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AR4x, little mystery ...


Giorgio AR

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I purchased my second pair of AR4x, like the previous one, this too is of late production (the first pair is around the end of '69: the date imprinted on the woofers' magnets is 69-46 and 69-47, no other date 'interior of the cabinets; in these woofers there is a damping ring on the cone around the dustcaps), the new pair, has date on the magnets of woofers 71-01 and 71-08, in a cabinet there is a stamp with date 06-71.
The veneers of both should be walnut, but darker than usual (the shades differ slightly, however dark).
The strangest aspect for me are the progressive numbers on the back labels: the suffix indicating the model (FX usually) is preceded in both pairs by the letter M (MFX) and the progressive numbers are:
006195 / 0075xx the first couple
022415/022680 the second pair

If they had been assembled in the USA, probably the number on the labels should have been around 300000/380000, the letter preceding the abbreviation identifying the model should indicate the country of assembly (e.g. H = Holland, E or EA = England, AU = Australia), I wonder if it is possible to establish where my two couples were assembled (perhaps in Italy? Here at us, from certain news numerous AR speakers have been assembled, including replicas in the 90s of the AR10PII of which I have a couple !).

In addition, this numbering difference, I had already noticed in other AR speakers, as late specimens of AR3a and AR7, this in my opinion makes me think that more speakers have been produced than reported by the US numbering !! I hope to stimulate further research and information on AR speakers labels with different numbers compared to the normal USA chronology.


In addition to the photos of the two couples, I also include photos of the original capacitors (wax box in the older AR4x pair, with values very out of specification , almost 40uF, the Sprague capacitors are still within tolerances, however I have replaced all the capacitors, all now very close to the 20uF of the project (these photos are to satisfy Ra.ra's knowledge, always very careful on the types and values of the original capacitors AR speakers !!).

In both pairs, the woofer seat (the baffle is in chipboard) with sealant gasket, was cracked laterally and was restored by gluing the fractures with two-component glue to guarantee the original seal of the air suspension.

Above the older couple

ar4xm1.thumb.jpg.f8390ce49c3ab57a93007fd50b2dbe22.jpgar4xm2.thumb.jpg.8d7bc807b4399d23b52fa78f76b68080.jpg

 

'69 pair

ar4xm3.jpg.0410839bbbc0acd312eb6b9b5d0b1736.jpgar4xm4.jpg.de6cbbdb5ab337019ed9c0ae317f5850.jpgù

Up '71 pair

 

ar4xm5.thumb.jpg.bc23da93d452b0f83ae9018cbdbc896c.jpgar4xm6.thumb.jpg.d72f116f1e6fa1131df3096f0b70bb4c.jpg

'69 labels up, '71 down

ar4xm7.thumb.jpg.3736b1897d06d53950aa5ebc52e6c3d3.jpgar4xm8.thumb.jpg.9d3f099aad1fb3de05b59d4874df7b90.jpgar4xm9.thumb.jpg.3f27039c7937e9f51ad9247c92b08e25.jpgar4xm10.thumb.jpg.0e903993924d4d1c060211a410b30842.jpg

 

'69 capacitors

ar4xm11.jpg.522ab393f408a1a52d22e7e6b679145f.jpg

'69 new capacitors

ar4xm12.jpg.6aa15671ad43e5140c154575ff8025a5.jpg

 

'71 new capacitor

ar4xm13.jpg.4a030a795e7376e6118a42124828e824.jpg

'71 Sprague capacitors (values painted in black up)

ar4xm14.jpg.4012db8fedf16b133cad95de35cda407.jpg

 

Date on '71 cabinet

ar4xm15.jpg.ce02c6b8a9ee325e788f4f05470b3559.jpg

 

'69 woofers

ar4xm16.jpg.4b5368b9f69486605552ab980a0365bc.jpg

 

'71 woofers

ar4xm17.jpg.b7c06c68cbfb88ceac0b5522fa233ca5.jpgar4xm18.jpg.bb1458448db69a853c7ab4a577e7c842.jpg

 

 

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Hi Giorgio, that's a fine-looking quartet of AR-4x's you have. My response here will include a little bit of personal documentation along with some conjecture to try to assist with your mystery serial numbers.

The original AR-4 used the letter prefix "F" in the serial number identification. Shortly thereafter, this model was revised to become the AR-4x - - with different woofer, tweeter, and crossover - - and adopted the letter prefix "FX" in the serial number ID. From my own collection, I can confirm these serial numbers for 4x speakers assembled in the USA:

  • 1966: 38,000
  • 1968: 160,000
  • 1970: 320,000
  • 1971: 380,000

I believe you are correct that the extra prefix letter in your serial numbers designates assembly outside the USA, and it is clear that your numbers and dates do not coincide with the USA serial numbers I have listed for general comparison. Clearly, the two European factories (England and Holland) used a numbering system completely removed from the USA production numbers, but I would not know if the two Euro sources shared and combined numbering or if they acted independent of each other.  

My guess here: in your case, I believe the added prefix letter is not "M"; but instead is a crudely scripted "H" to designate the Amersfoort, Holland location. I suspect that new paper labels had not yet been created to show the European address printed on them - - but as your AR-7 speakers from Holland show in this attached thread, the Holland address was indeed included by 1973.  

 

 

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1 hour ago, ra.ra said:

Hi Giorgio, that's a fine-looking quartet of AR-4x's you have. My response here will include a little bit of personal documentation along with some conjecture to try to assist with your mystery serial numbers.

The original AR-4 used the letter prefix "F" in the serial number identification. Shortly thereafter, this model was revised to become the AR-4x - - with different woofer, tweeter, and crossover - - and adopted the letter prefix "FX" in the serial number ID. From my own collection, I can confirm these serial numbers for 4x speakers assembled in the USA:

  • 1966: 38,000
  • 1968: 160,000
  • 1970: 320,000
  • 1971: 380,000

I believe you are correct that the extra prefix letter in your serial numbers designates assembly outside the USA, and it is clear that your numbers and dates do not coincide with the USA serial numbers I have listed for general comparison. Clearly, the two European factories (England and Holland) used a numbering system completely removed from the USA production numbers, but I would not know if the two Euro sources shared and combined numbering or if they acted independent of each other.  

My guess here: in your case, I believe the added prefix letter is not "M"; but instead is a crudely scripted "H" to designate the Amersfoort, Holland location. I suspect that new paper labels had not yet been created to show the European address printed on them - - but as your AR-7 speakers from Holland show in this attached thread, the Holland address was indeed included by 1973.  

 

 

Ra.ra, you are always helpful in your posts, today I finished and closed after the repairs of the cabinet and replacement of the capacitors (in the older AR4x pair a woofer still has small leaks in the seal, tomorrow even this small problem will be fixed ) both pairs.
I checked my photographic archive and I attach the labels of the second pair of ar7, in which the letter H is written correctly, from a survey with my family, it should be an M prefix, I hope that over time they will be found other testimonies on the existence of this prefix (as previously written, from certain news, AR speakers were assembled in Italy in the 70s as well).
In the attached thread I add the photos of my recent acquisition of the third pair of AR7!

 

1006648666_ar7ul8.thumb.jpg.fec77525a0c5fb9de5bfc884bfb81dba.jpg

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4 hours ago, Giorgio AR said:

.....it should be an M prefix........AR speakers were assembled in Italy

I'm sticking with my theory about the sloppy handwritten "H" indicating Holland, but if a plausible explanation for an "M" prefix turns up, it will be news to me. Additionally, I am not familiar with the notion of assembly taking place in Italy, so all of this could be very informative if it can be suitably documented. Your collection is indeed impressive. :) 

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