Hello so about a week ago i spend alot of money buying and installing speakers. I have Hertz speaker all around and two kenwood subs. The problem that I have is that once i put the volume up past 40 (my head unit goes up to fifty) the 4 inch speakers start popping and crackling. is there some sort of like regulator or someone i could put on them to stop that happening anyone got any ideas of solutions?

Could be distorting as they are at their max?

Try turning down the setting for them ie. bass, loud etc.

Yeah I've put it all on 0db which is what it should be at

What wattage are the speakers rated at? RMS and Peak?
Are they run through an amp or straight off the head unit? either way what make/model is the stereo?

60 watt peak and 30 continuous and it's a jvc one I'm not sure on model number it's a pretty popular though

And they are in a circuit with the door speakers but yeah powered from the head unit is

Well your HU probably outputs around 50w RMS per channel
You say your speakers are with the door speaker circuit? does that mean you have added these speakers alongside your original ones, or have you replaces the original ones?
How are the subs wired up and what are they connected to? Amp i presume?
All HU have a distortion level, some alot higher than others, if it's getting to 80% and then clipping it could be because the HU is not really up to the job (possibly because it's JVC...)
Also your HU may be putting to much into the speakers, meaning the speaker are clipping/distorting.
Have you got anything to test this with, maybe another HU or some speakers?

Well your HU probably outputs around 50w RMS per channel

Probably more like 15-20w. And if it's at 80% volume then it's clearly struggling. Also it's made by JVC.

Pick up a low-end amp from eBay (something like an Alpine/Kenwood 4x50w RMS) that can handle that many speakers properly.

And they are in a circuit with the door speakers but yeah powered from the head unit is

Hang on- do you mean HU > Speaker > Speaker > HU? Because then you're probably messing with the HU's output resistance...

Well they are plugged straight into the existing loomes which I think is hu speaker speakers hu

need I've replaced all the speakers to high end hertz speakers which are apparently the second best speakers on the market and my subs go straight to an amp and then straight to the rcas on the back of my head unit I was looking at a new head unit, anyone wanna recommend me one ?

The thing is no other speakers are struggling just the dash speakers other than that it sounds fat

I've replaced all the speakers to high end hertz speakers which are apparently the second best speakers on the market and my subs go straight to an amp and then straight to the rcas on the back of my head unit I was looking at a new head unit, anyone wanna recommend me one ?

Hertz do produce some very good speakers, but I'm guessing you got something like this: http://www.caraudiodirect.co.uk/speakers/full-range/4-inch-coax-10cm/hertz-dieci-dcx-100-3 which isn't exactly their flagship model. I don't think replacing the head unit is the answer, you're likely to just get another one with very similar specs as they're not really designed to power aftermarket speakers on their own.

Alright so what should I do ?

If it was my system I'd buy a 4-channel amp to power the speakers and have them one per channel.

Something like this: http://www.ebay.co.uk/itm/JBL-GTO-75-4-/291059714667?pt=UK_In_Car_Technology&hash=item43c482ca6b or this http://www.ebay.co.uk/itm/alpine-mrv-f307-2-3-4-Channel-Amp-/171221141651?pt=UK_In_Car_Technology&hash=item27dd934893

Most amps allow you to control the front and rear channel gain and frequencies separately. I wouldn't take the "power ratings" too seriously.

How would I wire this amp in ? Because I only have one set of rcas on the back of my head unit. Would I have to rip out the existing loomes and replace them ?

You'd have a few options. If you've only got one RCA out on your head unit you'd need to split this between the in on the amp and the amps for the subs. With the speakers you could either patch into the original loom or replace the wiring. I'm not sure what it's like on a 6n, required some drilling of the door frame on my 6n2 though.