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DavidR

Picked up some more AR speakers

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A 100 mile drive (each way) made me the proud owner of a pair of AR9's and 10pi speakers.

The 10pi are almost perfect. Just a small back corner chip on the top of one and dirty and thirsty for oil. They should clean up nice.

The drivers in the 9's are all good. One speaker has lifting of the veneer on the side/bottom. The MDF has swelled some. These too need a good cleaning. The side grilles are original and all but one has a small hole in the fabric. The front grilles have been replaced and need to be stretched better. Its odd but these have the plastic pegs reversed - mounted to the cabinet and plug into the grilles. Also, I have a few broken ones. A few small nicks here and there but not significant. They are beasts and my back will attest to that.

Having trouble uploading the full pic of the 9's

 

IMG_0927.jpg

IMG_0931.jpg

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Congratulations, David - those are some great speakers, and the AR-9 will be a lot of fun to restore!

I've seen the reversed pegs before, but have no explanation as to why it was done.

I've never owned one, so I'm a bit jealous about that 10pi. ^_^

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The serial numbers are obliterated on the 9's.

I'm curious about the 10pi speakers (they are MkII models) as well. I have not had time to hook them up.

Spent most of the remaining daylight hours with compressed air and a vacuum cleaning all the grilles. Dust, dirt and dog hair. I usually clean grilles by first blowing off with compressed air, vacuum and then the garden hose followed by compressed air again. BUT with the frames being wood (and not plastic) I doubt I'm hitting them with water. It did work on an old pair of Polks though.

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Hell of a haul! Congrats!

The 9 veneer repair may be a bit tricky. What's your plan to tackle that? Foam on the woofer looks pretty new in the one pic.

Let us know how both sound, and compare to each other.

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Thanks Glenn.

All of the foam on both speakers are good.

57 minutes ago, GD70 said:

The 9 veneer repair may be a bit tricky. What's your plan to tackle that?

Since you're the expert in this  area I was hoping you'd give me some pointers.

I've been told there is a product that will harden up MDF so I'll be looking for that.

What product do you guys use to clean dirt and grime from the wood. I use Murphy's Oil Soap but don't know of any other product that might be better.

 

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Good for you DavidR,  you've been desiring those for a while. Now I can go ahead with my good feelings about keeping my own AR-9's and still come to you for spare parts.

I did feel sort of guilty as you had asked about mine a couple of times.

Now, you have your own and no body can touch you.

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Welcome to the AR 9 club. A nice set of 10pi's to boot. You must have a large vehicle to haul all that. I used a 5' hand truck to move my 9's into the house.  Here are the products I used to clean and spruce up the cabinets. 

rDH8MDT.jpg

There is a lot of information and opinions on restoring and recapping the 9's. I just had to sort thru it and decide what direction I wanted to go. It will keep you busy for a while.

Congratulations again on your double find.

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@larrybody, do those products darken the original finish in anyway?

My AR-9's are a lighter shade of wood compared to a walnut.

My goal is to keep them light toned and not even attempt to approach the walnut shade.

I had refreshed the cabinets upon purchase with Pledge whatever spray and I really saturated them heavily but, that kept the same tone though it faded in a couple of weeks and they're starting to look a little dry once again.

FM

 

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Howards RAF comes in 9 colors. My cabinets were in such good condition I used a very light application of the walnut and immediately wiped it off. I did not notice that it darkened the veneer very much. They do have a neutral shade that may be a good choice. What I did notice is that the veneer had a slight color variation where to side woofer covers are. Probably due to years of sunlight.  I does not bother me with the covers installed. Forget about the Pledge. The Howards Feed and Wax is a excellent product and makes a big difference. We use it on our Cherry veneer kitchen cabinets with great results.  

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21 hours ago, larrybody said:

You must have a large vehicle to haul all that.

Nope. Just a Subaru Outback. Had the back seats down and both 9's on their backs. Pushed one way up and placed a 10pi on its side and the other pi on the front passenger seat.

I'll have to look for that cleaner. I've never seen it before.

Finally got a pic of the 9's to successfully load.

AR9.PNG

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Congratulations David.

By the pics you posted they would seem to have all Tonegen woofers.

Although they certainly are the best "not" original AR woofer replacement, I do prefer the 200003-woofers made in USA in the same period (about 1978 to 1982) of AR 10 PI mkII and AR9. In my experience, although all original AR 12" woofer (# 200003)  are considered interchangeable, every AR loudspeaker has a more balanced and natural sound with the drivers manufactured  and used in the same period. At least in my listening enviorement and with my electronics.

Luigi

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37 minutes ago, fedeleluigi said:

Congratulations David.

By the pics you posted they would seem to have all Tonegen woofers.

Although they certainly are the best "not" original AR woofer replacement, I do prefer the 200003 woofers made in US in the same period (about 1978 to 1982) of AR 10 PI mkII and AR9. In my experience, although all original AR 12" woofer (# 200003)  are considered interchangeable, every AR loudspeaker has a more balanced and natural sound with the drivers manufactured  and used in the same period. At least in my listening enviorement.

Luigi

Luigi makes an interesting point, and while I'd certainly agree with the essence of this reasoning, I'd also be inclined to believe that the differences in flavors of the 12" woofer from this period would be more discernible when the driver is used in a 3-way system, where its output extends well up into the midrange. As employed in the AR-9 - in pairs, that is, and with a very low crossover point - it could almost be seen as a subwoofer, and I've never personally been able to hear any difference between the Tonegen and the standard 200003-1 driver in this circumstance.

 

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I need some help understanding the 10pi ohm readings I'm getting. I want to run the 10pi speakers on my tube amp that is wired for 4-ohm speakers. I have the 10pi switches as follows: woofer> 4pi, mid> 0dB and tweeter> 0dB. I get an ohm reading of around 16 ohms ???? If I flip the woofer switch to pi and the ohm reading goes up to around 26-ohms. I know they have a transformer in the xover so this is probably giving me these high readings.

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How did you exactly get these readings? What instrument did you use to measure the loudspeker impedance?

Anyway:

 with Woofer in Pi, Mid in -6 dB and Tw in -6 dB you'll have a 16 ohm loudspeaker ( an easier load but with the smallest loudspeaker sensitivity);

With Woofer in 2 Pi, Mid in -3 dB and Tw in -3 dB you'll have a 8 Ohm loudspeaker;

With Woofer in 4 Pi, Mid in 0 dB and Tw in 0 dB you' ll have a 4 Ohm loudspeaker (a more difficult load but with the greatest loudspeaker sensitivity).

In my experience, using a tube amp you have to practically try both the amplifier different outputs and the different positions of loudspeaker switches to find out the best sonic match.

Luigi

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I used a digital VOM on the ohm setting and measured the speaker output terminals.

Thanks for that info and that's what I thought. I hooked them up to a class H amp with the switches in 4 ohm position. Bass was EXCELLENT, Mids are great, tweeters do not stand out well.

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Using a digital multimeter you can't actually measure a loudspeaker impedance. Anyway using it  as you did I can read only about 10 Ohm regardless the switch positions. You actually measure only the 10 Ohm resistor in series with the autotransformer.

You should check every driver has a correct DCR and is correctly wired. 

Woofer: red wire must be connected to positive and black wire to negative

Mid: orange wire must be connected to positive and brown to negative

Tweeter: yellow wire must be connected to positive and  blue to negative.

Driver terminals (especially tweeter's) must be cleaned well.

Please, post some pictures of all the drivers.

Luigi

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On 1/28/2018 at 8:26 PM, ar_pro said:

 I've never personally been able to hear any difference between the Tonegen and the standard 200003-1 driver in this circumstance.

 

Probably it could depends on your listening enviorement, amplifier, loudspeaker position or personal taste.

Anyway, the 200003-1 part number you mentioned was usually used for the square magnet 12" woofer introduced with the LS series (9LS, 98LS, 78LS a and also used in the AR 58S) at the end of 1981  and manufactured until nearly all 1984. In 1985, the LSI series used Tonegen drivers. 

The 200003 woofer used for AR11 MKII and 10 Pi MKII, AR 9, AR 91 and 915 had the classical round magnet, aluminun voice coil former, a paper cone and a spider sligtly different from the previous 200003 and was produced from about 77/78 until just the introduction of the square magnet 12" woofer.

Many years ago Kan Kantor's assistant Ruchi Goel (last post of this page) measured various AR 12" woofers and the Tonegen showed measurements rather different. Unfortunately those measurements are lost (their links do not work any longer since many years)! 

As said in my previous post the Tonegen woofer is definitely the best drop in replacement part for the originals AR 12" woofer. But I do think that If you want to get the best possible in terms of balance and naturalness of sound, the original woofers, manufactured in the same period as loudspakers, perform better.

Untill now I haven't spent much time to try to optimize the Tonegen woofer sound by modifying crossover and/or cabinet stuffing. I think that some very good improvements could be reached. 

Anyhow if you are happy with the Tonegen woofer sound, don't pay too much attention to my considerations and subjective opinions.

Luigi

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I forgot to say that the switches terminals shoud also be carefully cleaned to remove oxidation.

Pay close attention to how the switches are wired and double check them using the schematics. AR 10 PI switch wiring connections are rather complex!

The capacitors are about 40 years old. So they shoud be checked too. You have to desolder at least one of their terminals and measure them by a good capacitance meter.

Luigi

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On 1/27/2018 at 9:18 AM, DavidR said:

Thanks Glenn.

All of the foam on both speakers are good.

Since you're the expert in this  area I was hoping you'd give me some pointers.

I've been told there is a product that will harden up MDF so I'll be looking for that.

What product do you guys use to clean dirt and grime from the wood. I use Murphy's Oil Soap but don't know of any other product that might be better.

 

Hi David,

The first thing I would do is to carefully remove some of the swelled MDF/particle board, so you can get the veneer flat with the surrounding areas. Make sure to keep any of those lifted pieces of veneer for reuse. The less new veneer needed for patching the better. Next is to firm up the remaining MDF, which I use ZPoxy for this. It's a very thin epoxy that is absorbed easily and makes the MDF rock hard, giving you a stable structure to continue your repairs on. While the epoxy cures, the surrounding veneer should be weighted down flat. The pieces currently missing will need some harvested Walnut from an old project for splicing in. All the new pieces should be cut as wedges as angled butt joints show less than square perpendicular cuts do. Luckily this is on the bottom area, so it won't be so noticeable. After the epoxy has cured, then carefully sand the finish off to the raw veneer, cut out the shapes where the pieces are missing, match the cutouts with the new veneer and glue in place. Sand smooth to the surrounding original veneer and when satisfied, finish with Oil or whatever you like to use. I use Watcos natural color oil on all my restorations. The red hue in the veneer will come back once the oil is applied, which I do with a piece of old t-shirt or an old sock. Just wipe on a light coat. The veneer will soak it right up.

Glenn

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Thanks so much for the tips Glenn. In case I can't find ZPoxy Stimpy mentioned Minwax wood hardener. Any experience with that?

I'll have to see if I can get a donor speaker from my brother inlaw for the veneer. He has a lot of oddball speakers he picks up at the town recycling center. He owes me for the AR94 restoration and a pair of small Infinity speakers.

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9 hours ago, DavidR said:

Thanks so much for the tips Glenn. In case I can't find ZPoxy Stimpy mentioned Minwax wood hardener. Any experience with that?

I'll have to see if I can get a donor speaker from my brother inlaw for the veneer. He has a lot of oddball speakers he picks up at the town recycling center. He owes me for the AR94 restoration and a pair of small Infinity speakers.

You can get ZPoxy on line. I haven't used the Minwax wood hardnener.

A donor speaker will be a perfect source for the veneer repairs.

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On 1/30/2018 at 7:27 AM, GD70 said:

A donor speaker will be a perfect source for the veneer repairs.

First of all, congratulations DavidR, I am envious!  Good luck with your restoration, I'm sure they will be marvellous.

Glenn's tip just caught my eye, I had never thought of a cast-off cabinet as a source for veneer.  Someone was showing me a pair of derelict Optimus speakers which have a beautiful veneer.  Maybe there is a way to repurpose them, they are large speakers, lots of nice veneer (looked like walnut).

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