An interesting challenge.. if the schematic is to be trusted...
I'd measure the resistance of R15 and R17.
my guess is that one has 'drifted' upwards... not uncommon in old carbon resistors, or more likely a BADLY Soldered one
The reason that this will make the mids sound horrid, is that there is a draw of current to the top rail from output (ie it isnt at 0V) that is partially met by the filter to ground...
So, l would look for a bad solder joint on one of those resistors, and then look for a drfited value, for there the problem lies.
Have fun
Owen
I'd measure the resistance of R15 and R17.
my guess is that one has 'drifted' upwards... not uncommon in old carbon resistors, or more likely a BADLY Soldered one
The reason that this will make the mids sound horrid, is that there is a draw of current to the top rail from output (ie it isnt at 0V) that is partially met by the filter to ground...
So, l would look for a bad solder joint on one of those resistors, and then look for a drfited value, for there the problem lies.
Have fun
Owen
I have switched MLPs from LCH to RCH - the quiescent current problems went to the other side but the dull sound stayed on the RCH.
So the dull sound problem is not the transistor problem - RocketScientist was right.
I think I will recap the whole amplifier and then pray that after doing this the problem will go away
If not - in the act of desperation I will swap all the parts one by one from RCH to LCH and see what destroys the sound.
So the dull sound problem is not the transistor problem - RocketScientist was right.
I think I will recap the whole amplifier and then pray that after doing this the problem will go away
If not - in the act of desperation I will swap all the parts one by one from RCH to LCH and see what destroys the sound.
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