Input Gain Setting?

[CorsaHP]

hey.
I have a 1242d Sub 500w rms in a RS12V alpine ported box, powered by a MRD-M605 which is 600w rms, but certificate reads 666w.

On this amp, you can set the gain digitally, so it goes goes from 6v down to 0.1v.
Everywhere Ive searched and read, it says you have to match the voltage output on your HU, which is 4v for mine.
So i set it at 4v on the amp and theres hardly if any bass coming from the sub.
Lower I go, (ive now set it at 1.5v) and its really loud, and gets louder by setting the gain lower and lower.

Is this normal?

Its the same for my JBL 75.4 Amp which powers the components.

[CorsaHP]

anyone know how to set alpine amps? or got the best settings?

[Martin]

yes this is normal. I'd set it to 4v, then have a fiddle with the sub out volume mate, you might have it on its lowest setting.

turning it down to 1.5v will introduce clipping

[CorsaHP]

the sub out volume setting was balanced in the middle, all the sound enhancements were off etc. What do you mean by clipping...distorting?
At 4v its nowhere near what a sub should sound like.

[CorsaHP]

oh by the way, do you kno how to make the bass go low? frequency settings?

[trixta]

the amp should have a low pass filter, you need to set it to that and filter at about 80-100 Hz have a play about to see what you prefer.

Try setting the sub out to max while having the gain on 4, see what that sounds like