jimbodisco · Dec 30, 2008

I dont know why but the black wire dosent get used, i left it on the original orange connector.
The outer wire on the rca i cut back as far as i need to solder the inner wire and cut it off there, then after i had solderd it i wrapped the whole lot in insulating tape to stop it coming into contact with anything.
jimbo

vivnap · Dec 30, 2008

thats it then ill have ta have a go at mine sometime now ! thanks.

gotoneatlast · Dec 30, 2008

i'm thimking that you still need the black and sleeve braided wire connection as this acts as an earth for the audio signal circuit, on an unbalanced line, which the phono input and output connection is, you may find it'll hum, or become noisy with out it.
BTW iwas talking bllx with the phase reverse at this stage of the connection, it would just not work if you wired it up wrong.

thebiglad · Dec 31, 2008

Have tried to do this on both our Discos - can't get either of them to work, unfortunately

:baby:

jimbodisco · Dec 31, 2008

ive just got to my parents house after driving 200 miles..... i have no buzzing or noise apart from bass coming from the speakers.
fingers crossed i have cracked this problem!!
jimbo.

gotoneatlast · Dec 31, 2008

yeh,
you should be ok,
lifting an earth is not an uncommon practice, both with audio, and audio mains wiring, it does help when trying to eliminate ground loops.

discool · Dec 31, 2008

gotoneatlast said:
yeh,
you should be ok,
lifting an earth is not an uncommon practice, both with audio, and audio mains wiring, it does help when trying to eliminate ground loops.

Do it all the time on data wiring, ground the screen but at only one end not both. Don't know what ground loops are haven't heard of that one.

discool · Dec 31, 2008

jimbodisco said:
ive just got to my parents house after driving 200 miles..... i have no buzzing or noise apart from bass coming from the speakers.
fingers crossed i have cracked this problem!!
jimbo.

Well Done jimbo.... What Vibe FLI loudspeakers did you fit were they a direct replacement or did you have to do a few mods to the subs door pod.

The Mad Hat Man · Dec 31, 2008

discool said:
Do it all the time on data wiring, ground the screen but at only one end not both. Don't know what ground loops are haven't heard of that one.

Earth loop piccy - should be self explanatory.

gotoneatlast · Dec 31, 2008

oh cheers mhm, was just about to explain this,
whadda guy!!

discool · Dec 31, 2008

The Mad Hat Man said:
Earth loop piccy - should be self explanatory.

Ok but you don't say what the application is.

gotoneatlast · Dec 31, 2008

it looks like a simple audio circuit to me.

discool · Dec 31, 2008

gotoneatlast said:
it looks like a simple audio circuit to me.

That's why then.. Not my field, to me it looks like a two core cable with a screen linking two units, but as i said with data ground only at one end of a screen cable or cable with an earth drain, that will be unit A in the pic and not terminated on a patch panel.

The Mad Hat Man · Dec 31, 2008

the application is irrelevant
if the earth screen is connected to ground at BOTH ends, yu induce noise into the earth plane. with mains equipment, yu get hum, with other systems, you get electrical noise.
That is why on all good cat5+ system, screened cable is used, but the screen is not connected at the wall outlets - so that the screening is broken between the system cabinets and the data equipment (PC's etc). same with audio systems - never connect the screening at both ends to earth.

gotoneatlast · Dec 31, 2008

yeh, i see,
i think what i'm tripping up on is differentiating between the earth 'screen', and the mains earth.
At work in general we've wired balanced circuits with the screen going to the chassis of a unit or racks, i can see the danger of having the earth mains in the 'loop', and also in audio terms the introduction of 50HZ hum would be an obvious problem.

Thanks.

gotoneatlast · Dec 31, 2008

what's meant by the term "floating earth"then?,
i've come across this often.

The Mad Hat Man · Dec 31, 2008

Voltage is a differential quantity, which appears between two points having some electrical potentials. To measure the voltage of a single point, a reference point must be selected to measure against. This common reference point is called ground and considered to have zero voltage.
This signal ground may or may not actually be connected to a power ground. A system where the system ground is not actually connected to another circuit or to earth (though there may still be AC coupling) is often referred to as a floating ground.

discool · Dec 31, 2008

The Mad Hat Man said:
Voltage is a differential quantity, which appears between two points having some electrical potentials. To measure the voltage of a single point, a reference point must be selected to measure against. This common reference point is called ground and considered to have zero voltage.
This signal ground may or may not actually be connected to a power ground. A system where the system ground is not actually connected to another circuit or to earth (though there may still be AC coupling) is often referred to as a floating ground.

A cut & paste from "Circuit ground versus earth" on the www.

The Mad Hat Man · Dec 31, 2008

and? its still valid.:brick:

discool · Dec 31, 2008

The Mad Hat Man said:
and? its still valid.:brick:

can't argue with that, I must look at the rest of it

Regards & Happy NY

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