# Infinity Kappa Four Z 4x125rms class d



## sqshoestring (Jun 19, 2007)

I'll have to add to this I just tossed it in the car.

Install points:

Pretty obvious but a few things; you can assign the inputs to what set of outputs you want don't recall seening that before. The terminals are nice but phillips set screws I know you will not find anywhere...but that is not a new thing with many amps. They have gold for + speaker and silver screws for -, a nice touch. I didn't use the 4ga power adapter that comes with it, I assume needed mostly for running sub or midbass maybe. It has a pair of 40A fuses.

The RCA are at one end everything else at the other. It is about as long as my dragster 4x50 but more narrow and thinner for sure. One thing that I found is it has a bottom sink like my kicker did, and I don't really prefer those. I went digging for spacers to mount it on as the end 'legs' are flush with the bottom. Maybe not needed for high pass use but just the same I did it.

I put the front speakers on the rear because it has a bass boost at 50Hz (kind of high for a sub?) Anyway, just for the slight chance I might try it and see if it boosts 80Hz at all. With a 16 band EQ in the HU not sure why I bothered.

Fired it up:

So I put the main fuse back in at battery wondering if my pico fuse in the 880PRS would blow lol, no problems though. It does turn on slower than the alpine class D sub amp that is different, maybe 2 sec delay or so. It certainly has more power than the 4x50, I turned the gains higher (louder) than the 4x50 was because the sub would eat that amp all the time. Only turned it up a few times and had to run but it goes loud and clean I'll get more into that once I use it for a while. The dragster 4x50 was a stout 50rms compared to other amps I ran in there and this hammers it for power (as it should), also sounded good and this seems very close. It will take me a while to tell any differences if there are any. I didn't even run the engine yet to check for noise will do that later today.

I could not keep it real loud for long there but ran it for maybe 20 min and could feel no sign of heat when I shut it down.

Lol I have a 100A fuse on a 5ga kit running the system, the Infinity instructions are not overly detailed but say run minimum 120A off battery. Maybe they are considering sub amp as well. I plan to move from this 500rms on sub to 350 but after I check this setup out, assuming the 125rms is not going to give me as much dB as the subs overrun the highs with...but maybe who knows.

So, I'd say it works fine so far.

The two LED on top light blue when its on, the third must be for protect will have to look at them. The Infinity logo is a hologram like a CD. It is a solid feeling (somewhat hefty for its size) and nice looking amp, though I don't much care nobody will see it including me.

I wondered about getting a second one to run midbass and sub, just not sure 300rms is enough for the pair of 15s IB and I don't like using 4ch on subs. Likely would split them and run MB on one and sub on the other so only half the amp had a bass load. But why give up the freedom to run whatever sub amp when nobody sees the amps anyway....would just be an ideal solution if it worked. Or, a kappa 5 is 350rms on sub and the 4x50 can be bridged that might work better.


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## sqshoestring (Jun 19, 2007)

Update:

Have to say this is working very well in the car, it has all the power I need on highs. Still need to play with the gains a little think they are too high. It about blows me out of the car at 50 and I think that is right near clipping. I'm not sure I want to reduce sub power now, but need to hammer some bass intense music to really tell for sure. I think this alpine mono is not very sensitive; I have the gain wfo on it and still can max the level in the HU on old CDs with lower bass levels just to make it sound good....which is way too much bass on new music. Sure is a pita, I really want an amp remote or bass controller remote....something.

The Kappa sounds very clear and I still have the EQ a little flatter than before around 5K. Its significantly more clear at high outputs, but that is to be expected with over twice the power.


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## [email protected] (Jun 12, 2008)

nice, I have been wondering about these, you dont see them brought up much.


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## sqshoestring (Jun 19, 2007)

No you don't even though they are Infinity's high line stuff. I wish Andy would comment on them. I have no electrical noise, did have a tiny bit with the kicker but could not hear it in the car unless I had the volume off and listened, that was while driving. It was in the tweeters only, alternator whine. This is quiet just like the dragster was, the f345 alpine was also quiet.

I'm really trying to find some criticism for it but its difficult. One thing is the RCA at one end and everything else at the other, it essentially makes the amp longer when installed with the wires/plugs sticking out. But really that is standard and could be an advantage for some installs. My power wire was not long enough so I had to mount it with the top labeling/controls upside down, but since its in the rack I don't really care plus I still have to find some 8ga and put a block in there then I can move it. Right now the 5ga goes in the alpine and I have it jumpered from that since the terminal is huge. I only get voltage drop at idle with everything turned on, and this car idles pretty slow. It will drop voltage with the stereo off if the everything is on, brake lights too, and the cooling fan kicks in, at idle. It never does off idle.

Have a couple blocks sitting here plan to put 8ga to the amps and figure out how to organize the wiring. Intend to set it up so I can bolt about any three amps in there that fit. If I could remember to find some 8ga someplace.... 5ga will run 1Kw class D <.5v drop, and since I hardly ever max it out that should be plenty.


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## jaguardoc504 (Mar 25, 2009)

I've been using the Kappa Four, and Kappa One for over 1.5 years with no issues. Very clean. The Kappa Four is a little bright compared to similar amps (alpine specifically). The Kappa One just never seems to run out of usable power. 

Very happy with relatively low cost amps.


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## sqshoestring (Jun 19, 2007)

This was very similar to the dragster 4x50 I had in there, which was similar to the mrv-f353 alpine I had in there before that. It may be a little brighter but that seems customary for newer amps.

No problems yet its working great. Only issue that has showed is if I time it right the following can happen: Turn car on, radio comes on, start engine, radio comes back on and I get a slight pop from the infinity. Its not very loud and only if it is shut down by the HU for the right amount of time. I want to put a cap on the HU to delay it anyway just one of those things I don't get around to doing. It is more like a quick crackle than a pop actually.


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