Why does my amp run hot?

chipper · 23rd April 2009, 06:08 AM

I have a kicker ZR240 (i replaced my old one that blew) anyways it runs pretty hot after awhile of play time. I'm using it on some 6x9 speakers in the back with the proper impedence crossovers connected to them and i've checked and checked all the wiring everything seems good. It just gets hot even with 4 ohm stereo. Could the amp be bad?

Perry Babin · 23rd April 2009, 08:28 AM

What are you using for crossovers?

Does the amp heat up if you power it up and let it idle (no audio output)?

chipper · 23rd April 2009, 10:40 PM

Quote:

Originally posted by Perry Babin
What are you using for crossovers?

Does the amp heat up if you power it up and let it idle (no audio output)?

I'm using kicker reslution impedence crossovers

Yes it does get very warm with no music playing.

The thing is i don't understand the previous ZR240 i had did the same thing??

I also had read reviews that these were "know for running hot".

Perry Babin · 23rd April 2009, 10:43 PM

If it's getting hot with no audio, the bias may be set too high.

Disconnect the speaker wires from the amp. If it still heats up, the bias is very likely too high and needs to be adjusted.

chipper · 24th April 2009, 12:44 AM

Quote:

Originally posted by Perry Babin
If it's getting hot with no audio, the bias may be set too high.

Disconnect the speaker wires from the amp. If it still heats up, the bias is very likely too high and needs to be adjusted.

What is the bias? I don't see no other adjustable control besides the gain.

Perry Babin · 24th April 2009, 12:47 AM

Did the amp heat up with no speaker wires connected to the speaker terminals?

chipper · 24th April 2009, 01:08 AM

Quote:

Originally posted by Perry Babin
Did the amp heat up with no speaker wires connected to the speaker terminals?

On idle? Yes it did.

Perry Babin · 24th April 2009, 07:55 AM

To check the bias/idle current, you'll need to measure the DC voltage across the emitter resistors (large resistors with red, red, silver, gold bands). It should be near 0.001v at idle.

What do you have on the side of the amp with the transistors marked Q14/Q16?

On the side with Q30/Q32?

I'd recommend that you replace the two 30 amp fuses with a single 10 amp fuse. This will help protect the amp if you make a mistake (probes slipping...).

Westerp · 24th April 2009, 08:35 AM

Just stop worrying and read some reviews online.

These cheap and under dimensioned amps get hot period.
Something which says 60+60 watt on the box might
be able to supply around 20+20 real watts and when
you connect 4 ohm speakers you can only expect it to
heat up and prolly distort as well

I Am An Idiot · 24th April 2009, 10:11 AM

I could have sworn his amp was heating up WITHOUT a speaker connected to it. I too vote for a bias problem.

23rd April 2009, 06:08 AM	#1
chipper diyAudio Member Join Date: Oct 2008	Why does my amp run hot? I have a kicker ZR240 (i replaced my old one that blew) anyways it runs pretty hot after awhile of play time. I'm using it on some 6x9 speakers in the back with the proper impedence crossovers connected to them and i've checked and checked all the wiring everything seems good. It just gets hot even with 4 ohm stereo. Could the amp be bad? __________________ Feel the PUNCH

23rd April 2009, 08:28 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What are you using for crossovers? Does the amp heat up if you power it up and let it idle (no audio output)? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd April 2009, 10:43 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If it's getting hot with no audio, the bias may be set too high. Disconnect the speaker wires from the amp. If it still heats up, the bias is very likely too high and needs to be adjusted. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th April 2009, 12:47 AM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Did the amp heat up with no speaker wires connected to the speaker terminals? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th April 2009, 07:55 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	To check the bias/idle current, you'll need to measure the DC voltage across the emitter resistors (large resistors with red, red, silver, gold bands). It should be near 0.001v at idle. What do you have on the side of the amp with the transistors marked Q14/Q16? On the side with Q30/Q32? I'd recommend that you replace the two 30 amp fuses with a single 10 amp fuse. This will help protect the amp if you make a mistake (probes slipping...). __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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24th April 2009, 08:35 AM	#9
Westerp diyAudio Member Join Date: Jan 2006 Location: Amsterdam	Just stop worrying and read some reviews online. These cheap and under dimensioned amps get hot period. Something which says 60+60 watt on the box might be able to supply around 20+20 real watts and when you connect 4 ohm speakers you can only expect it to heat up and prolly distort as well __________________ http://tda1541a.com The Final List

24th April 2009, 10:11 AM	#10
I Am An Idiot diyAudio Member Join Date: Mar 2007	I could have sworn his amp was heating up WITHOUT a speaker connected to it. I too vote for a bias problem. __________________ If it ain't broke Don't fix it

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