Ok, you’re clearly the expert here.
But for other people that might happen upon this thread, this person is completely incorrect. This nominal 4 ohm speaker is not a pure resistance and will change its value dramatically over its frequency range. Specifically, it will rise to dozens of times its nominal value at the speaker’s resonance. There isn’t a solid state car amplifier on the market that won’t drive an 8 ohm speaker without massive distortion. I have already stated my qualifications with respect to Alpine amplifiers but I will also add that I have 25 years of amplifier and power supply design experience.
First of all, the amplifier needs at least a 10A power supply to function properly. A 5A supply can cause the amplifier to oscillate between startup and shutdown. It doesn’t matter if the idle current is low - startup current can be 10-15 Amperes for a few tens of microseconds. Secondly these amplifiers are known for having cold solder joints on in their output stages. This will cause a crackly sound with any load, not just “8 ohm speakers”.
Suspiciously this person says he has an MRV-T503 and he didn’t correct himself. Alpine didn’t make that model and there are many “look alike” knock offs of V12 amplifiers. Perhaps a photo of these amps as well as a video of the supposed distortion is in order. Because what is being portrayed is false characterization of a scientific fact. And this is an engineering forum where most of us don’t take too kindly to misinformation.
EVERYTHING that I described is how it is. I am not pretending to be an expert but I can read. I didn't correct myself previously because I had nothing to correct.
The imaginary MRV-T503's USER manual is here -
https://www.manualslib.com/products/Alpine-Mrv-T503-2762227.htmlThe photo is attached.
The amplifiers were bought directly from an Alpine main dealer owned by a good friend of mine at the time and I even registered them with Alpine at the time.
I came on here to ask for help finding the repair manual because I believed that these amps SHOULD drive 8 ohm speakers without any problem at all. Whilst trying to get that manual I tried the speakers attached to a Denon household amplifier and all four worked. They are Gale 3010S shelf speakers. I got the same output from both amplifiers when attached to the Gale speakers in that the sound came through with lots of crackling noise.
When I found, in the manual for the V12s, that they only drive 2 and 4 ohm speakers I got a pair of old 4 ohm speakers out of the garage which, when connected, had no issues at all.
As for the power supply, it IS only rated at 5 amps but at no time, including startup, did it go beyond 2 amps.
I am NOT at all saying that I am the expert! The whole point is that I am not but I am not a lying or mistaken either. I've just given the forum the facts as they appear to me!
I really would like these amps to drive 8 ohms!