with monoblocks. will not the safety earth's meet in the mains and get conected together?
remove the resistor between PCB power ground and the main audio ground.
Keep the Power Thermistor between the Main Audio Ground and the Chassis.
I recommend you carry out the same test as I did on the Power Rectifier to prove that my cobbled together Mains Fault connection did not rupture/explode if it were ever required to protect me or any visitor from fatality
Keep the Power Thermistor between the Main Audio Ground and the Chassis.
I recommend you carry out the same test as I did on the Power Rectifier to prove that my cobbled together Mains Fault connection did not rupture/explode if it were ever required to protect me or any visitor from fatality
The Chassis to PE is a safety thing. It has absolutely nothing to do with the audio.
Think about ClassII equipment that are NOT connected to PE.
They cannot have a chassis to PE connection. But, the audio still works. Think about a battery power device, the audio still works.
All my Test Builds are done without a chassis. They cannot have a chassis to PE connection. They work and work very well.
I have said many times that I have NEVER been able to build a steel chassis amplifier as quiet as a no chassis amplifier.
I cannot get an aluminium chassis amplifier quieter than a no chassis amplifier. This does have a bit to do with twisted pairs = good rejection of interference.
Think about ClassII equipment that are NOT connected to PE.
They cannot have a chassis to PE connection. But, the audio still works. Think about a battery power device, the audio still works.
All my Test Builds are done without a chassis. They cannot have a chassis to PE connection. They work and work very well.
I have said many times that I have NEVER been able to build a steel chassis amplifier as quiet as a no chassis amplifier.
I cannot get an aluminium chassis amplifier quieter than a no chassis amplifier. This does have a bit to do with twisted pairs = good rejection of interference.
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that one will not hurt. but you gain nothing. the current will not pass the resistor when it can go the other way
If the Signal Ground is connected to the Power Ground, then that connection becomes the Main Audio Ground. All other Ground References must come to the same meeting point. 6L6 shows this arrangement in post401.
For a monoblock amplifier, this arrangement is perfect.
But if you use what is effectively a monoblock PCB and use two or more of them inside a common Chassis then the combined Signal+Power Grounds creates a Ground Loop.
I can understand a High Dissipation amplifier PCB having that combined Sig+Pow. It perfectly suits a monoblock.
Now back to post429.
That pic is the Leach alternative for a multichannel amplifier. It almost works. I have found that it is not perfect, there are some interconnecting arrangements that hum slightly. But I have not found any arrangements that have the zero hum that a monoblock can have.
If the PCB can be modified to separate the Sig G from the Power G then the post429 wiring arrangement should give the best chance of avoiding hum in a two channel amplifier.
For a monoblock amplifier, this arrangement is perfect.
But if you use what is effectively a monoblock PCB and use two or more of them inside a common Chassis then the combined Signal+Power Grounds creates a Ground Loop.
I can understand a High Dissipation amplifier PCB having that combined Sig+Pow. It perfectly suits a monoblock.
Now back to post429.
That pic is the Leach alternative for a multichannel amplifier. It almost works. I have found that it is not perfect, there are some interconnecting arrangements that hum slightly. But I have not found any arrangements that have the zero hum that a monoblock can have.
If the PCB can be modified to separate the Sig G from the Power G then the post429 wiring arrangement should give the best chance of avoiding hum in a two channel amplifier.
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The Star Ground or Main Audio Ground (MAG) can go anywhere in the space inside the Chassis.
It must not be attached to the Chassis. It must not be attached to the link between the smoothing capacitors. It can be anywhere else.
I try to place the amp PCB and the Output terminals in a close grouping. Then I place the MAG in between these two. That gives me shortish cable pairs for all the interconnections between the modules.
I have not done it yet, but I think the Speaker Return Terminal would be a good location for the MAG. Maybe it's time for me to experiment and report.
6L6, Do you have a picture shot straight down into your amp so we can see the full wiring setup.
Trying this has been in the queue for a bit longer than I was hoping. Sorry.
Long story made short, Andrew is quite correct -- placing the speaker Negative at the point where the input and the PSU all connect has made it quieter by an order of magnitude.
Even the transformer even has less mechanical hummm.
So, the scheme is -
PSU GND to circuit board GND. Input and speaker negative all attach at that point.
In the photo;
PSU GND (white)
Speaker Negative (black)
Speaker Positive (red)
V+ (green)
V- (blue)
It looks a bit kludgey, but remember that the PCB is quite small (2x3 inches)
