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Post subject: Passport 250 Keeps Overheating...
Posted: Sat Nov 07, 2015 4:22 pm
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Joined: Sat Nov 07, 2015 4:00 pm
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This system is magnificent, however lately it overheats at about 10 minutes of use. I've tried lowering levels, lowering volume, attaching different speakers, but nothing makes a difference. I suspect the problem is in the output speaker jacks, the jacks don't grip the posts very tightly. I'd like to bypass the jacks and wire the speakers directly to the output of the amp (bypassing the jacks). I disassembled the unit but I can't tell for sure which are the hot speaker wires. Any advice would be groovy 'n all...


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Post subject: Re: Passport 250 Keeps Overheating...
Posted: Sun Nov 08, 2015 6:22 am
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Joined: Fri Feb 05, 2010 4:31 am
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Location: Province de Québec, Canada
Hot speaker wire is connected to the tip of the jack / plug .

Show us photos from inside your amp , speaker jacks


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Post subject: Re: Passport 250 Keeps Overheating...
Posted: Mon Nov 09, 2015 7:58 am
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Aspiring Musician
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First, make sure you are using the original speakers that came with the unit, or an equivalent. Trying different speakers might not be a good thing. These speakers were designed to go with this power amp.

Next, consider that each input channel has a "microphone preamplifier", often called a "mic pre-amp" or just "pre-amp". The volume level of that pre-amp is set with the small volume knob at the top of each channel.

The mixer combines the signals from these pre-amps and sends them to the power amplifier. The volume level for the power amp is controlled by the large volume knob on the mixer.

The thing that's overheating is the power amp, not the pre-amps.

So, maybe you are overworking the power amp by having the volume levels of the pre-amps set too low. Maybe the small signals are too small, overworking the power amp.

Try setting the individual channel levels louder so you can run the overall power amp at a lower volume. Let the pre-amps do more of the work so the power amp doesn't have to work so hard.

In an ideal world, you'd make the pre-amps as loud as possible -- just a little quieter than the level which "clips", creating an ugly noise. In the higher-powered Passports, each channel gets a lit dot above it that is black when there's no signal, green when there is a signal, amber when the signal is getting loud, and red when it is so loud that it clips. On those systems, you set the pre-amp volume so the dot is green and flickers amber during the loud parts, but you don't want it to turn red. On the 250, you don't get a dot, so you have to trust your ears.

Anyway, start out with the overall volume set low and the individual channels as loud as possible without making distortion noises, then ease the main volume up to as loud as you need the system to be. That's less likely to overheat the power amp than having the mic pre-amps set low and overcompensating with too high a volume setting for the main volume.

Also, hey, the 250 is old. Maybe it's dying.

In any case, I doubt that hard-wiring the speakers is going to make the difference. Try the volume settings again with a priority on high-volume individual channels and low volume overall and see if that helps.


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