could it also be a heat issue?? one of my old amps would just clip out when it got too hot

 

Shifty, not trying to target you, but i have to stop and point out this statement: "You can add a line driver to step up the input signal, if the headunit you're using has a weak preout."
while this makes a good point, it really isn't entirely practical. this just isn't quite right. unless his preamp out on the HU is below the amp's minimum input gain, this shouldn't matter at all. if the HU outputs 1 V and the amp has 1 V in it's input range, he should be fine. and most amps i've seen have something in the range of like a .2 V minimum input. so that really should be a non issue. honestly, most of the time, a line driver shouldn't be needed for the average amp, unless you've moved from typical equipment.

in the end though... iirc, the 9851 has a 2 V preamp out. so, he should be good there.

also, as best i can recall -- that Alpine is not one of the digitals but has traditional adjustment pots.



what 10" SVC subs are you running?
it really does sound like you're cutting out on a low impedance load.

heat sounds like another target though... how long are you running everything before it shuts down?
what bothers me is when you mention that if you turn it up fast, the subs shut down.

another potential target seems like you could be shutting down on low voltage to the amp.
have you replaced the fuses on the sub amp and on the distribution block to the sub amp? i've seen fuses that appeared to be fine and ohmed good, but when asked to carry heavy loads, they fart out. it's rare, but i've seen it on occassion.
where are your grounds located? how big are they? how long are the runs?

 

also there is no need to run a dedicated power line to the head unit -

I use my car's factory wiring because the internal head unit amp should be switched off (my 9835 is off) because the amps feed the speakers / sub and not the head unit-

i believe alpine stated that by switching off the head unit

 

PJK3,

the reason for the line driver is so he can run a high input signal, of course, resulting in lower gain settings to match that input.

I believe his problem is hes trying to get too much out of the amp, hence the high gain settings, and hes just driving the amp to clip.

Higher input means lower gains, less chance of clipping on an amp that small.

And as pointed out, the amp has the levels to match in the input sensitivity, like you said, but most people dont understand the concept of matching the input signal to the amp, and most of the time the amp is not enough to do what the person wants. In this case, if you have to crank on the gain to get the desired bass output, you need to pony up and buy a more powerful amp.

 

agreed.

my fear here is that if he does this, instead of driving the amp to clip, he'll either end up clipping the input signal, which will make everything sound like crap, or he'll use the additional pre-amp signal to try and get things even louder by turning the gains sensitivity up (gains up), and we'll be back to where we are now. line drivers aren't a solution here... they're an attempt to dodge around the problem. i know what you're getting at, but disagree that it is a solution.

either way -- gains should be set properly. neither scenario (gains set too high at the amp or too high a power signal into the amp) gives you good quality sound.

the real solution for that scenario is either: set the gains right, or buy a more robust amp/sub combo.



at the end of the day though, we still don't know if that's his problem.

 

just my 2 cents, but wouldn't the turn-on lead have the ability to do this. If it isn't getting enough voltage to the amp then wouldn't it shut off. Are you running a separate turn on lead for each amp or are you sharing one at the back of the vehicle. If you are sharing maybe running a larger size would be a good idea. I don't know, maybe I'm way off.

On the over heating of the amp, can you just touch it and see if it is too hot? I have the same amp running two 12" (2 Ohm load). I run the hell out of it and have never had an issue with it cutting out. I have found it go into protection mode when then + and - of the speaker wires have touched.

 

I *think* PJK3 has it right. After checking over things, i think the sub amp is being driven too hard trying to keep up w/ the others. I will be putting in a beefier sub amp this weekend and expect that to take care of the issue (hoping anyway). I'll post how it turns out.

 

cool... looking forward to the update.

 

Ding ding ding! We have a winner!

PJK3 was exactly correct. A beefier sub amp did the trick. No issues now except my own imaginstaion.

See, now i've got an extra MRP-M350 sitting around and the two 8's left over from my previous install. The only thing in my tirewell if a board w/ my crossovers mounted, so now I'm thinking just for grins about glassing a couple small encloses ala WLaurent and putting the two 8's in there driven by the extra M350. I've got enough fibreglass and MDF left over that it would basically be free except for my time. I'm trying to talk myself out of it now

 

glad to hear you got it right...


(i'm not sure i was 100% correct tho... looks like i listed a few things to check... )