Pioneer A-400X upgrades


2009-05-02 9:24 pm
I have an old pioneer A-400X in an allmost new condition , Thought it would be a shame to just sell it so I thought about upgrading it so I have a few questions :

Is it possible to replace the 10,000 uF caps to new caps ? what difference could i expect ? Or can I replace them with higher uF caps ?

Is it possible to replace the transformer ( again , same of bigger ) and what could I expect ?

Any other tweaks and upgrades that could boost the juice or the performance ?
I changed the power supply caps to Nichicon KG. You have to watch the diameter of the cap as there are wire links in this area which can short or not allow the cap to sit directly onto the PCB. I think the existing transformer is on the limit to suit the cap size and a I think larger caps could be a problem.

I changed signal caps to film or Nichicon ES (can't remember exactly). Cleaning the pot is a good idea as mine was quite scratchy.

I tried a few different op amps and preferred the original as the others changed the character of the amp so were not necessarily better..... just different.

These changes did add more body, better clarity and maybe better bass but the differences were small. I think if you do go over board, the character can be lost but recapping is not a bad idea considering the amp's age.

Some have changed the diodes in the power supply and have reported good results.