Amp Current draw confusion!?

[Bumpdump]

Hey guys, new to the site, so thank you in advance for taking time to read and give me your thoughts on this subject. Ok, first Im pretty familiar with all the procedures of correctly installing amps, subs, etc. and I was installing another amp into a friends car. He already has a alpine mrv-f300 4 channel for his doors, and a kenwood kac-9105d (900w rms @ 2ohms) pushing a Soundstream reference r.2 12" (500w RMS) subwoofer and that sub hits pretty hard and doesnt put a dent in his voltage even at high volumes windows rattling and all that. but he acquired a crunch groundpounder 30th anniversary addition 2 channel amp (250wx2 @ 4 ohms or 500w rms x1 (bridged) @ 4 ohms) that is pushing a kenwood KFC-???? 12" subwoofer that is rated for 400w rms. now when I added the crunch amp and kenwood sub and turn up the gain on it It starts to make the voltage drop drastically and the lights dim and all that. And my first thought is well its too much current draw so I turn the other amps gain all the way down to where the sub isnt even playing. then crank the crunch amp up to abou 50% gain and to my disbelief it is still making the voltage drop and its not even playing very hard. turn up the gain even more to where it starts to actually hit and sound good but his lights are dimming so badly that its unrealistic to think it could be safely enjoyed while driving at night. I have two seperate power wires going to each. both 4 guage wire that are fused correctly, and with a good solid ground that is under 12" long going straight to the chassis. then i even did big three upgrade for him and sure it made his lights seem a little brighter his voltage doesnt drop at all playing his kenwood/soundstream set up but when you crank the crunch amp it just rips the power from the alternator like mad. and when both subs are playing the more you turn up the gain on the crunch amplifier the softer the soundstream sub hits until neither sub sound very good and then they begin to clip before it even sounds good. so my question is what would make a less powerful amp pushing a less powerful sub playing quiet suttle bass pull more juice than a nearly double sized amp pushing a slightly more powerful sub that will rattle your chest and windows, i just cannot make sense of it? also the kenwood amp going to the soundstream sub (the good and loud match up) is a Class D amplifier. and the crunch amp is a A/B amplifier, and i know theyre less efficient but **** i didnt think a a/b would drain THAT much more power or why the hell would anyone want one? so im just wondering if the amp is fucked up or am i missing some kind of rule of thumb about multiple amp installs or placement or what? thanks again for your time!

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[LosIsATool 5,000+ posts]

The crunch is a giant POS. You probably have the gains to high to get noise because it's massively overrated.

 

[hispls 5,000+ posts]

A/B is very inefficient and Crunch hasn't produced anything good since the 80's when they were American made. Also mix matching amps and subs is going to sound horrible 19 times out of 20.

Really you're at the point where you need actual electrical upgrades to run more amps so even with a better efficient amp you'll be running into trouble without more batteries or larger alternator.

 

[LosIsATool 5,000+ posts]

Double check the ground also. That will tank voltage.

 

[wew lad 5,000+ posts]

Also mix matching amps and subs is going to sound horrible 19 times out of 20..

Woah what, I have an idea of what you mean but please elaborate

 

[Bumpdump]

Yeah I knew the crunch was doodoo firstly by the grossly in appealing name then after reading up about them my suspicions were validated but he insisted because he had just bought a upgraded alt from a 90 amp to a 130 amp so I just did it because I really enjoy practicing it so I can become better at it. It's just stumped me because the crunch amp even at Max gain and volume shouldn't pull more that 500w (rms) (it's max power was rated at like 1,100 (give me a friggin break with those manufacturers lying ***)) but I double checked with a multimeter and it gets about 420ish watts rms before clipping what sounds like something blowing *** underwater but when it hits those 420w dim his lights when the 900w rms Kenwood that gets right at 891w a couple levels before clipping and it doesn't dim his lights. So I'm just wondering what or why it is harder for the vehicle to push the smaller amp vs the bigger one. I guess that's just what butthole quality amps do for ya?

 

[ChaseinBass]

Yeah I knew the crunch was doodoo firstly by the grossly in appealing name then after reading up about them my suspicions were validated but he insisted because he had just bought a upgraded alt from a 90 amp to a 130 amp so I just did it because I really enjoy practicing it so I can become better at it. It's just stumped me because the crunch amp even at Max gain and volume shouldn't pull more that 500w (rms) (it's max power was rated at like 1,100 (give me a friggin break with those manufacturers lying ***)) but I double checked with a multimeter and it gets about 420ish watts rms before clipping what sounds like something blowing *** underwater but when it hits those 420w dim his lights when the 900w rms Kenwood that gets right at 891w a couple levels before clipping and it doesn't dim his lights. So I'm just wondering what or why it is harder for the vehicle to push the smaller amp vs the bigger one. I guess that's just what butthole quality amps do for ya?

I am no expert but my guess is amp efficiency is much less on the crunch ( takes twice the DC power to make half as much AC power ) or as you said Junk !