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My New Speaker Project: Advice Requested


danajohnhill

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Hello, everyone. This is my first post, but I have spent the last month or so browsing the forum, and I can tell that this is an amazing place.

My story: For a long, long time I have been wishing I had a nice pair of loudspeakers. I spend a lot of time listening to music, and deserve something better. Last month, looking for advice, I asked the engineer at my work (a classical music radio station) what he would recommend. He told me that we had an old pair of speakers collecting dust in a back room that we would never use. The boss said I could have them, so, exited by the freebie, I got to looking at them.

They are two AR-3a loudspeakers, and are in practically immaculate condition. They have obviously been well cared for. They even came with all the original documentation, including an AR brochure, spec sheets, an article praising the speakers, and more. Taking a look at the invaluable AR-3a manual on this site, I determined that this is a fairly early pair. I opened one of them up (the original glue tells me that they had never been opened before), and confirmed this: the woofer is stamped "Aug 19, 1969".

So far, I have opened only one of the two, and, following the instructions in that great guide, I have cleaned the potentiometers (which had only a little tarnishing to begin with), re-coated a woofer surround, and am preparing to replace the capacitors.

I am getting great guidance from the engineer at my work (it's great to have a professional audio engineer as a friend), and am getting some great tips from this site. But, before I go any further, I would just like to as if anyone else has any advice they can give, or point out any potential stumbling blocks. My experience in this field is limited, but I am trying hard to learn.

As I move along through this project, I'd be happy to post pictures if anyone would like to see them.

Thanks.

Dana

4299098550_a43534e1d0_b.jpg

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Hello, everyone. This is my first post, but I have spent the last month or so browsing the forum, and I can tell that this is an amazing place.

WOW!!! You lucky so-and-so!! :D

And Welcome to CSP!

One of the resident 3a experts like Roy should advise you but you may not need to do a thing beyond cleaning the pots. If you do ahead with the recap, Madisound has Solen caps in the 6uF and the 150uF values but the 150s are $41 each. You could instead use Bennic 150uF electrolytics for less than 1/10 the price (3.70 ea). Carli makes nice 6uF mylars for 1.50 each.

Enjoy those beautiful speakers!

Kent

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danajohnhill,

Last week I too acquired a pair of 3a's that have not been opened. They appear to be early models like yours. Mine have been well cared for and all the speakers seem to work well. I will be recapping and cleaning the pots soon so I will be watching your postings to see how you are progressing.

The AR3 refurb guide is great but its also nice to see how others do the work.

thanks,

Monte

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My work is coming along well. I took the grill off of one of the two speakers (clearly the first time it had ever been opened), and I noticed something odd on the cone: the wire and a little bit of solder are peeking through the paper. It seems like it has always been like that, rather than having been the result of damage, since the cone looks great otherwise (minus the cloth surrounds, which I have recoated). Is that abnormal/potentially dangerous? You can see it in the photo below.

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I am pretty much wrapped up with my project. All that remains is a light coat of something to freshen up the cabinets a bit. For their age they are in practically perfect condition, but a little cleaning might be due. Also, I am going to make my own stands for them to match the rest of my living room furniture, which seems like it was designed just to match the AR-3a. I'd like to duplicate the legs on this console:

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As for the speakers, it all went mostly well. The restoration guide was invaluable. It deserves the Pulitzer Prize, really. It was spot on in almost every regard except one. The glue holding the grill on one of my two speakers had not loosened at all in forty years. The drywall screw trick didn't work, and I didn't want to ruin the hole for the badge, so I had to try Plan B, which was, unfortunately, prying off the grill. I protected the cabinet, and used a small pry bar, but the grill really didn't want to come off. In some places, the glue holding it on was obviously holding tight to the linen, and the linen was ripping. I had to use a razor to cut the linen away from the glue or risk damaging the frames or further tearing the linen. I got it off, finally, and though the linen did get torn, it was only on the back side, and will be invisible once the grill is back on. I tool a little glue and secured the torn areas back onto the frame. Nobody will ever know. It is odd that they went a little glue-crazy at the factory that day. There were about half again as many glue points as on my other AR-3a speaker.

The guts of both speakers looked exactly like the illustrations and schematics indicated. All the wire colors matched, which made my job a lot easier. I am not especially experienced in this arena. I left the old caps in there, and put their replacements nearby. Cleaning the potentiometers was the funnest part. One of the four was actually pretty clean. The rest, however, were quite oxidized, covered in a turquoise powder. The Dremel took care of that. Soldering in the tight confines of the cabinet wasn't easy, but I enjoyed the challenge.

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I ordered some new goo to seal the woofers, and though it didn't go as far as I thought it would, I did make it work. They seem acoustically sealed now.

Today's the day I am going to test them. I am extremely excited.

Here's a gallery of pictures of my AR-3a speakers, including close-ups of many components.

AR-3a Gallery

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Dana,

Nice job on the AR3a gallery photos!

What did you use for caps?

Monte

I don't know much about them. The engineer at my work ordered them for me. I'm sure they'll do, but if I ever need to swap them it won't be a big deal.

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Today was my AR-3a listening test, but, alas, it was only a partial success. One of the restored speakers was perfect, but the mid-range driver on the other produced no sound. Now I have to figure out where the trouble lies. Is it the driver itself? Is the (cleaned up) potentiometer the problem? Has some other wire inside come loose?

Can anyone rank the scenarios from best to worst? I won't fret too much if I have to spend a little, since these speakers were free and my friend gave me the new caps. Considering that the cabinets are perfect, and all the other drivers sounded great, I am lucky. Even the original pots, after cleaning, function very well (except from the one mid-range, where I cannot tell what is the culprit).

Thanks for reading my posts, and thanks in advance for any advice.

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My guess is a wiring error. Did you solder the caps? Did you make sure your wiring matches the schematic? You can start troubleshooting the components--check the speaker with an ohmeter, then check the pot with an ohmeter, but I'm guessing a wiring error or bad connection.

Worst case would be a bad mid-range driver. If you have a bad pot, I have a couple and you can PM me if interested. Bad pot would be no big deal. But check the wiring of the components. Also check the jumper on the screw terminals--there should be a wire or strap connecting T and 2.

Kent

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My guess is a wiring error. Did you solder the caps? Did you make sure your wiring matches the schematic? You can start troubleshooting the components--check the speaker with an ohmeter, then check the pot with an ohmeter, but I'm guessing a wiring error or bad connection.

Worst case would be a bad mid-range driver. If you have a bad pot, I have a couple and you can PM me if interested. Bad pot would be no big deal. But check the wiring of the components. Also check the jumper on the screw terminals--there should be a wire or strap connecting T and 2.

Kent

I am hoping it is just a wiring error. I will check the driver first with a meter before taking the speaker apart again. Of course, I really, really hope it isn't the driver. I am somewhat hopeful, since this pair of speakers appears to have spent its first forty years being well cared for in the home of someone who listened primarily to classical music. Perhaps I'll know as soon as tomorrow.

Thanks again.

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Using a borrowed Fostex TT-15, which I connected to the wire leads of the mid-range driver on my AR-3a, I heard a clear tone, so, I am happy to report that the mid-range driver isn't the problem. I'll have to open her up to find what is the problem, but as long as it isn't the driver that's all that matters. If it is the pot, JKent, I may get in touch with you. Thanks for reading this thread. I appreciate it.

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Wow. Those are in great shape. Take your time and get ready for some great sound.

What amp will you be using with them?

Thanks. They really are in almost indescribably good condition. I put a light coat of tung oil on them, and they look brand new. And now that I know that all the drivers in both speakers work, and that my mid-range problem is probably just a loose connection somewhere, I am pleased as punch.

I know that a lot of people spend a lot of time thinking about and working on the AR-3a. That I just got lucky and happened upon a flawless pair for zero dollars makes me extremely grateful.

I wish I could tell you all that I am an audiophile with nice equipment. At home I just have a later model Kenwood receiver (100W per channel) and Kenwood CD changer. Of course, I appreciate good quality electronics, but I get my fix satisfied at work, where we have nicer gear than I could ever afford. That's where I spend my whole work day listening to music, anyway, which simultaneously satisfies my music-listening needs. But, now that I have these AR-3as, I feel this urge to go through and re-listen to the thousands of CDs I have sitting in my library at home.

I see these AR-3as as an extremely positive development in my life.

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I wish I could tell you all that I am an audiophile with nice equipment. At home I just have a later model Kenwood receiver (100W per channel) and Kenwood CD changer.

IMHO the AR3a is the most important part in that chain. Kenwood has always made quality stuff and 100wpc should be fine. Some of us like old stuff. I had an AR amp (60 wpc) that was adequate to drive these speakers, but sold it--too many things to break down. You can get LOTS of opinions about amps but really--as long as it has enough power and is new enough that the parts aren't wearing out and breaking down--sit back and enjoy the music through those wonderful speakers!

If you're an old guy (like me) and get nostalgic you can always add a turntable and listen to vinyl.

Kent

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IMHO the AR3a is the most important part in that chain. Kenwood has always made quality stuff and 100wpc should be fine. Some of us like old stuff. I had an AR amp (60 wpc) that was adequate to drive these speakers, but sold it--too many things to break down. You can get LOTS of opinions about amps but really--as long as it has enough power and is new enough that the parts aren't wearing out and breaking down--sit back and enjoy the music through those wonderful speakers!

If you're an old guy (like me) and get nostalgic you can always add a turntable and listen to vinyl.

Kent

I've gotta second that, Kent. I've enjoyed my AR3a speakers for about 30 some years with 60wpc Pioneer reciever power. They've never ceased to impress me and now thanks to the help of you and others here they're like new again. I recently bought them 2 APT-1 amps and revived my old Thorens turntable. The old vinyl sounds sweeter than ever.

Bill

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Well, I've hit the wall.

Using a tone generator and now a multi-meter, I have confirmed that my mid-range driver does work. Today, I took the AR-3a apart (which is kind of a chore), took out the mid-range pot, checked it, re-soldered it, and checked the connection to the capacitor, too. Still, I am not getting any sound. I checked the connection of the speaker leads to the terminal on the front of the cabinet, and those are okay, too. So, I don't know what it is. I am in over my head.

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Well, I've hit the wall.

Using a tone generator and now a multi-meter, I have confirmed that my mid-range driver does work. Today, I took the AR-3a apart (which is kind of a chore), took out the mid-range pot, checked it, re-soldered it, and checked the connection to the capacitor, too. Still, I am not getting any sound. I checked the connection of the speaker leads to the terminal on the front of the cabinet, and those are okay, too. So, I don't know what it is. I am in over my head.

It's a highly unlikely scenario, but since ypu seem to have checked everything else you might as well check the midrange cao and inductor to be sure there isn't a circuit break there.

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I agree with Gene. Take it one step at a time. Logically, you have

midrange driver

mid pot

capacitors

inductors

wires

You've checked the driver, the pot and all the wires/solder joints (right?)

That only leaves the inductors (virtually indestructible but check anyway) and the caps. The caps are new but it is "possible" one is bad. They are NON-POLARIZED electrolytics, right?

It's hard for me to trace everything on your flickr photo. It IS a puzzler but it has to be one of those 5 variables.

Check the pot again to be sure that the wires are on the correct lugs. Do you get anything as you rotate the pot's control all the way back & forth?

Kent

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You've checked the driver, the pot and all the wires/solder joints (right?)

That only leaves the inductors (virtually indestructible but check anyway) and the caps. The caps are new but it is "possible" one is bad. They are NON-POLARIZED electrolytics, right?

It's hard for me to trace everything on your flickr photo. It IS a puzzler but it has to be one of those 5 variables.

Check the pot again to be sure that the wires are on the correct lugs. Do you get anything as you rotate the pot's control all the way back & forth?

I have checked the driver, which gives me readings on my multi-meter, and produces a test tone when hooked up to a Fostex TT-15 tone generator. My next suspect, then, was the pot, so I took it out, and tested it. It looked right when I hooked it to my multi-meter. That is, current was clearly passing through it, and the meter responded when I rotated the wiper shaft. I next thought that my wiring might be loose, and, indeed, it seemed like the small yellow wire connecting the two pots might be the culprit, but I re-soldered it, and, still, no mid-range. I thought that maybe the wires between the pots and the back of the terminal on the front of the cabinet might be loose. I cannot see the connection, of course, but my multi-meter showed that the current is making it from the pots to the front. That leaves something before the pots, right?

I did get non-polarized electrolytics, yes - identical ones for each speaker, and the other speaker works perfectly. I suppose a cap could be a dud, right? How do you test a capacitor? What setting should I use on my meter? Also, how does one check inductors? What about the coils of copper wire? Those couldn't possibly go bad, right?

I agree that this is probably a blunder on my part. I just cannot figure out where. The woofer and tweeter work fine, but I get no sound from the driver, and no amount of pot rotation makes a difference. If I hadn't repeatedly checked the driver I'd be convinced that that was the problem.

Here's a bigger picture, though tape obviously obscures some soldered connections, and shadows from the flash are confusing, too.

4314715166_9f177b0c8d_o.jpg

I know I'll get it figured out eventually, but I will go back in an check everything wire by wire if I have to. First I need to figure out how to test inductors and capacitors.

Thanks a million.

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I know I'll get it figured out eventually, but I will go back in an check everything wire by wire if I have to. First I need to figure out how to test inductors and capacitors.

Not removing enough of the enamel coating from the inductor wire before re-soldering is a common oversight, resulting in a bad connection. That would be the first area to check out. Another area to examine is the wire resistor in the midrange circuit. I doubt your issue is related to defective caps or inductors. The pot section of the circuit is the usual culprit, even after cleaning and re-installation.

If you intend to test caps and inductors, an "LCR" meter of this type is very helpful:

http://www.mcmelectronics.com/product/TENMA-72-8155-/72-8155

Roy

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In this case it's not so much about testing coils and caps for correct values, but just seeing if there's a break in the circuit. A common VOM would probably be sufficient for that. But a wiring error or bad solder joint are definitely more likely. I think what I would do is just fire up the iron and reflow the joints in the MR portion of the crossover, making sure that all the soldered bits are clean as well.

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Those big coils of wire are the inductors and there's really nothing to go bad there BUT as Roy said, if you disconnected one and then re-soldered it, that could very well be the problem. I learned that through personal experience ;) . The wire in that coil is insulated with a thin coat of very tough varnish. If you need to solder it, you MUST scrape and sand the varnish off to get down to clean shiny copper, then solder. I have not worked on a 3a, just the 2ax and 4x, so I'm not sure whether the work you did involved disconnecting the inductor coils, but if it did that is the most likely culprit.

Kent

PS An LCR meter is handy for checking caps. Roy gave you a link to a nice one but you can find them on ebay, from Hong Kong, for half that price. If you will use one infrequently that may be the way to go. But check that inductor solder joint.

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I am hoping it is just a wiring error. I will check the driver first with a meter before taking the speaker apart again. Of course, I really, really hope it isn't the driver. I am somewhat hopeful, since this pair of speakers appears to have spent its first forty years being well cared for in the home of someone who listened primarily to classical music. Perhaps I'll know as soon as tomorrow.

Thanks again.

Check to see that you have reassembled the midrange potentiometer correctly. Be certain that you haven't re-installed the moving contactor upside down, it's an easy mistake to make. If it is upside down with the short contactor facing away from you, it will not make contact with the fixed center contactor when you re-assemble it. It is also easy to misorient the two assemblies when you put them back together so check that too.

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Ahhh! I did disconnect one of those solid copper wires when I took apart the mid-range pot. In fact, I think I initially clipped it, meaning the part that I re-soldered might still have that coating on it, preventing a good connection. I am going to sand the wire down and reconnect it.

Fingers crossed big time!

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