps to the side. The nylon mounting blocks can be found here. https://www.parts-express.com/cable-wire-tie-adhesive-1-mount-50-lb-tensile-10-pcs-black--080-518 I have used the adhesive ones and also with short screws. Just make sure the material you are going into is thick enough for the screw length. I have also seen these mounting blocks at Home Depot. As far as the wire gauge, Kent is right about using 18 gauge. I am of the philosophy that bigger is always better so in the picture above I use 16 gauge and wind up splitting the conductor filaments to get them thru the tiny tab holes in the potentiometers. The idea of replacing the disk is interesting. I have a bag full of originals with pitted and missing metal on the disk edges. Believe it or not most of the wipers are in good shape. Quote Link to comment Share on other sites More sharing options...
MikeW Posted March 14, 2018 Author Report Share Posted March 14, 2018 2 hours ago, larrybody said: A lot of people here are aware of how I like to hide the new caps inside the wax box, but not always. Here is a picture of some 2a's where I left the original cap box and mounted the new caps to the side. The nylon mounting blocks can be found here. https://www.parts-express.com/cable-wire-tie-adhesive-1-mount-50-lb-tensile-10-pcs-black--080-518 I have used the adhesive ones and also with short screws. Just make sure the material you are going into is thick enough for the screw length. I have also seen these mounting blocks at Home Depot. As far as the wire gauge, Kent is right about using 18 gauge. I am of the philosophy that bigger is always better so in the picture above I use 16 gauge and wind up splitting the conductor filaments to get them thru the tiny tab holes in the potentiometers. The idea of replacing the disk is interesting. I have a bag full of originals with pitted and missing metal on the disk edges. Believe it or not most of the wipers are in good shape. Thanks for the links! I added the mounting blocks to the order. Like you, my wipers are all in fine shape. It was the disks that were corroded. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.