Kenwood Kac 8452 Amp Protect Mode Wierdness

[Birth]

I have installed a Kenwood KAC 8452 amp into my R32. I have set the amp up with no head unit and I plug my iPhone into the amp using the earphone out from my iPhone into the RCA in on the amp which has worked for me previously.

The Kenwood KAC 8452 is a four channel amp.

I recently bought the amp second hand from eBay. The seller communicated poorly during the sale however in the advertisement the seller described the unit as "This item is second hand but still in good working condition, quite a reliable model from Kenwood". For the purpose of sorting this out I am assuming I wasn't ripped off and the amp normally works.

Problem 1 - when I attach a speaker wire to the Channel A left speaker positive outlet on the amp it goes into safe mode. If I leave the Channel A left speaker unconnected the amp seems to work ok. When the amp goes into safe mode, music stops playing and the power light flickers every second or so.

Problem 2 - After getting over Problem 1; if I try to turn the volume on the iPhone up over say 60% the amp goes into safe mode. When the amp goes into safe mode, music stops playing and the power light flickers every second or so. If I turn the volume on my iPhone back down music starts playing from the amp again.

To resolve the issue I tried relocated the earth wire to a new spot. I drilled a new hole into the metal on the floor of the boot, sanded away the paint and connected the earth wire.

The wire I have used is from an amp installation kit that I bought from Supercheap Auto. The wire is 8 AWG. I did not installed the inline fuse that came with the kit. The fuse on the amp itself is not blowing obviously given that the amp gets power all the time (even if it does go into protect mode).

This is pretty frustrating and I am tired of driving around with earphones in all the time. Please help.

[Carbon 34]

I have installed a Kenwood KAC 8452 amp into my R32. I have set the amp up with no head unit and I plug my iPhone into the amp using the earphone out from my iPhone into the RCA in on the amp which has worked for me previously.

not the ideal way to use the amp , easy to distort the input

The Kenwood KAC 8452 is a four channel amp.

I recently bought the amp second hand from eBay. The seller communicated poorly during the sale however in the advertisement the seller described the unit as "This item is second hand but still in good working condition, quite a reliable model from Kenwood". For the purpose of sorting this out I am assuming I wasn't ripped off and the amp normally works.

Problem 1 - when I attach a speaker wire to the Channel A left speaker positive outlet on the amp it goes into safe mode. If I leave the Channel A left speaker unconnected the amp seems to work ok. When the amp goes into safe mode, music stops playing and the power light flickers every second or so.

Does the problem follow the channel 1 speakers , if you remove all rca ?

If you swap the left or right speakers which every is channel 1 in your wiring ? a grounded or pinched speaker wire will do that or fried voice coil creating a low ohm load ?

Problem 2 - After getting over Problem 1; if I try to turn the volume on the iPhone up over say 60% the amp goes into safe mode. When the amp goes into safe mode, music stops playing and the power light flickers every second or so. If I turn the volume on my iPhone back down music starts playing from the amp again.

Once again you need to buy a interface preamp to use not direct to iphone , audiocontrol, audison

Or a few others make one or use a deck ? Your distorting the preamp and clipping the speakers most likely and it could be related to problem 1 a fried voice coil ona speaker

To resolve the issue I tried relocated the earth wire to a new spot. I drilled a new hole into the metal on the floor of the boot, sanded away the paint and connected the earth wire.

Same 8ga wire 8 ?

What are you using for 12v turn on ? A relay or ?

The wire I have used is from an amp installation kit that I bought from Supercheap Auto. The wire is 8 AWG. I did not installed the inline fuse that came with the kit. The fuse on the amp itself is not blowing obviously given that the amp gets power all the time (even if it does go into protect mode).

Your asking for a fire the fuse goes as close as possible to the battery ( TO PROTECT THE CAR !!! Not the amp in case of a dead short ) without it the full power of your battery will melt the car like arc welder gone wild

The amp fuse only protects the amp internals nothing else

And a good clean battery positive connection ?

What exactly are you using for speakers ?

How are the speakers wired ?

Is the amp getting hot fast ?

This is pretty frustrating and I am tired of driving around with earphones in all the time. Please help.

Edited July 19, 2012 by Carbon 34

[Birth]

Carbon34 - thanks for the quick response. I'll have to confirm some of the stuff tonight / tomorrow but my thoughts so far are

Does the problem follow the channel 1 speakers , if you remove all rca? | Yes. The unit goes into protect when the Channel A / Left / Positive is connected

If you swap the left or right speakers which every is channel 1 in your wiring? | I have tried all of the speakers on Channel A / Left. It happens no matter which speaker is connected to the terminal and all of the speakers work on any of the other terminals

Once again you need to buy a interface preamp to use not direct to iphone , audiocontrol, audison | I have an iPhone cable which connects to the bottom of the iPhone (not the earphone connection) which provides a line-out via RCA. The purpose of the cable is to connect to home stereos etc. I'll try that as I gather it will have the same effect as running through a headunit etc?

Same 8ga wire 8? | Yes, the same wire is used for the earth that is used for power

What are you using for 12v turn on? A relay or? | I have spliced an accessories power source on the car

And a good clean battery positive connection? | I've checked it previously but I'll have to check again

What exactly are you using for speakers? | Pioneer 12 inch sub, Pioneer 6" 3-ways

How are the speakers wired ? | The sub is currently connected to Channel A / Right. The 6" speakers are currently connected to Channel B / Left and Right

Is the amp getting hot fast? | No

***

If I open the amp will I visually be able to see a fried voice coil creating a low ohm load?

Thanks heaps for your time and help!

[Carbon 34]

Is this the silver and black vintage amp from about 2006 ish , They have loose rca jack issues !!

Do this volume way down !!

Ok no speakers or rca plugged in, protect mode?

Yes amp is low voltage or farked , or screwed down and warped board inside

No protection mode yet

Plug in rca no speakers ? Now what ?

Protection mode pull one at a time to find the culprit short

Not protection yet

Add 6 inchers one at a time ?

Protection mode ? Yes which one , no ? stray copper hairs shorting screwdowns ? No then wire or speaker is stuffed

Still no protection mode??

What ohm load is the sub ? Two voice coils or 1? Exact model # if you dont know

One coil only your most likely at 4 or 8 ohms

All good

Hook up in bridged mode you will see the screwdowns for left positive and right negative on channel A is bridged mode for one coil of 4 or 8 ohms sub

Protection mode yet ? No ? Its sorted

Yes unplug last item to see if it cleared ?

if the sub trigger protection make sure it moves free still and inside box wires arent touching metal frame or each other ?

Do you have another source unit besides iphone ? Cd player or anything ? Someone elses car radio rca ? Anything ??

That iphone output device isnt the best and doubt it drives the amp to full output Clean ??

Bosch relay should be used not accessory splice

Or current sensing relay to know when music is on , low voltage on trigger can cause issues too

Let me know how ya go

[Birth]

Hi Troy,

I took another look tonight. First thing is I checked that the power wire is getting a good connection at the battery and its fine. With the relay, to avoid any issues, I temporarily bridged it from the positive terminal so as to avoid any question about inconsistent power from my splicing effort.

Test 1

If I unplug everything and plug in only power, earth and remote - no protect mode

If I then plug in the RCAs - no protect mode (with nothing attached to the other end of the RCA cables)

If I then plug in the RCAs - no protect mode (with with an iPhone on the other end of the RCA cables - I didn't have another source handy)

After having unplugged the iPhone but leaving the RCA cables in the amp-side

If I wire up the sub to bridged to Channel B - no protect mode

If I wire up a 6 inch (right-side of the car speaker) to Channel A / right - no protect mode

If I wire up a 6 inch (right-side of the car speaker)to Channel A / left - protect mode

Test 2

Disconnect the 6 inch (right-side of the car speaker) to Channel A / right - still in protect mode

Disconnect the 6 inch (left-side of the car speaker) to Channel A / left - comes out of protect mode

If I wire up a 6 inch (left-side of the car speaker) to Channel A / right - no protect mode

If I wire up a 6 inch (right-side of the car speaker) to Channel A / left - protect mode

Conclusion

It seems that there is something wrong with the Channel A / left circuit. No matter what speaker I connect to it, no matter what else is connected to the amp (other than power, earth and remote obviously) the result is the same - protect mode.

Do you agree? What are my options from here. I am ok (not great) with electronics; that is I can de-solder/solder parts. Is it as easy as replacing a component with-in the amp?

In your first reply you said it might be a voicecoil. How can I confirm this?

Thanks again for your help. Ben

[Carbon 34]

Do you have a digital ohm volt meter?

check the ohm load on the front speakers not connected to the amp just for giggles , anything around 4 is ok , if you can check or dead short

Car ground to speaker leads each one on front channels

If I can make out correctly your amp is stuffed

, really to dig into it is not worth doing these amps or replacement would be cheaper and less hassle

One thing you could check is the rca joint where it meets the curcuit board could be cracked on channel "a" you could smell test it once open if fried you will smell it ( remove from all power first !! High voltage inside ) or look for obvious burns on the board

just as easy to junk it at that point they only cost about 150 new ?? if your on the cheap i have 4 amps collecting dust i would sell or swap cheap as ? 4 , 4X 75 watts 990 watts max custom painted , 1 , 5 channel 55x4 220 mono rms ,1100max , someday i'll pop them up for sale lol

Either way you could replace that amp cheaper then fixing it in most cases