alpine pdx 5 running hot, not sure why

Completed a new build recently, but the PDX-5 installed is running really warm, almost too hot to touch. It is mounted in the same spot as my previous class D amp (Eclipse XA1000) and that one ran COLD. The PDX-5 will be this warm even at 50% volume.

Connections are: 6ch rca from Eclipse CD7200, 4ga. power and 8ga. ground (4ft). The 4 channels are bi-amped for a 2-way component set, and sent to the passive crossovers in bi-amp mode. Speakers are Morel Hybrid Ovation (yay!). The sub channel is wired to a 4ohm Infinity woofer that was powered by the forementioned Eclipse amp.

Pots and switches are: full pass on all crossovers, all gains at minimum including the sub channel. All channels checked with oscilloscope for clipping, there is absolutely none.

This is my first time using passive crossovers in a system. Are there considerations I am overlooking? Wiring diagram for the crossovers is in the installation manual.



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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

Forgot to mention, will be out of town for a week.

Thanks in advance for your help!

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

Does it heat up if it is turned on and the volume is at Zero?  Leave it like that for about 10 minutes.  If it is heating up in that state, do not leave it on for the 10 minutes. 

I am not familiar with those speakers, but is there a trace or jumper that needs to be cut to use the crossovers in Bi-Amp mode? 

What is the frequency range of the amp's internal crossover?  Does your radio have a high pass crossover for the front channel?

If it does not heat up with no volume, there is either a problem with one or more channels of the amp or a broblem with one or more speaker/crossovers.  To find your problem, Unplug the speaker plugs for the components from the amp.  Play the sub for a few minutes, does it heat up?  If no, plug the 2 channels that feed the woofers of the components.  Play it for a few minutes, does it heat up?  Plug the tweeters back in also, play it for a few minutes, does it heat up? 

If it only heats up with the components woofers and tweeters connected, I would be looking into the bi-amp jumper or switch.

Maybe you need a shorter, 4g ground...

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

As JMelton has already pointed out, it may be a good idea to use a proper size ground wire.  However I do not believe it will help the problem at hand.

Thanks for the replies, finally got around to troubleshooting. The amp would remain cool with no channels running, but it would get hot with the left-tweeter channel running. This was the first one I tested, lucky me.

Long story short, my crossover network is has a selectable slope of either 6db/octave or 12db/octave. I only knew the 12db filter has a shorting inductor on the tweeter channel after reading this excellent page (https://www.audioholics.com/education/loudspeaker-basics/crossover) detailing crossover designs. So instead of running the bi-amp compatible crossover network at a 12db slope, I run it in 6db slope and everything is fine.

So to answer my initial question, yeah, there is something special about a bi-amp capable crossover network. A 2nd-order, or 12db/octave, crossover has (among other things) a shorting inductor in the tweeter signal path. This will effectively short the amp's output at lower frequencies, resulting in a larger separation between tweeter and midrange frequencies, but also excess heat in my case.

I wonder why it's not mentioned in the installation manual, or more of common sense for installation of active systems?

Perhaps because most people don't run a passive crossover network, and use the active crossovers on their head units? I decided for the other way around to protect the tweeters should anything happen to the settings on the heat unit by accident.

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

Thanks for getting back to us and letting us know what you found out.  Glad you were able to figure it out.

It'll run hot. My PDX1.1000 is so hot I can't touch it. Seriously. I run it at 4 ohms, and I hardly EVER beat on it. The two PDX4.150s run really warm (all eight channels at 4 ohms), but not NEARLY as hot as the 1000.

Besides that, those are poorly designed crossovers if the parallel inductor is not placed electrically AFTER the series capacitor. It shouldn't EVER go before the cap, electrically speaking. What you are describing is EXACTLY what will happen.

BTW... It's not a "shorting inductor". I checked the page you listed, and much of their terminology is FAR off base. It's a 6dB low-pass filter. When cascaded on a 6dB high-pass filter (a series wired capacitor) it is additive, creating a 12dB slope. Once the high-pass cap comes into play, there is VERY LITTLE of the signal that is actually "shorted" across the amplifier terminals. (And an inductor returns all of it's "absorbed" energy to the circuit anyhow - there really isn't ANYTHING "shorted".) If the device is of the improper value, it could certainly cause issues, but a properly selected and implemented 12dB crossover puts NO MORE LOAD ON AN AMPLIFIER than any decent 6dB crossover.

What's that tell you? It tells me that you might want to reconsider your crossover manufacturer. I know they came with the speakers, but it sounds like some kind of QC got missed, somewhere. I would disassemble the boxes, and check for solder bridges or open or cold solder joints.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

My PDX4.100 gets a lot warmer than I thought it would.

You wouldn't think they would get so hot considering that they have "ICE Power" technology (ice does mean 'cold', right? LoL).

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

haemphyst:

This makes sense. I'm not sure when I'll get the time, but it's worth a look at the crossover to both check the connections and the circuit itself. For a 2-way system and network from a highly reputable brand that has such a high street price, I find it hard to believe the design is to blame. I'll poke around some more and keep learning, I feel there is something I'm overlooking.

-J

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.