Calling all you stereo experts

[pat123]

I instaled a new stereo in my 69 pickup, but its haveing some issues. As i turn up the volume a fuzzy sounds occures and get worse as i turn it up. I have 2 speakers under the seat and one in the dash. I took the one above the deck out because i thought it was possibly messing with the signal but didnt help. I tried running my ground right to the batterie, didnt help. The speakers are fine because i pluged them into dads deck with no problems. The decks fine because i took it back and got a new one. The only other think i can think of is where i connected it or my connections. Unfortunatly me solder gun was broken so i crimped and heat wrapped the connections. The stereo says it need 12 Amps, i ran it to the cigarette lighter on the fuse box. I dont know how many amps are there but it blew a fuse once witch was a 3amp. I replaced that fuse with a 10amp one, still not working.
Any help would be awsome

Thanks
Pat