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fedeleluigi

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About fedeleluigi

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  1. fedeleluigi

    AR Tweeter replica/replacement

    Open the AR 10 PI "door". You should very gently detach the three black "cups" ( 5, 27 on the drawing). They are glued to wood so use a cutter blade to very delicately detach them. Be careful not to deform the black cups! Under the three cups there are three nuts (4 on the drawing) and you have to unscrew them and then the PCB can be removed. Anyway if the rivets are not oxidated, I would not remove the PCB from the cabinet. I would only detach the faston terminals one by one to clean them. Without removing the switch board you have to use a mirror or take a photo to see if the PCB rivets are oxidated or not. Obviously, also some other AR such as AR9 may have the same sort of PCB oxidation problems or some old solder joint issue. Should you decide to remove the switch PCB remember to resolder all the old solder joints present on the PCB itself.
  2. fedeleluigi

    AR Tweeter replica/replacement

    I forgot in my previous posts to suggest that you clean from oxidation the numerous electrical connectors (faston terminal) present on the switch PCB in the AR 10 PI. The faston terminal oxidation could be a cause for detail loss. Before detaching the numerous faston terminal from the switch PCB, take carefully note of their wire colour and precise position on the PCB otherwise it will be impossible to reconnect them in the right position. Probably, to be on the safe side, it's better to clean one by one. In the last picture, the oxidation present at the rivets of the faston terminals is also a certain cause of signal (and detail) loss. You should check out this possible problem as well.
  3. fedeleluigi

    AR-12 crossover

    The 20 Ohm resistor in the schematic is a misprint. Actually It is 2.0 Ohm and not 20 Ohm. You can see it from the AR 12 crossover picture. That's why the 20 Ohm resistor is not listed. In other words in the crossover network there are two 2.0 Ohm resistors and no 20 Ohm resistor is present. Luigi
  4. fedeleluigi

    AR-11 Crossover Frequency Response Simulation

    Thank you for the clarification, Pete
  5. fedeleluigi

    AR-11 Crossover Frequency Response Simulation

    Hello Pete, Thank you for sharing all these simulations. Did you measure the anecoic frequency response of the midrange? If you didn't, what midrange frequency response did you use to make these simulations? Thank you Luigi
  6. fedeleluigi

    AR Tweeter replica/replacement

    That is a matter of taste. As you prefer the AR91s mid and tweeter, you could use the same Clarity caps you used for recapping them. You could also get some improvement bypassing the 2500 uF npe cap with a poly cap. But personally I think that the clarity and detail you are missing could depend on woofers more than caps. Luigi
  7. fedeleluigi

    AR Tweeter replica/replacement

    In the future, if you prefer the AR 10 Pi "voice", you can use better quality caps like in the 91. Anyway If you want to get the best quality sound (not only in the bass) from your AR 10 PI, when you have time, I suggest that you try the original 200003 woofers in place of Tonegen's. You will get a great improvement even in the mid-range. Obviously the 200003 woofers should be the ones used for the AR 10 PI MKII (as your 10 PIs are MKII). As I have already told you in other posts you could try your original AR 91 woofers (200003) in the 10 PI. In fact AR 10 PI MKII and 91 had the same 200003 woofer. In my experience (in my listening room and with my amplifiers) the difference between AR and Tonegen woofers is not negligible. Have a nice day Luigi
  8. fedeleluigi

    AR Tweeter replica/replacement

    David, Thank you for sharing information about your AR 10 Pi restoration and the Midwest Speaker replacement tweeters you have used. As regards Midwest Speaker, you told us in another thread that the first pair of tweeters they sent to you had low output and limited frequency response compared with the good 200084 tweeter you have. The bent and loose terminals surely depend on shipment issues but the low output and the limited frequency response could also depend on not good manufacturing tolerance. Did Midwest somehow explain the low output and limited frequency response you observed? Please, let us know about your impression on the sound of your restored AR 10 Pi in your listening room and especially with your different type of power amplifiers (tube and solid state). Thank you Luigi
  9. fedeleluigi

    Anatomy of a 200029-1 Tweeter

    @seventy1 Thank you seventy1, but the picture you post is not visible.
  10. fedeleluigi

    Anatomy of a 200029-1 Tweeter

    @seventy1 Could you please post some photos of all tweeter parts? I mean some photos also of the dome, voice coil and flange. Was the dome glued to the magnet or the flange? Thank you Luigi
  11. fedeleluigi

    Restoration stopped at woofer

    Check both the voice coil and the tinsels (braid wires) by an Ohm meter. Old tinsels could be broken and measure open whereas the voice coil is OK. Luigi
  12. fedeleluigi

    Where to find 10" Bass Drivers for AR9LS

    As you can see here (http://www.classicspeakerpages.net/library/acoustic_research/special_sections/additional_ar_documents/ar_parts_list_price_sheet_n/ar_parts_list_price_sheet_n_3.html) the AR 200033 woofer and later the Tonegen 1210033-0 woofer (used from about 1985 and later on) was used in AR 92 (and 925), 9LS and 9LSI, 30b, 28bx, 28bxi and AR Sub Woofer. Hope this can help you to find the correct woofers for your 9LS. Luigi
  13. fedeleluigi

    Picked up some more AR speakers

    David, I'm sorry for the the snow storm and power outage. Hope they are "pessimistic" and you can have power again in a short while. Luigi
  14. fedeleluigi

    Picked up some more AR speakers

    A parallel R and C circuit in series with a loudspeaker load can also be used with pro amps in order to protect them from very inductive loads. As an example, you can look at this link:https://adn.harmanpro.com/site_elements/resources/1010_1425481978/Macro-Tech-Series-600-1200-2400-Reference-Manual-130252_original.pdfthat's the Crown Macro-Tech amplifier manual. Please look at fig 3.14 at page 17. Even though the Macro-Tech amplifier were very stable amps into reactive loads, they can have problems with very inductive loads such as those caused by the presence of an autotransformer. Anyway, although the RC circuit shown in the fig. 3.14 will probably not give a flat frequency responce in the lowest frequencies (especially with a low impedance loudspeakers ) it will effectively protect the amp from most of dangerous inductive loads.
  15. fedeleluigi

    Picked up some more AR speakers

    It is lowering the cap resistance. Just like when you put (2) 10 ohm resistors in parallel you get 5 ohms and when you put (2) 10 ohm resistors in series you get 20 ohms. The 2500 uF cap and the 10 Ohm resistor carry out a protective role against the inductive load caused by the presence of an autotransformer in the 10 Pi crossover network. Moreover, the 10 Ohm resistor, the 2500 uF cap and the autotransformer inductance constitute a special type of RCL network with a specific Resonance Frequency and Q factor. The resistor is important to determing both the Q factor and the Resonance Frequency of this particular type of RLC circuit. The Q factor can greatly affect the speaker bass response. You can examine the mathematics at the attached links (exersice 8 with solution). Pay attention that Q Factor, Resonance Frequency and Voltage drop through the capacitor also depend on R (R2 in the example) value. Unfortunately it is in Italian. Excercise n.8: https://it.m.wikibooks.org/wiki/Esercizi_di_fisica_con_soluzioni/Correnti_alternate solution https://it.m.wikibooks.org/wiki/Esercizi_di_fisica_con_soluzioni/Correnti_alternate#8._Circuito_risonante_con_2_R_2 Also In English you can observe how the R affects the Resonance Frequency of this type of RLC circuit at fig.5 of this link: https://en.wikipedia.org/wiki/RLC_circuit Luigi
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