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In Reply to: RE: Take a look at this. posted by totosooner@yahoo.com on June 26, 2016 at 06:17:40:
By the way....When I test THD and frequency response it is ALWAYS at the rated power......in the case of an MC275 MK IV that would be 75 w/ch, not 1 watt. The frequency response is like nothing I have ever seen.......completely flat from 20 to 20Khz.I think you were addressing me on that question but nobody denies the specs that Mac amps are able to produce because they are absolutely marvel in design with their output trafos and overall execution of the driver,voltage amp, and nested loop FB. The early reissues didn't make rated power but I blame that on govt regulation because they were running a lower B+ so they could meet UL specs and they wanted to keep the original look..After customers started complaining about not making rated power,they made a change to where they put part of the output tube bases below the chassis and then put heat venting holes around the tubes and then raised the B+ up accordingly.
McIntosh, like other commercial designs,would often cut corners in some areas even back in the early days.I own six Mc60s and one of the amps was born without a choke and yet,the holes are there for a choke to be installed.They did have a few iterations of this amp so maybe this particular one was setup for a background music system in a commercial application..I ended up putting a choke in so it matched the other five but also,Mac used to used to use copper lined chassis in many of their earliest Mc30 and Mc60s and that was done away with as well. The Mc30s all should have had a choke installed by the mere fact of the amount of current the amp draws at or near full power. Mac also used bias windings on some Mc30s and Mc60s and some they didn't.They would take the AC off one half of the high voltage secondary,put in a dropping resistor.and then rectify it..It's ok to do this but it is kind of cheezy when you think about it. My point is,even the best companies are not immune to the bean counters.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 06/26/16
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- RE: Take a look at this. - Michael Samra 11:24:58 06/26/16 (0)
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