i would like to build a 1800watt Amplifier (maz output 1800watt]. 4 channel producing 450watt x 4 at 8 ohms, but then i want it just like te Pyramid PA 3600watt amplifer, i want it to be able to reach 3600watts at 900watts x 4 at 4 ohms. i only want one volume contral not two for each side. Can anyone help me, i need to know how to put it together and what parts i need.
I agree, it's not something to be attempted by an inexperienced constructor. Also I doubt you could build it much cheaper than commercially available amplifiers, high power audio parts are extremely expensive - and you can destroy them very easily!.
Have you considered using commercially available modules to build your amplifier?, companies like BK https://www.bkelec.com make ready built modules - you just need to fit them in a box.
Also be aware of the power limitations, as you are in the USA you can only draw 1650W from a single socket, an 1800W amplifier is likely to need 2700W.