[E60525d]

Bmw offer a Alpine amp that fits under the boot/trunk carpet. I believe this amp is a class D.

My question is, is it advisable to install a Class A/B amp here? I am told that these run hotter than a class D.

Thanks

[ctuna]

The main consideration is headunit or idrive signals.
There is no problem installing anything you want as long
as you don't have L7.
Stereo has speaker out levels
Hi Fi is a 5 volt out differential signal
L7 is an optical signal this presents a big problem.
A lot of the Mosconis and Zapcos are a/b no problem
with them. But the class D's are really good these days.
Yes class A/b do take more power but if you are not overdoing it
there is not problem. There is something called a class g
that is a a/b with a variable voltage rail that is suppose
to be more efficient but offer class a/b operation.
For a sub amp class D is the only thing that makes sense.

Read this

BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://www.e90post.com/forums/attach...1&d=1209780865
http://technicpnp.com/menuDiagrams/d...e90_92_93.html
electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.musicarnw.com/page-2/
http://www.bimmerfest.com/forums/sho...d.php?t=903551
http://www.e90post.com/forums/attach...4&d=1278871872

Best System examples
Logic 7 upgrades
http://www.e90post.com/forums/showthread.php?t=826683
http://www.e90post.com/forums/showthread.php?t=590420
Base System Upgrades
http://www.e90post.com/forums/showthread.php?t=445266
http://www.monsteraudiodesign.co.uk/
http://www.1addicts.com/forums/showthread.php?t=634957
http://f30.bimmerpost.com/forums/sho....php?t=1003810
http://www.e90post.com/forums/showthread.php?t=822366
http://www.e90post.com/forums/showthread.php?t=581379
http://www.e90post.com/forums/showthread.php?t=451941
http://www.e90post.com/forums/showthread.php?t=540954
http://www.e90post.com/forums/showth...ghlight=Dotech
http://www.e90post.com/forums/showthread.php?t=495855
http://www.e90post.com/forums/showthread.php?t=494299
http://www.diymobileaudio.com/forum/...morel-jbl.html
http://www.e90post.com/forums/showth...ht=amp+upgrade
http://www.bimmerfest.com/forums/sho...d.php?t=550771
http://www.e90post.com/forums/showth...1#post16679904
http://www.e90post.com/forums/showth...1#post16679904
HI Fi upgrades
http://www.e90post.com/forums/showth...ighlight=level
http://www.m3post.com/forums/showthread.php?t=540446
http://www.e90post.com/forums/showth...hlight=technic
http://www.e90post.com/forums/showthread.php?t=532585
http://www.e90post.com/forums/showthread.php?t=833581
http://www.m3post.com/forums/showthread.php?t=443043
http://www.e90post.com/forums/showthread.php?t=324214
http://www.e90post.com/forums/showth...hlight=level+3
http://www.e90post.com/forums/showth...ight=processor
http://www.e90post.com/forums/showth...&highlight=BSW
http://www.bilstereoforum.se/showthread.php?t=2356
http://www.diymobileaudio.com/forum/...creations.html

[tdgesq]

Class A/B will run hotter than Class D. I guess I'd be more worried about fitment since Class AB will have a larger footprint than Class D with the same current capability.

[E60525d]

Thanks for the replies. I have got a question on how to best install a 4 channel on the factory HU. I have done lots of reading and I believe I have a few options.

I am not an audiophile, just want to boost my base system which I will be replacing the mids and subs with L7 one's and adding tweeters.

The front mid's, tweeters and subs will run from the amp with the rear shelf speakers from HU.

1. Use existing connections to connect amp via the speaker high level inputs. This was my preferred option but I have seen others with noise with this setup. http://www.e90post.com/forums/showthread.php?t=1239613 Is this method viable without getting any interference or noise?

2. Similar to option 1 but add a LOC which inturn connects to amp. Is this option any better than 1?

3. Code system to hifi, add RCA's on exiting speaker wiring and connect to amp. Will this work, is it better than option 1? By coding to hifi i believe the rear speakers will not work? Correct?

4. Use an amp with "BALANCED DIFFERENTIAL INPUT". I believe this is the best way but there are not many amps with this feature. JL amps have this feature but they are over my budget.

Any advise?

[E60525d]

Anyone able to assist?

[taibanl]

For ease and avoidance of noise use:
Technic 2/4 harness w loc
4 ch amp

[E60525d]

I've spoken to a few people are there also suggesting option 2, so using a loc.

Any more views?

[ctuna]

Unless you recode to Hi Fi or use a frequency flatten-er
with the base system you can't get a good eq curve.
This is documented in the audio build thread and many other
threads and builds.
The cheap guys solution it to set the crossover frequency to - db
but you have to have aftermarket speakers with crossover to do
that, and it is not the best path.

http://www.e90post.com/forums/attach...1&d=1411521234

There are many solutions in the links I posted
and the audio build thread also describes exactly what to do.
If you want audiophile noise free sound using locs or frequency
flattening devices is never the best solution, but it may be
a cheaper one which is why its done.

[E60525d]

Originally Posted by ctuna

Unless you recode to Hi Fi or use a frequency flatten-er
with the base system you can't get a good eq curve.
This is documented in the audio build thread and many other
threads and builds.
The cheap guys solution it to set the crossover frequency to - db
but you have to have aftermarket speakers with crossover to do
that, and it is not the best path.

http://www.e90post.com/forums/attach...1&d=1411521234

There are many solutions in the links I posted
and the audio build thread also describes exactly what to do.
If you want audiophile noise free sound using locs or frequency
flattening devices is never the best solution, but it may be
a cheaper one which is why its done.

I dont really want to reocode to hifi as i believe the rear speakers will not work from the HU. Correct?

I am not an audiophile, just want to give the system a boost. My current system is the base stereo but fitted with front tweeters, L7 mids and underseat subs.

[E60525d]

Think I found an amp which a good specification and suits my needs, http://www.rainbow-audio.de/en/amplifier/dream/

Any views on the Rainbow Dream 4?

Thank you

[E60525d]

Anyone??

[taibanl]

Originally Posted by ctuna

Unless you recode to Hi Fi or use a frequency flatten-er
with the base system you can't get a good eq curve.
This is documented in the audio build thread and many other
threads and builds.
The cheap guys solution it to set the crossover frequency to - db
but you have to have aftermarket speakers with crossover to do
that, and it is not the best path.

http://www.e90post.com/forums/attach...1&d=1411521234

There are many solutions in the links I posted
and the audio build thread also describes exactly what to do.
If you want audiophile noise free sound using locs or frequency
flattening devices is never the best solution, but it may be
a cheaper one which is why its done.

I should have said "use a cleansweep-not lust a loc" because youll need to flatten the signal