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Ar LST Restoration


giovanni56
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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.

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1 ora fa, Carnivore ha detto:

Cosa sono quelle cose ovali? Qualcuno ha installato le porte? I miei non li hanno.

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.

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In Italy there are several examples of AR LST speakers, not as numerous as in the USA, but I think several dozen couples (let's not forget that 30 couples were adopted by the La Scala theater in Milan)
Under mine dated as from the stamp on a 1971 tweeter with external terminals, for tweeter and mids. and contacts on masonite panels.

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Date printed on the tweeter back: Aug 7 - 1971

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