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Scrawf



Member Since: 24 Jul 2016
Location: Matlock
Posts: 25

United Kingdom 2010 Defender 90 Puma 2.4 XS CSW Tamar Blue
New high power head unit - where to ground it?
Hey guys

Been doing some research but I can’t find the answer to this question.

I’m fitting a Sony Sony MEX-GS820BT into my Puma 90. This head unit has a D class amp built in and should give 4 x 100w

The wiring diagram says it needs a direct positive power feed from the battery with a 15 amp fuse which I have installed direct from the positive on the battery via a small fuse box. I have used 17 amp cable and a 15 amp fuse and I plan to connect that directly to the harness that plugs into the back of the stereo. So no problem there.

But it also says it needs a negative connection of equal capacity. So I’ve installed another 17 amp cable and connected that to the wiring loom that connects into the back of the stereo. But my question is where should I terminate that? I could run it back to the battery and connect to the negative terminal but I read a couple of articles on the internet that say that’s not such a good idea.

So is ther a good place for a ground behind the dash or in the battery box??

Pictures would be most helpful!

Thanks

Scrawf
Post #748304 31st Dec 2018 5:22pm
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miker



Member Since: 13 Sep 2015
Location: Surrey
Posts: 1763

United Kingdom 1999 Defender 110 Td5 CSW Rioja Red
No problem at all running it back to battery negative!
Post #748345 31st Dec 2018 8:00pm
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desender



Member Since: 06 Aug 2017
Location: Perthshire
Posts: 34

Scotland 2007 Defender 90 Puma 2.4 CSW Stornoway Grey
Looks like an interesting head unit. Sony lists it as a CD receiver, but it looks like it doesn't have a CD player built in.
https://www.sony.co.uk/electronics/in-car-...s#features

Would like to hear how it's performing.
Post #748365 31st Dec 2018 9:04pm
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custom90



Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20367

United Kingdom 
You should really upgrade the loom on each channel run to each speaker too. Perhaps you are?

The seatbox rear lip has some good fixings into steel, interconnected in the vicinity of the seatbelt bolts.
(Obviously don't use the latter.)

There are also some substantial fixings on the front bulkhead under the mat / carpet above the acellerator pedal about 2" down from the lower dash lip.
These however I would error on caution as the ground path in that vicinity I'm unsure of.
(They do seem substantial however.)
You can always continuity test however, both should be okay for the wattage concerned. $W33T $0U7H3RN $UG4R
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Post #748372 31st Dec 2018 9:48pm
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Badger110



Member Since: 06 Feb 2018
Location: South hams
Posts: 1039

United Kingdom 2011 Defender 110 Puma 2.4 USW Buckingham Blue
Any bare steel area will be sufficient, it's a sub £150 headunit with a small amp inside, you're not pulling anymore than most modern headunits wired into the loom.
Post #748411 1st Jan 2019 12:03am
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Scrawf



Member Since: 24 Jul 2016
Location: Matlock
Posts: 25

United Kingdom 2010 Defender 90 Puma 2.4 XS CSW Tamar Blue
Thanks for you’re help guys! OK I’ll find an earth point on a bolt somewhere!

Out of interest this is the article I was reading:

https://www.w8ji.com/negative_lead_to_battery.htm

Might be of help to someone?

Scrawf
Post #748432 1st Jan 2019 9:20am
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300TDi CSW Phil



Member Since: 03 Apr 2016
Location: Bracknell
Posts: 750

United Kingdom 1995 Defender 110 300 Tdi CSW Epsom Green
That's interesting for one thing as far I'm concerned.

The web address looks like an American Amateur Radio call sign.... so I looked it up and it is.

In the wonderful world of amateur radio it is normally advised (even by the manufacturers of the radio equipment) to take the Positive and Negative straight from the battery with fuses in both conductors. This is to reduce the possibility of RF interference between the radio and the cars systems.

I guess it is possible that amateur radio transceivers are built in such a way as to eliminate the problems he has mentioned whereas an audio head unit may not be.

Personally my Transceivers are wired straight to the battery via an aux fuse box which includes the power to the audio head unit (in my Defender of course my van is a bit different). 1995 300 Tdi Epsom Green - It's a keeper.
Wide Track Sankey- In bits- Gone to a new home
M0XQS
Post #748438 1st Jan 2019 9:58am
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Scrawf



Member Since: 24 Jul 2016
Location: Matlock
Posts: 25

United Kingdom 2010 Defender 90 Puma 2.4 XS CSW Tamar Blue
desender wrote:
Looks like an interesting head unit. Sony lists it as a CD receiver, but it looks like it doesn't have a CD player built in.
https://www.sony.co.uk/electronics/in-car-...s#features

Would like to hear how it's performing.


So I’ve got it all wire in. It’s actually pretty good! I picked this head unit because it has a Class D amp built in and supposedly give you 4 x 100w and I have to say I’m not disappointed! I have Focal speakers all round. Front rear and teeters and a Pioneer powered sub and the addition of this head unit has really made the difference. Ther is definitely more power but it’s not that that really make the difference. It seems as though you can hear all aspects of the music more clearly! Like there is better sound range if you know what I mean! You can push it up to higher volumes but there is no distortion and you can really ‘hear’ all the music. Bass, mid range and top are really clear and the music seems to fill the cabin. Anyway these things are all subjective but I think that was a well spent £139!


Thanks for your help guys!

Scrawf
Post #749591 6th Jan 2019 4:57pm
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Badger110



Member Since: 06 Feb 2018
Location: South hams
Posts: 1039

United Kingdom 2011 Defender 110 Puma 2.4 USW Buckingham Blue
Good to hear! ( no pun intended! )

On the note of 100w pr channel, you won't ever pull that through the speakers and it is a little misleading.

100W is theorectically possible, but music power is a little over half that, around 40-50 watts.

As for wiring into the battery directly, most HU manufacturers state this so any faults would be down to the HU and not other factors ( ie bad wiring on the vehicle ). Thumbs Up
Post #749622 6th Jan 2019 7:02pm
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