Fitted new head unit, display now dims with beat

[SteSE]

New stereo fitted because the old one died. Que me going chuck norris style on the cd changer to retrive my beloved spice girls EP during my lunch break.

Anyways, the new head unit's display dims in time with the kick beat like power is being sapped from it to power the speakers. Happens only at medium to high volumes - down low the display is fine and consistent in brightness. Car only has two speakers to the front footwells, i would assume these are standard but will check this weekend.

Head unit is ok as it's one i pulled out of another car and i haven't had any issue with it prior to fitting it to the E30??

What do i need to do, upgrade wiring or fuse or something else

[hazd31]

i have a simular problem but not with the headunit, i have a sub fitted and when its running loud the headlights dim even while driving, i think it is to do with a weak battery, i had mine tested and he said it was poor, starts the car fine so i never found it a problem

[pac1982]

You need a permanent live straight from the battery to your head unit, fused of course.

In some cases this will actually make you head unit sound better as it can send more power to the speakers, did on my alpine anyhow

[SteSE]

I can power the headunit with out the engine running or key in ignition?

The old stereo was a kenwood as is the new one so i just pulled the old broken one out and slotted the new one in. Didn't need to change any wiring as the connector block fitted.

Dims with the engine running so not sure if it's a battery issue?

I am a ICE doughnut though so please be patient with me.

[pac1982]

yeah it just needs a nice thick wire straight from the battery to the head unit with a fuse, same way you would run a power lead for an amp.

Just make sure its at least twice as thick as the standard wire TBH the wire thickness aint that important its more about the direct feed from the battery but a thicker wire will help matters.

My alpine used to look like it was flashing it was that bad but a direct power feed sorted it out.

You may find your headunit has a spare power lead for a direct feed like most Alpines do but if not just disconect the power one from the ISO connector on the headunit side and link it to your direct feed

[SteSE]

Ok i'll try this, can i take the feed from the junction box in the engine bay as my battery is in the boot.

What rating fuse do i need. The inbuilt fuse on the headunit is a 10a

[pac1982]

Use the same as the standard fuse, I would recommend taking the feed direct from the battery, if it’s in the boot it should be even easier than taking it through the bulk head you'll just need more wire

[harry_p]

my alpine HU has a blackout mode which turns off the display lighting, the handbook says using it can increase sound quality.

if you're going to fit a dedicated live feed it will be worth running a new earth too with decent thickness cable and a good clean, secure earth to the body.