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MAC Autoformers?

Someone is selling a MAC MA6500 Integrated claiming its superiority over the Ma6600 due to the fact that "it does not have the degrading autoformer design found in the MA6600". That is the first time I've heard a claim that the autoformer was a hindrance to better performance; I thought quite the opposite. What do you MAC Maves think?
pubul57
unsound
7,329 posts
 

http://roger-russell.com/mcintosh1.htm#autoformer

What is failed to be mentioned is that with most loudspeakers as  impedance decreases / sensitivity decreases and as impedance increases / sensitivity increases. So if the speakers presents an impedance that swings between the impedances of the taps there will be potential for corruption to the ouput linerity.


roxy54's avatar
roxy54
8,016 posts
 
Thanks unsound. I think your link makes a good case for autoformers.
unsound
7,329 posts
 
….Because despite the never ending reports over the last 50 years of the amps not using autoformers  overheating, destroying speakers and causing fires, consumers keep buying them in such vast quantities as to provide a huge and continuing to grow sample size for such inspection?
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
@unsound

Could the impedance swings of the Magico S5 explain the poor linearity - see deviation from linearity plot showing loss of SPL from the tweeter?


https://www.soundstage.com/index.php?option=com_content&view=article&id=1043:nrc-measurements-magico-s5-loudspeakers&catid=77&Itemid=153

The crossover is at 2KHz and the sensitivity would have been matched at that point to the mid range. Note the impedance is quite high at 2KHz and drops rapidly above 2KHz - perhaps the crossover design may not be ideal as the revalator tweeter resonance is much lower (500Hz).

georgehifi's avatar
georgehifi
10,312 posts
 

It seems you are consistently more interested in the technical data on hifi equipment that I'll bet determines what system or systems you own and like.  

Do you ever throw care to the wind and just trust your ears?
I alwasy do both Pops. As do all designer of good amps, without bench testing, laws of electronics, tech data, if you bought such an amp off some who doesn't do these you'd have a pile of junk. 

Cheers George
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