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NAD 272 Channel drop out

I have a NAD 272 power amp linked to a NAD T752 A/V amp and have had ** end of problems. Purchased in 2005, 6 months after, the right speaker (Paradigms studio 60) channel would just fade away periodically, and then come back with a thump. Noone (NAD audio repair shop) could initially find any fault but when I powered just thru the 752, there was ** channel drop out.

The 272 was supposedly fixed, (altho NAD still say they could find ** fault)it happened twice again, and last fixed in November 2006. Last week, 6th March 2008, the same problem arose with the left channel. I have taken the CD player out of the equation, problem still existed, DVD player out of the equation, problem still there, the FM tuner in the 752, problem still there. Take the 272 out and put all speakers thru the 752, everything runs fine.

The speakers have been stripped down to ensure ** crossover wires are touching. I run a NAD CD, an OPPO DVD, a Project turntable thru a NAD preamp.

I'm bside myself as is the local NAD agent.

Posted by on

  • delta2 Mar 10, 2008

    I have hard copies of both manuals, but there are ** specs in the 272 manual!

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  • 3,587 Answers

Well..this is one for the books. Can you tell me what the ratings are between the 252 and the 752 impedance matching wise? even though it might work sometimes, impedance matching can wreak havoc between mismatched amps.

what are you driving from the 752 into the 252?

Posted on Mar 10, 2008

  • 2 more comments 
  • Patrick Michaels
    Patrick Michaels Mar 10, 2008
  • Patrick Michaels
    Patrick Michaels Mar 10, 2008
  • Patrick Michaels
    Patrick Michaels Mar 10, 2008

    so, with that noted, there appears to be a jumper change needed(see 752 manual) for using the 752 as a pre amp driving another amp...seems that since the 752 works fine, and the 272 does NOT, that would suggest that perhaps the 752 is over driving the 272 making it clip after a certain amount of time.

    try this..run one channel only with them both hooked up, and monitor the heating effect on the 272. the symptoms remind me of a class A amp overheating.

    take a close look at the specs on the output characteristics of the 752 to make sure it's not over driving the 272..

  • Patrick Michaels
    Patrick Michaels Mar 10, 2008

    yes..saw that...the key here is why there's a buildup of mismatching, which is causing the fade, and then the whoomph(a classic recovery signal from cutoff in an amplifier)..

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