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Sundown U-12 Bottoming out after amp upgrade?


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Ok, so my setup is a

-Sundown Audio u-12 wired to 1ohm

-Skar RP-2000.1D (this is the amp I upgraded to from a Hiphonics 1800.1D)

-LC2i Line output converter coming from OEM subwoofer harness

-Lincoln navigator w/stock head unit and stock electrical (Upgrading soon)

Now that we've got that out of the way, I got the skar amp recently and I installed it. I went to set my gains with a poor mans DD-1 (I'm doing it with the little speaker and the capacitor method) as soon as I get the gain more than a quarter way it sounds like the subwoofer is bottoming out? I'd suspect this to be distortion, so I checked the gains on my line output converter and no distortion was present. I tried again. Same result. Normally I wouldn't be complaining, but something is wrong when a sundown u12 can't even get remotely loud without some form of bass boost on higher than rms power?  

I was on some other forums with the same problems and I troubleshooted everything from my wiring, to the amp (Replaced it twice) to the Line output converter. I even hooked my RCA's to someone elses stereo. The amplifier was hooked up to multiple subs in prefab, and oem boxes and the same thing happened. It bottomed out at 35hz and 55hz specifically if the gain or bass boost was too high. At this point the only thing I can think of is the box and even that seems unlikely simply because I've tried this on a wide range of sub woofers. It's simply not near the output of the same setup on a much less powerful amp.  Any help would be much appreciated.

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2000 watts rms on a U series sub should be fine, all of Sundown subs are conservatively rated, along with many other brands.. Ive had that kind of power on SA-12s before without issues..
These subs can take some serious power, and the Sundown Unofficial youtube channel has videos proving just that!

That being said and out of the way, when using a LC2i, it can boost the RCA preouts on it up to 9.5 volts (13 volts peak), with it being able to put out such a high preout voltage you shouldn't need to put the gain on the amp very high at all. Even if you had an aftermarket headunit with 4 volt rca preouts the amps gain shouldnt have to be above 1/4th the way.
Now that your using a LOC that is capable of putting out way more than than 4 volts and the fact that you have no idea what its actually putting out Im going to say that you are probably using too much gain and clipping something to death especially if your running stock electrical. 

Any sorts of bass boost shouldn't be needed such as the accubass on the LC2i, or the bass eq on the amp which should be set at 0db for that amp to make and will most likely just add distortion.

Now if this problem is happening across multiple subs in multiple boxes as you say I think its safe to say its not the sub with the issue and most likely the amp (after all its a cheap $230 budget Chinese 2000 wrms amp), or something causing the amp to do it such as lack of power being supplied to the amp, or maybe even a loose power or ground connection on the amp/battery/fuse, or a bad crimp/solder job on a ring terminal that is only causing an issue now because your using an amp that demands more current than your previous amplifier.
 

 

 

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1 hour ago, audiofanaticz said:

2000 watts rms on a U series sub should be fine, all of Sundown subs are conservatively rated, along with many other brands.. Ive had that kind of power on SA-12s before without issues..
These subs can take some serious power, and the Sundown Unofficial youtube channel has videos proving just that!

That being said and out of the way, when using a LC2i, it can boost the RCA preouts on it up to 9.5 volts (13 volts peak), with it being able to put out such a high preout voltage you shouldn't need to put the gain on the amp very high at all. Even if you had an aftermarket headunit with 4 volt rca preouts the amps gain shouldnt have to be above 1/4th the way.
Now that your using a LOC that is capable of putting out way more than than 4 volts and the fact that you have no idea what its actually putting out Im going to say that you are probably using too much gain and clipping something to death especially if your running stock electrical. 

Any sorts of bass boost shouldn't be needed such as the accubass on the LC2i, or the bass eq on the amp which should be set at 0db for that amp to make and will most likely just add distortion.

Now if this problem is happening across multiple subs in multiple boxes as you say I think its safe to say its not the sub with the issue and most likely the amp (after all its a cheap $230 budget Chinese 2000 wrms amp), or something causing the amp to do it such as lack of power being supplied to the amp, or maybe even a loose power or ground connection on the amp/battery/fuse, or a bad crimp/solder job on a ring terminal that is only causing an issue now because your using an amp that demands more current than your previous amplifier.
 

I plan on upgrading electrical soon, do you think that would make it audibly louder at the correct gain? I'm not really sure how all of that works. Also the gain is set correctly on both. I used a crappy distortion detector that does the job pretty well. but the thing can't even break like 95db. 

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You can’t set the gain properly with that cap/speaker way tony Damore explained something like all its doing is showing amplifier noise that’s enhanced by the cap or something I don’t remember if I remember and have time later I’ll find it....

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18 hours ago, CstrokerV said:

You can’t set the gain properly with that cap/speaker way tony Damore explained something like all its doing is showing amplifier noise that’s enhanced by the cap or something I don’t remember if I remember and have time later I’ll find it....

Well, regardless even with the gain set low enough for that to not happen there's very little coming from the speakers. Could this be due to stock electrical?

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  • 3 weeks later...

Seems strange. What's the specs on the box?

So you hooked your amp and sub up in another vehicle and it acted the same? What about when you had the hifonics?

Have you tried hooking your sub up to someone else's amp in another vehicle? Different subs and amps in your vehicle? 

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