quick ohm/voltage question for a U.S. AMP....

[dlg0187]

I HAVE AN EXTERMINATOR CLASS D MODEL XT400D

SPECS:

DYNAMIC POWER 4,000WATTS

RMS (1 OHM) 1,500X1

RMS (2 OHM) 450X1

RMS 4 OHM 200X1

WITH 2 12 INCH CLIFF DESIGN SUBS SEALED INCLOSURE

SPECS:

CLIFF DESIGNS cdaw120 high performance "sq" sub

600 watts rms 1200 watts peak

dual black aluminum 21/2" 4ohm voice coil

60 oz. magnet 91 decibels @ 1w/1m

NOW...THE guy at the store convinced me to buy this amp. he said im better

off with power to spare than not enough power...

with some experiance installing systems, i hook it up.

but this is calss d....my first one.

there was a knob that went from 6.0v to .5v i think...

i set the gain at my liking and everything else... i made my subs hit really hard by messing with the knobs.

but i guess i put it at a very low ohm level? cuz a day later, after i hit hard on a dip (low car) my amp blew up....with smoke and everything.

this was BEFORE i realized that the subs...were NOT as good as some RE subs that i wanted to buy...

but then again, my car is very low to the ground, before the amp blew, i hit a dip...hard...couple minutes later, it blew up...i had it at 12 volume level.

so my questions...

what ohm level should i run the amp at?

is the ohm level that knob that goes from 6.0v to .5? the higher the ohm setting the safer i am or what??

how would i know where to set it?

i heard cliff design **** ***....and us amps is respectable though...

oh and one more thing...i took the amp back, and even THEY were surprised i blew it....shocked really.....

i had it for only 2 days. it hit really really hard....and i have seen bass competitions before.... it was aight....but i guess i had the ohms too low.

im gettin it back tomorrow. any advice on how to make my amp last this time?

particularily about that little....6.0v knob thing...i know what gain is for, sub sonic as well, bass boost, yea i hooked all my wires right, good ground, the right wire gauge.

i know the problem is from the back...since all 3 of my 25amp fuses blew at once.

sorry for the life story....i know how it is with noobs.... i hate it when they dont explain everything at first post. u can find me at techguy forums though.....one of the top posters there.

hope u guys can help me real quick. i just cant seem to get the whole ohm thing no matter how many guides i read.

Click to read more...

 

[95stroked1500 10+ year member]

the knob you're referring to is the "gain". has nothing to do with the ohms you load the amp down to.

it's fine to parallel all the coils on those subs and drop the amp to 1 ohm.

it is a decent bang for the buck, but it is not to be compared to their merlin or AX line as far as balls go.

do you have at least 4 ga wire on the power and ground?

 

[dlg0187]

the knob you're referring to is the "gain". has nothing to do with the ohms you load the amp down to.
it's fine to parallel all the coils on those subs and drop the amp to 1 ohm.

it is a decent bang for the buck, but it is not to be compared to their merlin or AX line as far as balls go.

do you have at least 4 ga wire on the power and ground?

ok...NOW things are gonna get confusing.......

yea i have 4 guage wiring...

and yes sir...i guess i thought i knew what the gain is... but there is two knobs one to increase decibels and one to increase volts?

so if u say that i can run these subs at one ohm...why did my amp explode?

how do u adjust the ohms? is it the volt knob from 6.0v to .5v? because there isnt any other knob which im not familiar with

 

[dlg0187]

 

[dlg0187]

i just want to find out what was the problem:

bad amp?

or wrong ohm settings?

i had the bass eq all the way up to 12 db

and the volts or whatever that is all the way DOWN to 0.2v

on my speaker specs (posted earlier).....was there anything wrong with my setup?

 

[juststartin 10+ year member]

you control the ohms buy how you run your subs, parellel-series you dont control your ohms with your amp, meaning...theres no ajustment on your amp that will allow you to say have your subs running at 1 ohm, you can only control your ohms with how you run your subs

 

[dlg0187]

i see...

so there was nothin wrong with my setup?

and turning the knob down to .2v had nothin to do with my amp smoking?

here are the specs again.

SPECS:

DYNAMIC POWER 4,000WATTS

RMS (1 OHM) 1,500X1

RMS (2 OHM) 450X1

RMS 4 OHM 200X1

WITH 2 12 INCH CLIFF DESIGN SUBS SEALED INCLOSURE

SPECS:

CLIFF DESIGNS cdaw120 high performance "sq" sub

600 watts rms 1200 watts peak

dual black aluminum 21/2" 4ohm voice coil

60 oz. magnet 91 decibels @ 1w/1m

so it was a bad amp?

 

[juststartin 10+ year member]

so at 4 ohms one sub is putting out 600 watts rms, if you run one sub in parellel, which is conecting both VCS togther, it will create a 2 ohms load at the amp, pushing 1200 watts rms, if you hook up the other sub parellel as well, that will create a 1 ohm load at the amp and 2400 watts which is maxin out your subs...your amp is only pushing 1500 watts at 1 ohm, so that is your problem....i think your amp gave up 2400 watts.....1500 watts i think you over did it lol

yea i think your amp is done...but i could be wrong

 

[dlg0187]

no, you are right... that amp is fried to hell.. U.S. amps already replaced and shipped me a new xterminator.....

finally im beginning to understand....

so i need a better amp and keep the subs...or less powerfull subs and keep the amp i guess...

i guess i need a 2,400 watt rms amp then? (just to make things clear)

is there anyway i can keep what i have and have it running safely?

wow....so u say i was pushing 2,400 on a 1,500 rms.... it took 2 days to fry that amp.

R.I.P.

whats the knob that goes from 6.0v to .2v then?

 

[95stroked1500 10+ year member]

sometimes things just happen.

bass boost cranked all the way up with the gain set were it was is not good imo. at full tilt your settings are going to be trying to make that amp put out way more than it is capable of. i'm surprised the subs didn't smoke.

gain cranked + bass boost cranked 12db is not good. 12db boost is an enormous electrical increase. elecrically, every 3db you tell the amp to increase is double the power. start at 100w go 3db to 200w. 3 db more to 400w, 3 more to 800w. next thing you know things are being killed from being overdriven.

 

[Rc 415 10+ year member]

yeah, having the gain at .2 volts on a us amps means its all the way turned up, and i think 6 volts is all the way off. also you should have bas eq at zero.

 

[enzowho 10+ year member]

Alright, I don't exactly know why your amp blew...but in the future here's what you need to do.

1: Go read the sticky on setting your gains (the potentiometer that goes from .2 volts to 6 volts). Set them where they need to be otherwise your subs will get a clipped signal and you will smoke them too.

2: Turn down your bass boost on both your amplifier and hu. It adds low volume bass but remember, your amp can only produce 1500 watts at 1 ohm. By turning everything up so its super loud when your hu is at 2/32 doesn't mean you are going to get 100000000000 watts when its at 32. It means you are going to drive you amp into clipping and hurt something again.

Additionally, I saw the comment that your amp blew because your subs were 2400 watts max. Don't believe that, that's ludicrous.

You do have a good amp there, treat it right and it should last you for a long time.