markc0220k Posted October 21, 2009 Share Posted October 21, 2009 as the title posted, i'm going to replace my stock HK amp (385w, 7channel) with an aftermarket amp (400w, 50x4 + 200x1). My question is: can i just attach a wire directly from the HK amp (+12v) to the new amp's (+12v) instead of running a long wire from the trunk to all the way to the front battery? i guess it should be ok since they both are asking for similar amount of power (watts)? please let me know if what i'm going to do is ok: 1. draw power from HK amp (the blue harness - R317, pin 1 or 5 = +12V battery) to the new amp +12v power 2. connect the new amp's REM back to HK amp's white harness - R316, pin 12 = + 12v as the new amp's remote-on. 3. Ground from new amp would just attach to metal/bolt nearby the trunk. (thanks David Mr.Carter, David, for very clear pin-out description here - http://legacygt.com/forums/showthread.php?t=112168 !) thanks, mark Link to comment Share on other sites More sharing options...
timmahh Posted October 21, 2009 Share Posted October 21, 2009 In theory it seems like it would be fine, but in practice this seems like a bad idea.. Is the +12v for the HK amp thicker than the rest of the wire in the harness? Link to comment Share on other sites More sharing options...
markc0220k Posted October 22, 2009 Author Share Posted October 22, 2009 Is the +12v for the HK amp thicker than the rest of the wire in the harness? yes. but thing is... rest of the wires they are looked like about 16~18gw and the +12v wire is just slightly bigger than that. i guess it 's about 14gw? Link to comment Share on other sites More sharing options...
OGG Posted October 22, 2009 Share Posted October 22, 2009 No. You'll melt your wiring if you try to hook it up that way. You want at least an 8 GA power and ground for that amp. http://www.bcae1.com Link to comment Share on other sites More sharing options...
markc0220k Posted October 22, 2009 Author Share Posted October 22, 2009 No. You'll melt your wiring if you try to hook it up that way. You want at least an 8 GA power and ground for that amp. www.bcae1.com then how come subaru runs a 16g (14?) ga wire for its 385w HK amp? mark Link to comment Share on other sites More sharing options...
brooklyngenius Posted October 22, 2009 Share Posted October 22, 2009 well here is why, because like most amps on the market except for the good HIGH end amps, they dont put that power out excpet maybe once in a blue moon. this is why one should pay attention to an amps RMS wattage and not the advertised peak. 2nd reason is the class of amp. the amp you want to run is in a different class of amp. not to mention that remember how many speakers are on that "385" watts. 7 so math tells us that thats only a whooping 55 watts per speaker. useless signature line where i cant mention my sponsors "First Bagged BL5!" Link to comment Share on other sites More sharing options...
markc0220k Posted October 22, 2009 Author Share Posted October 22, 2009 i thought per each 4 channels is 50w ( = 200w) plus 185w go to the sub? correct me if i'm wrong pls. i believe the front tweeter/woofer are crossovered after amplifying the HU signal, we can't see it is just because it crossovered them internally, and thus we can only see x7 output. And no wonder the woofer and tweeter output are in diff harness. secondary, the cost of 7 channel is way expensive than 5 channel amp. To solve the problem, i guess HK just simply add a crossover after the front left&right channel. mark Link to comment Share on other sites More sharing options...
cchen1 Posted October 22, 2009 Share Posted October 22, 2009 That watt rating on the OEM H/K is definitely a peak power rating, not RMS which is a constant power rating that most aftermarket units go by. So whereas your aftermarket amp probably actually produces 400 RMS watts, the OEM H/K amp probably makes less than 180 RMS watt. Crutchfield.com has a pretty good explanation of the power ratings. At least double the power means you'll need thicker gauge wiring. Link to comment Share on other sites More sharing options...
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