Jump to content

My AR4x resto...


fran604g

Recommended Posts

Hi again, folks!

The 3a project is humming along nicely and working with them caused me to revisit the 2 pair of 4x's that I've had stashed for another day. Today is that day.

I remember doing a little precursory research a couple years ago, but didn't get too in depth with my search. This pair is a great restoration candidate, completely original and complete. The drivers all work, I will measure everything as I do the restoration. SN are; FX 76489 and FX 85141. I got them from the original owner.

I'll be cleaning the pots, as usual, using the surround sealant that I got from RoyC a while back, and replacing the 20uF cap with a MPP Dayton, I don't know if that's the best substitute, but if I don't like the sound, I'll try a motor run electrolytic next. The cabinets will only require light cleaning and some oil to bring back, IMO.

Can someone tell me production dates for these 2?

DSC03890.jpg

The second pair are basically parts donors, I should be able to make one good speaker with the tweeter and one of the woofers. I will try to clean up one of the tweeters and see if either one works. One woofer has a good cloth surround, that I resealed with RoyC's sealant. It and has a U(?) shape magnet frame sealed with masking tape.

These are from the donors:

PNunknown1.jpg

PNunknown.jpg

The other has a foam surround that is gone, and a square magnet the part number on the frame is 200001-1.

Did AR use foam surrounds on the 4x woofers? Or is this from a different system?

PN200001-11.jpg

PN200001-1.jpg

 

 

 

 

Link to comment
Share on other sites

I just realized that I started a thread for these last year after my spinal surgery, and forgot all about it.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6398&hl=fran604g#entry87714

If a mod could merge the two threads, cool , if not I'll continue with the newer post.

Sorry for being brain-dead. ;)

Link to comment
Share on other sites

Thanks Mike for the reply. It measures 5.8ohms, very close to the other, but the basket is very new looking and lighter in weight, so I was thinking someone may have decided to do a little replacing.

I wonder if that driver was ever sold as a "replacement" for the originals?

Link to comment
Share on other sites

Thanks Mike for the reply. It measures 5.8ohms, very close to the other, but the basket is very new looking and lighter in weight, so I was thinking someone may have decided to do a little replacing.

I wonder if that driver was ever sold as a "replacement" for the originals?

This woofer was listed as a "universal woofer" in the 1977 and 1979 AR parts list. It (or some slight cosmetic variation of it) was used in many AR speakers from the AR-6 and 7 on.

The serial numbers of your 4x's indicate a manufacture date of early 1967.

Roy

Link to comment
Share on other sites

Even though these universal woofers will fit and generally perform well in a variety of AR speaker cabinets, it appears that even the replacement units may have had a variety of configurations. Two pics attached are from AR-7's that have factory replacement woofers.

Frontal pic shows a heavily textured paper cone similar to yours, but this woofer has a slightly domed dust cap with sort of a rubbery texture. Also, it surprised me to see that these woofers had this outer gasket ring, which is some type of dense compressible foam material - - am not used to seeing these on AR drivers.

The rear pic shows a very different magnet structure from your square ceramic magnet and some alphanumeric information. The red sticker denotes this driver as a "Service Replacement Unit"; the back of the magnet is stamped with 1210037-2A; and the white sticker has the designation 1200001-1. On the other woofer from this pair, which is identical, the white sticker is located differently on the magnet, and another number (503TNB) is also visible.

I cannot determine any date of production for these woofers, but this stamped AR logo is much more recent than the logo used during the 'classic' years.

post-112624-0-68586500-1347636247_thumb. post-112624-0-94443700-1347636293_thumb.

Link to comment
Share on other sites

Even though these universal woofers will fit and generally perform well in a variety of AR speaker cabinets, it appears that even the replacement units may have had a variety of configurations. Two pics attached are from AR-7's that have factory replacement woofers.

Frontal pic shows a heavily textured paper cone similar to yours, but this woofer has a slightly domed dust cap with sort of a rubbery texture. Also, it surprised me to see that these woofers had this outer gasket ring, which is some type of dense compressible foam material - - am not used to seeing these on AR drivers.

The rear pic shows a very different magnet structure from your square ceramic magnet and some alphanumeric information. The red sticker denotes this driver as a "Service Replacement Unit"; the back of the magnet is stamped with 1210037-2A; and the white sticker has the designation 1200001-1. On the other woofer from this pair, which is identical, the white sticker is located differently on the magnet, and another number (503TNB) is also visible.

I cannot determine any date of production for these woofers, but this stamped AR logo is much more recent than the logo used during the 'classic' years.

post-112624-0-68586500-1347636247_thumb. post-112624-0-94443700-1347636293_thumb.

Fran604g's "universal" replacement woofer is an AR driver from the 1970's and would be a perfect replacement for any 8 inch woofer of that era.

The replacement found in ra ra's AR-7 is an early to mid 80's replacement driver manufactured by Tonegen in Japan for AR. It is a good match for 1980's era AR models, but has somewhat different characteristics than the foam surround woofer used in mid 70's AR-6, 7, 4xa models.

Roy

Link to comment
Share on other sites

Also, it surprised me to see that these woofers had this outer gasket ring, which is some type of dense compressible foam material - - am not used to seeing these on AR drivers.

Typically you'll see woofers as you describe in mid/late-1980s AR speakers, such as the AR-18 AV Rock Partners and the AR Red Box II.

They were probaby an "as close to original as we can supply" replacement during the time period in which the AR-7 in question were serviced.

See also the following topic: http://www.classicsp...?showtopic=7344

Robert_S

post-101656-0-68830900-1347643608_thumb.

AR-1210037-2A

Link to comment
Share on other sites

Excellent responses . . . I continue to be impressed with the depth of knowledge some of the members here have for these products.

To fran604g, I just re-read your original post and had to chuckle when I realized that you had one 4x speaker with a woofer similar to the one originally used in an AR-6. My amusement was reflecting on my own situation - - - not all that long ago, I came into possession (sight unseen) of a pair of AR-6's, and they arrived with original cloth woofers from the AR-4x. Sheesh, if you only had a matching pair of these AR-6 woofers, I'd be tempted to suggest a swap!

To Robert_S, those Rock Partner woofers look identical to the ones I have as factory replacements for the AR-7's. Thanks for the quick reference.

To RoyC (and others), these Tonegen woofs seem like very decent drivers, but they are clearly a generation removed from the 8" woofers originally intended for use in the earlier 70's speakers - - - the models 4xa, 6 and 7, as you've mentioned. But now that we're speaking of 8" woofers from the 80's, I'd be curious to hear any opinions about how the 8" drivers from the AR-93 speaker (see attached pic) might work as substitute replacements for the AR-6, 7 or 4xa. The part numbers for these drivers are: 200035 (woofer) and 200036 (lower mid-range).

post-112624-0-88624000-1347677027_thumb.

Link to comment
Share on other sites

To RoyC (and others), these Tonegen woofs seem like very decent drivers, but they are clearly a generation removed from the 8" woofers originally intended for use in the earlier 70's speakers - - - the models 4xa, 6 and 7, as you've mentioned. But now that we're speaking of 8" woofers from the 80's, I'd be curious to hear any opinions about how the 8" drivers from the AR-93 speaker (see attached pic) might work as substitute replacements for the AR-6, 7 or 4xa. The part numbers for these drivers are: 200035 (woofer) and 200036 (lower mid-range).

The 1210037 discussed above was used as original equipment in at least one version of the AR-94 as well as other AR9xx era models. Most of the 80's AR woofers would probably work acceptably in the older models when used in pairs. They just won't sound exactly the same as the original woofers.

Roy

Link to comment
Share on other sites

Excellent responses . . . I continue to be impressed with the depth of knowledge some of the members here have for these products.

To fran604g, I just re-read your original post and had to chuckle when I realized that you had one 4x speaker with a woofer similar to the one originally used in an AR-6. My amusement was reflecting on my own situation - - - not all that long ago, I came into possession (sight unseen) of a pair of AR-6's, and they arrived with original cloth woofers from the AR-4x. Sheesh, if you only had a matching pair of these AR-6 woofers, I'd be tempted to suggest a swap!

That's too funny. I don't really know what I'm going to do with it yet, if I don't end up using it, I'd be happy to send it off to you.

Fran

Link to comment
Share on other sites

Thanks, RoyC, Robert_S and ra.ra. for your responses!

I finished up my 3a's today so, in a couple days I'll dive into the 4x's. I ordered the new caps for them when I ordered my 3a's stuff.

It'll be nice to listen to the 3a's when I'm working on the 4x's. I'm a very lucky man right now. :)

Link to comment
Share on other sites

fran604g, keep us posted on your upcoming 4x restorations.

RoyC, thanks for the comments on the history of the 8" woofers. I've been curious about the particular refinements made for the 6-7-4xa woofer which resulted in such exalted performance - - - I believe this was the first AR 8' woof with a foam surround, but I have assumed that this long-throw voice coil was a prime factor in its success. First attachment here is AR literature; second and third attachments are from 1972 English magazine audio review. I know we've been discussing the ceramic magnet version and this article shows the earlier alnico magnet, but I wonder if this long voice coil feature became commonplace as AR developed subsequent 8" woofer designs.

post-112624-0-83152300-1347756294_thumb. post-112624-0-06010000-1347756309_thumb. post-112624-0-03579700-1347756321_thumb.

Link to comment
Share on other sites

Good to see your progress here......

I got a real kick out of seeing that the insides of both of your cabinets had the liitle personalized stamps of the factory assemblers, and in the case of s/n 85141, it was the same guy who put together my AR-4's in 1964.

Just for reference or for your own comparison, attached is a close-up of some woofers I re-sealed some months ago using Roy's sealant - - - AR-4 on left and AR-4x on right. As you know, this stuff is very easy to apply and it originally sets up to be extremely tacky - - - I thought it felt almost like flypaper strips - - - but it settles down to become a nice soft coating after several weeks of curing.

The second pic shows the simple re-cap with a single 20 mf Dayton - - - and oops, this x-o is for the 4x and not the 4 - - - I had it incompletely labelled when I shot the pic but corrected the label before I closed it up.

post-112624-0-24775900-1347910926_thumb. post-112624-0-47226000-1347910942_thumb.

Link to comment
Share on other sites

Nice ra.ra! That's the exact cap I bought from PE. Your 4x, is it older than mine are? the surrounds on both of mine are black, not orange/red (whatever you call the color.)

I got a kick out of the "keep on truckin'" guys' stamp! What a hoot!

I know the original owners' son, so I know these have never been opened up, that's nice...no nasty surprises! I should finish these up tomorrow and get them in system later in the day :)

Keep on truckin'!

Link to comment
Share on other sites

The pair of 4x's (which was shown in post #16) have the following serial numbers: FX316924 and FX320139. I admit to having some confusion about the dating of these because sometimes 4x's have the FX prefix and sometimes they do not. Nonetheless, I think it might have been RoyC who pointed out to me that at some later date, AR decided to add lampblack to the butyl mixture that was used to seal the woofer surrounds, and from that point forward, they no longer appeared orange but were mostly, if not entirely, black.

You can see in the attached pic that my two pairs of 4x's have slightly different woofers: one pair has smooth gray cones with the orange surrounds; and the other pair has ribbed black cones with black surrounds. Also, one pair had the Industrial Condenser wax block caps while the other had the silver Spague compulytic cans. One pair has aluminum pot controls and the other has red plastic. Indeed, several small variations do exist in this very popular model of consumer speaker, but they are all reasonably equivalent.

It's nice to find these old speakers that have not been tampered with, but after 35 or 45 years, they do deserve a little attention.

Now, don't get me started on Robert Crumb's cartoons.

post-112624-0-16029800-1347942658_thumb. post-112624-0-67344700-1347943518_thumb.

Link to comment
Share on other sites

. . . personalized stamps of the factory assemblers

Veering off topic but perhaps of interest, questions were previously raised regarding the signification of the stamped figure, in the following post:

Interesting note: What is the significance (if any) or meaning of the the little stamped figure on the inside panels of the speaker cabinet? It looks like a cartoon of a girl (boy?)

See the full topic below for more on this subject:

http://www.classicsp...002

Robert_S

post-101656-0-26788000-1347953595_thumb.

Link to comment
Share on other sites

Veering off topic but perhaps of interest, questions were previously raised regarding the signification of the stamped figure, in the following post:

See the full topic below for more on this subject:

http://www.classicsp...002

Robert_S

post-101656-0-26788000-1347953595_thumb.

Your image is much clearer than any of mine, Robert, thanks for the clarification, although I am a little disappointed that it's not the K O T guy :(

Link to comment
Share on other sites

I have them back together, I managed to clean up both pots and they both measure ~14.8 - 14.9 ohms. I used my little electrolysis rig and it has proved be more effective at restoring the operation than just sanding/wire brushing or using silver tarnish remover. I noticed that many of the lugs on these and the ones out of my 3a's showed a lot of dirty flux and crud that was at the base of the lugs around the rivet. I found that after cleaning, heating up the lugs enough to melt and remove the old solder and flux, seemed to improve the reliability of the pots.

When I finished them, they were smooth and accurate. I also re-formed the wipers when they were too flat, or in one case, where the wiper was traveling along the edge of the disc. Some of the pots' discs weren't centered in the ceramic. After re-forming the wipers, I feel confident that they will work for an extended period of time simply because they are travelling a new, unworn, path on the disc.

Anyhow, I'm listening to them right now, and I was a little surprised at how much sound these little guys put out. :)

post-111058-0-89275400-1348005038_thumb.

post-111058-0-40951900-1348005060_thumb.

post-111058-0-88770300-1348005094_thumb.

post-111058-0-37414800-1348005111_thumb.

Link to comment
Share on other sites

Hey, nice job on these 4x's - - - for not all that much work, one can get a great deal of satisfaction from restoring a pair of these. It was difficult to see the condition of your cabinets, and I suspect these may no longer have grille cloths, but I do know how impresive the sound can be from these speakers.

I had noticed the plywood cabinets (i.e. no visible particle board or MDF) and the five digit serial numbers suggesting a reasonably early production date, but was still a bit surprised to see Roy's note that these date back to early '67. It's always fun to give these old buggers a new lease on life.

Regarding the stamp images inside the cabs, I followed the link from Robert_S and it still seems inconclusive as to their origin, so until I learn otherwise, I'm going with the thought that some AR assemblers on Thorndike Street in Cambridge were having a little fun and just leaving their mark before they closed up the cabinet and sent it off for inspection...........sort of like the steelworkers chalking their initials on the topmost beam.

Link to comment
Share on other sites

Thanks, ra.ra.

I'm still going to hold onto my feeble belief that the keep on truckin' guy built my cabinets, lol ;)

Overall, the cabinets are in very good condition, no large defects or serious cracks, etc. The finish should come back with a little cleaning and some oil, I think. I have the grills, they're not torn or otherwise damaged, but are a little dirty, I will clean them with some soap and water. They both have badges, one is broken at the stake, but I think I can hot glue it onto the grill, for appearance sake. I got lucky again.

The other pair that I have are really roached. I found them at a garage sale...in the rain, and they had been in some guys garage for a long while. They are the particle board version.

post-111058-0-33521800-1348068626_thumb.

Link to comment
Share on other sites

Regarding the stamp images inside the cabs . . . it still seems inconclusive as to their origin.

Yes, I agree. There's also an ambiguity as to what the image may depict. Matt's description of "a cartoon character of a carpenter wearing coveralls and a hat with a pencil behind his ear" is, to my eyes, perhaps more plausible than Vern's "The rubber stamp is a little girl with her school books."

Regardless, a fun example of personalisation.

Robert_S

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...