Kenwood kac-7202 i was riding and my subs just went out, i check all cables and i cant find anything, the amp comes on red light in the triangle and fan blows, but no bass what could it be.

Nope it's not a high-to-low level converter problem, it's most likely a problem with one of two things. 1) either you've blown the output stage in the amplifier, or 2) you've hooked up your subs wrong and your amp is seeing to low of an impedance. The amp is supposed to be 1ohm stable, but we had the same problem. When the indicator light goes red it means that the amp has gone into protection mode, now you have to figure out why. If something in the amp goes bad or just disconnects from the board it will cause power protection mode. If you fry something on the board because you are running the amp to hard or at the wrong impedance it will go into thermal protection mode, however there's no simple way to figure out which has happened.

Have you tried hooking up some different subs to see if the problem remains? try this. If the problem no longer happens then you know it's your subs, if it does still happen then you'll know it's an internal problem.

Years ago I had a Kenwood KAC-821; long story short, I melted the main power wire right off of the board, everytime I turned the system up the amp would shut down.

Take you amp to an authorized dealer and have them bench test it for you.

Let me know what you find out.