[Technic]

Originally Posted by Justin7894

The LOC came with Technics harness. I don't know the output level.

Technic?

Max of approximately 3V (Logic7) or 4V (Individual Audio), but that is at maximum OEM amp volume.

This is the KAC 728 series gain diagram... 0.2 (max) to 5V(min) range:

[Justin7894]

very confused... :/

[kmarei]

Originally Posted by Justin7894

very confused... :/

have you tried this?

Originally Posted by VP Electricity

Have you tried running an iPod with a 3.5mm to RCA adapter into the RCA inputs?

so plug an ipod into the rca input of the amp, and see if it still distorts

[Justin7894]

I'll give that a try today

[Technic]

Originally Posted by Justin7894

very confused... :/

Try another amp...

[Giotek]

Hey all!

This has been driving me nuts for a while now, so any input / thoughts would be much appreciated.

Purchase this 2015 F30 a little while back, just had the base stereo system and I wanted an upgrade.

I've replaced the the cic unit with an aftermarket android unit, which has been amazing. But it doesn't have RCA outputs.

Bought a 6 channel spline amp, replaced with 4x door speaker with 4" kicker comps and the 2x underseat subs with earthquake flat subs.

I've had to use the speaker line outs from the stock system to run to the alpine amp, this amp supports both low and high lvl inputs.

This all sounds amazing and in very happy with it all.

The issue I'm having is when starting the vehicle, I'm getting like a popping sound through all the speaker for about a second, then everything is fine. When I exit the car and lock it, approx 10 seconds AFTER locking the car, I'll hear the same popping sound again. As mentioned above it's only a second for 2 (like 4 or 5 consecutive pops) then it's all ok

I recoded the ecu to use hifi output, and this fixed the issue, but it sounds horrible, really tinny, almost as if the 100-300hz is resonating.

Reprogrammed it back to stereo and sounds amazing, but still having issues with the popping.

I can't for the life of me figure out what's going on, or what's sending that popping signal.

Outside of that issue, I'm very happy with the upgrade.

Hope someone here has an idea of what I can try to remedy this issue.

Thanks in advance

[ctuna]

If you pulled the stock BMW Head unit you pulled the central control
for the Hi Fi system .
Does the android head unit replace the stock head unit or is it a piggy
back type.

Stock BMW system are designed to use the stereo system for gong and alarms
and are never really off until the car goes to sleep.
They power on the amplifier when you unlock or enter the car and it times
out and power off the amp time delayed when it senses no more activity
around the car or a fixed amount of time after it is locked.

This is not the F30 board however BMW hasn't really changed it's stereo
types since the E90 was released .

Technic makes several base system harnesses some of them have a turn on relay .
Also search the internet for Car stereo amplifier pop.

Programming a Head unit that isn't there will have no effect on the sound.

Unclear if there is and OEM head unit still driving the amp from your description.

6 channel spline amp did you mean alpine?
If you driving the amp from a OEM head unit it needs to be able to accept 5 volt differential
signals (reduced speaker outs no common ground)

If there are LED's on the amp that can observe see if the popping happens at the same time
the amp goes off and on.

[Giotek]

Yes, it’s piggy backing off the original head unit using the aux input.

Yes, I did mean a 6 channel alpine amp. It is able to accept 5v inputs, and I do have it set correctly.

I’ll need to check the LEDs if the amp power is turning off and on while it’s popping. As the amp is located in the trunk under the little flap, I haven’t tested to see if it pops with the trunk still open. Something to check though.

Just wanted to say thanks for the prompt response, very much appreciated.

[ctuna]

You have to check the specs in the alpine manual.

[Giotek]

Hmm, doesn’t seem to say. All it says is
“Low-level RCA Inputs and High-level Speaker Inputs”

The amp model is the Alpine R-A90S

Alpine recommend using their RCA - speaker wire conversion (KCE-SP2R), but we made our own. I can’t imagine there being any difference.

I’ll test if it still pops with the trunk open today and see if the LED is doing anything during the popping.

Again, thanks for your help

[ctuna]

there is a difference between single ended RCA and differential signals
essentialy low level speaker outs but I am guessing that that is not your
problem . There are a lot of articles on speaker pops on the web.

[Giotek]

I’m not too sure.

I thought it would be worth asking here as it only happens when initially starting the car and approx 10 seconds after locking the car. Outside of those times, it’s had no issues at all.

Also when coding to hifi, I don’t get the pops, however it sounds way too flat for the current setup unfortunately

Sounds best with stereo coded, however I get the popping issue.
Not a huge problem, but an annoyance.

[Giotek]

So the amp is on when the popping occurs (the power LED is solid) it happens right before it powers off. Seems to be receiving some kind of signal as it turns off. Not sure if can attach a Video with my phone