Hi Folks
I just can't resist wading in! Andrew has reminded me that when current demand increases, the bridge shunts the capacitors. Proper capacitor selection is obviously a concern for longevity. In my case, I ended the debate by simply building a temporary DC blocker cct. (with various capacitor configurations), and found it to be ineffectual with my transformer noise.
I am making an assumption only, but my toroid noise was due to loose windings and completely eliminated by multiple dipping in varnish. This was an extremely tedious process, verified by anyone following this thread. If I had to do it again, I would heed the advice here and remove the plastic connectors allowing the transformer to be vacuum impregnated and cured at elevated temp. My solution was cheap, time consuming, but it worked!
I just can't resist wading in! Andrew has reminded me that when current demand increases, the bridge shunts the capacitors. Proper capacitor selection is obviously a concern for longevity. In my case, I ended the debate by simply building a temporary DC blocker cct. (with various capacitor configurations), and found it to be ineffectual with my transformer noise.
I am making an assumption only, but my toroid noise was due to loose windings and completely eliminated by multiple dipping in varnish. This was an extremely tedious process, verified by anyone following this thread. If I had to do it again, I would heed the advice here and remove the plastic connectors allowing the transformer to be vacuum impregnated and cured at elevated temp. My solution was cheap, time consuming, but it worked!
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Well I may very well also end up with no good result but that is just one of those things. Easiest for me would be to just move the whole amp downstairs and mount on backets on the wall.
The main reason why I am dragging my heels on the DC blocker is because the board is part of: Preamp supply and regulator, DC protection, muting and its supply, EMI filter, ground loop breaker.
Nobody is holding their breath anyway and I am learning albeit slowly
The main reason why I am dragging my heels on the DC blocker is because the board is part of: Preamp supply and regulator, DC protection, muting and its supply, EMI filter, ground loop breaker.
Nobody is holding their breath anyway and I am learning albeit slowly
the dc blocker is designed to be effective if there is dc that needs to be blocked from entering the toroid.
if the transformer has manufacturing issues that are causing noise, the dc blocker is not designed to compensate for those.
Some guys who have had minor manufacturing issues in their transformers told me that using the CL60 (and similar) thermistor as a soft -start device reduced the noise for them, but I have not verifed that personally.
mlloyd1
if the transformer has manufacturing issues that are causing noise, the dc blocker is not designed to compensate for those.
Some guys who have had minor manufacturing issues in their transformers told me that using the CL60 (and similar) thermistor as a soft -start device reduced the noise for them, but I have not verifed that personally.
mlloyd1
Some added resistance in the primary circuit will reduce the current peak that is drawn to charge the capacitor filter.
A lower current peak will reduce the vibration forces exerted on the laminations and on the wires. So it seems resonable to conclude that added resistance may make vibration less audible.
The advantage to using a PTC here would be to automatically adjust for different power draws at SPL rises and falls with the audio signal.
A lower current peak will reduce the vibration forces exerted on the laminations and on the wires. So it seems resonable to conclude that added resistance may make vibration less audible.
The advantage to using a PTC here would be to automatically adjust for different power draws at SPL rises and falls with the audio signal.
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