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Old 20th May 2010, 09:36 AM   #7881
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the signal and ground is far apart from my transformer :/

here is my simple graphical example of my wiring on the pot.
Click the image to open in full size.

i will show up the picture later once i get a camera on my hand
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Old 20th May 2010, 10:52 AM   #7882
AndrewT is offline AndrewT  Scotland
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i think you have three problems, although one or two may be much worse than the third.

First.
The potentiometer body should have a separate wire back to the main Audio Star Ground.
Second.
The wires (green & black) from input to pot should be very close together to minimise loop area. Usually this is done by twisting.
Similarly the red and black wires from pot to amp input should be very close together, again usually twisted.
However, you have L+R+Return as a group, twisting will make crosstalk worse.
Third.
All the mains and secondary AC wiring must have a small loop area. This is to minimise the mains signal that your wiring transmits to the air. This is done by taking pairs of wires that form a flow and return circuit and twisting them together. The DC supply to the boards is +&-&Return. These three wires should be twisted as a triplet to minimise loop area.

Try First, then third, before attempting second.
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Old 20th May 2010, 10:54 AM   #7883
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I guess if I was doing something like this, I would:

- replace all signal wiring with good coax
- remove short jumper from signal ground to pot
- connect mains earth ground to chassis
- route all signal wiring well away from transformer / any primary wiring
- wire from pot shaft to earth ground if necessary
- connect circuit ground to chassis / earth ground in the manner Nelson suggest
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Old 20th May 2010, 11:18 AM   #7884
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Drawing
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Old 20th May 2010, 11:22 AM   #7885
awc is offline awc  New Zealand
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Quote:
chchyong89
Can you do a drawing coming back the other way, from wall plug and speakers out, showing all "positives / phase" in red, "negatives / -" in black and all "ov's / earths" in green,

it concerns me when you say
Quote:
1. My F5 is running naked, there is no earth wire from my wall plug
Also you could have a dry joint in power supply caps etc,

mine dose that with my caps connected by copper wire rapped around bolts into caps, so I give them a tap to make contact and hum lessen and go's away further as I move further from speaker and crank the volume up, Its that "sweet spot" Nelson talks about ?
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Old 20th May 2010, 12:03 PM   #7886
AndrewT is offline AndrewT  Scotland
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Bobo's diagram shows minimum loop area for each pair of flow and return wires. These can be twisted to maintain and average that minimumloop area.

However, in Stereo, there is a problem. The source usually has the RCA phono output grounds connected to each other. That creates a loop in the returns and minimising the Hum Voltage around the ground loop is difficult. The loop area of the interconnect grounds and the two channels of grounding wires inside the amp must all be laid out to minimise loop area. But even this does not remove the Hum Voltage. It merely attenuates it.
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Old 20th May 2010, 12:11 PM   #7887
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I use this wiring diagram (double mono) in my F5.
I have no hum at all without even the need of connecting the audio ground to chassis.
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Old 20th May 2010, 12:14 PM   #7888
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Quote:
Originally Posted by AndrewT View Post

However, in Stereo, there is a problem. The source usually has the RCA phono output grounds connected to each other. That creates a loop in the returns and minimising the Hum Voltage around the ground loop is difficult. The loop area of the interconnect grounds and the two channels of grounding wires inside the amp must all be laid out to minimise loop area. But even this does not remove the Hum Voltage. It merely attenuates it.
In that case, one may disconnect one RCA ground wire.
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Old 20th May 2010, 12:23 PM   #7889
AndrewT is offline AndrewT  Scotland
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Default disconnect 1 RCA ground

Which one and where?

I have never been able to eliminate hum coming from the ground loop created by a common ground in the source and the signal grounds of a stereo amplifier.
That's why I cop out and build monoblocks.

Help me.
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Old 20th May 2010, 12:31 PM   #7890
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Quote:
Which one and where?
Unsolder the ground wire from one RCA input (into the amp)
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