I have owned this for quite a few years . (Original lot) Have never had a problem with it.
I recently purchased an SVT 3 and actually prefer the sound of the PF . Both are great amps , one is much less expensive .
Ampeg PF-500 500-Watt Portaflex Bass Head
Compact 500W Bass Amplifier Head, 3-band EQ, Mid-tone Presets, Lo/Hi Boosts, Compressor