Hello everyone,

Been doing a lot of reading and decided to put together a quick budget upgrade for my MINI's sound system. I want someone to check my sanity because I am not sure about one thing: Can I use one channel (or in this case two channels; the front left and the front right) as inputs for my amplifier? My front speakers have been upgraded to C components

Here's what I'm using for the amp, it's a Kenwood KAC-M3004: Installation Manual Link

My thought here was to run 2 sets of RCA cables to the front right and the front left speaker outputs at the X9331 connector, and cut the output wire.These would be the inputs to my amplifier Channels A & B. (See "2-Channel + Subwoofer System" diagram on page 2 in the link above)

Channel A outputs would have no filter, and I would wire those output sto the front left and right speakers.

Channel B output would go through a low-pass filter and would be bridged to run a small subwoofer in the rear of the car.

Here is where I'm confused, can I splice two sets of RCA wires into one channel? Effectively sending the same signal to two inputs? Or do I need to have separate RCA cables and utilize the rears (which I thought don't get the full audio signal)? The instructions say to let the speakers go through a high-pass but I would like them to output the FULL sound in tandem with the subwoofers. Does this make sense?

 

It does make a bit of sense. You can use the front left and front right signal and split them. You need an LOC to go from the x9331 speaker signals (FL and FR) to the RCA cables. You can use a y-splitter at the amp and that will split your signal.
With this kind of system you can have the speakers on FULL and the subwoofer with a LPF, but the recommended way would be to choose a frequency (say 80Hz) for the sub LPF and the speakers HPF. If you have multiple sources producing the same frequency, they then tend to cancel each other out.

 

Thanks for the reply,

Actually I believe this amplifier can sense speaker level inputs on the RCA cables, so I don't think I'd need an LOC in this case. You make a good point about the frequencies though, I'll play around with the filters in this case. I just want to make sure I'm not robbing the fronts of all the mid level goodness

 

They make an adapter for exactly what you’re thinking about. Atleast based on what I read. I saw it the other day on outmotoring

https://www.outmotoring.com/amplifie...-upgrades.html

 

That price seems insane. The plug housings and pins can be sourced directly from BMW/MINI. A fitting crimping tool, wires and heat shrink tubes are all standard. I paid less than € 40 in Germany for everything including the crimping tool (!) and more than the required wire, pins and heat shrink tube.

The pin layout is availaible here on NAM. The part numbers for the X9331 plug housings are:
Male: BMW 1378137
Female: BMW 1378139-B5
(from the Front/Rear channel swap thread)

Unfortunately, I can't find the BMW invoice any more so I can't post the part numbers for the pins. However, the plug housing part numbers was all I had when I went to the dealer and the employee was kind enough to look the pins up. YMMV.

The original adapter I made was in order to swap front and rear channels. It looked a lot like the one posted in this picture:
https://cimg3.ibsrv.net/gimg/www.nor...db62c18da1.jpg

Later, I cut the audio wires in the middle in order to tap into the output signals as well as in order to feed the front speaker output from my amp back into the existing door speaker wires.

Note: the non-audio wires passing through the connector need to be thicker than the audio ones. And one has to make sure that they are crimped perfectly, otherwise this may result:
https://www.northamericanmotoring.co...ss-failed.html

PS: high level inputs of amplifiers are usually not cinch connectors so it is unlikely that cinch connectors need to be included in the shopping list.

 

Thank you for the great post and thread !

I'm as frugal as the next guy... but sometimes I like things to be easy (like buying an expensive sandwich at the airport when I'm hungry)

Those part numbers are helpful to anyone wanting to build a custom harness.... good work !

The outmotoring piece is reasonable cost in my opinion when I place the value on my time to deal with ordering and assembly of the harness into the equation.

 

In that case, you may want to have a look at Integral Audio's slightly lower offer, too:
https://integralaudio.com/mini-coope...ess-x9331.html

IIRC, such adapters were available for less than $ 50 just a few years ago. Unfortunately, my income hasn't evolved like that since...

By the way: assembly took less than 30 minutes (using a wire stripper), despite having two left hands, seemingly no thumbs and pretty much nothing but air above the shoulders.
:-)