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AR48b woofer (200040) anomaly?


Jay
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I bought new AR48b speakers back in the mid-1980's and had the surrounds of the woofers replaced once by a stereo repair shop around 2000 and a couple years ago I replaced the surrounds myself.

From what I've found in this forum is that the surrounds should be mounted on the back of the cone. My pair of woofers look like the surrounds were factory mounted on the front of the cones. The pictures show the back edge of the cones are absolutely clean with no glue residue or old surround remnants. One other thing which I think is an anomaly is that both of my woofers are coated on the front. I have no reason to believe the stereo repair shop coated the woofers when they replaced the surrounds in 2000.

The speakers sound fine. I'm just curious if anybody here has any knowledge of these anomalies A.) surrounds factory mounted to front of cone and B.) factory coating of the cones?

 

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Edited by Jay
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I happen to have a couple of AR-48B (200040-0).  The surround mounts to the back face of the cone, and it doesn't have a shiny coating.  My guess is that the coating on your woofer was added later.

I have no idea why AR choose to mount some surrounds on the front face of the woofer cone and others on the back face.  While AR-48B's surround was factory mounted to the back face of of the cone, the surround on the 10"woofer (200004-2) found in AR-12 & AR-14 was factory mounted to the front face of the cone.  You can also find examples of this with AR's 8" cones - 200050-0 back face - 200001-1 & 200037 front face.

image.png.d8d3cd8b7c20131370dec73bc232a4ab.png

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@briodo

I'm not sure if a coating was added or was factory. The only time the pair of speakers was not in my possession was when I brought them in for the surround replacement around 2000. Unfortunately I don't recall after these past 20 + years if the cones were uncoated or not when I brought them in for repair. They've been this way for as long as I remember.

@AR55

Kind of weird I guess. The back of both of my woofer cones are clean as a whistle, no glue or surround remnants. So would appear like factory mount to the front of the cone. I had downsized the original pictures before posting the opening post, but here is a section of the coated cone. You can see the cone surface under the coating is not like flat paper. For lack of a better description, I'll call it a stippled paper surface. Are your cones plain flat surface or do they also have this stippled surface?

Maybe the repair shop replaced the cones when they did the surround replacement? I'm not sure after all these years but from what I recall it wasn't that expensive. The speakers sound fine, but I guess I'll never know the difference unless I can get a hold of some 200040-0 woofers and A/B listen to them.

You mention the 200004-2 woofers. Do you think they would be a good replacement if I can't find 200040-0 woofers?

Thanks for your replies guys.

 

IMG-2862-detail.jpg

 

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Unbelievable, but I think I found some clues to this mystery. After searching ebay I got some hits for a couple AR-14 woofers. The cone is stipple textured. The magnet on this woofer is round, but I also found another AR-14 woofer with a square magnet.

This round magnet AR-14 woofer has the surround mounted to the back face of the cone.

AR14-woofer.jpgAR14-woofer-round-back.jpg

Here's another picture of a square magnet AR-14 woofer. The cone has a stippled texture.

This square magnet AR-14 woofer has the surround mounted to the front face of the cone.

AR14-woofer-square-front.jpg

AR14-woofer-square-back.jpg

Both round and square magnet woofers have a common number "561". 

Here's my woofer. Which also has the "561" code. Could it be that my AR-48b speakers had AR-14 square magnet woofers with front mount surrounds installed but with the 200040-0 label? At this point I'm pretty confident that AR used the same 10 inch woofer design in several different speakers. The model # 200040-0 or 200004-2 may have been different but it was still a "561" speaker.

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I'm still curious about the cone coating though. Was it a factory applied coating or not? It would be great if there were some AR speaker assembly line people on this forum who might know the true story.

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"561" is simply an AR code for AR drivers. The "84" is the year of manufacture, and the two numbers after the 84 represent the week of manufacture in 1984.

I have seen shiny original AR cones on later AR-94 woofers.

It was not at all uncommon for AR to make minor changes to drivers along the way. The over/under surround difference is a non-issue, having more to do with manufacturing technique than anything else.

Roy

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Hi Roy,

Thank you for your insight. Question about the date code. In one of the pictures of the AR-14 woofer it's showing a date code of 7786. I can understand how 77 would be the year, just not sure how 86 could be the week. Maybe AR had another way to interpret the date code?

Anyway on another note, thanks for supplying your cloth surround treatment. I bought a small bottle from you (ebay) awhile back and used it to recondition AR-2 woofers. It work great. Got the AR-2's restored, replaced the standard cross-firing midrange assembly with an AR-2ax midrange to make my own "upgraded" upright standing AR-2x's. I still have to stain the new mounting board for the midrange speaker and make a new grille cloth board and attach grille cloth to it. Some work left, but they do sound great.

AR2-woofer.jpg

 

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To help you, I am attaching photos of a pair of my original AR48B woofers (I own all the AR48B kit except the cabinets!), these have the foam glued to the rear of the cone.

They are numbered 200040-0, 84/32 dated.

1035929668_AR3al14.jpg.b38bb6b4a89bbb79611eaa9191723deb.jpg647109178_AR3al18.jpg.a606ba4c25d756d819a77f78c8696977.jpg645420524_AR3al19.jpg.473c1ac606a481a167e9d120a9fc4818.jpg2033413931_AR3al20.jpg.848c0efe5c0c552c2ab733ea03c70b85.jpg

Finally woofer always 200040-0, dated 82/01 replacement AR intended for AR38s

163970955_AR3al17.jpg.081547967e269aeb2b517e1a32658a36.jpg173243683_AR3al16.jpg.96494425df1e60676708c978b9ce2e5d.jpg

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Hi Giorgio,

Thanks! I don't know how to interpret this evidence. I really think in my pair of AR-48b speakers that AR installed 200004-2 with square magnet version and put a 200040-0 label on them. From the pictures I found the 200004-2 with square magnets have the surrounds mounted on the front face of the cone. Anyway I'm ready to put all this to rest and just enjoy the music from these speakers. Well, ok, not exactly to rest yet. I did buy some 200004-2 with square magnet woofers on ebay and will need to replace the surrounds. I could not find 200040-0 woofers, maybe is bad timing.

Once I get the 200004-2 woofers (uncoated cones) restored then I can do an A/B listening test and see which woofers I like better. I suspect I won't hear much of a sound difference between the coated and uncoated woofers.

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From the close up picture of the coated cone, it looks like it was treated with Parts Express Wet Look.  I've used it before, to treat stained woofers, and Wet Look has that same translucent shiny appearance.  After coating, I didn't hear any negative effects from the treatment.  But, I don't have test equipment to measure for differences, so I have to just trust my ears.

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I don't know if there are technical differences between 200040-0 and 200040-2 woofers, but the magnets are the same, even cone paper will be the same, probably different color shades, just wanted to add that the 200004-2 round magnet woofer  is a replacement probably after the second half of '84 made by Tonegen for AR: tipical TNG the anti-rust treatment in yellow nickel of frame and magnet, moreover the identification plate on the magnet covers the original TNG code and the red label on the sides of the frame indicates that this speaker is a replacement (this will probably sound the same as the others, as per AR tradition).

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19 hours ago, Jay said:

I bought new AR48b speakers back in the mid-1980's and had the surrounds of the woofers replaced once by a stereo repair shop around 2000 and a couple years ago I replaced the surrounds myself.

 

factory coating of the cones?

 

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IMG-2861.jpg

 

Hi Jay,

I think that around 2000 the stereo repair shop reconed your 200040-0 woofers instead of just replacing the foam surrounds! 

The part # of the 200040-0 original paper cone is 203043x and is printed on the back of the paper cone itself. 

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Jay,

AR was very reluctant to change item part numbers. When it did, in general something really important had changed!

On the AR drawings you can see that the on axis frequency responses of the 200040-0 and 200004-2 woofers are rather similar but the former has a 2-3 dB higher sensitivity than the latter.

The Tonegen 1210040-xx woofer you posted was the replacement part for the 200040-0 woofer.  When it was used as replacement part for the 200004-2 woofer it had a big resistor (probably to be connected in series to "tame" its greater sensitivity). Unfortunately I have never seen an official AR or ABtech document showing how to connect this Tonegen replacement part in the AR2ax, 5, LST2, 14 and 12.

 

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13 hours ago, Jay said:

 

AR14-woofer.jpgAR14-woofer-round-back.jpg

 

AR14-woofer-square-front.jpg

 

Jay, these pictures you posted are the pictures of a Tonegen 1210040-xx woofer used as replacement part for the 200004-2 original woofer. The Tonegen part # is printed under the 200004-2 label. Contrary to what the label reports, I don't think this woofer was ever built in the USA.  Note the big resistor.

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2 hours ago, fedeleluigi said:

Hi Jay,

I think that around 2000 the stereo repair shop reconed your 200040-0 woofers instead of just replacing the foam surrounds! 

The part # of the 200040-0 original paper cone is 203043x and is printed on the back of the paper cone itself. 

Oh my gosh, you nailed it! I took one woofer out of the cabinet to check the cone part number and it was not a match to 203043x, it was 337584.

337584-small.jpg

Did a google search and found this: 337584 10 inch replacement cones.

337584-cones-small.jpg

Mystery solved. I know the AR-48b and other Teledyne AR speakers is not considered to be AR's finest, but I do like their sound and will have to make them right again.

Thanks to everyone for helping me to solve this.

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Bravo Luigi, a good anamnesis, experience, observation and an eye accustomed to grasping details are able to make a correct diagnosis without other help!
The same can be said of Xtophr, the enigma here is easily solved with the only help of a 1.5v battery to find the correct polarity, Jay will inform us of the right positive contact of this Franken cone.

P.S. Jay, The date of the AR14 cone is easily 7736, the stamp probably hand-stamped and variously positioned on a magnet or basket is sometimes moved, not very impressed, partially canceled, sometimes even 2 stamps with different dates, an example in my 2 AR3a tweeters below.

6441 or 7505 ? Probably the stamping worker was confused that day or did some printing tests!

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Even here it might look like 7488

347894500_AR3al21.jpg.46d3bf2b38c103d608afe2b8606030f2.jpg

 

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36 minutes ago, xtophr said:

image.thumb.jpeg.91852c0c0c886a6a1e23fe4d9c8fae19.jpeg

Is this driver hand marked out of phase? Usually AR marks the + connection with the red dot on the adjacent label. Has something changed during re.coning?

When I replaced the surrounds in 2019, I tested the phasing with a 1.5 volt D battery. With battery momentarily touching the connectors (with jumpers) and the cone popping outward then I knew the proper phasing and marked the cage. It could very well be that during the re-coning that they reverse connected the wires. I do remember having to swap the wires at the terminals after that shop repair because the bass didn't sound right, but I never checked the phasing back then.

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6 hours ago, fedeleluigi said:

On the AR drawings you can see that the on axis frequency responses of the 200040-0 and 200004-2 woofers are rather similar but the former has a 2-3 dB higher sensitivity than the latter.

 

The Tonegen 1210040-xx woofer you posted was the replacement part for the 200040-0 woofer.  When it was used as replacement part for the 200004-2 woofer it had a big resistor (probably to be connected in series to "tame" its greater sensitivity). Unfortunately I have never seen an official AR or ABtech document showing how to connect this Tonegen replacement part in the AR2ax, 5, LST2, 14 and 12.

 

Hi fedeleluigi,

How are you viewing the AR Drawings? When I visit the AR Drawings resource it is a flash file and flash is not supported by Adobe or any web browser anymore. Maybe I am missing something here. I know you are not site or forum admin, but maybe an admin can update the AR Drawings from unsupported flash to some other format so people can view it?

 

Quote

 

AR Drawings

The attached drawings were released into the public domain by Acoustic Research in 1990.  They are provided here for historical purposes only.

- Ken Kantor

AR Drawings Index in Adobe Flash Format

 

 

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