giovanni56 Posted October 11, 2021 Report Share Posted October 11, 2021 I noticed that the curved edge width in the Ar 200003 woofer suspension in the Restoring AR3a document is listed as 5/8" which corresponds to 15.875 mm. Dealers of replacement suspensions, for example Simplyspeaker or MidWest, have suspensions with 19 mm (6/8 ") and 17.6 mm (5.6 / 8") curved edge. Can someone explain the reason for these differences? The 5/8" format listed in the Ar3a Restore document, is that the correct one? Thanks to all Quote Link to comment Share on other sites More sharing options...
JKent Posted October 11, 2021 Report Share Posted October 11, 2021 Never mind Quote Link to comment Share on other sites More sharing options...
giovanni56 Posted October 12, 2021 Author Report Share Posted October 12, 2021 On 11/10/2021 at 21:11, JKent said: Non importa Thank you, for translating Quote Link to comment Share on other sites More sharing options...
Giorgio AR Posted October 13, 2021 Report Share Posted October 13, 2021 Hi Giovanni, I have been buying suspension foam from Larry for years and recommended as optimal by many AR enthusiasts. My last work with these foams: 2 x 200003 woofers (AR10TT MK2) and a '71 AR3a woofer with three notches magnet, the final aesthetic and sonic result is perfect. I got a suspension so I took a picture of the diameter of this roll: 17.5 mm. The same suspension was placed on the cone of an early woofer with Alnico magnet and cloth surround: it is perfect in all sizes! The same suspension resting on the cloth of the early woofer: perfect! Note the noticeable color difference of the 200003 woofer cones caused by the room arrangement (one speaker was sunny for many hours in previous years), I have kept the old deteriorated foam of aesthetic cover of the basket which will hide the screws when assembled. Quote Link to comment Share on other sites More sharing options...
giovanni56 Posted October 15, 2021 Author Report Share Posted October 15, 2021 On 13/10/2021 at 10:34, Giorgio AR said: Ciao Giovanni, compro da anni la schiuma di sospensione da Larry e consigliata come ottimale da molti appassionati di AR. Il mio ultimo lavoro con queste schiume: 2 x 200003 woofer (AR10TT MK2) e un woofer AR3a del '71 con magnete a tre tacche, il risultato finale estetico e sonoro è perfetto. Ho ricevuto una sospensione, quindi ho scattato una foto del diametro di questo rullo: 17,5 mm. La stessa sospensione è stata posizionata sul cono di un primo woofer con magnete in Alnico e surround in tessuto: è perfetto in tutte le misure! La stessa sospensione appoggiata sul tessuto dei primi woofer: perfetta!Notare la notevole differenza di colore dei coni del woofer 200003 causata dalla disposizione della stanza (un diffusore era esposto al sole per molte ore negli anni precedenti), ho mantenuto la vecchia schiuma deteriorata della copertura estetica del cestello che nasconderà le viti una volta assemblata. From the attached Ar drawing the curved edge of the foam is 0.72" or 18.299mm. Quote Link to comment Share on other sites More sharing options...
fedeleluigi Posted October 17, 2021 Report Share Posted October 17, 2021 On 10/15/2021 at 4:26 PM, giovanni56 said: From the attached Ar drawing the curved edge of the foam is 0.72" or 18.299mm. Hi Giovanni, I posted that AR Drawing of the 12" Woofer Cone\Skiver Assembly in a thread where we discussed about the date of the introduction of the 12" ferrite woofer. So you can see that I highlighted the date 1 July 1969 in that drawing . Note that the last revision (revision F)of that drawing is dated 23 August 1976. Quote Link to comment Share on other sites More sharing options...
fedeleluigi Posted October 17, 2021 Report Share Posted October 17, 2021 In 1977 a new 12" ferrite woofer was introduced. It had some differences from its predecessors and I do think that it was on that occasion that a new foam surround was also introduced. It measured about 5/8" (exactly 15.8496 mm) as you can easily calculate from the dimensions shown in the following AR drawing. I think that is why the restoring AR-3a document reports 5/8" for the foam surround. Click on the image and open it in a new tab to enlarge it. Quote Link to comment Share on other sites More sharing options...
giovanni56 Posted October 17, 2021 Author Report Share Posted October 17, 2021 10 hours ago, fedeleluigi said: Nel 1977 fu introdotto un nuovo woofer in ferrite da 12". Aveva alcune differenze rispetto ai suoii e penso che fu in quell'occasione che fu introdotto anche un nuovo surround in schiuma. Misurava circa 5/8" (più specificatamente 15,8496 mm) come puoi vedere dal seguente disegno AR. Penso che sia questo il motivo per cui il documento ritorno di AR-3a riporta 5/8 "per il rivestimento in schiuma. Clicca sull'immagine e aprila in una nuova scheda per ingrandirla. Hi Luigi, thanks for the clarification; so, if you want to be fussy, on Ar 200003 woofers, according to the years of production, you could install specific foam with the curved edge of different sizes. I have found 17.5 mm, 18.7, 19.2 and the infamous 14.7 with wide external flat edge, of which I have never understood the reason for being conceived. Quote Link to comment Share on other sites More sharing options...
Giorgio AR Posted October 18, 2021 Report Share Posted October 18, 2021 15 hours ago, giovanni56 said: the infamous 14.7 with wide external flat edge This image from the original AR brochure doesn't help, the AR3a woofer appears to have a wide external flat edge on the masonite (red arrow). At the bottom (black arrow) it seems much narrower ... it must have been a photo retouch of the time! Quote Link to comment Share on other sites More sharing options...
giovanni56 Posted October 18, 2021 Author Report Share Posted October 18, 2021 10 ore fa, Giorgio AR ha detto: Questa immagine dalla brochure AR originale non aiuta, il woofer AR3a sembra avere un ampio bordo piatto esterno sulla masonite (freccia rossa). In basso (freccia nera) sembra molto più stretto...deve essere stato un fotoritocco dell'epoca! That's a hybrid suspension! That brochure doesn't look like a photo, it looks like a rendering, the tweeter doesn't even have the three suspension points on it! Quote Link to comment Share on other sites More sharing options...
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