noob car audio question re: amps and channels
 

Hey Guys,

Silly question. I have the standard 6-speaker audio system--installed some JL's in the front this weekend. Anyway, off-topic. Eventually, I will be picking up some new 6x9s and an amp and wiring all 6 speakers to it. My question is: does that mean I *need* a 6-channel amp? Or can I get a 4-channel and wire the 4 front speakers to 2 channels, and the rear 6x9's to the other two?

If this is possible, what are the downsides? Since there is only one "port" per channel on a given amp, am I going to have issues plugging 2 speakers into one "port"? Does this sound like a good idea in order to get a balanced soundstage (my thought process is that the front speakers are smaller and thus dont' need as much power) or should I just get the 6-channel amp and wire the speakers individually?

thanks in advance!

Andrew

You can find wiring diagrams for the 6-speaker system on this or a close-by thread. The (Boost) radio has a 4-channel amp, with the 2 speakers in each door in parallel, so the 4 channels in the amp feed front left, rear left, front right, and rear right.

The realoem site has some pictorials of speaker placement and such, but not much on the actual wiring:

http://www.realoem.com/bmw/partgrp.d...31&hg=65&fg=20

(As an aside, the heritage of this car shows up in the technical drawings. When you're looking for a black wire in a diagram, don't look for the English-standard color designator, BLK, rather look for the German one - SW.)

With that, starting with a four channel amp is reasonable, following the existing design and re-using existing wiring where practicable.

There's a lot of talk on this thread about what goes on with the existing 4-channel amp, whether the rear channels are driven full range or not.

With respect to others who have hypothesized on how things work, I'm an electronics guy, and I'm going to take a good look at things to determine what's going on, and what I'm going to replace first. I figure the front speakers are pretty quick to go... From what I've read, they're relatively easy to get at, and would seem to rate high in bang-for-the-buck. In contrast, the rear speakers, while larger (6x9), are a PITA to get to. Yeah, I'll look at more power (audio power) as well.

But...

I'm not buying a car to listen to music! The kind of music I want to listen to in my Mini includes squealing tires (a squealing tire is a happy tire, my SCCA friends say), the turbo waste-gate, road noise, and the exhaust system.

It's always trade-offs...

Keep us appraised on what you decide; I'll do the same.

Awesome, thanks for the reply.

To answer your hypothesis--yes, replacing the front speakers is both easy and well-worth it. Definite increase in clarity and range. However, it just accentuates the awful-ness of the rear speakers and makes me want to do more :)

I'm thinking a 4-channel amp now, but I was also thinking I'd redo the wiring. It can't be that hard, right? My thought was that I'd just tap into the rear speakers' input (which would be problematic if those are full-range inputs or not), and run a line-level converter to an amp. I don't want to dig around behind the head unit, would rather use existing wiring for the signal, and then re-wire the speakers with my own higher-quality wiring. Thoughts?:thumbsup:

"It can't be that hard, right?"

<<insert raucous laughter here>>

To get to the rear speakers, you practically have to take the rear bumper off! (Okay, not quite that bad -- but close.) I'll reuse everything I can, unless it's junk, particularly if you're talking about wiring going into the doors...

You're going to be using line-level converters to feed the new amp. The diagrams I picked up of the wiring show that the connector on the head is about the only place to pick off all the signals you want. If I intercept them there, I run a harness back to a new amp.

I know I'll be taking the dash apart; I've got a bunch of goodies to locate and install. Since I don't have the nav box, there should be an open spot under the passenger seat for an amp and my comm gear (Icom IC-2720 or IC-7000, and yes, I do know how to get RF generating equipment to cohabitate with audio amps).

Cheers--

re: "can't be that hard", I meant the wiring. I'm well aware of the disassembly required :)

I don't see why the HU would *need* to be pulled..it seems I could grab the leads from one of the front speaker locations and extend them back thru the door to wherever my converter is, yeah?

you really should read the r56 speaker replacement thread. It'll answer everything.

poolemac: saw your post in the R56 speaker-swap-thread about no-hassle fitting of the JL TR400-CXi units for the front-upper positions (congrats) ... and now understand that you chose TR-650s (not TR-600s) for the LOWER-front six-inch positions ... thanks for the advice