Amp Getting Hot & Turning Off

[philwsailz]

Sounds like you are wired properly, so I would do the spacers, check your crossovers to make sure they are on, and check the bass boost to see how much you can turn it down on the sub. You say you have it half-way up on the amp, and to me that is really too much.

Bass boost can be a real killer, a heat generator. Basically it pushes the sub harder in a narrow range of frequencies to try to make up for lack of respose from the sub. Extreme use of bass boost really points to problems elsewhere with the subwoofer part of your system, a need for a different woofer, need for an enclosure, need for more woofers etc...

Try to grasp this analogy: Bass boost is like nitrous on a little motor. When used sparingly, you can get performance exceeding design, briefly, but if you run nitrous hard, or all the time, you will blow something up. You can get the same performance by swapping out your little nitrous-shot motor with a big-block V8 that will perform like the little motor, but do so all the time, all day.... Think of the motor in this analogy as the woofer, AND maybe an enclosure. Something might need to change with your woofer and/or woofer installation so that it works more like the big-block V8.

You may be looking for performance from the woofer that exceeds its designed capabilities. You might want to look into a different woofer while adding an enclosure. You also might look at your current installation to see if it can be improved on. Are there are any paths for the sound from the backside of the woofer to get out into the listening area? The MTX woofer you are using is a "free-air" woofer, so I assume you have it mounted on a baffle somewhere. Does that baffle or board go totally to all walls next to it, or are there openings? Any hole, or baffle board that is not totally sealed around the edges will let the sound from the back of the woofer mix with the front. Taking care to ensure a proper installation, whether it be "free-air" or ina sealed or vented box will go a long way towrds creating a subwoofer setup that requires NO bass boost......

I know, it seems funny I am talking about the subwoofer and bass boost when you have amp heating issues, but trust me, if you can get the performance you are looking for, with the bass boost lower or even off, you will have an amp that runs a lot cooler and will shut down way less, or not at all. Tell us about the sub install, how it is mounted, where, holes, etc...

Phil
Kicker

[THSEADOO]

Thanks for all of the replies. The sub is mounted in an enclosure under the area in front of drivers seat. The problem is it takes a lot of bass to give you the real bass feel in an open area such as a boat to be turning down the bass significantly. The MTX sub will shake the boat if you will let it. Does the bass boost control knob wired to the amp come into play on this also? Or just the controls that are actually on the amp itself?

[EarmarkMarine]

Yes, if the level control is a boost/cut for the bass EQ then turn down the EQ, raise the crossover point and reset the amplifier input gain to the desired output level. I know it doesn't appear to be much of a distinction, but, in effect what you're doing is broadening the sub's bandwidth to create more output with less current consumption, higher system operating efficiency, with an easier workload for both the amplifier and subwoofer. This way you're truely impacting the thermal stability rather than using a fan as a band-aid. Then add a fan if necessary.

David
Earmark Marine

[philwsailz]

Thanks for all of the replies. The sub is mounted in an enclosure under the area in front of drivers seat. The problem is it takes a lot of bass to give you the real bass feel in an open area such as a boat to be turning down the bass significantly. The MTX sub will shake the boat if you will let it. Does the bass boost control knob wired to the amp come into play on this also? Or just the controls that are actually on the amp itself?

The remote bass controller on that amp is a gain or level control device. It turns the sub's overall volume up and down. The knob on the amp is an EQ-modifying boost, specifically around a narrow band of frequencies centerd at 45 Hz. The BASS BOOST knob on he amp is the thing we are asking you to turn down.

David at Earmark is right. If you open the subwoofer section crossover, specifically to a higher frequency, and turn the boost knob, (on the amp) down you will be asking less of the amp thermally. You will still get a lot of bass sound, just not that enegery-wasting 45Hz material...


Phil
Kicker

[THSEADOO]

Thanks for all the help on this. This past weekend I put in 1.5" spacers and turned the cross-over up and bass control on the amp down. I think this helped as it did not cut off any. I would like to test another weekend although as we were not able to get out as much. Thanks again for the help.

[EarmarkMarine]

Seadoo,
It would appear those things did make a difference. Hopefully its enough to be a permanent fix.
Consider this: The few adjustments that wil dramatically alter the thermal stability have also increased system efficiency resulting in more dynamic headroom (contrast and clarity). What would the system sound like if your system selection and execution focused on maximizing efficiency every step of the way ?

David
Earmark Marine