hello guys,
i was just wondering if there was any was to hook up an aftermarket amp off of the factory head unit. i have hi level inputs, so i can tap into a speaker signal from the HU, but, the wirirng is probably all covered up and taped off so i cant acess any of it. does anyone know the comors of the signal wires back to the amp? i can splice my RCA's into a signal wire if theres one that i can tap into coming from the head unit.



Thanks,

Red N White

aka Rick

 

This is possible - in fact Paul just recently did it to his car & sent me details; see my weblog entry and check out Pauls site or my mirror of it

If you put in an amp, you will need to replace the speakers too, since the HK amp limits power to what the speakers can handle.

You cannot tap into the speaker outputs from the HU if the still want to use the HK amp - those signals are fixed level unaffected by volume. There are no RCA signals.
If you want to remove the HK amp and replace it, you are best to do it at the HK amp location since that is where all the speaker wires are run from.

 

well, all i need is a left and right , or just one side, + and - signal to power up my amp. what kind of power does the amp put out to each speaker? if its around 20 watts, i can just splice into one of the rear speakers and pull signal from that. BTW this new amp will not power any of the other speakrs, its solely for the subs i was hoping to add, i want to keep the factory system , just want to add the subs.

 

You should be able to pick up a signal from one or more of the speaker outputs going to the rear speakers - there are four (dual voice coil each side) and I don't know if the same signal is sent to each coil so you might need to do some experimenting.

The only issue is filtering. The HK amp might filter the low frequencies out of the signal going to the speaker, if it "knows" the speaker can't handle it. Alternatively you might want to filter the signal out so that it goes only to the subs and not to the speakers any more.

Someone on NAM did this long ago ... shame I can't remember who ... might be pooky13; you could try to PM him/her.

 

well, i found a wiring diagram on pauls site, the one you gave me. it appears that there is a woofer channel, so, unless mini is pulling a fast one and calling tweeters, woofers, then this should be a low level freq. and should work, but i wasnt too sure. i have a document with my potential mods drawn on the wiring harness, if anyone could take a look and see if it would work or not.i'll email it to anyone if you think you can help


thanks

 

There is a woofer channel because I believe Mini uses the same HU for their Harman Kardon System. The HK comes with a woofer.

 

i have the HK system in the car, so the woofer channel should be operating, and if my guess is correct, it should be able to send the amp the required signal. i'm not sure if the amp can take an already amped signal and use it though, it might just be used for hooking directly into a 20 watt head unit channel.

 

On Pauls wiring diagram, amp1 & amp2 are what he added. You see that he took all the outputs to the rear speakers, routed them to amp2, and used the filtering in amp2 to split off low frequencies to his subwoofer.

There is no "woofer" in the HK (or non-HK) MINI factory system - not in the normal sense. The HK system uses the rear speakers for low frequency and is closest to what you would call a woofer, but their top end frequency is much higher than a woofer and their bottom end is probably not below about 60Hz, nowhere near the 10-20Hz of a true woofer.
In the front doors, there is a low frequency speaker as well as a midrange and a tweeter - people sometimes call this a woofer but again that is not accurate.

 

well, if i can tap into the of the rear speakers, i can use the low pass Xover on the amp to try and filter out as much of the high freq coming from the HK amp. but my only problem is i dont know if the amp will be able to use the amplified signal coming from the amp. i have to read my owners manual or email the Mfg. to see if i can use an amped signal instead of the signal thats supposed to come from the HU. i think the beileve outputs on the amp are only supposed to use the 20 or so watts from a regular head unit.


and on pauls site, i 'm refering to the factory plugs coming from the HK amp, not his new wiring diagram. i was looking at the grey and black plugs

 

OK.
Well as I said before what they call "woofer" is not what I call "woofer" - those are wiring to the existing speakers you have already. Do you think it sounds like you have subwoofers already in the HK system?

 

no, thats why i need to know if i can tap into these safely without it effecting the speakers that are in there already. i believe these are only the rear channel, so it should be ok. but i'm still not sure if the hi level inputs on amp can use an amplifies signal. do you know the wattage going to each of the stock speakers from the amp?

 

Sadly the ratings of the HK amp are one thing difficult to discover.

Your subwoofer amp won't overload the HK but it is possible that the HK output could overload the amp input - depends on the design of the input. You need to check with the amp manufacturers.
I think the overall wattage of the HK system is 320W. Let's suppose 2/3 goes to drive the rear speakers - 220W so 110W per speaker, but each speaker is dual voice coil so only 55W per output.
The coils are 2ohm so the voltage would be about 10.5V max - is this enough to overload the speaker level inputs on the aftermarket amp?

 

i'm gonna read up in my manual and email the MFG and see what i get back, maybey they can give me some help



i'll keep you up to date