[carl_lazlo]

So I went to an "expert" with bmw installs. They wired my alpine mono amp with a 10" alpine sub. System worked great for about an hour then the amp cut out. The blue power light on the front would pulse but no sound.

They told me the amp was dead so I went to BB and got a new M-500 and installed it with the same retults.

I tried running a jumper from the 12v to the trigger but I get the same result, the blue light pulses about 2x per second. They called alpine but they don't seem to know what is causing this.

Anyone see this problem before?

They are running a splice from the factory floor subs into the speaker lvl inputs.

Thx.

[AWM3]

Your alpine subwoofer may be shorted out and overloading the amp.

[M3SWEETNESS]

Had the same problem with mine. They thought it was the wiring and then the sub to come to the conclusion that my car just didn't like that kind of amp. Upgraded it to a high grade amp and haven't had a problem. You might see if they will try that. I've got a Crossfire Amp in the car right now...

[carl_lazlo]

Here is what I don't understand; it worked for about an hour after the install. Tons of bass. I tuned the gain of the amp to lower the amount of bass and it played fine for another few minutes then nothing. Now after swaping the amp with a new one I have the same problem. Very strange.

If I don't go with alpine what other type of amp do you suggest? I want a mono amp that is not more than like 300 dollars. It would be nice if I can get it from a best buy or somewhere else close.

[Technic]

Although Alpine does not list the actual max input level at its high level inputs in the manual -it only say that it "accepts input from high power or standard power head units"- you cannot use the high level inputs of that amp with the woofer outputs of the OEM amp (70W at 4 ohms = 16V peak) for a sustained amount of time.

My recommendation is to use an adjustable high power LOC (at least 80W max handling capability) regardless of what amp you decide to replace this one with.

[Technic]

Originally Posted by carl_lazlo

Here is what I don't understand; it worked for about an hour after the install. Tons of bass. I tuned the gain of the amp to lower the amount of bass and it played fine for another few minutes then nothing. Now after swaping the amp with a new one I have the same problem. Very strange.

If I don't go with alpine what other type of amp do you suggest? I want a mono amp that is not more than like 300 dollars. It would be nice if I can get it from a best buy or somewhere else close.

http://www.bestbuy.com/site/olspage....=1170289781181 and get a LOC

[carl_lazlo]

What is so strange is that I bought both a new alpine amp and a new alpine sub and I am getting the exact same problem on the new amp.

Strange.

[Technic]

Originally Posted by carl_lazlo

What is so strange is that I bought both a new alpine amp and a new alpine sub and I am getting the exact same problem on the new amp.

Strange.

It is not strange, there's something wrong in the way all this is wired.

[Quasimodem]

Are they tapping the low level outputs from the headunit to the oem amp? Did they put a line driver in?

[carl_lazlo]

Well, its really simple with the wiring. They tapped the oem sub wires into the speaker level inputs on the amp.

There is power from the battery into the amp then the ground from the amp to the chassie. They ran the 12v trigger from a wire behind the head unit but for testing they jumpered the 12v trigger to the positive.

Both give the same results.

[Technic]

Originally Posted by Quasimodem

Are they tapping the low level outputs from the headunit to the oem amp? Did they put a line driver in?

This is a Logic7 installation... no analog pre-amp signals available.

[carl_lazlo]

Where are there low level outputs on the HU in a L7 system? I thought it is fiber all the way to the amp.

The only way to add an amp is using the speaker level outputs, correct?

[Technic]

Originally Posted by carl_lazlo

Where are there low level outputs on the HU in a L7 system? I thought it is fiber all the way to the amp.

The only way to add an amp is using the speaker level outputs, correct?

I forgot that your system is the Logic7... my bad.

So now it is imperative that you use a LOC, as it is 70W peak at 4 ohms (16V peak) what is getting into your Alpine amps high level inputs. That's enough to mess up the amps...

You need to get something like this... http://www.sonicelectronix.com/item_...Converter.html

[carl_lazlo]

It would have been nice if they told me about the loc. I even asked that question. I hope I did not blow the new amp too.

Are they smart enought to protect themselves?

[Technic]

Originally Posted by carl_lazlo

It would have been nice if they told me about the loc. I even asked that question. I hope I did not blow the new amp too.

Are they smart enought to protect themselves?

Well, the problem is that details like the OEM amp outputs are not that well known outside forums and dealers and it is also my experience that installers/audio shops are not that concerned about details like that... as long as whatever they install works the first time and the customer does not come back with issues. Then they will act concerned and maybe they will do their homework right this time.

So yes, your BMW "expert" should have known about this issue by just searching the Internet and looking at the Alpine website.

[carl_lazlo]

Well, I only went to them because a number of people on here said they were bmw experts and had good results with them.

If the problem is because of the speaker level inputs will the amp just shut down like this before it gets fried?

[cassey]

I've been running an alpine mono sub amp for a couple years now with no problems. Maybe you should check the ground connection. I connected to the factory ground point on the passenger rear shock tower.

[carl_lazlo]

update:

Ok I think we have the issue solved as of now. We removed the ground and cleaned off the powder coat on the spot and reattached the ground. I ahd the installers also add a LOC. So far so good.

The sound on the L7 with that alpine amp is AWESOME! Obviously not the best I have ever heard but a GREAT result for the money spent. The car being so well built and so well insulated makes for some sick bass SPL inside of the car even with a single 10" sub. I can't imagine what it must be like when people have move subs and or amps.

It is also pretty amazing how well sealed the trunk is. When I have the seats up and the trunk closed I really have to crank the bass levels to get a good result in the car. For now I folded down the rear arm rest and took out the ski boot giving me an open port to the trunk. That made a huge difference. I am going to make a cloth grill for that spot to make it look better.

I am now thinking about maybe swapping out the factory subs under the seats to see if that helps. I think I saw that a type of SRS is almost a direct fit. I just need to search the forums more to try and find that post.


Thanks again to everyone here for their help and thanks to Dave and Ron for their help getting this issue fixed. GJ guys

[M3SWEETNESS]

Awesome, glad you found the problem and fixed it. I didn't even think to ask if you had them install a LOC. I figured the shop would have known better, you may have been their first BMW for them to ever install a Sub and Amp. lol