Kicker ZX700.5 Sub Amp Shuts Down

[dBoy]

My Kicker 700.5 sub amp (the Class D amp ONLY) will regularly shut down at higher vol levels. The 4-ch A/B amp side powering the 4 door speakers is fine, does not shut down, just the sub amp - sub amp rated 420 RMS at 2 ohms. Any thoughts on why this is happening? It's driving me nuts.

Using a single 10" Kappa sub rated 350 RMS in a sealed 0.75 cu ft enclosure, set to 2 ohms (the sub has a 2ohm/4ohm switch). Had amp tuned/o-scoped at an audio shop. Gain on the sub amp is 10.5/11 (almost 100%) - the sub had some trouble keeping up at tuning so I built a much better box for it but havent changed the gains yet. Amp Bass Boost is about 40%, used new Kicker recommended Kicker 4 ga wiring kit, ground drilled/paint stripped thru chassis within 12" of amp, (system has zero noise/alt whine, it's dead silent).

Amp is well ventilated, sitting off floor on 1" end blocks w/4" space above and clear all around. GMC Yukon with stock alternator/battery/elec system excpet for the 4 ga amp wiring.

It's odd to me that only the sub amp side cuts out, any thoughts???

Thanks!

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[zako 10+ year member]

My suspicion with 95% certainty is that you are over-driving your amplifier because the Kappa subwoofer probably has pretty low sensitivity. You have maxed out the amplifier gains and added bass boost. 40% bass boost probably results in at least 6dB boost, quadripling the power demand. What did you expect?

I am somewhat familiar with the Kappa subwoofers because I own the 12 inch version, running in 2ohm mode with 250watts. I don't use bass boost, but I added 2dB boost at 65Hz in stereo's equalizer. The 10 inch version has pretty bad efficiency. For example, according to WinISD, the 120.9w needs around 90watts to hit 103dB in the optimal sealed box. The 100.9w needs 220watts to do the same. That's terrible efficiency. That is to say, if you wanted to drive your 10 inch Kappa as loud as I can drive my 120.9w with a 250watt amplifier, you would need around 600watts of power, which your amplifier does not have. The 100.9w even on your power could be adequate for a lot of pop and rock music (kind of like the stuff on Focal JM Labs demo CDs), but I can see people desiring more on some hip hop and other bass heavy stuff.. Here is an interesting example of 10 inch subwoofer such that when you double the cone area by adding a second subwoofer to add 3dB of SPL you still can't beat the 12 inch version of the same product, even though 12inch has less cone area than two 10.

I personally would suggest either put your 10 inch kappa in the recommended vented box or add a second one (just flip the impedance switch on both to 4ohms, then wire in parallel). A single sub in a vented box could hit the lows very well, you would never need to use any boost. (Actually, I wouldn't use amplifier boost, even with sealed box). Changing to the 12 inch version could be a good idea too. Sonic had them on sale for like $130. It's a very nice all around subwoofer for good SQ or getting loud (if you have the power), but the 10 inch version is kind of power hungry. Another possibility, get an Image Dynamics IDQv3 12 inch. These have very good sensitivity, even better than 120.9w. On your power, it could easily hit 110dB in a sealed box (free air, in car sound could easily be in 130s due to cabin gain).