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fedeleluigi

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  1. when you can , would you please inspect carefully the sides of the ferrite magnets because the manufacturing dates were also printed there? thank you
  2. yes. no, you are not missing any pieces.
  3. @cbolen your woofers didn't originally have the so called "masonite ring" on the frame (see the photo of the woofer I posted as it has the masonite ring). In your woofers the foam suspension was directly glued to the metal frame. If you want to keep your woofers original you don't have to use any masonite ring. Later AR used a masonite ring glued to the woofer frame and the foam suspension was glued to that masonite ring.
  4. @cbolen thank you very much for the woofer photos with dates. The date printed on woofer #1 should be MAR 17 1971. About woofer #2 I can clearly read only the month (MAR). Also if not leagible the year is almost certainly the same as the other woofer (1971) since your 3a have very close serial numbers. Please inspect carefully the sides of ferrite because the dates were also printed there. In the attached pictures you can see a woofer made only one month later (APR 22 1971). You can note that just one month later AR had switched to the so called "long wire" woofer. This woofer had a mounting ring on the frame for the surround and no damping ring on the paper cone. a
  5. @cbolen Yes, all the drivers are original. The woofers are very rare. If the woofer spiders and voice coils are ok, you only need to refoam them. Since this type of woofer is rare, could you please post clear photos of all the dates printed both on the ferrites and the bottom plates ? Thank you.
  6. @lARrybody the DC resistance you measured (3.9 Ohm) is not correct for the 200003 woofer (it should be about 2.6 Ohm +/- 10%). If your digital multimeter is accurate the tinsel wires could have some problem or the voice coil could have been replaced with a not appropriate one. The woofer basket looks like a 1975 one therefore the original tweeters were replaced with later versions since the tweter domes/suspensions were yellow until the first months of 1976 and later black. In any case there was no foam on the tweeter flange for the AR-10 Pi MKI. The original tweeter used in the AR-10 Pi MKI and AR-11 MKI are shown in the file "Restoring the AR-3a" (Fig. A.21 and A.22).
  7. You can find a higher definition drawing in the library (AR drawings). The drawing is the 241th and is named "no image". Luigi
  8. Hi Scoup, Thank you for answering my questions. I think that It's rather difficult to make accurate comparisons among speakers, especially if they are old, because there are many variables that can "distort" the perceived results. That's why I asked you some questions in my previous post. For example, in vintage speakers capacitors are often out of specs randomly. Different types and brands of caps may rapresent other unpredictable variables. Beyond capacitors, the drivers can also age differently depending on many factors. In other words, with aging, even speakers of the same model often sound differently from each other. Similar speakers like AR9 LS and AR9 LSI should be placed in an identical position if you want to make a correct comparison because speaker placement does affect the sound a lot. So, in this regard, I think you should have swapped the speakers position to get more objective results during your comparison. Different model of speakers often require different placements and/or amplifiers to get the best they can give. The SPL at the listeng point should be as similar as possible for all the speakers under test. Obviously our subjectivity is another variable but it's very difficult to eliminate it without resorting to a double blind experiment. Luigi
  9. @BjarneAndersen Hello Bjarne, Unfortunately the coil is out of focus. It seems that you made only one layer winding covering all the former. If so, this is not correct. 1) the winding must be a two layer winding and 2) the former must not be covered completely. In the AR Library I've found the tweeter voice coil drawing of the "Lamba driver" used in the AR 9 LS, 98 LS and 78 LS. It is the 241th drawing. As regards wire, even though the drawing reports: "2 wire: 22 to 24 turns of N° 38 AWG (about 0.1 mm) copper……….. in two layers, 11 to 12 turns per layer", actually I have usually found an inner layer of 14 turns and an outer layer of 11 turns. Hope you removed the tweeter diaphragm only mechanically since solvents usually change tweeter suspension stiffness permanentely and consequentely the tweeter FS and Thiele-Small parameters. Luigi
  10. Hello Scoup, Did the LS and LSI have new crossover capacitors? If both of them had, did their crossovers use the same type and brand of capacitors? Did you test each of their driver before comparing the loudspeakers? During the comparison test, were the LS and LSI alternately placed in the same room position? Thank you for any clarification about your comparison test. Luigi
  11. Hi Tom, Unfortunately, nowdays it’s very hard to accurately reconstruct the history of all that AR did and made. Unfortunately, many witnesses are no longer available (or the available ones do not remember the events exactly) and many important historical documents are lost. As regards the introduction of the 12” ferrite woofer, the dates of some AR drawings (magnet, cone-skiver and the spider in my previous post) would suggest that its production probably started in 1969 (please, see the attached pictures with highlighted dates). Obviously, the dates of these drawings do not prove with absolute certainty that the production of the 12” ferrite woofer definitely started in 1969. If the L.C.C., Loudspeaker Components Corporation, Lancaster Wisconsin (mentioned in some AR drawings) and today’s Loudspeaker Components, L.L.C., Lancaster Wisconsin are the same company, there might be a chance that it can still have some important documents (receipts, part orders etc.) that could be very userful for trying to establish the exact production date for some of the drivers made by AR. Luigi this drawing is the 4th in "AR Drawings" this drawing is the 316th in "AR Drawings"
  12. Hi David, Examining the crossover photo you posted, the pots seem to have been bypassed (not in the correct way) by the previous owner. The photo is not so clear to see all the wirings precisely. When bypassing these 16 Ohm pots, the 16 Ohm resistance should be left in parallel with the respective driver (tweeter or midrange) otherwise the crossover network (in this case a 4 uF and 6 uF capacitor for the tweeter and midrange respectively) will be loaded by a different impedance and this will change the frequency cutoff and shift the crossover points in comparison with those of the original design. Obviosly, bypassing the pots (even if carried out in the correct way) does not allow to decrease and adjust the tweeter and midrange volume any longer and this could be a problem. Attached you can see the normal pot wiring, the early AR 2ax schematic and the correct and incorrect way of bypassing pots. Luigi
  13. Differently from what is reported on some other pages of this forum (for example), the 200003 woofer spider has 7 corrugations (7 crests and 7 troughs ), not 6. Actually the 7th crest and the 7th trough seem to be a little smaller than the other ones and become almost "invisible" after the gluing between spider and cone. In other words the 7th spider groove hosts the paper cone as shown in the drawing I've made.
  14. Hi Pete, There is a lot of information on AR Drawings about the spider of the 200003 ferrite woofer . Examining these documents carefully it comes to light that the first drawing of the AR 200003 spider dates back to 22 Jul 1969. So, most likely around this date the production of first 200003 ferrite woofer started. Revision B dates 1 Jul 1974 and apparently there was no change in spider manufacturing from 22 Jul 1969 to 1 Jul 1974 because Revision B only reports “drawing no. change" but a previous revision (O) dated 12 Sep 1972 reports "Revised Notes, DWG No. was X-3705" and something could have been changed on that occasion. Revision C (ISS. C) dates 5 Jul 1978 and apparently there is no variation about dimensions, material, treatment, supplier (LCC, Loudspeaker Components Corporation, Lancaster Wisconsin. I think that the same company is still operating nowdays and they could still have the original molds for the 200003 spider www.loudspeakercomponents.com ) in comparison with Rev. B. Differently from the previous drawing, on this last revision it is also reported something about the spider compliance (maybe there was some compliance variation in comparison with the previous spiders) but it's difficult to understand the standard used (where and how must the 50 grams be exactly employed? where do you have to measure the deflection?). You can find images of higher resolution on AR Drawings. The drawings are the 422th and the 423th but unfortunately there is no numeration. The last drawing is the 492th.
  15. Hi Klaus, It's very important to preserve the woofer spiders. In order to disassemble the spider from the masonite ring I use an antifog nitro diluent as solvent. It is possible to use more powerful solvent to make faster the dismantling process but they could damage or alter the spider treatment changing its compliance. First it is necessary to gently remove the basket nets and unsolder the tinsel lead wires.Then I use a syringe to apply the solvent all around the glued spider-masonite ring. It's very important to apply it about every 2 minutes for about 30-60 minutes. This long time is necessary as the glue will soften very slowly. After 30-60 minuter you have to try to delicately separate the spider from the masonite ring beginning from the spider edge. You can use a needle (or somefthing similar). Be careful in order not to damage the spider. If the glue is still hard you just have to continue applying the solvent and wait until it softens Apply the nitro diluent where you can separate the spider from the masonite ring and keep on applying it all around the glued spider-masonite ring until you can separate them completely. After the separation you have to clean the spider and masonite ring from the glue remmants as soon as possible otherwise the glue remmants will harden again and it will be annoying to remove them later. Than you have to remove the paper former of the voice coil and the glue from the spider/cone. I's very easy to remove the paper former. As regards the epoxy glue I remove it by gently using a thin sand paper until the new voice coil fits the hole. If the new coice coil doesn't have the vent holes they must be created with a good punch pliers. Voice coil should have 55-58 turns per layer and DCR should be about 2.6 Ohm. Apart from the type of former material, the voice coils of AR-12in ferrite woofers were rather similar along all their lifespan. In the AR drawings you can find the aluminum voice coil (the drawing is the 299th and is dated 25 Jan 1980). If the original paper voice coils are not too damaged (you can see it only after carefully taking the woofer apart) and if you have good manual skills you could try to restore them but it's not an easy procedure. So be very careful when removing the voice coils from the magnet gap in order not to further damage them. Luigi
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