Re: Need my Marantz Receiver fixed...

Papa _ /
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To support my hypothesis with words from my google box:

“ The reactive load imposed on the amplifier by a speaker load causes far higher dissipation in the output transistors than the simple resistive load generally assumed during testing. At the extreme end, consider a load which is completely reactive (i.e. inductive or capacitive). The voltage and current are 90 degrees out of phase with each other, and no power is consumed by the load - even though there is voltage and current present (and measurable). Assuming a voltage of 20V and a current of 2A, the actual power is zero, so the amplifier must dissipate not only the normal internal losses inherent in all power amplifier designs, but the 40 Volt/Amps reflected back from the reactive load. (Volt/Amps - or VA - is roughly equivalent to Watts - but only when the load is resistive, implying that work is performed).

In reality, the reactance is always accompanied by some resistance, so the amount of power converted into work (moving the loudspeaker cone to create sound) will always be non-zero. An additional quantity of the supplied voltage and current are converted into heat (another form of work) due to resistive losses in the voice coil and crossover network. The reactive (also known in electrical engineering as the imaginary) component is reflected back into the output of the amplifier, where it must be absorbed and converted into heat.

It is the reflected power from the loudspeakers which is responsible for a great many amplifier failures. Because of the low efficiencies of most modern speaker systems, more power is needed from the amplifier. This means that the amp will have to dissipate more reflected power and this can lead to overheating (or internal "hot-spot" localised heating) which leads to the destruction of the output transistors. Some amplifier protection systems are sufficiently sophisticated that they can prevent this form of damage completely, but will generally provide an additional side-effect - the deterioration of sound quality. This is often noticed as a "grainy" or similarly described quality to the sound, and is difficult to eliminate when protection is used. A certain IC power amplifier I have tested has a very comprehensive protection circuit, which seems to work very well. However, as the amp reaches the point of clipping, the distortion component is multiplied tenfold by the protection circuit, with the result that what should be completely inaudible distortion becomes very audible indeed.”

Transistors are probably at fault. They don’t usually look bad.

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Subject Written By Posted
  Need my Marantz Receiver fixed...Topic by: Moped Lar (OFMC) Moped Lar (OFMC) 06/02/20 11:46AM
  Re: Need my Marantz Receiver fixed...Re: Overpriced Parts Overpriced Parts 06/02/20 12:59PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/02/20 01:23PM
  Re: Need my Marantz Receiver fixed...Re: Overpriced Parts Overpriced Parts 06/02/20 01:46PM
  Re: Need my Marantz Receiver fixed...Re: Papa _ Papa _ 06/02/20 01:45PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/02/20 02:09PM
  Re: Need my Marantz Receiver fixed...Re: Papa _ Papa _ 06/02/20 02:21PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/02/20 02:32PM
  Re: Need my Marantz Receiver fixed...Re: Jimbo Grand Daddy Jimbo Grand Daddy 06/02/20 04:24PM
  Re: Need my Marantz Receiver fixed...Re: - rwc - - rwc - 06/02/20 04:46PM
  Re: Need my Marantz Receiver fixed...Re: Overpriced Parts Overpriced Parts 06/02/20 05:45PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 07:28AM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:03PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 01:14PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:20PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 01:25PM
  Re: Need my Marantz Receiver fixed...Re: Pushrod Fifty Pushrod Fifty 06/02/20 09:02PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 07:30AM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 05:50AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 07:32AM
  Re: Need my Marantz Receiver fixed...Re: Aaron Blair Aaron Blair 06/03/20 07:36AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 07:46AM
  Re: Need my Marantz Receiver fixed...Re: Aaron Blair Aaron Blair 06/03/20 08:13AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 08:22AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 08:34AM
  Re: Need my Marantz Receiver fixed...Re: Pushrod Fifty Pushrod Fifty 06/03/20 12:55PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 12:59PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:10PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 01:17PM
  Re: Need my Marantz Receiver fixed...Re: Bas Autowas Bas Autowas 06/03/20 01:17PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 01:21PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:14PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:16PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/03/20 01:18PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/03/20 01:22PM
  Re: Need my Marantz Receiver fixed...Re: Pushrod Fifty Pushrod Fifty 06/03/20 05:24PM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/04/20 07:41AM
  Re: Need my Marantz Receiver fixed...Re: ♣Slew Foot♣ ♣Slew Foot♣ 06/04/20 07:42AM
  Re: Need my Marantz Receiver fixed...Re: Blaine- The artist formerly known as Plumber Crack "(OFMC)" Blaine- The artist formerly known as Plumber Crack "(OFMC)" 06/03/20 06:12PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/04/20 09:21AM
  Re: Need my Marantz Receiver fixed...Re: Satan 666 Satan 666 06/03/20 07:56PM
  Re: Need my Marantz Receiver fixed...Re: Rebel Moby Rebel Moby 06/04/20 10:13AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/04/20 10:30AM
  Re: Need my Marantz Receiver fixed...Re: - rwc - - rwc - 06/04/20 10:53AM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/04/20 11:38AM
  Re: Need my Marantz Receiver fixed...Re: Pushrod Fifty Pushrod Fifty 06/04/20 12:53PM
  Re: Need my Marantz Receiver fixed...Re: Papa _ Papa _ 06/04/20 12:56PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/13/20 06:25PM
  Re: Need my Marantz Receiver fixed...Re: Stephen Keller Stephen Keller 06/13/20 08:15PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 06/13/20 08:34PM
  Re: Need my Marantz Receiver fixed...Re: Stephen Keller Stephen Keller 06/14/20 04:53PM
  Re: Need my Marantz Receiver fixed...Re: Satan 666 Satan 666 06/14/20 05:50PM
  Re: Need my Marantz Receiver fixed...Re: Stephen Keller Stephen Keller 06/14/20 05:52PM
  Re: Need my Marantz Receiver fixed...Re: __̴ı̴̴̡̡̡ ̡͌l̡̡̡ ̡͌l̡*̡̡ ̴̡ı̴̴̡ ̡̡͡|̲̲̲͡͡͡ ̲▫̲͡ ̲͡ ̲̲̲͡͡π̲̲͡͡ ̲̲͡▫̲̲͡͡ ̲|̡̡̡ ̡ ̴̡ı̴̡̡ ̡͌l̡̡̡̡.__ __̴ı̴̴̡̡̡ ̡͌l̡̡̡ ̡͌l̡*̡̡ ̴̡ı̴̴̡ ̡̡͡|̲̲̲͡͡͡ ̲▫̲͡ ̲͡ ̲̲̲͡͡π̲̲͡͡ ̲̲͡▫̲̲͡͡ ̲|̡̡̡ ̡ ̴̡ı̴̡̡ ̡͌l̡̡̡̡.__ 06/16/20 01:26AM
  Re: Need my Marantz Receiver fixed...Re: __̴ı̴̴̡̡̡ ̡͌l̡̡̡ ̡͌l̡*̡̡ ̴̡ı̴̴̡ ̡̡͡|̲̲̲͡͡͡ ̲▫̲͡ ̲͡ ̲̲̲͡͡π̲̲͡͡ ̲̲͡▫̲̲͡͡ ̲|̡̡̡ ̡ ̴̡ı̴̡̡ ̡͌l̡̡̡̡.__ __̴ı̴̴̡̡̡ ̡͌l̡̡̡ ̡͌l̡*̡̡ ̴̡ı̴̴̡ ̡̡͡|̲̲̲͡͡͡ ̲▫̲͡ ̲͡ ̲̲̲͡͡π̲̲͡͡ ̲̲͡▫̲̲͡͡ ̲|̡̡̡ ̡ ̴̡ı̴̡̡ ̡͌l̡̡̡̡.__ 06/17/20 07:05PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 07/06/20 01:04PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 07/06/20 03:20PM
  Re: Need my Marantz Receiver fixed...Re: Satan 666 Satan 666 07/06/20 03:29PM
  Re: Need my Marantz Receiver fixed...Re: Moped Lar (OFMC) Moped Lar (OFMC) 07/06/20 03:42PM

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