Subwoofer Amplifier Cutting Out And Going Into Protection Mode

[Kingman]

Alright, so I currently have 2 JL Audio 15s and a Nitro 800W amp (200W actually, only 1 20A fuse). The subs were hitting hard enough to make your hair stand up, but one sub came onhooked inside the box so I disconnected the amp completely and then reconnected the subwoofer.

 

Problem is, during that process some knob got turned and now it can't hit as hard without the amp cutting off and going into protection mode. Also the sound isn't as clear and it cuts off mostly when a song hits very low bass. This is all listening at the same level that it was able to before, yet the amp cuts out early and refuses to provide as much power.

 

It has the following adjustments from left to right on the amp. LPF: 30-250, x-over switch: LPF-HPF-FULL, HPF: 50-1K, bass boost: 0dB-18dB, level: min-max. From memory of where it was originally set, bass boost was 1/2 way up and level was on max. I do not know what LPF or HPF are and it sounds extremely weird if I mess with them. The switch is set to LPF where it's always been, sounds like sh*t and becomes hollow sounding if I change it, like it's letting treble and vocals through.

 

My deck is a Panasonic, and the volume goes from 0-40. The amp will cut off on a hard-hitting song at 28-30 where I usually listen at, less bass songs can be turned up to sometimes 34. The bass is set at 0, treble all the way up, fade or balance set at neutral. Sometimes I'll have to turn the deck down to -3 or -6 for bass to keep the amp from shutting off. When it shuts off I have to turn the key all the way off for a few seconds and then turn it back on...pretty fun doing on the freeway.

 

It still hits hard but no where as near as hard as it used to, and I'm lost on what adjustment to make or check. I've already gone through all the RCA cables, power and ground cables, remote power wire, and speaker wiring.

 

Any audiophiles have some ideas on what I can do? Thanks in advance...

[5523Pathfinder]

How do you have the subs wired? Bridged or not? Im assuming you have adjusted at the amp, as the deck should not of changed. Plus, you are running a lot on kind of a small amp, sure your are not just overloading it?

[Kingman]

They are bridged. The system used to be in my friend's Subaru and he never had any problem with the set up.

 

 

[Simon]

LPF is Low pass filter. That should be used for Subs. It filters out high end frequencies HPF is for mid-high range speakers, and is obviously the opposite of LPF.

 

It's possible that something may have blown in the amp when one of the subs got disconnected. Otherwise, try lowering the bass boost, and see if you can get it to kick like it did before.

[Kingman]

Will do. I should also mention that the LPF is set all the way up, so is the HPF. Should I turn that all the way down even though it's set to LPF?

 

It used to be by far the loudest system in the student parking lot at school, now a damn 12" is almost even with it. They definitely aren't performing like 15s.

 

Is it possible that when the wire came undone in the box it wiggled around and tapped the other wire and that could have messed up the amp?

Edited April 28, 2010 by Kingman

[silverton]

your low pass filter should not be set higher than 90. basically, figure out your travel, you want to turn it a third of the full range of your knob.

 

You also want to set your filter selector to LOW, that means it will be using the low pass.

 

I'm going to say that your amp is going into protect mode because it's trying to make the subs operate in a range that they were not meant to be, and it's going into protect mode to save your subs. I think your issue is in your low pass knob and the selector.

 

I hope this helps.

[Kingman]

Alright I'll tinker with that knob too. I made it a little better, I turned the bass boost all the way up and the gain down. Has a lot more punch before cutting off, but still not as much. So eyah I'll adjust the LFP. Thanks!

[silverton]

You are clearly new with audio. And I don't mean this offensively, as I just literally tuned my first amp today, but I was doing it with the guidance of an audio specialist.

 

You want the gain to be at the same voltage as your pre outs. So you need to figure that out and adjust accordingly.

 

You also don't want to have your bass boost ALL the way, I would suggest an extra decibal or two. Adjusting the deck settings is much easier.

 

Again, I hope this helps.

[Kingman]

Lol yeah I've never tuned one. I just hook them up and hope they work, and luckily they do usually.

 

What do you mean by pre-out voltage? Those kind of terms confuse me... once I know what that is how do I know what I've set the gain at? This amp only lists minimum and maximum levels, nothing in between so there's visually nothing to go by. Is it something I can figure out with a Fluke meter?

 

I'll turn the gain down a little, will just an 1/8th of a turn down do?

[Precise1]

PSA: Good.

 

B

[Kingman]

[Precise1]

I don't want to hear what you are listening to, I want to hear what I'm listening to. If you blast your stereo to stupid levels, I can't hear mine at reasonable levels, so good, your system doesn't work to the stupid level it is capable of.

 

I'm curious of the effect of a cattle prod to a car body, would it fry the electronics?? If so, I have a cure for the roling beat box mentality...

 

B

[silverton]

it's nothing to do with the amp itself. Each deck has it's own pre out voltage and you need to match your amps gain, to what the deck is putting out. It should be listed in the owners manual, or the internet...

[Kingman]

Oh... it's a 40W per channel deck.

[Kingman]

I don't want to hear what you are listening to, I want to hear what I'm listening to. If you blast your stereo to stupid levels, I can't hear mine at reasonable levels, so good, your system doesn't work to the stupid level it is capable of.

 

I'm curious of the effect of a cattle prod to a car body, would it fry the electronics?? If so, I have a cure for the roling beat box mentality...

 

B

 

Well, good thing we don't live in the same area. If I feel the want or need to blast music in my rig then I will do so. You have the same right as well, though you might choose not to, I do. Don't like what I'm listening to? Too damn bad.

 

Driving around through neighborhoods is obviously different, the stereo gets muted when pulling into one. Out on the road it's free game.

Edited April 29, 2010 by Kingman

[silverton]

the per channel wattage doesn't matter. the voltage that the deck is putting out the pre outs for amps is what you need to know.

[Simon]

Looks like Silverton's got you covered. Follow his instructions. LPF on 15's should be around 90 as he said. MAX you would want to go is about 120. Turn the "bass boost" all the way down, match your gain to your pre-out voltage, and go from there. HPF level doesn't matter as it's not being used.

[Kingman]

I adjusted the LPF down to what I think is around 90. The bass is much clearer and it doesn't cut out nearly as much, still not as loud though. Gotta do some more fine tuning in a desolate area where I can crank it for a long time and get it just right. Thanks for the tips guys!

[Kingman]

I finally got way too tired of the system cutting out and not performing, so I bridged one sub to the amp and turned the gain and bass boost up. I also got a new Alpine deck as my old one decided to eat a CD and wouldn't give it back. I had to destroy the deck to get it out. The new deck controls frequencies/hz and has a 4V pre-out, as well as a high and low pass filter for each speaker and subwoofer. I turned the bass to the speakers all the way down and the mid and highs up, and the sub almost all the way up. I can throw everything the amp and deck has at the sub without cutting out and only rarely does it distort. I've matched all the levels to the point of distortion and it sounds clear and powerful. Way louder than trying to run both subs.

 

Thanks for the inputs guys.