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Sub kicking off


saskicker32

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So I have rockford fosgate everything, I believe my sub amp is a t-400.2 (I'll double check a little later when I can), anyway my sub keeps kicking off after about 2 hours. It will kick off whether I'm blasting it or not. I thought first about putting a fan in the compartment. (Both my amps are in the passengers compartment). But then I thought maybe it's just that the amp is not strong enough for the sub. I have a 12" rockford sub under the dash. I will hopefully grab what sub that is also when I check the amp. But what are peoples thoughts? When the sub kicks off I checked the amp and it definitely went into a standbye type mode (power light going red) after a little while it will turn back on.

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Definitely sounds like overheating. Are you sure your gains are set correctly? I believe that will cause an amp to overheat even at a lower volume level.

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David will chime in soon. He will definitely point you in the right direction.

Well I guess I'll keep my 25 years of car audio experience to myself then and so will the rest of the guys. :whistle:

Kidding of course. Doesn't bother me because David knows his stuff even though his thoughts may be hard for some to follow or understand. There are more pro audio guys on board here than most know about. I just don't advertise it because I don't do internet sales and that's not really why I'm on board here anyway.

Stock answers:

Make sure sub is the correct impedance for the amp. That amp needs to see 4 ohms bridged (or dual 2 or dual 8 wired to 4). May need to pull the sub to verify.

Along with that make sure there are no shorts in the speaker wires up to and at the sub.

Is your gear (jackets, towels, etc.) suffocating the amp, or is there room around it for air flow?

Is the amp mounted on stand-offs so air can get behind it, or mounted directly to a carpeted board so there is no chance of cooling on the back side?

You are correct that gains should be checked and set properly, but if the amp "wasn't enough" for that sub it would just not play up to it's potential, not shut off. Other than the impedance I mentioned in the first line, of course.

After all that is checked over and verified, then it may be time to talk about fans. Until then I would try and avoid them. Just one more thing to fail or go wrong.

Edit: English.

Edited by jk13
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David knows his stuff even though his thoughts may be hard for some to follow or understand.

My bad. I know there are plenty of smart guys. He was the one that I could think of off the top of my head. And I totally agree with the quoted statement. Sometimes I have to read his responses a few times before I feel like I understand. Especially when all you start talking about the science of sound and not the implementations

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All good ideas as to what the problem could be and the actions to take. Definitely act on every one of these.

Also, make certain that there is no bass EQ active as that is a real strain on an amplifier and woofer, particularly in an open boat.

Make sure that the woofer impedance is reading at least 85% of its rated impedance. It could be in decline with a voice coil that is partially burned/shorted (and therefore shorter) but still works. This can really tax an amplifier until the coil cools down.

Make sure that the lowpass crossover to the sub is not inordinately low which causes the sub and amplifier to be worked to death. If it is very low, as a trial, try doubling the crossover frequency which will produce way more output and will force you to gain it down. See what happens.

Thermal issues are definitely compounded by low voltage. So measure the voltage at the amplifier terminals when under load within the time frame it shuts down.

Double check every termination related to the amplifier supply. Hopefully you have sufficient gauge power cable.

A fan may be in order on the hottest July/August days. But don't use it as a bandaid when core issues remain intact and unresolved.

David

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Surprised nobody suggested reviewing how the subsonic filtering is setup. If you have a vented enclosure with the SS setup wrong, it could be aiding in the "working the amp to death" as was mentioned before.

One thing that I've seen come up ALOT lately with local boats that stop by our offices for advice is, that they have miss matched gear spec wise.... meaning a 500W amp pushing a 2500W woofer. Or the opposite. It all creates issues. All of the advice in this thread is good stuff. All or none of it may apply to your situation. You might want to go by a (local to you) audio shop with these points in mind and run down the list with them. If someone pushes you to new gear, start askng "why", before you buy.

just my 2 cents.

-Brian

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Update on this, my amp is a t400.2 (i have a t400.4 for the cabin) there wasn't any clearance room behind my amp (don't know why an installer wouldn't have done this) so I'm adding spacers today, here is a picture of the gain and equalizer (somewhat tough to see), but gain is set to 9 out of 11. and the frequency is just about 125 and the punch equilizer is basically half way in between min and max. also the second picture shows the entire back, the wires were connected into the far left and far right "Speakers" section so i'm assuming that line means that it's bridged if that is important. Anyway, let me know if that 9/11 gain is too high, meanwhile I'll be adding spacers to both my amps today.

http://i1295.photobucket.com/albums/b631/coryjpeterson1/2013-07-13140955_zps1a465f58.jpg

http://i1295.photobucket.com/albums/b631/coryjpeterson1/2013-07-13141009_zps8f84f217.jpg

Edited by saskicker32
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The amplifier appears to be set to LP (lowpass) which is correct.

The bass EQ should be completely at zero (Off). Why? Because you are already having issues and this particular type of equalization is especially hard on your amplifier and woofer. It takes four times the woofer excursion and four times the amplifier power to produce one octave of lower bass at the same amplitude. And the EQ center frequency is probably around 45 Hz which is below the real meat of the bass (50 to 80 Hz). On a slightly separate note, even a modest 6 dB bass boost requires four times the woofer excursion and four times the amplifier power. Compound that with the difficulty of producing frequencies that low, as previously stated, and you are really taxing your amplifier and subwoofer. Okay in an enclosed vehicle cabin. An impossibly uphill battle in an open boat.

The lowpass frequency is probably at bit high but your amplifier and woofer does not have to work as hard when it is covering more upper bandwidth. A little higher frequency will provide the perception of more output which allows you to gain the amplifier down a bit. 125 Hz is as high as you would want to go. Make sure the 4-channel amplifier is set symmetrically on the HP.

Hopefully your sub enclosure is in good shape and well sealed. A failed enclosure can cause over-working issues.

Make sure you have no boost or equalization anywhere else in the system including HU or EQ. You can have a lot of volume OR a lot of low bass equaliztion....but not both.

Go back to all the previous suggestions and checklists starting with those from jk13 and followed by me. Every one of them.

David

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David thank you for the response, I am a little confused on your comments (sorry you are dealing with an audio idiot)

-Does my amp have a bass eq? (there is only the punch eq)

-Is the EQ center the Punch EQ? (so your saying that should be turned up a little? Like 3/4?) (and this will allow me to turn my gain down)

-I will set my frequency to 125 exactly

My sub seems to be sealed and in good condition. Once again thank you so much for the response.

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David thank you for the response, I am a little confused on your comments (sorry you are dealing with an audio idiot)

-Does my amp have a bass eq? (there is only the punch eq)

-Is the EQ center the Punch EQ? (so your saying that should be turned up a little? Like 3/4?) (and this will allow me to turn my gain down)

-I will set my frequency to 125 exactly

My sub seems to be sealed and in good condition. Once again thank you so much for the response.

Okay, your amplifier has a 'Punch EQ' dial with a 'minimum' to 'maximum' setting. Rotate the setting counterclockwise to 'MIN', which is 'Off'.

David

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Perfect, that's the clarification I needed, so Punch EQ set to off, Frequency set to 125, and gain I'll drop to 7 from 9 out of 11

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Also I just pulled the sub, everything looks solid down there, the sub is a rockford punch p3D212, is that t400.2 enough to push that sub like it should? I see the rms for the sub is 500, is 400 watts close enough?

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Also I just pulled the sub, everything looks solid down there, the sub is a rockford punch p3D212, is that t400.2 enough to push that sub like it should? I see the rms for the sub is 500, is 400 watts close enough?

With a dual 2-ohm voice coil sub you need to be wired either 2-ohm stereo or 4-ohm seriesed and bridged. The power is equal. Just make sure you are not paralleled and bridged.

That amplifier should be just enough. In pure amplitude terms what you are missing out on is barely audible. It never hurts to go to the top of a woofer's thermal or RMS power rating, especially in an open boat environment.

Woofers with longer excursions will ultimately produce more output, but only with additional power. Woofers with larger voice coils will handle more power. However, both upgrades may reduce a speaker's base responsiveness/sensitivity and add more moving mass to control, thus the need for more power in reaching the speaker's potential.

So at some point you can dedicate your four-channel amplifier to the in-boat coaxials, move your two-channel to the tower and get a larger subwoofer amplifier. Look at something that will produce an honest 600 watts into a 4-ohm load. In a monoblock amplifier it might be a 1000 watt model as rated into 2-ohms. This will mean additional supply/ground cabling too and places more need for a stable voltage supply. There is always a domino falling somewhere else in every upgrade.

No one but you can estimate how hard you drive your existing system, what level of clipping you tolerate, and what your expectations are.

David

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I was reading up on the dual 2 ohm voice coil last night after I pulled the sub. Once again thank you so much David, you have been unbelievably helpful.

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