Resistors should be at least 1/4W types with 1% tolerance recommended. I used 0.6W 1% metal film resistors and they work well. Capacitors I used were electrolytic cans for C2, C5 and C6. At the time of building, I did not have enough 100uF caps so I used 220uF caps instead, this will not cause trouble, unless you use caps that are smaller than 100uF for C5 and C6.
C1 can be electrolytic, I used a tantalum myself (don't ask why, since they are actually more expensive). Some readers may want to use a polyester capacitor for the input (C1), this would work too but I am not sure whether any benefit will arise from the extra expense. Other capacitors (bypass caps C3 and C4. and C7) are ideally polyester caps. Mylar may be used but I prefer polyester caps and they are not expensive unless you get large values.
The values of R5 and C8 are worked out from the equations in the datasheet, but I used 1.8k ohm for R5 and 220pF for C8 and they work fine. Diodes should be 1N4001 or similar (make sure you solder them in the right way round).
A good heatsink is important and this should be a large size with good thermal conductivity. When you operate the TDA2030 from the (recommended) split rail power supply, you must insulate the device from the heatsink using a mica washer or similar. With single rail supply, this is not needed.
