Hello! The preamp Mark Levinson no 26 rustles one channel on a black background. what could be the problem? He recently underwent preventive maintenance with replacing old capacitors with new ones, but there is still rustling at all outputs and even in mono mode only one channel rustles. What advise to check? This rustling is not particularly annoying, but I really love this preamp and I want it to work like a Swiss watch 🙂.
Time for insulated poking-stick or cold-spray to hunt down hairline crack or damaged components. Checking all grounding hardware is properly tight and not corroded is worth doing.
Could be a bad transistor or maybe capacitor in the line stage. I've seen transistors do this a bunch of times over the years. Check for bad solder connections as well.
Checking to see if it is present on both sides of the balanced output will help you to isolate the problem.
Take care,
Doug
Checking to see if it is present on both sides of the balanced output will help you to isolate the problem.
Take care,
Doug
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Does it do it with the input shorted? If you have the schematic and an oscilliscope you can start at the input and look at one channel at a time, then go back and forth looking first at the good channel then the bad one as you walk your way through the circuit until you find at what stage the noise is being generated. Then look closely at the components at that stage. As mentioned above, look for cracked components, cold solder joints even reflow any joint that does look smooth and shiny. Worst case is you can swap one component at a time between the good and bad channel and listen between each move to see when the noise moves channels, not a great way to find the problem but it usually works.
Good luck.
Good luck.