AdamT Posted November 19, 2018 Report Share Posted November 19, 2018 Hi everyone. This is my first post here. A little bit of background on how I ended up here... I’m 32 years old and have been fascinated (obsessed) with hifi since a young age. I’ve had all manner of equipment over the years and have just started to venture into vintage gear. I restored a pair of AR4-xa speakers a couple of months back and was so impressed by the sound of them that I wanted to see what else AR did. This has led me to a pair of AR-3a in need of work. The pair I have were acquired from a guy who had refoamed the woofers. He said the sound was muffled on the speakers. I took a punt on them after doing a bit of research, and deduced that the pots were the problem. Upon getting the speakers to my house, the first thing I checked was the woofers for coil rub. One woofer was absolutely fine, but the other made that dreaded rubbing sound when pushing it in. I’m hoping this is just down to a bad refoam job, as when you push it slightly off axis, the coil rub is gone. So the plan here is to refoam this woofer. I then fired them up and low and behold, the mids and tweeters were making no sound at all. Upon messing about with pots, I managed to get sound out of the midrange, but not the tweeter. Both pots were obviously faulty, as you could twist them right the way around My next job was to attemp to clean the pots. I opened them up and they were obviously corroded. I cleaned them up with some wire wool and contact cleaner. They looked visually okay to me. Wired everything back up and played some music. I only had sound through the tweeter, and it was intermittent when rotating the pot. The mid made no sound at all (this was the other speaker to the one I had previously tested with the intermittent mid), but I didn’t test whether it worked before cleaning the pots. I then removed the drivers from the cabinet and tested them off of a low level signal from my amplifier. All drivers played okay. So either the pots are no good, or there is an issue with the crossover. O am either going to replace with L-pads or try and source the correct pots. How do the L-pads affect the sound compared to the pots? Also, another issue I have is that I stupidly snipped off the copper wire from the mid to the tags on the front wired terminal thing. I didn’t realise the wire was wrapped around the the tag, and was struggling to remove, so I just snipped it off. Problem now is the wire is too short to reach the terminal. What can I buy to reattach the wire to the tag? I guess it is some sort of copper braided wire? For clarity, I live in the UK and my pair are the standard AR-3A with the European cabinet. Thanks everyone! Link to comment Share on other sites More sharing options...
RickB Posted November 19, 2018 Report Share Posted November 19, 2018 Lpads would in my opinion be the best way to go, save the pots. They may be repairable-pictures please. Link to comment Share on other sites More sharing options...
djcheung Posted November 19, 2018 Report Share Posted November 19, 2018 Hi Adam, Have you checked to make sure that the inside of the pot actually connecting to the outside terminals ? It has happened to me on one occasion after cleaning the pots, they look perfect, but the middle terminal somehow separated slightly from the metal disc inside. I had to put a bit of solder to make good contacts. Congratulations on getting the AR3a as I know they are hard to come by in the UK where I am also located. Link to comment Share on other sites More sharing options...
AdamT Posted November 20, 2018 Author Report Share Posted November 20, 2018 Thanks guys. I’ll post some pictures either tonight or tomorrow. I’ll definitely check to see if they are making contact, as visually they seemed okay after cleaning. Link to comment Share on other sites More sharing options...
AdamT Posted November 21, 2018 Author Report Share Posted November 21, 2018 I found the problem with why the midrange wasn’t working. The wire from the mid pot to the inductor coil has an insulation over it. I’d snipped off the wire from the pot when I was removing it, as it was a pain to de-solder, but obviously when I soldered it back on, there was only contact with the insulated part of the wire. So the sound from the midrange is now okay. However, the sound from the tweeter is quite low. But then again, I’m not sure how loud it should be. I still get slightly intermittent sound when I rotate the pots, so it’s probably for the best if I replace with l-pads. But possibly a new tweeter is needed. The most concerning issue is that with all the drivers hooked up and the cabinet sealed, the sound is muffled from the woofer. It sounds odd. I thought it could maybe be out of phase, but would I notice that when only playing through one speaker? As I mentioned earlier, the woofer does rub when I push on it (but doesn’t rub if pushed slightly off axis, suggesting bad foam job), so maybe the woofer is damaged? However, iirc, the measure resistance was okay. I will double check it tonight. If the resistance is okay, does that guarantee a working woofer? Thanks for any help. Link to comment Share on other sites More sharing options...
AdamT Posted November 21, 2018 Author Report Share Posted November 21, 2018 Quick question... I see mention of a special sealer for the drivers. On my speakers, there is a gasket, which I guess was used in place of a sealer. Was this gasket used on AR-3A models? Or has somebody else put this in? Link to comment Share on other sites More sharing options...
stupidhead Posted November 21, 2018 Report Share Posted November 21, 2018 Hi Adam, Nice thread and project, take your time and research and get answers before doing anything that might not be reversible. On your sealer question, if we are talking about the "gasket" between speaker and baffle then using either a clay like product (mortite) or a foam strip is generally the approach for "sealer" but possibly your reference is a sealer for the surrounds on a cloth surround woofer? If you have foam surrounds, replacing with fresh appropriate rings is fairly simple, if cloth surrounds there is much bad info on the web and can lead to using a material (permatex for example) that will dry out and stiffen the surrounds leading to other than desirable performance. There is an appropriate product for this application developed by one of our members here and will "seal" the cloth effectively but will not stiffen over time. In all cases, sealing is a very important aspect to acheiving acoustic suspension. Take your time and enjoy! Geoff Link to comment Share on other sites More sharing options...
AdamT Posted November 21, 2018 Author Report Share Posted November 21, 2018 Hi Geoff, Thanks for the info. Yes, I mean the gasket between the driver and the baffle. Woofers have already been refoamed. I will try to get hold of some sealer for the speakers. Does this go between the baffle and the gasket, or between the gasket and the driver? My main area for concern at the moment is the muffled sound from the woofer. More investigation needed. I’ll try the battery trick tonight to see if I have wired the woofer out of phase. Thanks guys. Link to comment Share on other sites More sharing options...
RickB Posted November 21, 2018 Report Share Posted November 21, 2018 Have you downloaded the PDF AR3a restoration guide and read it. It will help you very much in your work. It is located on this site. http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/restoring_the_ar-3a/restoring_the_ar-3a_full_pd.pdf Link to comment Share on other sites More sharing options...
AdamT Posted November 21, 2018 Author Report Share Posted November 21, 2018 Hi Rick, Yes, I’ve downloded this manual and have been following it. It’s been very useful. Having a break tonight from restoring the speakers to carry on with the underpinning of my house. I know which I’d rather be doing! Link to comment Share on other sites More sharing options...
ReggaeBen Posted November 24, 2018 Report Share Posted November 24, 2018 Hello Geoff and welcome, Regarding the wire that you snipped on the mid, I recently re soldered broken tweeter wire the width of a hair, very carefully!, and found this out that could solve your problem. The wire on the left has not ever been disturbed and shows how AR fixed it down with tape with a loop in the wire thus preventing a hard tug that would lead to breaking the fine lead wire. There is probably enough excess lead wire there once you lift the tape (very gently!) to give you the extra length needed to re solder back onto the lug. Hope this is the case. Best Ben Link to comment Share on other sites More sharing options...
ReggaeBen Posted November 24, 2018 Report Share Posted November 24, 2018 Apologies for getting your name wrong, Adam!! Link to comment Share on other sites More sharing options...
ra.ra Posted November 25, 2018 Report Share Posted November 25, 2018 20 hours ago, ReggaeBen said: I recently re soldered broken tweeter wire.... Nice job, Ben. Am happy to see someone else make the effort to repair the damaged wire of an otherwise perfectly functioning tweeter. I performed a similar repair once a couple years ago in order to salvage an original AR-6 tweeter having the outboard tinsel wires, and at that time, I made several wire extensions for possible future use. As long as it's a copper-to-copper connection, I assume this technique will work for all early AR drivers with exposed tinsel wires. 20 hours ago, ReggaeBen said: The wire on the left ... shows how AR fixed it down with tape with a loop in the wire thus preventing a hard tug that would lead to breaking the fine lead wire. Yeah, I've often noticed this as being a very conscious detail, but have never given it much thought - - I suspect your reasoning is correct. Link to comment Share on other sites More sharing options...
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