This is the way it works:
A manufacturer is free to set price controls within its chain of distribution. Sony can choose it's dealers and require that they adhere to pricing policies. The theory is that this is permissible because it benefits consumers by allowing higher margins and better customer service. Therefore, it strengthens the brand.
But, Sony and JVC cannot between themselves decide to set prices as some minimum level. This is an impermissible conspiracy in restraint of trade.
So, vertical price fixing is okay. Horizontal price fixing is not.