4 Channel amp goes silent/turns off with increase in source volume - diyAudio
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Old 3rd January 2013, 01:04 AM   #1
Kalmah is offline Kalmah  United States
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Default 4 Channel amp goes silent/turns off with increase in source volume

I did a quick search through the threads and could not find my same issue, so here goes...

I recently purchased an Infinity Kappa Four (4 channel 1200watt) amp to replace a used Hifonics zeus z440 that has issues.

I just got the Kappa today and installed it. I followed every procedure you normally would in installing an amp. I removed the ground from the battery, then the positive from the battery. Got all the wires secured to the new amp.

Went to go hook back up the positive, fine...

Went to go hook back up the negative, heard a small pop. At this moment I realized exactly what I did.

Hifonics has their 12V+ power supply input on the left, remote in the middle, and ground input on the right.

Kappa had it flipped, and out of my own excitement for having a new and more powerful amp I installed them quickly and thus popped both 40 amp fuses.

I quickly undid the negative and positive off the battery, and re-hooked up everything.

Infinity provided 2 extra 40amp fuses for the amp, so I replaced those.

The amp turned on, I could hear radio, my iPod/iPhone worked through my head units auxiliary input.

Here's the issue: When you turn the volume up (by using either the head units volume or my iPhone/iPod to a medium to higher level, the amp cuts out for a few seconds then turns back on, then cuts out again if you keep it at that level.

The amp functions fine at lower listening levels, but once any kind of bass hits it just goes silent or off.

Using my head units High Pass I turned it all the way to 125 Hz so most of the music coming through was 125 Hz or above, so basically treble, the amp functioned fine and I could turn it up pretty loud.

I have the following....

- 4 gauge power, 4 gauge ground.
- Infinity Kappa 693.7i (6x9) rear (rated at 2ohms, 110W)
- Infinity Kappa 60.9cs (6 1/2" components) front w/ crossover. (also 2ohms, 90W)
- Pioneer DEH-6800MP (2.2 volt pre-out)



The instruction manual for the amp reads:
125W RMS x 4 channels @ 4 ohms
150W RMS x 4 channels @ 2 ohms
1200 watts total peak power


The setting for the amp is on full range mode, the gains are not high at all....not sure what's going on here, but there was a brief moment where it sounded awesome and I can no longer replicate that.


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Old 3rd January 2013, 01:28 AM   #2
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With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the red probe on the B+ terminal, how low does the voltage drop when the amp shuts off?
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Old 3rd January 2013, 02:43 AM   #3
Kalmah is offline Kalmah  United States
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Quote:
Originally Posted by Perry Babin View Post
With your multimeter set to DC volts, the black meter probe on the ground terminal of the amp (not on the point where the ground wire connected to the vehicle) and the red probe on the B+ terminal, how low does the voltage drop when the amp shuts off?
FYI, it was steady at 14.17 +/- 0.1 volts DC. Then i turned the music louder and louder and then I stuck the probes back on and waited.

The amp dropped off into protection mode so I'm not sure if it registered, but I did see 14 drop down to about 12, then the amp kicked back on and it went back up to 14.
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Old 3rd January 2013, 03:34 AM   #4
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Place the black probe on a KNOWN good ground but not the point where the amp is grounded.

Place the red probe on the amplifier's ground terminal.

Drive the amp to shut down. What is the highest voltage you read. You may need to do it several times to get reliable readings.
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Old 3rd January 2013, 03:38 PM   #5
Kalmah is offline Kalmah  United States
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Quote:
Originally Posted by Perry Babin View Post
Place the black probe on a KNOWN good ground but not the point where the amp is grounded.

Place the red probe on the amplifier's ground terminal.

Drive the amp to shut down. What is the highest voltage you read. You may need to do it several times to get reliable readings.
the 20 volt setting registered nothing, so I went to 2 volt and got a slight reading.

ending up going to 200 mV

I would get a reading of around 6.0-6.5 mV fluctuation when the song would hit hard and loud and the amp would then shut off, the reading would steady to 2.2 mV while the amp was in protection mode, and then start giving readings in between 2.2 mV to 6.5, with 6 mV generally being the point at which the amp went into protection mode.

I'm thinking my ground is no good...
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Old 3rd January 2013, 05:10 PM   #6
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Anything in the millivolt range is OK. The problem appears to be in the B+ line (wire too small, defective fuse, bad connection, weak battery...).
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Old 5th January 2013, 06:25 AM   #7
Kalmah is offline Kalmah  United States
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Quote:
Originally Posted by Perry Babin View Post
Anything in the millivolt range is OK. The problem appears to be in the B+ line (wire too small, defective fuse, bad connection, weak battery...).
I played with the gain settings for the front and rear channels. I noticed that the front 6 1/2's can take more gain than the rear 6x9's without the amp going into protect. The rear channel's gain is not at a level that is balanced with the front, therefore I'm not getting the whole listening "experience" from inside the car.

Another thing to note is that I put my amp's front and rear channels on High Pass and set them both to about 80hz; I've done this so I get some lows and the mids and highs without the amp going into protect.

Perry,

There is more to the whole story that I forgot to mention.

I may be dealing with a short in my RCA and/or speaker wires. When I go over bumps or take hard right or left turns, everything moves to the right channels, or all front, or all rear. It was like that in the old Hifonics amp (which had channel problems anyways), but it is like that with a brand new amp, so 1 major issue lies with my head unit and/or wires.

It seems I'm gonna have to pull my car apart and inspect the RCA's and the speaker wire and run new wire if need be.

I got my battery and charging system tested yesterday. I ended up getting a new battery because I was due for one anyways, and my charging system checked out ok. As I expected, getting a new battery did not make the amps issue worse or better.
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Old 8th January 2013, 03:05 PM   #8
Kalmah is offline Kalmah  United States
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Front channels crank and sound awesome!

I do believe the culprit are one or both of my 6 x 9's and/or the wiring to them.

Rear channels gain turned up even to 1/2 (which is still not audible in car in terms of balance with the fronts) will put the amp in protect... Any ideas?

Shall I wire the rear speakers with new wire and see of that helps, and of that doesn't , switch them to front channel and see if they put the amp into protect then?
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Old 8th January 2013, 05:03 PM   #9
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Yes, connect the front speakers to the rear channels and rear speakers to the front channels. Does the shutdown problem move to the front channels?
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Old 9th January 2013, 03:55 AM   #10
Kalmah is offline Kalmah  United States
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Quote:
Originally Posted by Perry Babin View Post
Yes, connect the front speakers to the rear channels and rear speakers to the front channels. Does the shutdown problem move to the front channels?
Did this and I believe I isolated the problem to the right rear 6 x 9. I changed both the speaker cables, which were quite old and oxidized with some cheap speaker wire and the rear speakers could take a lot more before the amp went into protect.

I also had to snip the ends my 4 ga. power and ground as I had it rigged to fit a 8 ga. hole on that old Hifonics. (split the 4 gauge into 2 equal strands and peeled one away and taped it back with electrical tape.).

So now I'm truly utilizing 4 gauge for all it's worth, and I will probably be cutting and the 4 gauge power wire where it connects to it's fuse, and the battery and making a cleaner crimp as it's been about 4-5 years since that cable was installed.


Problem is a bit better now, but I'm sure i can still crank on those Kappa's a bit more.
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