Ken Anderson said:
Your voltage regulator may not be working correctly or you will need to install one of those huge capacitors in circuit with your amp, if your system is drawing more than 10 amps.
checking the voltage regulator is a good idea and check your grounds on the audio sytem very carefully (as we all know, good grounds on a vette are a lot more difficult than on a regular car) but unless you are running a LOT of power in that aftermarket amp or running multiple high powered amps, one of the big capacitors is NOT necessary. The only advantage to using one of the big caps is that it acts as a reserve of power for when the amps need it on high loads and it helps get the power to the amps very, very quickly, allowing for better transient response and control of the drivers (speakers). They are typically used mainly on amps running subwoofers as subs usually require more power and when you have the system "cranked up" the subs draw a lot of power from the amps and the caps will deliver purses of power to the amp quickly.
Anything less than an amp running at least 500 watts RMS (NOT peak) of power on a subwoofer will NOT require installing a large 1. 2, or 5 farad capacitor.
Is the whole system cutting out (power) or just the radio or just the amp? Is the power staying on but just the sound cuts out?
Check all your wiring.
If it's the whole sytem that cuts out, check all your main power cable on the radio and the switched power on the radio and also the ground connection plus check the main power line from the amp to the battery and it's fuse. You DO have the power line of the amp running straight up to the battery with a fuse within 12" of the battery don't you? You should never try to hook power of an amp into the fusebox or other power wires under the dash - ALWAYS run an amps power line direct to the battery! Also check the amps switched power line and it's ground connection.
If the pwer stays on but it's just the sound that cuts out, than check your wiring from the amp to the sprakers for a loose connection or bad wire that is shorting out (could have gotten pinched, nicked, etc).
If all the power, ground, and speaker connections check out good than the problem is in the radio or amp itself but chances are it's just a wiring issue.
hope this helps a little. It should be enough to get you started on finding the problem anyway.
Regarding your question if it could be your battery, there is only a very slim chance the battery could be causing the problem. On these older cars (someone correct me if i'm wrong regarding the older ones with generators versus alternators) but once the car is started everything is actually run by the alternator (in your case a generator) and after the car is started you can actually remove the battery and still run the car. The battery is really only used for starting the car and once it;s started the alternator runs everything and the battery is really just acting as a reserve to supply power when needed and the alternator can't supply enough all at the same time (such as at night when running lights, windshield wipers, radio, heater or A/C, etc. Short of running pretty much every accessory on the car at the same time your battery will not factor into anything after the car is started. You can check this if it makes you feel better though by simply running jumper cables from the vette to another car. Have both cars running after hooked up and try your stereo system - if it still cuts out on you you will know it's not a battery issue as you will be running power from BOTH cars at the same time. If it stops cutting out on you jumped to another car than your generator isn't pumping out enough power for your amp. I don't know the output ratings on the generators and I don't know what kind and size amp you are running but there is almost always enough output capacity from a generator or alternator to allow adding a reasonably sized amp without any problems. If you are finding an output problem with the generator than i'd take it back where it was rebuilt and have them look at it again.
Oh - one last thought........if it's a bad wiring issue anywhere check all connections and wires VERY carefully as it may only show up when driving the car and the movement of the car causes the connection to fail or a nicked wire to short out against something.
Back when I was in the car audio industry, we had a car come into one of the shops I was managing and it took us the longest time to find the problem. The system would start to crackle and cut out and we couldn't find the problem until the owner mentioned it only happened when he was driving (in the shop the car was parked of course) AND while he was making a left hand turn AND it was intermittent. Turns out one speaker wire had gotten pinched during the install (not our install) and a small section of the wires insolation got rubbed away exposing the bare wires very slightly. During driving and making a lefthand turn, the wire would shift position slightly but just enough to touch the metal of the door causing it to short out. What a bi**h it was to find that but after we did it took all of 5 minutes to fix.
Usually the problem is actually something simple but it can take a bit of work to find it.
Good luck!
Barry