funtimes

hi i'm tryin' to attach the wiring diagram. i have researched lots and lots, still not sure if i need to hook up +b1 and +b2 to my 12v battery. i don't have or use the cd changer.... my amp is the nak from ls400 1998. the diagram is from a 2000 ls400 nak...so...i have gotten all the fl fr rr and rl channels to work alright, but i can't get the sub to make much noise, its just real, real weak, not just "factory sub" weak. so i finally tried to get all four rca's leads into the nak amp...i maybe have an issue with a tried to basically make my own Y adapter type thing on one of the rca pairs because i also wanted to feed that pair to another amp i am using at the same time (a radio shack optimus xl-400, don't laugh it seems alright 90db snr beats lots of head units). so why can't i get the sub on the nak to work? why do car audio shops always say "well you will lose the sub when we install that aftermarket head unit, the factory sub you will lose, so you'll have to buy a new amp for the sub and probably a new sub"...is that bs? why do you lose the sub? i don't know if one can take an rca pair and try to splice in another rca pair line....isn't that just what a "y" adapter does? i get that the voltage on those preouts will take a bit of a hit, but... i just don't know why i can't get the sub working


lastly, why am i trying to use this nak amp? other than to make that trip to the junkyard less of a loss and to avoid spending more money on some other amp?
i am fairly happy with the xl-400 amp and i guess i could just use my head unit's amps for anything else i need, my head unit is a DEH-P4100UB

http://www.pioneerelectronics.com/PU...rs/DEH-P4100UB

its specs are:
http://www.pioneerelectronics.com/PU...-P4100UB?tab=B

1-bit D/A Converter Yes (8fs/16-bit)
Audio Features
Built-in Speaker Power MOSFET 50W x 4
Continuous Power Output 22W x 4

so, i wonder, doesn't the common wisdom say its better sound quality to not use the on board amp on the aftermarket head unit, but instead to, say, use an outboard amp like the nak? or are these new MOSFET things in today's head units game changers such that the sound quality is actually better from my head unit than using the nak? how do i tell if the sub channel is just blown on my nak? does the sub channel have its own amp+ wire? its own ground? sorry so many questions. does anyone know the specs on the nak amp like thd and snr and rms and what would be a comparble amp on the market today and price? oh, i am just using all the speakers, including the sub that came with the nak system, i am not using the factory head unit, but pioneer deh-4100ub peace

BLKonBLK98

*edit - my mistake.

*double edit - i'm not familiar enough with the nakamichi system to give solid advice, but i do know that the external sub amp for the premium system runs through the hu. my guess is there is somthing that occurs there (most likely level attenuation from oem hu) that is interupted when the hu is removed.

if the sub worked with the oem hu then the channel is not blown.

there is no reason other than not wanting to upgrade to keep any of the oem components in place. all can easily be outperformed.