# mounting amps upside down



## kizz (Jun 22, 2009)

Can anybody think of any issues that might arise from mounting my PPI phantom amps upside down? the location would be the bottom of the rear deck.


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## Hanatsu (Nov 9, 2010)

Try to avoid it if you can.

Amps can't disperse heat very good upside down.


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## Chrisw21 (Nov 28, 2011)

I've got my ARCs mounted upside down and in a small enclosure (spare tire well) with no issues. They do have built in fans, though, which may help. And I put some small spacers in to increase the air gap and ensure better flow. Where are your heat sinks on the amp? If you're really concerned, mounting some small 12v fans would be very simple, too.


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## Hanatsu (Nov 9, 2010)

Good point^^

Grab a few fans to cool them


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## reunited (Jan 22, 2012)

Mounting most amps contrary to manufacturer's recommendations is generally a very bad idea. Sure, you CAN do it but there is a very strong possibility that you will significantly shorten the life of your equipment. You place your bets, you take your chances ...

Circuit boards layout, location of heat sinks, enclosure design, reliance on chimney efffects are done in particular ways to dissipate heat (and of course to accomplish other objectives) which is a prime enemy and cause of component failure.

MTBF (Mean time between failure) calculations are done within a certain ambient temperature range assuming the equipment is installed as per the manufacturer's recommendations. I don't know of many (a single?) manufacturer who does heat soaking/cycling testing on products that are deliberately installed incorrectly. Would fans make an upside down installation acceptable? There is no way to answer this question for sure but they would probably help.
Also, the Class of amp would be a major factor as well.


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## TrickyRicky (Apr 5, 2009)

If you can keep the chassis cool then there's no real/serious problem. Now if you do it and use no cooling system and your amps get hot then you will have serious problems. The heat can go directly into the circuit board damaging several components inside. Transistors mounted on the chassis would probably go out first though.


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## fish (Jun 30, 2007)

Probably still a good idea to PM Grizz on this to get his opinion.


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## kizz (Jun 22, 2009)

thanks guys i appreciate it. they are class D so I would assume they would stay cool but i do believe the heat sink is on the top. and that is exactly why i was asking, heat goes up! I will pm grizz and get his opinion. thanks.


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## robert_wrath (Apr 24, 2011)

Bad idea in general. The internal capacitor pots DO NOT dissipate heat downward, even with the use of fans. Mounting the amp(s) upside down induces more stress in Class D rail power.


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## MarkZ (Dec 5, 2005)

robert_wrath said:


> Bad idea in general. The internal capacitor pots DO NOT dissipate heat downward, even with the use of fans. Mounting the amp(s) upside down induces more stress in Class D rail power.


Uh...what? 

kizz, I had this very debate with a guy about 12 years ago. It prompted him to go out and make temperature measurements of the amp in both orientations after playing for a certain period of time. The temps were a lot closer than I had expected. The moral of the story was 1) yes it makes a difference, but 2) the difference isn't big. I would suggest only avoiding it if you're running this amp to its temperature limits. This is unlikely to be the case with a class D amp unless it's a hunk of junk or you're doing something wrong.


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## IBcivic (Jan 6, 2009)

Myth Busted...

Now back to building my magic magnet wire RCAs


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## minbari (Mar 3, 2011)

robert_wrath said:


> Bad idea in general. The internal capacitor pots DO NOT dissipate heat downward, even with the use of fans. Mounting the amp(s) upside down induces more stress in Class D rail power.


caps dont dissipate power, so heat in caps is not likely a concern. 

mostly the issue is that heat rises. if you trap heat in the heatsinks, they will not do thier job. if you have a way to move that heat away, IE: fans, then there is no problem.


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## TrickyRicky (Apr 5, 2009)

minbari said:


> caps dont dissipate power, so heat in caps is not likely a concern.
> 
> mostly the issue is that heat rises. if you trap heat in the heatsinks, they will not do thier job. if you have a way to move that heat away, IE: fans, then there is no problem.


Okay if caps did dissipate heat then mounting them upside down is a great idea and great for caps.


To Robert Wrath
BUT I guess you never opened an amplifier upside down and notice that the caps are ABOVE the board thus making it a good idea to mount the amps upside down so the caps can be "right side up" and dissipate heat, but I forgot caps dont get hot unless something is wrong with them.


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## IBcivic (Jan 6, 2009)

With my amps, right side up...the caps are upside down....from the factory


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## TrickyRicky (Apr 5, 2009)

amitaF said:


> With my amps, right side up...the caps are upside down....from the factory


Lol, thats exactly what I was reffering too. Anyone heard of capacitor pots?


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## kizz (Jun 22, 2009)

Wow, lots of replies. So what I take from this in simple terms, is with class D the difference in heat would be negligible given that install is done correctly. But how does this differ from mounting amps sideways or under a seat where heat can still be trapped.


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## TrickyRicky (Apr 5, 2009)

kizz said:


> Wow, lots of replies. So what I take from this in simple terms, is with class D the difference in heat would be negligible given that install is done correctly.* But how does this differ from mounting amps sideways or under a seat where heat can still be trapped.*


Certain amplifiers can be mounted sideways due to the heatsink location. For example the JL slash series (that had the heatsink on the side) when mounted verticle the heatsink would be on the top side (which is best for that certain amp).

For amplifiers below seats, clearance should be kept in mind. If there is an inch or two of space it might be enought to get some air. Although there are a bunch of amplifiers out there that really never get hot, just warm.


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## Gary S (Dec 11, 2007)

Yes, heat rises, but as long as you have adequate space around the amp, mounting the amp upside down won't make much diffrence. I'd do it.


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## kizz (Jun 22, 2009)

The idea was to mount them to a baffle on the bottom of the rear deck so it will be wide open. To further aid in cooling the top side(bottom of amp) can be opened up into the cabin to further help with cooling. Just as long as im not inhibiting the amps performance or longevity due to upside mount and heat then for me that's the best place to put them.


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## Notloudenuf (Sep 14, 2008)

kizz said:


> The idea was to mount them to a baffle on the bottom of the rear deck so it will be wide open. To further aid in cooling the top side(bottom of amp) can be opened up into the cabin to further help with cooling. Just as long as im not inhibiting the amps performance or longevity due to upside mount and heat then for me that's the best place to put them.


You'll be fine. Mine have been like this over a year with no issues.


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## Chrisw21 (Nov 28, 2011)

Here's another idea...... Make or buy some stand-offs, then mount your amp "right side up", but from the top. In other words, "hang" the amp rather than mounting upside down. Just make sure you keep an air gap in there for cooling. It would work, but personally I would either do what I suggested above (fans), or just mount it upside down and not worry about it. It will be fine either way.


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## kizz (Jun 22, 2009)

Chrisw21 said:


> Here's another idea...... Make or buy some stand-offs, then mount your amp "right side up", but from the top. In other words, "hang" the amp rather than mounting upside down. Just make sure you keep an air gap in there for cooling. It would work, but personally I would either do what I suggested above (fans), or just mount it upside down and not worry about it. It will be fine either way.


I thought about "hanging" them, and that still might be an option if I can make it work with the few tools that I have.


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## Flipx99 (Jan 13, 2012)

Let me know how this works out. I am looking at the same amp with the same idea. I could have two 8s in the package tray with a completely stealth setup.


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## kizz (Jun 22, 2009)

Flipx99 said:


> Let me know how this works out. I am looking at the same amp with the same idea. I could have two 8s in the package tray with a completely stealth setup.


Will do! what car? and what 8's are you going to use?


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## JsUltimateSounds (Nov 29, 2011)

a simple fan will do the trick.


remember.... Keep it simple.


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## Morgan West (Jan 28, 2012)

I have not tested the PPI amplifier but based on the heatsink mass I saw in the pictures I wouldn't expect much for heat issues if mounted upside down. 

Class D designs are just so much more efficient compared to A/B. Especially at lower power levels. Here are some efficiency numbers on three different amplifiers recently tested. 

300w Class A/B @ 2 ohms:
1/3 Power: 36%
Full Power: 63%

300w Class D @ 2 ohms:
1/3 Power: 77%
Full Power: 79%

4200w High End Class D @ 2 ohms:
1/3 Power: 85%
Full Power: 88%

We have made amplifiers with right side up, down and vertical PCBs. If you build it right there is no difference in PCB orientation.


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## kizz (Jun 22, 2009)

Morgan West said:


> I have not tested the PPI amplifier but based on the heatsink mass I saw in the pictures I wouldn't expect much for heat issues if mounted upside down.
> 
> Class D designs are just so much more efficient compared to A/B. Especially at lower power levels. Here are some efficiency numbers on three different amplifiers recently tested.
> 
> ...


Interesting, thanks!


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## brandontw (Jan 21, 2012)

I'm planning on doing a semi-stealth install under my rear deck, with the amp mounted upside down... I think it will get plenty of airflow and be just fine.

Heres a build log started on it if your interested.


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## Flipx99 (Jan 13, 2012)

Great info


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