Printer Friendly Forum Posts - KAC 9152D amp goes into protect

I purchased a KAC 9152D MONO amp recently and when I hook it up and play it for awhile the amp goes into protect. why?

Amp runs 900 RMS @2 ohm and I have a pair of 4 ohm SVC subs that run 300 RMS/600 PEAK. I shouldn't be overloading the amp with these subs would I?

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

depends on if you are driving the amp past its limits or a simple connection issue. This is typically caused by heat.

check these things:

is it hooked up via rca?
how is the gain set?
do you have a good ground?

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@ 900 RMS i would think the amp would never go past its limits since I only have 2 300 RMS subs hooked to it...

RCA check

Gain set low....BUT I have this part from PAC audio that jacks between the RCA's of my headunit and AMP to give +- 8 DB gain on the RCA's even if I have the gain on the amp low and the PAC part set to 0 DB boost it still does it when I use the AMP's remote bass boost, I don't have to turn it all the way up...

Ground is a check too

I also have a 2 Farad Cap hooked into it too if that matters...

I had an American Bass SQ540 Amp that wouldn't play as loud but it NEVER went into protect...

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

And another thing... the Kenwood isn't nearly as hot as the SQ540 would get...

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

05z71crew wrote:

@ 900 RMS i would think the amp would never go past its limits since I only have 2 300 RMS subs hooked to it...

Amplifiers and speakers just don't work that way. If they did, then by the same reasoning a 911 Turbo that is capable of speeds over 170 mph would only do 85 if you put a set of tires on it that are only rated up to speeds of 85 mph. (I'll let everyone else have fun with this analogy) The amplifier will produce the same output into a given impedance regardless of what the speakers are rated to handle. Have a peek at the sticky topics here: https://www.the12volt.com/installbay/forum_topics.asp?fid=2

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posted_image

the12volt • Support the12volt.com

But overpowering the subs wouldn't put the amp into protect would it? Wouldn't the subs just start distorting and stuff as if about to blow?

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

Does the amp stay off or does it just shut off for 30 seconds or so and then kick back on? I have the same amp and when I push it hard it will cut out so that it doesn't overheat. Although I'm running mine at 1 ohm with a much more power hungry speaker (DD 9512F). I installed a few fans in my amp rack which helps prevent this from happening quite so often..

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2 x DD9515f's, Digital Designs Z1 amplifier

It turns off and then kicks back on....but the amp isn't really hot....

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

Remove the PAC part as you shouldn't need it anyway. Search this forum for 'gain' and follow the procedures. You will be using test tones to find clipping levels on both the head unit and the amplifier. When that is all done, see what the amp does during play time...if it still continues to kick off and then back on you should suspect a defective amplifier.

Point is: when you describe how you set gain as "gain set low", that is an indication that you didn't set it properly.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

I set it low so I could adjust the gain using the PAC part without reaching maximum amp power at low volumes....

It only plays for about twenty minutes first turned on and them maybe two between cut outs...

I noticed the amp manual was a little dingy when I opened the package...like the unit had been used before but everything else seemed new...

To use The12volt's analogy.....the tires may be rated @ 85 and if you go past that you will certainly blow the tires before the engine, Right? So I would start killing the speakers way before the amp.... I think.. :-)

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

stevdart wrote:

When that is all done, see what the amp does during play time...if it still continues to kick off and then back on you should suspect a defective amplifier.

I have been adjusting gain, boost and volume control and it still cuts out when the speakers are driven clean, no audible pops, distortion or bottoming out... It sounds real good all the way up until I get nothing

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

05z71crew wrote:

To use The12volt's analogy.....the tires may be rated @ 85 and if you go past that you will certainly blow the tires before the engine, Right? So I would start killing the speakers way before the amp.... I think.. :-)

While that may be possible, the more likely scenario is the tires would cause you to lose control of the car before they ever blow out. The engine, transmission, suspension, tires, etc. all work together as a system and any one of them could be damaged if not the entire vehicle (system). The point of my analogy is the amplifier will continue to produce the same amount of power regardless of what the speakers are rated to handle just as the car will still go faster than the tires are rated to go.

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posted_image

the12volt • Support the12volt.com

If the amplifier is not clipping when it shuts down, the first thing I would suspect is a poor connection with either the ground or power, however I would not rule out the PAC line amplifier you have as the culprit either. After you verify your power and ground connections and have also verified that you have sufficient operating current at the amplifier when it cuts out, do as stevdart suggested and remove the PAC piece to eliminate it as the cause of your problem. If all else is good and you have set the gain properly and killed the bass boost all together and it still cuts out, then I would suspect a bad amplifier.

One other possible scenario is the woofers are presenting a lower imepdance at certain frequencies to the amplifier than amplifier can handle. To understand this you need to know that impedance is relative to frequency and just because a speaker has a 4 ohm nominal impedance does not mean the speaker maintains a 4 ohm impedance at all frequencies. So, one last thing to try if everything else has failed to reslove your problem is wiring one woofer to each channel of the amplifier instead of both to it's bridged outputs.

EDIT - Just realized you have a mono amplifier, so the best you could do with presenting the amplifier with a higher impedance from the woofers you have would be to wire them in series instead of parallel.

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posted_image

the12volt • Support the12volt.com

It is a MONO block amp with two pairs of speaker terminals. Would the gain being set too high clip the amp? I would think it would just reach max power faster.

I know my ground and power are good... they work fine for the Cap. I also have a PAC OEM interface part for turning the class II data bus signal into a usable audio signal. Would that have anything to do with my problem.

Everything worked fine for my previous amplifier...

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

ok, I have had this exact same thing happen three times with these exact amps, putting fans doesnt help, I think that these amps just shut off when it gets barely below 12 volts, Thats what mine does eeeevery time, no matter how hot it is, maybe that doesnt make sense, but thats the only way i can explain them, but every single kac-9152d (according to my experiences.) does it. try taking a volt meter and checking what voltage you hit before it shuts off, and it may not even show below 12 because it only has to barely drop below, so youre volt meter may not pick it up, ive tried everything on this forum, nothing helps, i put two fully charge optima redtop batts and it worked... till i ran out of charge (due to the no ho alt., but its coming soon) Thats just my 2 cents

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I @m a B@D []D.[].[]\/[].[]D

It plays fine with the engine off though. Of course I don't turn it up but without the Alt charging the battery the volts would drop below twelve quite fast.

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

by the way, im running two 10" l5 dual 4 ohm voice coils, producing a 1 ohm load ( i think...) Running it at 900 watts seriously drains some amps, it seems like this is always the case too, with both of my batts charged my headlights still dim like crazy, but its worth it for the 2 min. of showing off posted_image

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I @m a B@D []D.[].[]\/[].[]D

well if you crank it im sure theyll shut off, cause mine sure does

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I @m a B@D []D.[].[]\/[].[]D

I also side with a bad ground and or a overdriven input stage of the amp caused by the PAC interface. Sell me on what you believe is a good ground, then we can discuss whether it is good or not.

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Top Secret, I can tell you but then my wife will kill me.

I took the stud that the jack handle is attached to (behind the rear seat) and bolted the ground to that...it is welded to the chassis.

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

Is it possible to send too much gain to the amplifier? And if that is the case wouldn't turning the knob on the PAC part to zero set the gain as if the part wasn't there? The amp still cuts out when the PAC part is at zero and the amp's remote is turned up about halfway.

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lil nicky
06 Elantra (No more z71)
2 12" powerbass subs; 6x9's and 5 1/4's
Kenwood KAC-9152D
American bass SQ540

Bad ground, after reading how you grounded it, I would look at it even closer. Do not assume that a bolt is a good ground. Read the "What is a proper ground" sticky for further info.

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Top Secret, I can tell you but then my wife will kill me.

But even with a bad ground.. the symptoms would make me think that is not the only problem. With the amp working for 20 minutes and then cutting in and out every few minutes after that I would think that either the amp was overheating or the power supply was being depleted to drop below 12volts. Maybe the combination of a not-so-great ground and insufficient power would make the voltage drop lower/faster. Have you upgraded the big 3?

On another note, how good is your remote turn-on line to the amp? Are you running any other devices off this remote wire and are your connections good? I used to run too many fans and lights off this line without a relay. With everything turned on it would drop below 10 volts and all the amps would shut down.

Either way, I would change your ground and check the voltage at high volumes on the main power and on the remote line. And you might as well check the impedance theory by simply unplugging one of the speakers.

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2 x DD9515f's, Digital Designs Z1 amplifier