I just recently installed Alpine Type R coaxial 6.5, 100 RMS speakers for the doors, a Sony HU, an Alpine 70X4 amp and an Alpine Type E (250 RMS) 10" sub. The gain is set to about 75 percent for both speakers & sub, with crossover set to 250hz for speakers & sub. The 3 & 4 terminals on amp are bridged going to the sub. It is a nice setup and I love the sound and is loud enough for me. However, if I have the music on for about an hour at about 80% volume, the amp overheats and cuts in and out. It is mostly the sub that is causing the overheating I think as it is drawing 200 watts RMS in bridged mode. Question is, anyone else having similar problems or know of a solution aside from getting a more powerful amp or a separate sub amp, something I want to avoid if at all possible for budget & space concerns.

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So, this thread is being updated with pics of the Fan Mod that a couple of my friends John, Vinny and I did over the weekend to solve the heat issue. John gets all of the credit for the engineering, wiring and electricals. Vinny gets props for some kickass ideas, feedback and picking the right parts. I played the part of Steve Jobs, making sure everything was done professionally, making sure the fit and finish was there.

As most who's seen this long thread would remember, the amp would cut in/out after about 1 to 2 hours of playing on near max vol (80% of volume) and run oven hot, esp with songs that have a lot of bass. After the fan mod, I gave it a test run and turned the vol up even higher than before (%90+) and left it on for close to 4 hours with no cutting in/out, no more going into protection mode. The 5 computer fans right next to each other in an inline position really moved a lot of air over the top keeping the amp cool. On max volume (almost deafening) for about 4 hours, the amp was hot still, but not as hot as before and it never went into overheat protection mode like it used to at only about 2 hours.

In case anyone is having the same issue, and wants to do a similar mod, we used an aluminum 90 degree bracket, using an aluminum cutter, cut a rectangular hole on the top part and mounted five 60mm PC fans inline. Attached a relay and then hooked it up to the amp so that the remote signal to turn on the amp also activated the relay and turned on the fans. We tapped the amp's power to power the 12 volt pc fans. All the wiring went behind the board. If anyone has any questions, let me know.

 

Where is the amp installed & do you have any fans installed?

 

amp is installed on a board to the left side of the spare tire. Do not have a fan installed, didn't think it was necessary? If necessary, how would one go about doing the mod?

 

Are you sure the loading is correct for the wiring to the sub? If it is a DVC 4-ohm or an SVC 2-ohm sub, it cannot be wired to this amp. Are you sure its "overheating" and not clipping to entering protect mode for another reason? As long as there is clear space around the amp (only a few inches needed), it should have internal fans / heat sink to control temp issues.

John

 

That sub is SVC, so that is out. It sounds like what the above said with either clipping or overheating. What size power cable was run to the amp?

 

Question - why would a svc 2 ohm sub not work if the amp is 2 ohm stable (isn't the mrp-450 2 ohm stable?)? Thanks!

 

same issue here... but i live in san antonio, tx where temp avg 90F. but no prob at night time when its cool.

 

when you say the amp is installed to the "left of the spare" does that mean
in the main part of the trunk vertically against the back wall, or above the
gas tank behind the trunk liner?

 

[QUOTE=Saki GT,Jun 18 2007, 06:29 PM] Question - why would a svc 2 ohm sub not work if the amp is 2 ohm stable (isn't the mrp-450 2 ohm stable?)?

 

The Amp is mounted inside the trunk on a board attached to the wall left of the spare. If you open the trunk, you'll see it vertically on the wall. There should be plenty of airflow around it, the model is the Alpine MRP-F450 70X4 @ 4 ohms, being sold in Tweeter and Best Buy stores. I don't know the exact gauge of the wires, but they are really thick, about the same size as the wires that are used for electric guitars. To describe the issue in more detail, it would play for an hour or so at high volume fine, but then I think it goes into protection mode or something, symtoms, all of a sudden there is no sound, and about 5 to 10 secs later, the sounds comes back on for another 15 to 30 secs or so and this get repeated (is this clipping or overheating??? and what is the difference???). If I turn down the volume or the sub output on the HU, it seems fine...that is why I suspected it was the sub or just general heat issues...maybe the bridged connection drawing 200 watts from the amp to the 250 rms sub is causing the overheating? Am I just maxing out the amp by playing it near max maybe? If any local members nearby have some free time to take a look at it, I'd be willing to drive over to your place whenever it is convenient for you. I myself, have no clue about these things, other than the basics, but I just wanted to throw this out there to the community and experts to see if it is fixable or whether it is just normal.