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giovanni56

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Everything posted by giovanni56

  1. giovanni56
    No it's not weird, on the last LST Ar manufactured Ar used those resistors as well. I found one that was faulty.
  2. giovanni56
    Did you measure the Re of the tweeters? what value did you. read?
  3. giovanni56
    These LSTs are among the last ones produced, they do not have midrange and tweeter with external wiring, those oval things close the holes of the external terminals. The original tweeters have been replaced with 200011-1, the crossover network has been modified by inserting a high-pass inductance of adequate value and the tweeter connection is in antiphase with respect to the midrange and woofer.
  4. giovanni56
    After restoring this pair of Ar LST, I did some checks and to my great surprise, I found broken the 10 Ohm 10W resistor in parallel to the 2500 nF C and the fuse holders with a very high contact resistance value. I decided to remove the fuse holders and replace the faulty R; I wonder what could have been the cause of this breakage that I hypothesize could occur if the 2500 nF C was interrupted leaving all the power of the amplifier to pass on the resistor. Does anyone have experience with this? thank you.
  5. giovanni56
    Sostituzione obbligatoria dei condensatori, questi Callin sono tutti fuori tolleranza.
  6. giovanni56
    Si tratta di una coppia di Ar LST a cui hanno sostituito tutti i tweeter Ar 200013-1 con AR / TNG 1200011-1 e il woofer Ar 200003, con Ar / TNG 1200003-AB dell'Ar3a Replica, quindi il filtro passa alto deve essere modificato; i midrange sono originali. Intendevo eliminare l'autotrasformatore ma non sono del tutto convinto.
  7. giovanni56
  8. giovanni56
    My collection of Ar
  9. giovanni56
    Have you checked to see if the filters in the two cases have identical component values
  10. giovanni56
    In 1969 it happened to buy a pair of Ar3a with Alnico woofers, both with smooth and corrugated cone; it was difficult to notice the difference on the woofers, because the frames were glued and removing them would void the warranty. The engineer Gianfranco Maria Binari (later editor of SUONO STEREO HI-FI), in 1969, bought a pair of Ar3a, with a woofer in corrugated cone and the other smooth; he noticed it, because with a flashlight he illuminated the woofers through the front cloth; later he was able to get a pair with both smooth woofers from the seller.
  11. giovanni56
    I'd be curious to measure the R of the bracket that's part of the filter wiring, which is under the woofer's low pass inductance
  12. giovanni56
    16 uF va a 32 uF ?? I don't understand, with the switch in INCREASE, C1 and C2 are put in series and in this case, the capacitance is halved and becomes 8uF. Am I missing something?
  13. giovanni56
  14. giovanni56
    In realtà, quel valore non è Fs ma Fc; tutti questi dati sono relativi al woofer installato nell'altoparlante e collegato al filtro crossover. Quindi il Qts è il Qtc, Qes è il Qec e così via. È anche evidente dal titolo, AR3a (European).
  15. giovanni56
    The spiders are fine; after the refoam, I checked the T&S parameters, all ok.
  16. giovanni56
    Everything made in Romagna, 😎
  17. giovanni56
    The capacitors are original Sprague, but the wiring harness wires are not original. The wiring harness has been redone. The AR10's are among the earliest produced, they have the external protection fuse next to the input terminals.
  18. giovanni56
    They sound very good; in my opinion, they are tops among the various Ar6 models
  19. giovanni56
    Restauro Ar6
  20. giovanni56
    Ar3a con tweeter ricostruito installato. The foam, unfortunately, is not 5/8". However, in my opinion, they sound very good.
  21. giovanni56
    Qts 0,025 ????
  22. giovanni56
    A prototype of Ar10Pone with slide selectors, was sent for testing to SUONO STERO HI-FI magazine in 1975. The test and measurements of the loudspeaker was conducted by engineer Renato Giussani (later ESB 706 designer), who reproduced, in the crossover filter scheme, the high pass of the tweeter with the 8 uF capacitor; by the way, the 8 uF value is also reported in sheet 15 of the spare parts list issued by Acoustic Research and indicated as spare part for the AR 10 (see attachments), part list 830025.
  23. giovanni56
    If I am not mistaken, the light hazel dome tweeters, which do not have ferrofluid, in the very early versions of Ar 10 Pi One (the ones with slide switches), had the high pass filter with 8uF capacitor and 0, 1 mH inductance, while all later versions had the 10 uF capacitor; Roy, could you kindly give me a confirmation about the tweeter and the 8 uF capacitor, thanks
  24. giovanni56
    Tweeter Ricostruzione AR3a: 1) Apparecchiature mobili e gruppo magnetico 2) Misurazione del peso dell'equipaggio mobile rotto 3) Misurazione del peso dell'equipaggio mobile rotto 4) Misura di R 5/6) Tweeter completato e cablato 7) Controllo e verifica centratura 8) Misura dell'impedenza e parametri T&S
  25. giovanni56
    Thanks
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