Amp Shutting off + more

[GlassWolf]

how many watts RMS does each amplifier you have put out as they're wired up now? Answer that and I can tell ya what size fuses ya need.

as for gain, those numbers are voltages, to match to your head unit's pre-out voltage.
if the head unit is 2 volts, you set the amp gain to "2" and if it's 4 volts, you set the amp gain to "4" etc.
gain on an amp isn't a volume knob. the "gain" setting is actually your input sensitivity, and it's used to match the line input voltage to the input stage of the amplifier.
if the gain is set too high, your input stage is overdriven, and you get clipping and distortion, and you'll fry the subs even if they are underpowered.
If you set the gain too low, you amplify a weak signal and get poor signal quality.

read this article:
http://www.bcae1.com/2ltlpwr.htm

[smoker]

what kiki said......sounds like the gain is set wrong and the fuses may be too small...

[r3ap3r911]

Well sh*t... Turned out I had the subs running in 0.5 Ohm on my 1 ohm stable amp... thats why the fuses were popping like a new hooker.. So I wired the subs back up in series to gain a 2ohm load, sucess... listened to one of the subs with my ear right up to it and it sounded a bit distorted.. hmm, kept on going playing it, then about 15 minutes later at not even high volume the sub cuts out... no noise.. push on it and no "scratchy" sounds.. take it out look and one of the positive connectors from the cone to the post melted off and just dangling there... tried to solder it back but No luck, solder wont stick!.. guess back to the shop they go!.. also my problem with all that car crap was figured out, turned out i changed my ground from amp and desk and it was all fine after that..

[r3ap3r911]

how many watts RMS does each amplifier you have put out as they're wired up now? Answer that and I can tell ya what size fuses ya need.

as for gain, those numbers are voltages, to match to your head unit's pre-out voltage.
if the head unit is 2 volts, you set the amp gain to "2" and if it's 4 volts, you set the amp gain to "4" etc.
gain on an amp isn't a volume knob. the "gain" setting is actually your input sensitivity, and it's used to match the line input voltage to the input stage of the amplifier.
if the gain is set too high, your input stage is overdriven, and you get clipping and distortion, and you'll fry the subs even if they are underpowered.
If you set the gain too low, you amplify a weak signal and get poor signal quality.

read this article:
http://www.bcae1.com/2ltlpwr.htm

I have two Kicker CompVR's 2 ohm DVC. Rated at 400 RMS and 800 Peak.. Amp set to one notch over half gain.
I have a Kenwood KAC-915D Mono amp that puts out:
Max Power 1800 Watts
RMS 500 Watts (4 ohm,20-200Hz,0.5% THD)
RMS 900 Watts (2 ohm,100Hz,0.9% THD)
RMS 900 Watts (1 ohm,100Hz,1% THD at 14.4V)
Also has:
Dual Mono drive, 1 ohm stabe, Variable Low _pass Filter, Remote Bass Boost Control(hooked up), Infrasonic Filter, Line Output, Speaker Level Input

[GlassWolf]

900 watts would need a fuse around 80-90A to handle the current draw without blowing.

the amp clipping was what burned up the one sub though.
that was due to the mis-wiring and trying to run at half an ohm.
2 ohms is ideal anyway with that amp. 450 watts per sub, which is already 50 watts over the rated power handling.. go more than that and you will end up cooking those subs.

[r3ap3r911]

900 watts would need a fuse around 80-90A to handle the current draw without blowing.

the amp clipping was what burned up the one sub though.
that was due to the mis-wiring and trying to run at half an ohm.
2 ohms is ideal anyway with that amp. 450 watts per sub, which is already 50 watts over the rated power handling.. go more than that and you will end up cooking those subs.

I was wondering what someone said earlier about the gain being set improperly due to voltage on the deck etc... well... i dont see how the voltage on the deck makes any difference to what level of gain i can put on the amp/subs since it only effects the amp and not the deck, correct? I can turn the deck down to number 3 or whatever matches the pre-outs on the deck.. but theres barely anything coming out of the subs.. i think that was a missunderstanding or something? anyway. can u clear this up with the subs i am using and what i SHOULD have gain set at... if i want 900watts rms.. should i put the gain to FULL? and what frequencies? 100hz @2ohms sound good? or more or less??? ALSO what do u mean..are u saying my amp is not truley 900watt rms since it has 2x30amp fuses in it? or maybe it just doesnt need more?.. or what

[smoker]

the preamp voltage not the power supply voltage. the subs hooked to the amp have nothing to do with the gain setting. there is a certain amount of voltage coming out of the preamp section of your hu, the gain on the amp should be set to match that voltage regardless of what you have it connected to on the output side of the amplifier.

[GlassWolf]

reaper911, I'd recommend reading http://www.bcae1.com
that site answers a lot of your questions very concisely.

the "gain" setting on your amp (actually it's properly called "input sensitivity" since it's not truly a gain adjustment) is not used to vary how much power the amp puts out or meant to act as a volume knob. The only purpose of input sentivity is to match the input stage of the amplifier to the RCA line voltage coming from the head unit (usually between about 2 and 5 volts depending on the head unit.) I've explained this so many times now, but once again if the gain is set too high, thr amp's input stage will be over-sensitive and you'll overdrive the amp. the amp puts out no more power, but it distorts and clips, causing DC voltage to go to the speakers and that fries speakers, as you found out the hard way.
If your head unit is a 4 volt unit then set the amp gain to "4"
If the system isn't loud enough then adjust the bass level at the head unit, or buy a larger amplifier or better subs or both.

set the LPF on your amplifier to 60 to 80Hz.. for 12" or larger subs I usually don't go higher than 60Hz if you want tight bass.

as for power output, your amp only puts out 900 watts at 2 ohms at full volume with a test tone. actual power output to a reactive load like a speaker playing music at normal volumes is several magnitudes less tahn 900 watts. This has to do with power and sound pressure relationships.

as for fusing.. 30A+30A is 60A of current. that * 14.4VDC at 80% efficiency for a class D amplifier is about 690 watts RMS at best. I'm guessing either your amp has a third 30A fuse, you have the wrong fuses in the amp, or your 900 watts is "pwak" and not RMS.. since peak is generally two to three times the real power output.
This would also explain why the subs sound weak with the gain properly set. your kenwood amp is just too small. you need to get a better amplifier that puts out a real 900 watts RMS at 2 ohms.
Then the subs will hit properly, and you won't blow the coils up with clipping by overcompensating with gain for lack of real power.

ya know with those two subs.. an Orion275HCCA would be a great amp at 1 ohm stereo. You'd get 300wRMS per sub, and it's be true, balls to the wall class AB amp power. Plus your amp would be "rated" in competition as a 2x75 watt amp (at 4 ohms)
you can find 275HCCAs on ebay pretty often in good shape for a good price

[smoker]

once again thank you kiki. i love your answers sometimes. what they seem to do is take a relatively simple concept ( the gain on your amp or input sensitivity should be set to match the output voltage on the preamp section of your head unit, adjust this too high and distortion occurs) and turns it into this...........

the "gain" setting on your amp (actually it's properly called "input sensitivity" since it's not truly a gain adjustment) is not used to vary how much power the amp puts out or meant to act as a volume knob. The only purpose of input sentivity is to match the input stage of the amplifier to the RCA line voltage coming from the head unit (usually between about 2 and 5 volts depending on the head unit.) I've explained this so many times now, but once again if the gain is set too high, thr amp's input stage will be over-sensitive and you'll overdrive the amp. the amp puts out no more power, but it distorts and clips, causing DC voltage to go to the speakers and that fries speakers, as you found out the hard way.
If your head unit is a 4 volt unit then set the amp gain to "4"
If the system isn't loud enough then adjust the bass level at the head unit, or buy a larger amplifier or better subs or both.



the reason i love your answers is because sometimes while answering the question it also terrifies the individual who asked the question.....well that and sometimes your kind of a smartass at the same time and i get a kick out of it...

[GlassWolf]

it's the result of a warped mind, I tell you.