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Questions for Pat Turner
"patrick-turner" Phil mentioned... - show quoted text - ** The AR9 was first sold in 1978 and used two 12 inch woofers, same ones used in the AR11 released in 1977. ** AR constantly refer to the above woofers as being 12 inch. But they are closer to 11 inch, in reality. I remember now there was something odd about the woofers in a friend's AR11s. The impedance curve of the AR11 was so wild I drew it out and kept a copy - here is a listing: DC = 4.2 ohms 10Hz = 5 ohms 32Hz = 30 ohms 100Hz = 4 ohms 500Hz = 10 ohms 1kHz = 4 ohms 2kHz = 2.5 ohms 5kHz = 2 ohms 10kHz = 2 ohms 12kHz = 2 ohms 20kHz = 3 ohms 50kHz = 8 ohms BTW: The low figures above 2kHz are because the 4ohm dome mid and 4ohm dome tweeter are operating in parallel. The owner was originally using twin wire he got from Tandy / Radio Shack ( 14x0.14 stuff ) - so each run was about 1.5 ohms resistance, plus about 2.5 ohms of inductance at 15kHz. So I made him up some leads using "Tocord" ( aka Mogami cable) with near zero inductance and about 0.2 ohms resistance. His mouth dropped open when he heard the difference. .. Before completely re-forming the pair of AR9 I was given to fix, I did manage to get one working as it may have worked when new by swapping out working mid/HF drivers so that enough working drivers were in the same box. I found the acoustic response response using the middle position of mid-HF level switches was anything but flat and extremely poor by my standards. I don't recall any HF dips to 2 ohms as you state exists above 2kHz, ** Please, read my post more carefully - it's the *AR1 * that has absurdly low impedance above 2 kHz. But your post said AR11, ** Yeah - NOT the AR bloody 9 !!!!!!!!!!!!!!! ( AR1 is an obvious typo) IMHO, it is very easy to make a better pair of speakers than the AR9. ** The various AR speakers I have seen and tested were riddled with unholy compromises and evil Yankee dodges - plus built as cheaply as possible. Their Aussie built models were even worse, with plastic veneer - yuck. But still better than Bose by a mile. ------------------------------------- I'd certainly agree with you on that. Ah, the un-glorious 1970s, full of Krapp from all directions. Hardly anyone knew what hi-fi was about, and hardly anyone attended concerts with unamplified music to calibrate their ears. Mostly ppl experienced music when boozed up, smoking and talking with ppl mostly liking highly processed pop music. I cringe when I listen to some old records I have. ** OTOH I was enjoying digitally recorded Bartok piano via half speed mastered LPs from Denon, as early as 1976, played through my Quad ESL57s. For low processed pop - early Beatles or some live recordings of Jimi Hendrix were excellent. Jazz recordings were always pretty natural sounding too. .... Phil |
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