Hissing

[blades]

Just completed the sound install consisting of Lanzar Mids & tweeters (front)
Legacy mids & tweeters (rear) & 12" Kenwood Sub. I'm running two amps lanzar 600w 4 channel & lanzar 300w bridged for the sub. I've ran all the cables down different sides of the car (power left, speakers right & rca Middle) and used distribution blocks in the boot. After all this I'm getting a hissing noise I'm using the bolt that held the original changer bracket to the chassis as the earth so there shouldn't be a problem. Has anyone any ideas ?

[Stimps]

See if you can find a different earth point?

On the fabia there's one behind the rear speakers - it has a plastic spoked 'crown' around it to hold the wires; can't miss it...

Is the hissing coming from all speakers, or just one set? My install has the power running the full length, with the output from the changer on the same side from under the passenger seat (so about 1/2 length) - the remote and RCA then go down the right side, with no hiss...

[humsk]

As Stimps asks, is it all speakers?

For the ones that hiss, disconnect the RCA amp inputs and short the appropiate input terminals out by connecting the inner contact to outer contact with a short piece of wire (paper clip will do as a last resort). Take care not to touch anything else. If the hiss is still there then it's the power supply eg the earth connection (make sure the earth terminal connects to clean metal and not through paint).

Sounds like you have done the right thing by keeping all the cables separate. Is the hiss there all the time or only when the engine is running?

[blades]

Only when engine is running. I had it before on a previous install but re-routed the wires and it sorted it. I'm hoping it's the earth as I can't face re-routing the wires this time

[humsk]

Yes, check your earthing first - nice short thick cable directly to the bodywork. Is your power connection directly to the battery (via a fuse I hope)?

If the hiss is still there and you do not want to start messing about with re-routing then try a suppressor (capacitor) - Halfords used to sell them (I've not checked recently). They are connected between the +12V and chassis, ideally at the source of the interference but will have a benefit when connected at the amp. Do not go for the suppressors that fit in the power cable - at the currents you will be pulling they will burn out.

[humsk]

Me again, just to recommend a separate earth wire for each amp to the chassis connection.

[blades]

Reckon it could be the earth as I seem to think it's from each speaker will try the seperate earth theory in morning. I may have a problem with the amp running the sub as it keeps protecting it's self. I've got a apare amp so I'll swap them over tommorrow

[vRS_Si]

Out of interest any tips for routing of the wires?
How did you get the RCAs under the middle console and carpet?

Put my headunit in at the weekend, need to sort the rest now.

[Stimps]

BTW, I have a 1 farad capacitor in the boot which may or may not remove any "hiss" - never tried it without the cap...

[blades]

Originally Posted by vRS_Si

Out of interest any tips for routing of the wires?
How did you get the RCAs under the middle console and carpet?

Put my headunit in at the weekend, need to sort the rest now.

If you take the ashtray out of the back of the centre console there's two screws I can't remember exactly but if you work from the back seats the centre console comes apart into two pieces

[humsk]

Originally Posted by blades

Reckon it could be the earth as I seem to think it's from each speaker will try the seperate earth theory in morning. I may have a problem with the amp running the sub as it keeps protecting it's self. I've got a apare amp so I'll swap them over tommorrow

Recommend you sort out the earthing before condemming the amp - is it tripping out due to overheating? If the earthing is poor, it may be because the power supply is all over the place.

Any photos of your install?

Originally Posted by Stimps

BTW, I have a 1 farad capacitor in the boot which may or may not remove any "hiss" - never tried it without the cap...

It will certainly help - depends on the frequency of the "hiss". It is intended to act as a local battery / reservoir to provide the high current surges for the bass notes.

[blades]

Tried new amp but that tripped out. So moved position of amp so that cables weren't flexing as much this seems to have worked. With regards the hissing I've altered the earth point and swapped the set up for the RCA leads around and this seems to have cured it. The final set up is a 600w lanzar 4 channel amp two channels running the front components and a bridged channel for the sub and a lanzar 200w 2 channel amp running the rear (original was a 300w lanzar but I still think it was a bit suspect) components. The good thing about the amps is that they have their own cross overs and have both rca inputs and outputs. I've got the RCA leads from the stereo (two sets) running the small amp and the front two channels on the large amp with the rear channel (bridged) running from the rca outputs from the front two channels of the large amp. It sounds complicated but it's actually quite simple. I will get a photo once I've tided it up a bit - also by pure look I think I can still get the spare wheel out !!

[humsk]

Glad to hear you've got to the bottom of it.

[vRS_Si]

Originally Posted by blades

If you take the ashtray out of the back of the centre console there's two screws I can't remember exactly but if you work from the back seats the centre console comes apart into two pieces

I can't seem to find any screws
Got the ashtray out and the little cubby hole.
Then the console unclips, lifts up at the handbrake end but seems firmly stuck at the back end.
Is there something i've missed, are you able to post any pics?

[blades]

I've just gone outside and had another look. If you pull the ash tray right out (complete) there are two torx scres which need taking out. I will take some pictures when I can find the charger for the camera - if not I'll use the phone when it's light and email them