myth or not

[VWBobby 10+ year member]

Definitely amp dependent. I have seen some amps that will run hot enough to almost burn your hand, but not fail (old Lanzar, Orion, SoundStream). I've seen other amps that barely get warm to the touch and fail (Kenwood Excelon).

If the amp is mounted flat, chances are it will dissipate heat better than mounting it on it side or vertically. Most heat sinks are designed to radiate the heat away from the amp upwards (heat rises) away from the board. Not along the board (mounting it anyway but flat).

Load (speaker impedance) is a definite factor in amp heat! Heat is a byproduct of power consumption. The more power it takes to drive the speaker, the hotter the amp will run. Thus, some amps have a high current or high power switch on the bottom (SoundStream). Other amps can switch automatically depending on load (Alpine).

Most amps are more efficient (run cooler) at 4 ohms, compared to 1 ohm or lower.

Why all the talk about heat before even mentioning vibration? Vibration will cause damage to the amp, if the amp is running hot enough or heat cycled enough while experiencing vibration. Example: Cold morning - 32F, start bassing at full power and heat up the amp quickly. Expansion and contraction kills electronics, just like any other material.

It likely wouldn't be a solder joint failing as much as a physical failure of one of the transformers (coil packs) getting knocked loose. The mosfets and other components that depend on the heat sink or other mounting points could be damaged also during extreme vibration and heat conditions.

If you want to run your amp mounted to the box, it would be best to mount it flat (fins facing up) or run lower load or an amp that can put out more power than you need (headroom) to keep the heat down. Keeping the heat down will help prevent vibration from damaging your amp. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[Spooney 10+ year member]

Vibration is the second most common reason for amp failure IMO right after abuse. These bigger class D amps and even some of the smaller ones don't always have the board properly supported in the heatsink(even in some quality amplifiers) . I myself used to mount my amps to the sub box for years until I started to get into amp repair. When the board isn't properly supported there is a lot of stress on the legs of the fets ,rectifiers, and any other heatsink mounted component. I've seen way too many amps fail for nothing more than a snapped leg on a single fet or rectifier causing 100's in damage in some cases. Don't do it if you don't have to

 

[hispls 5,000+ posts]

Not saying you can't mount your amp to your box because it will get damaged, but just increases the probability of something happening. I never heard the part about the wiring down to 1 ohm, but when an amp is wired lower, it does work harder creating more heat, so it kind of makes sense to me.

^^^ this

From what I'm told by guys in the repair business some amps are more prone than others to being damaged by vibration as well, and yes, lower impedence operation is MUCH more stressful on your equipment.

 

[outsideshot23 10+ year member]

sounds like an idiot.. you can run the jbl 5000 or w/e it is at 4 ohms and do 8k watts.. some amps at 1 ohm might only do 600 watts and its not going to rattle ****.. some do vent through the bottom and i could see it getting slightly hotter but thats what heatsinks are for... there is some truth to it but someof it sound like him being an idiot

 

[502CEC 10+ year member]

It really looks like I have nowhere else to mount the amps where they will stay cool. So let me ask this, what if I come off the back of my box and make a false back for my amp rack to be mounted to the box, my amps will have an inch or so of dead space between the board the amps will be on and the box. Also was gonna try real thick rubber under the amp to help with vibration. Do you all think it would be best to put rubber only under the corners or a whole piece under the whole amp? And do you all think the false back will help any at all???

 

[Pataforce8 10+ year member]

It really looks like I have nowhere else to mount the amps where they will stay cool. So let me ask this, what if I come off the back of my box and make a false back for my amp rack to be mounted to the box, my amps will have an inch or so of dead space between the board the amps will be on and the box. Also was gonna try real thick rubber under the amp to help with vibration. Do you all think it would be best to put rubber only under the corners or a whole piece under the whole amp? And do you all think the false back will help any at all???

Not sure I understand the false back, but I personally would only do a piece of rubber at each corner. You'll have to mount it like a bushing though, where the amp mounting hardware does not directly touch the box. If you simply place the rubber between the amp and the box, and then screw through the rubber into the box, it's only a little better than just mounting the amp to the box.

 

[VWBobby 10+ year member]

Most amp manuals say to give several inches of air space around the amp for proper cooling. One smart trend I've seen lately is people will mount the amp under the box and make wood blocks to space the box up about 3 inches above the amp. That way the amp is out of sight, out of mind (theft) and solves the vibration/location problems. Otherwise you can mount it to your back seat back and move your box back a few inches.

 

[bgowdy 5,000+ posts]

I Wouldnt recommend that. i always like mounting mine on the back of my seat

 

[Wingman0121 10+ year member]

You can add some rubber feet/grommet between the amp and the mounting screw so it'll dampen the vibration.

I don't ever mount my amps on a box though, usually either behind the backseat or make a false floor in the trunk.

 

[smgreen20 10+ year member]

I say, plausible. But I feel it's a myth. Think about it, the sub box is to be firmly mounted in place therefor vibrating the whole vehicle, plus road vibrations. The amps are built with this in mind. Tell me, when the bass hits, do you not feel it? The amp is seeing almost as much vibration not on the box as it would on the box.

 

[i2ain2thunder 10+ year member]

If you have the option to mount it anywhere else that would be better....I mount all my amps to my boxes. Never had a single problem ever, never mest up a mosfet or rattled anything loose on the board. My boxes don't flex much though IDK. If you have other locations to mount it go for it if not don't worry too much.

 

[Tone415 10+ year member]

I could see that happening with a hifionics amp

Have you owned a hifonics amp?