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I wish to add a " bleeder" to my amp and need to know which cap is the first filter cap?

"Solder a 220K 2W resistor across the first filter cap from the + to the - terminal of the cap or to ground. It will provide a tiny load to the power supply when the amp is in use but enough load to drain the stored energy to ground when the amp is turned off. Voltages inside the amp should be safe [non-lethal] within a minute of switching the amp off."

It will be the cap connected to the Standby switch. It is one of the 32uf sections of the "can" type cap. The side closest to the transformer.
Stew