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About fedeleluigi

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  1. A lurker steps out!

    Thank you Chris, When you have your LSTs repaired, I would appreciate it if you could let me know how they perform using both the ML-11 and ML-9. If I remember correctly these Levinson amplifiers were designed by Tom Colangelo. Unfortunately, I've never listened to the Levinson amps designed by him. I only listened to Levinson amps designed by Madrigal's engineers. In any case, if I were you I would also try the "little" Radford STA 15. If its caps, resistors and tubes are OK and if your listening room is not very big or your listening position is not very far from speakers, it could work very well with LST despite its low power. Once I listened to a pair of LSTs driven by a 35 Watt tube amp (the Unisis by "Tube Technology") and the sound was very good and enjoyable. Luigi
  2. AR 11 Diagram

    Yes, that's right! Obviously, tweeter and midrange switches are completely independent of each other and can be used to independently get different attenuation of sound pressure in high- and mid-range frequencies. Luigi
  3. A lurker steps out!

    Hi and welcome Chris, Which are the best sounding amplifiers you have used (or listened to) to amplify AR loudspeakers ? Luigi
  4. AR 11 B schematic

    I've drawn the AR-11 MKII (B) crossover schematic. I've preferred to use old style types and drawing. Hope it can be useful. Luigi
  5. AR 11 Diagram

    I've drawn the AR-11 MKII (B) crossover schematic. I've preferred to use old style types and drawing. Hope it can be useful. Luigi
  6. Here is the AR 10 Pi schematic coming from a copy of an AR original drawing sheet. Unfortunately the copy I have is not complete and a part of the AR drawing sheet is missing. I couldn't find this schematic in the "AR Drawings" section, so I hope it can be added to the other files somewhere in the Library in order to allow everybody to see it. I think it's a rather rare document even if, unfortunately, not complete. I have scanned it as TIFF format then I've converted it to JPEG to insert it directly into this post. To get a higher resolution, save the attached file in Tiff format. Differently from LST, in the AR 10 Pi the auto-transformer and the 3 dB step switches permitted the listener to have more flexibility with a total of 27 different combinations of driver output level (that is 27 different frequency responses) without using any attenuation resistor. The auto-transformer enabled the user to control bass output by a 3 step switch as well. Differently from midrange and tweeter, the woofer switch (Woofer Environmental Control switch) is actually not a 3 position +/-3dB step switch but a 0dB (4Pi), -5dB (2Pi) and -8dB (Pi) switch. Luigi PS: I had already posted this schematic in the Acoustic Research forum pages but I think that the most appropriate place is probably here. AR10 Pi original schematic TIFF.tif
  7. AR-9 Restoration - Pete Basel

    Pete, could you post some pictures? Luigi
  8. AR3a Tweeter Voice Coil Wire Gauge

    Hello David, The AR drawing (DRG. NO. 202029, ISS. C of 14 May 1982) reports the use of N. 38 AWG insulated copper wire for the 3/4" lamda driver voice coil. It also reports 22-24 turns in all and a DC resistance from 3 to 3.7 ohms REF. Taking into account that AR 3a tweeter voice coil has about 20 turns, (that is 10-20 % less than lamda driver's), using the same wire gauge, the resulting DC resistance should be OK. Examining some AR 3a voice coil by a biomicroscope, I have counted about 8 and 12 turns for the outside and inside layer respectively. Luigi
  9. AR-3a / AR-91 Combo Build

    About the risk of overdamping the last generation 200003-0 woofer by using 20 oz of fiberglass, you can read this other John O'Hanlon's post:
  10. AR-3a / AR-91 Combo Build

    Hi ar_pro, You did not post a picture of the woofer magnet you used but your AR woofer seems the last production of the 200003-0 woofer with round magnet. So, if I were you, I would also try about 8.82 oz of the "white" polyester wadding as the last production of AR11 or 10 Pi that used the same woofer as yours. As far as I've observed in Italy, AR11 and 10Pi never used fiberglass with the last generation 200003 woofer. Moreover, it seems that the real enclosure volume of the ar 3a is exactly the same as AR11 or 10 Pi's , read Johnieo's (John O'Hanlon's) post here: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/1194-ar3a-vs-ar11-cabinets/&do=findComment&comment=55341 . So, using the last generation 200003 woofer, the amount of polyester to be used in the 3a cabinet should be the same as in the last AR11 or 10 Pi (using the same type of polyester). I don't know the precise "physical" characteristics of the white polyester wadding AR used in AR11 or 10 but, if available, I'd try the polyester used in the AR 9 or LS series as all of them look identical. I think your 3a/91 balance between bass, midrange and treble could improve. I would also try polyester wadding even if I had the 200003-1 square magnet woofer. Luigi
  11. AR-3a / AR-91 Combo Build

    This is what I've observed in Italy: The 10Pi and AR11 for the Italian market were assembled in England and Holland. All of them share the same drivers and the same enclosure volume. In the last months' production of AR10Pis and AR11s assembled in 1979, I've observed about 250g (8.82 oz, so rather close to the 10 oz reported in AR11 drawing ) of white polyester wadding inside each loudspeaker. It seems exactly the same type of polyester wadding used in the 9 and, later, in LS series. Generally I've found just one polyester sheet (about 2.5-3" thick) per loudspeaker. In some AR10 Pi and 11 assembled about in the same period or just some month before or in a different factory, I've found about 350 g (12.34 oz) of grey-purple-red-green polyester wadding (per loudspeaker). Its texture is different from the white polyester wadding. Inside each loudspeaker there were several square or rectangular polyester sheets (about 1-1.5" thick). From about 1977 to about all 1978 I've found about 450 g (15.87 oz) of grey-purple-red poliester inside each loudspeaker. This was the same polyester also used in the 3a improved (that initially used fiberglass) . It was "softer" than the polyesters previously mentioned. As regards the 3a improved I've observed about 500g (17.65 oz) of this polyester per loudspeaker. From 1975 to 1976 I've found an average of about 500 g (17.65 oz) of fiberglass inside each loudspeaker. I've never found fiberglass inside AR11 or 10Pi "B" or "MKII". Luigi
  12. Dome mids vs. cones--meaningful difference?

    Hello Steve, Which BA loudspeakers used this 3-1/2" cone midrange and how did they altogether sound in your opinion? Regards Luigi
  13. Yes, a not correct dope for the woofer cloth surrounds, but also a wrong foam surround for the ferrite woofer can change the Thiele and Small parameters of the woofer itself and consequently its performance in the same enclosure volume. I would have carefully tried a solvent like toluene in the hope that it could refresh and revive the old dope instead of using a dope of "unknown characteristics". Talking of this subject, does anybody know what AR exactly used to dope cloth surrounds? Luigi
  14. There have already been some topics about today's differences between AR3 and 3a sound . http://www.classicspeakerpages.net/IP.Board/index.php?/topic/8815-difference-in-sound-between-ar3-and-ar3a/#comment-107669 http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9195-stopped-for-toilet-paper-found-a-pair-of-ar3s/&do=findComment&comment=111657 It's very strange that you can listen to evident differences in bass frequencies but when comparing loudspeakers they should be exactly placed in the same position otherwise the differences you note could only depend on speaker positioning. Although old reviews that compared perfect functioning loudspeakers said that the differences between AR3 and AR3a were subtle, today, after about 50 years, things are different. Today, AR3s often have problems especially with midranges (low midrange output) whereas AR3as very often have problems with tweeters (low tweeter output). Luigi
  15. As can be seen by the schematic, differently from midrange and tweeter, the woofer switch (Woofer Environmental Control switch) is actually not a 3 position +/-3dB step switch but a 0dB (4Pi), -5dB (2Pi) and -8dB (Pi) switch. Luigi