Marantz 2270 Bass rumble

[TellMeWhy]

Dear all,
My 2270 has a funny quirk whereby for the first minute or so after cold start up, any adjustment of the Bass level causes a strong subsonic rumble. After that the bass adjustment is fine, and I hear no issues with the sound... There is also bass rumble when the Low Filter is engaged (not that it ever is!).

What do you think- dodgy capacitor in the low filter or EQ circuit? Dirty pot / switch?

Something not to worry about?

Thanks for any suggestions!
Jon

 

[Osibisa]

While by no means an expert, I would say since this issue occurs repeatedly after a cold start your caps may be in need of a refresh especially if the original ones are still in place.

My thought is that an extended time is now necessary for them to charge.

 

[TellMeWhy]

While by no means an expert, I would say since this issue occurs repeatedly after a cold start your caps may be in need of a refresh especially if the original ones are still in place.

My thought is that an extended time is now necessary for them to charge.

Hi! Thanks for the advice... most of the caps were replaced by the previous owner... But my thought is also that as it's a start up issue with the bass pot, and also with the low filter, that there is a malfunctioning cap in that part of the preamp circuit... But I am also not an expert...

 

[Fairlane]

Post some pictures of it with the covers off and the experts on here will be able to tell you what has been replaced or looks suspect. We like pictures anyway.

 

[highvoltage_]

Hi! Thanks for the advice... most of the caps were replaced by the previous owner... But my thought is also that as it's a start up issue with the bass pot, and also with the low filter, that there is a malfunctioning cap in that part of the preamp circuit... But I am also not an expert...

Sounds like the bass pot is in need of a good application of Deoxit. A potentiometer start up issue would be scratchiness when turned after sitting for a while. That starts to go away with repeated usage, then returns after the unit sits for a while. At low frequencies that scratchiness could give you some rumble.

 

[TellMeWhy]

Sounds like the bass pot is in need of a good application of Deoxit. A potentiometer start up issue would be scratchiness when turned after sitting for a while. That starts to go away with repeated usage, then returns after the unit sits for a while. At low frequencies that scratchiness could give you some rumble.

Thanks! I found the source of the problem. Would you believe it was that I was using a splitter Y-cable to feed an additional preamp, and this was the cause of the ground hum! Back to the original pre-power jumpers and the problem dissappears- problem solved!