Crackling subs on a JL audio 450/4 amp
 

Hi there,

I'm building a system for my new campervan, and I'm running some issues with the (used) JL audio amp:

450/4v2 - Car Audio - Amplifiers - Slash v2 - JL Audio

The two channels that put out 75W each work perfectly fine, but the two channels putting out 150W each for the subs sound horrible (crackling). The same happens with other subs, and the subs I have for the system play beautifully with another amp.

Any idea what might cause this and whether it's fixable?

Thanks!