Do you mean a 'real' 500W amplifier, or a 'car' 500W amplifier?.
If you mean a 'real' one, you will need 'real' speakers as well.
There's not many circuits about as they cost so much to build, and you can buy them for very little money - as long as you don't believe the specs!.
I connected one up last week, for a lad at work, I sold him a mains PSU for it - it was rated at 360W (supposedly!), yet only had a 15A fuse fitted!. Bit of a giveaway I thought :lol: 12V x 15A = 180W maximum CONSUMPTION from the battery. Being nosey I took the top off and measured the HT rails, the off load supplies (ignoring and losses) would only allow 90W RMS per channel. With losses in the amplifier, and losses in the inverter, I suspect 50W per channel 'real' power is about what you would get.
However, it was quite a nicely made piece of kit, and I doubt you could buy the bits for less than two to three times the retail price of it?.
I connected one up last week, for a lad at work, I sold him a mains PSU for it - it was rated at 360W (supposedly!), yet only had a 15A fuse fitted!. Bit of a giveaway I thought :lol: 12V x 15A = 180W maximum CONSUMPTION from the battery.
If you don't mind going " old skool " , there are some really solid designs in some of the old RCA transistor dat books. They are very durable, suitable for PA use, and have true ratings.
What I mean by " old skool " is having huge banks of TO-3 output transistors. Years ago I did one of the RCA designs for a school project. The amp survived horrendous abuse, never giving any trouble.
GE usd to have some really good designs in their databooks also.
I will see if I have any of the data books at home. I may be able to scan something for you.
Here are some parts of the circuit for a Sony in-car amp, it's rated at 200W RMS per channel into 4 ohms, 250W per channel into 2 ohms, or 500W bridged into 4 ohms.
The Sony amp has only 34 transistors!
A lot of its max ouput power is wasted heating-up the output Mosfets due to their high G-S turn-on voltage!
It would be much more efficient with ordinary power transistors. The power that is wasted could be used to heat the speakers and your ears more. :lol: :lol: