gain setting?

[astra-cad-astra]

right, fitted a vibe blackair II 12" sub, only got a JBL gto 2060 (250 RMS) to run the 550 RMS sub for now, so what gain setting shall i have it on?

also, the amp suddenly stopped workin the other week, i thoguth it had blown, took head unit out today, and swapped them for the aux in L/R to rear L/R and now it works fine, but it was workin fine on the other connections so why did it stop?

[steve v6]

Well you should never run an amp on full cause this causes destortion. Runn it on 3/4s. You should really buy an amp that is more than what you need to stop destortion. Aux in is for a device such as dvd play etc. What head unit you got? When putting a sub in it should be plugged into the rear aux or sub out if ya head unit has it.

[wallopsri]

Well you should never run an amp on full cause this causes distortion. Run it on 3/4s. You should really buy an amp that is more than what you need to stop distortion. Aux in is for a device such as DVD play etc. What head unit you got? When putting a sub in it should be plugged into the rear aux or sub out if ya head unit has it.

ignore this post^^^mate, its not quite correct.

lets assume your head unit has a volume scale of 0 to 30,(30 being max volume).

lets also assume your head unit has 4v preouts.

ok, if you use an oscilloscope your headunit would possibly go into clip at around volume level 28, but you don't have an oscilloscope, so you should treat say volume level 25 as your safe max volume.

lets assume at volume level 25 your actual preout voltage is 3.5v.

to achieve full out put power your amp requires a certain input voltage along the signal path, now if you had no means to adjust this input voltage, the amp would play at a varying output level according to the input voltage from the source,(so effectively a headunit with 2v preouts would play at a lower volume than a headunit with 4v preouts).

to get round this problem an amp will have a gain control, this gain control allows the user to match the output voltage of the source, with the input voltage of the amp, so giving full output power at full volume.

increase the input voltage too high,(gain control too high), and the amp will reach full output before the source,(headunit). this will mean when the source reaches full output, the amp will be driven into clip,(will be heard as distortion).

no one can tell you how high or how low you should set your gain control, it needs to be set by either using an oscilloscope, or some other way that involves actually being there.

you must remember that a gain control is not a volume control, it just allows flexibility between input voltages, it simply allows the user to match the amps input to the sources output.

check out the sticky marked as,"a few audio questions answered", there is a guide on how to set gains by ear, this should help.