Selectable, head amp or outboard amp

nouseforaname wrote: mrjc480 wrote: You will only be using 111 watts if you have the amp and the head unit at full volume. Personally I would just use the external amp (better quality sound and cleaner signal). 111 watts is 111 watts reguardless of volume.

Yes, true, but in this case wrong application. Read on. If you head unit allows you 18X4, and you can listen to it at a resonable volume, i.e. loud enough for you to listen to it in the parking lot, and an amplifier playing the SAME source, at the SAME volume will pull NO MORE CURRENT THAN THE HEAD UNIT, probably a little less, due to it's eficiency, ESPECIALLY if your 111X4 is Class D! A deck, producing, lets say, 15 wpc, is significantly less efficient than an amplifier producing the same amount of power. Just because your amp CAN produce 111 wpc, that does not EVER mean that's ALL it puts out, wherever the volume control is. If you have the same source being amplified by the deck, producing a continuous 15 wpc, simply by the fact that the system will be cleaner and SOUND more intelligible, the externally amplified system will probably be making LESS power to the speakers - probably closer to 10 wpc. ALSO, if you implement the high pass crossover (like I know you were going to do ANYWAY, right?) for parking lot listening, the system will run even MORE efficiently, by virtue of not having to amplify low frequencies. A simple switch in the remote lead to the sub will guarantee that the externally amplified version will consume less power, overall, than the deck amplified version. Stop making it more difficult on yourself than you have to, put the system in, and love life! Oh, and yes, the HU will take damage, I guarantee it, if you connect it as described above! The outputs have no protection whatsoever (with the possible exception of short circuit) and audio signals are AC, so you CAN'T diode isolate them... Don't even think about following through on that plan, unless you want to go buy a new deck, and soon!It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

haemphyst wrote: nouseforaname wrote: mrjc480 wrote: You will only be using 111 watts if you have the amp and the head unit at full volume. Personally I would just use the external amp (better quality sound and cleaner signal). 111 watts is 111 watts reguardless of volume. Stop making it more difficult on yourself than you have to, put the system in, and love life!

AHHH! THANK YOU SO MUCH haemphyst !!! NOW I get it! Everything you said makes sense to me, now I feel comfortable with ditching my "ignorance-is-bliss" idea. I THOUGHT it was a good idea...yours is MUCH better! I'm so happy, another self-made hurdle crossed! Whew, really man, I DO complicate things for myself, from years of modding & fabbing all sorts of projects. Not that I'm not gonna keep complicating this project...I'm looking for a local welder to fab a new passenger seat mount, so I can fit the Infinity 7541a under there... heh. I sure appreciate your help bro! Pics will be posted when the project gets there...it WILL be unique! (hint: didn't like generic HU mounts for GM, so I made my own with pilots, sockets, switches...) I think you'll get a grin from this 'geezer's' work. Thanks again to ALL of you! - the12volt ROCKS!