Kicker amp cutting out

[LT206]

A few years ago I installed a new system in my boat and I've had the problem below since then, but have just lived with it - until now. Maybe someone here can point me in the right direction.

Evid tower speakers - 8 ohms each. They are wired in parallel to a bridged Kicker 450.2. The amp should be seeing a 4ohm mono load which is ok for that amp. According to the spec sheet that amp puts out 450 watts at 4 ohm mono.

When the speakers are played loud - occasionally the amp will cut out and the red light on the amp will come on for a few seconds and then turn back to green. When it turns back to green the speakers play again. I tried this a moment ago, and the amp was not hot when this happened - so I don't think it was going into thermal protection mode. Any thoughts on why this is happening? I can play all day long at low volume without the amp cutting out.

[EarmarkMarine]

LT,
While I'm not really familiar with the inner workings of the Kicker protection circuit, it appears the amplifier is doing its job in protecting itself. First, you've got to verify that your
voltage is adequate and that all connections for power and ground that can impact voltage
are solid. From there you can have a number of causes:
* Impedance is too low. Some 8-ohm rated speakers can have a DCR as low as 5.5-ohms.
* Partially burnt speaker voice coil or partially melted VC insulating enamel coating where
the speaker presents a lower load once heated up.
* The amplifier sensing DC from the RCA to souce unit link due to a faulty grounding and a
component seeking a ground through the wrong path.
* If it was wear and tear on the amplifier (overheated and damaged transformer for
example) then I would think you'll see evidence of immediate heat.
* Incorrect or inefficient tuning where an EQ is active or the highpass filter is set too low.

David
Earmark Marine

[LT206]

Thanks for the reply David. I'll double check the power and grounds to this amp to make sure they are solid, but I'm pretty sure that is not the problem. There is no eq on the system and the crossovers on the amp are set around 200hz.

If the amp is seeing a lower impedance than 4 ohms would that make it cut out?? I suspect this may be the source of the problem. So if each speaker has a lower impedance than 8 ohms - then wired in parallel the load would be something less than 4 ohms, correct? That very easily could be the problem. Is there a way to check the impedance on the speakers at the amp with a volt meter to see what they are doing?

[LT206]

Update - just took my multitester and checked the ohm reading at the amp touching the leads to the wires going into the amp and got a reading of 3.9 ohms.

Checked them at each speaker and got a reading of 7.8 to 7.9 ohms. Not sure if this tells you anything, but it seems that the impedance is in line with what I thought it was. I guess it is still possible that the impedance can go lower than 3.9 at the amp at certain times during the dynamic range of the song.... and cause the amp to shut down until the impedance goes back up??

Does this make any sense? I don't really know what I'm doing here so the above may not be of any benefit.

[EarmarkMarine]

LT,
You did it right. DCR (direct current resistance) is different than the actual impedance which is frequency dependent. Typically the DCR that you measured with a meter is a rough indication of the lowest point found in the impedance curve. As measured, your load appears to be perfectly safe.
However, I might eliminate one pair to see if the amplifier behaves differently. Try returning
the amplifier to stereo with one 8-ohm speaker only per channel. You may lose power but still get much louder if the amplifier remains on. Plus you can raise the input gain to offset
some of the effect of a higher load.

David
Earmark Marine

[Chexi]

Okay, this is probably not your problem, but I just had this happen to me and figured it out on my system. I have an Alpine 4 channel amp bridged outputting 2 channels to my tower speakers. I have not had a problem with the amp cutting out until this past weekend. Suddenly, whenever I turned my WS420 up past half on the tower speakers, it would play for a few seconds and then cut out... then come back a bit later and cut out again.... rinse and repeat. The cause was my ipod connector. I had recently installed an ipod proprietary to stereo mini plug to the aux of my WS420. I used to use a stereo mini out the headphone jack. When I switched back to the headphone jack method, all worked fine. I put the ipod connector to stereo mini back in... and the problem returned. I'm not sure what your source unit is, but if you are using an ipod / iphone connector that attaches to the bottom of the unit and converts to a stereo mini plug, try using the headphone jack with a stereo mini instead and see if that cures your problem. I have no idea why it caused a problem for me or why things work fine through the headphone jack... they just do.

[LT206]

chexi - I am using the ipod headphone out, but I was considering changing to a ipod dock line out so I could get a "line out" signal from the ipod instead of an amplified signal from the headphone output. I am thinking this will help with the sound quality. Interesting to hear your issue. What brand dock connector did you use that was giving you problems?