After converting 30 0 30 Ac 5A dual supply to DC with 4 Diodes and two 10000uf Capacitors I get DC out dual supply of 46 0 46 volts . How to regulate this dual supply to get stable 30 0 30 v . This supply is to be used for an Amplifier
The capacitors will tend to charge to the peak value of the sine wave. This will be root 2 x the RMS value
So 30 volts RMS will be about 42 volts peak. Also I assume you have very little load on the output so the output voltage of the transformer will be higher than when it is loaded to it's full rating of 5 amps.
A decent design of power amplifier has more than enough Power Supply Rejection Ratio to run on an unregulated supply.
As music has a high crest factor, you get more value for money off an unregulated supply as the amplifier can supply the peaks without pulling the supply down too far.