LudlamTheory

I know this question has been asked way too often, but i'd feel a lot better if i got a response specific to my own situation.

in about a month im planning to install some new amps (due to the fact that my amps are all flea market brand sh*t)

as of now im looking at a JBL BP1200.1 1200 watt mono block to power my 2 audiobahn aw1200x 12" subs (700 watt handling each)

AND

a 4 channel A/B (undecided on which as of now) pushing somewhere between 50 and 75 per channel to power the infinity kappa 6.5"s.

(all the watt measurements i've mentioned are obviously in rms since peak power is a foolish term)

So i have 2 questions since i know enough about car stereo to get me by but not enough to know the calculations to make on all this.

1 - Will this put too much stress on my alternator so that i would need a new one? (no neons, no nothing out there, my headunit has the internal amp switched off, but I live in miami where its a constant 187 degrees all year long so the A/C is on a lot).

2- If the alternator can handle this, how many farads should the cap be?

im glad mohawk is back, but im sure whiterabbit and some of you others will have input.

and, if this is too much power... i could downgrade 85 dollars and get 1/2 the power with the jbl bp600.1... if any of you know of any other amps between 700 and 1200 watts for under 285 dollars (price of the bp1200.1)

mohawkboom

iTrader: (1)

Okay..well one way to actually find out... try it.. if you want to be safe..I'd say grab up the 600.1 with 1200Wrms of class D power and ay 200Wrms of class a/b power at 33% music load you have 54 amp draw or so.. but that's only at full power... turn the volume **** a bit don't crank it you'll only be pulling about 30 amps with A/C on your more than fine... if your lights dim and it annoys you.. get a 1 farad cap...

LudlamTheory

the 600.1 doesn't run at 1200W... it runs at 600 at 2 ohms i believe, and although its 1 ohm stable, theres no power gain

mohawkboom

iTrader: (1)

I said go with the 600.1 to be safe as 1200wrms(from the 1200.1) may be too much...[IMG]i/expressions/face-icon-small-smile.gif[/IMG].. sorry I was not overly clear on that

LudlamTheory

will the 3 db difference ill be hearing from the 2 different amps really be all that noticeable... the reason im saying is because ive stumbled across these amps for dirt cheap...

mohawkboom

iTrader: (1)

get the 1200 and just don't crank it too often..or for too long...3dbs is a doubling of sound pressure...however..to the human ear approx 10dbs is what you'd perceive as being twice as loud..

LudlamTheory

yeah... i know db is a logarithmic function and alll... 10 * power = 2 * loudness and all that
its just my paranoia.... so if my car randomly shuts off from bass i've gone too far? hehe.. maybe ill drop the a/b power even lower... hifonics has a 55 x 4 amp for a decent price... by the way, is anyone else here using a bd1200.1 on a stock electrical system with about 220 watts of a/b power added on? alright... so if the voltage drops below 12.8 on average ive got the gains too high?


so has anyone tried putting a smaller pulley on the alternators?

mohawkboom

iTrader: (1)

White rabbit does... he runs a 1200.1 and a 100x2 amp I beleive.. he hasn't has any problems.. Also class a/b power for mids isn't much draw..

I run an Arc 1500D-r and an arc 2100Cxl. 1200Wrms Class D and 200Wrms class a/b.. I have a high output alternator.. At full unclipped volume listening to bass tracks I get about a 72 amp current draw on average..with peakes a touch over 100amps.. listening to heavy metal and such...I only draw about 60 amps...but if I actually sat in the car my ears would never be able to take it.. at a nice loud volume I draw about 40 amps with bass tracks..and 32 with most regular music..Gains have nothing to do with current draw.. set your gains according to clipping..and balance between your mids and bass. It's output (ie volume which is power output from the amps).. Just get the 1200.1 try it out with the music you listen to most.. crank it.. have someone with ear muffs on sit in the car doors and windows closed and rev the car to 2200 or so RPMS..and measure your voltage across the battery.. if it spends alot of time below 12.8 volts...it's not good... then set everything to a good loud listening volume..do the same test...after all you don't drive around with everything cranked 24/7..then see what kind of voltage your sitting at...

LudlamTheory

so according to arc audio your sub amp runs at 120 amps at 100% power and your other amp runs 43...
the bp1200.1 runs at a max or 114 amps and the hifonics z440 runs under 40 amps (has a 40 amp fuse)... not that big of a difference... well, maybe a bigger difference if you get into the percentage of how much is used... now the rambling begins:

yeah... my headunit lets me adjust the level of my subs from 0 - 12... i guess i'll just keep it at a low level... but i have a question... the time that most people crank it dirty is when you ARE parked because youre showing people the system... wouldn't that just screw the whole concept of having it revved and all... because my hearing is already fu*ked anyways so i dont drive with the bass cranked... its just i do a lot of installations locally so i like to show people what i CAN do myself... makes for good business... so you said it starts charging at 1500 and then charges enough at 2200... is there any way i could lower the rpm's at which it starts charging? a smaller pulley... i think i remember a recent post where mohawk states that a smaller pulley may be acquired... if a smaller pulley cant be found, could one maybe grind down the existing pulley to a smaller diameter... also would it spinning at a higher speed put the life of the alternator at stake at all... i could probably spend 50 bucks on a smaller pulley, and thicker wiring on it, but 616 on an ohio or 300 on having it rewound, i think not... how much do the optima redtops run? or should i use a yellowtop since its a deep cycle battery as well while the redtop isnt? and will this actually help me out in this situation... i dont care about dimming at this point so i'm not gonna deal with a cap. sorry for the excessive asking, i'm just a paranoic poor kid wanting to reap the full benefits of my setup without being stuck on the side of the road with a blown alternator... heres a thought... is there any way for me to do something o the casing of the alternator so that it runs cooler? heh

LudlamTheory

fu*k it... im just gonna get the 600.1 ... im bound to spend my damn savings account on a new alternator and regret it... one day i'll be able to afford massive power

AB

iTrader: (1)

just from skimming through all this and reading a post here and there on this thread, i can honestly say that I have no idea what you guys are talking about.

LudlamTheory

now you see how damn obsessive us I.C.E. freaks can really get... we learn all this crap just for a stereo... just think, i could have used all this time getting a job or doing something to help my fellow man... but i think i'll stick to my stereo... screw horsepower and performance... its a civic... if i wanted speed, i'd buy a wrx or something... its all about my system