iPhoneHome1

Hello all, the bass on my radio is cutting in and out, and from what I have read, the amp is likely overheating. I have a 2008 528i and I have located the Harmon Becker amp in the trunk. To my surprise the amp is very small and only has an aluminum heat sync system, no fans. So I am looking on eBay and see the Logic 7 amp that is larger and has fans. Is the wiring harness interchangeable? Can I simply buy the L7 amp, plug it in and be done with it, or are there more connections to be made.

Or, should I just buy a new small Harmon Becker amp to replace what I already have? I feel like if I do this the new amp will do this the new amp has a good chance of presenting the same problems.

Thanks for the advice

twh

Replacing with Logic 7 will require some programming in the car.

iPhoneHome1

If I have to change some programming that's probably not the way I want to go, not to mention that the L7 is about $400-500 more.

It is hot outside and I drive with the windows down a lot so the music is probably up a little louder than most people would listen to it which is probably most of the problem.

Any suggestions in cooling the original equipment or do we think a new OEM unit will fix the problem?

twh

Take the old one out and see if you can take it apart. Maybe something simple like a power transistor has come loose from the heat sink or something like that. Maybe needs some tightening or some new heat sink thermal grease. I haven't run across too many posts about these going bad, so I don't think it is a chronic issue.

iPhoneHome1

Thanks twh.

I pulled the unit out, disassembled, and noticed a slight corrosion. The corrosion didn't seem like it would have affected anything but cleaned it with some alcohol and 1000grit sandpaperer in about 2 minutes. I put some new thermal paste on the two components that touch the aluminum heatsink/case that I had laying around from a recent PC build. I reinstalled the amp and will test this week. I will post back with the results.

longnx

Can I replace Hifi OEM amp to Logic7 OEM amp (many used on Ebay) ? but I am wondering:
- What problem after I replace Logic 7 OEM amp with not enough 13 Speakers ?. It work ?
Other question:
- I have extra 4 OEM Speakers (Font left,right. Real left, right) because upgrade 4 BSW speakers. Can I use them for center speaker ?.

biz77

You can replace the OEM Hi-Fi amplifier with the Logic7 amplifier, but it is not a drop-in plug and play operation.


Here are things to keep in mind about the swap:


1. The Hi-Fi amp is analog, meaning it receives a differential balanced low-pass low-level signal from the main CCC unit. The Logic7 amplifier works off of the digital MOST bus system. You will need to tap into a MOST bus component and make the Logic7 amplifier part of the network loop. There is the physical connection that must be done and also coding that must be performed.


2. In the OEM Hi-Fi system, the power for the mid/hi speakers is provided by the main CCC unit, therefore all of these speaker connections are in the dash behind the main head unit. In a Logic7 car all of the speaker connections are at the rear of the car where the amplifier resides. The two options are to place the Logic7 amp at the front of the vehicle, or make wiring provisions to get the speaker outputs on the Logic7 amp back up to the front of the car. The most logical way to do this is to source the entire Logic7 wiring harness from a wrecked car that came with Logic7 from the factory.


For those that want to perform this upgrade, keep in mind that the Logic7 speakers are quite different from the Hi-Fi speakers. The Logic7 system was tuned specifically for those drivers, so running the Logic7 amplifier with the Hi-Fi speakers may not provide very good results.

iPhoneHome1

After a week of testing - I haven't had a single bass cut out. Mainboard cleaning and thermal compound seemed to do the trick. Thanks for the help!

twh

Great!