Hello,
So I was looking for suggestions regarding the following setup that I am building :
Power design : Mains - 3 x center-tap transformers - 3 x power supplies
Stage design : Pre-amp stage 1 -> Passive tone control -> P88 Pre-amp -> 2x P3A amps
1 supply handles a pre-amp stage before the passive tone controls and the P88 pre-amp after the passive tone controls
1 supply handles a P3A amp
1 supply handles the other P3A amp
Obviously all power supplies have their grounds connected to their respective transformer's center tap, and all components ( pre-amps and amps ) have their grounds connected to their respective power supplies, which eventually goes to the center taps.
NOW, the question is, where to ground to chassis in this setup ?
My idea to prevent ground loops would be to connect the mains to chassis , for safety obviously, and the connect the P88's ground to chassis.
This means that the P3A amps would be floating, with their grounds in the center taps. Also the preamp stage before the tone controls would have no chassis grounding, it would be connected backwards to the power supply and forward to the tone control gnd which is connected to P88's gnd.
Also, would I connect the speakers to chassis ground in this setup ?
I find this part really complicated.... Can you guys give me some help ?
At a certain level, all ground are actually connected to each other through PCBs and/or wires. I mean the P3A has a common ground for power and signal, which connects through the wire to the P88's common power and signal PCB trace, which connects backwards to the tone'control's ground bus , which connects backwards to the stage 1's ground trace, and since each of these ground planes are connected at a certain point to their power supplies, that means that all center taps are also connected to one another through the circuit.
My question to you is where do I actually need to connect all this insanity to chassis ground ? 🙂
Thanks !
So I was looking for suggestions regarding the following setup that I am building :
Power design : Mains - 3 x center-tap transformers - 3 x power supplies
Stage design : Pre-amp stage 1 -> Passive tone control -> P88 Pre-amp -> 2x P3A amps
1 supply handles a pre-amp stage before the passive tone controls and the P88 pre-amp after the passive tone controls
1 supply handles a P3A amp
1 supply handles the other P3A amp
Obviously all power supplies have their grounds connected to their respective transformer's center tap, and all components ( pre-amps and amps ) have their grounds connected to their respective power supplies, which eventually goes to the center taps.
NOW, the question is, where to ground to chassis in this setup ?
My idea to prevent ground loops would be to connect the mains to chassis , for safety obviously, and the connect the P88's ground to chassis.
This means that the P3A amps would be floating, with their grounds in the center taps. Also the preamp stage before the tone controls would have no chassis grounding, it would be connected backwards to the power supply and forward to the tone control gnd which is connected to P88's gnd.
Also, would I connect the speakers to chassis ground in this setup ?
I find this part really complicated.... Can you guys give me some help ?
At a certain level, all ground are actually connected to each other through PCBs and/or wires. I mean the P3A has a common ground for power and signal, which connects through the wire to the P88's common power and signal PCB trace, which connects backwards to the tone'control's ground bus , which connects backwards to the stage 1's ground trace, and since each of these ground planes are connected at a certain point to their power supplies, that means that all center taps are also connected to one another through the circuit.
My question to you is where do I actually need to connect all this insanity to chassis ground ? 🙂
Thanks !
The IEC safety ground is connected to the chassis.
There is one and only one connection between the chassis and the audio "ground" system within the chassis.
Sometimes this single connection is direct, or else can be a special ground loop breaker network.
https://sound-au.com/earthing.htm#s9
There is one and only one connection between the chassis and the audio "ground" system within the chassis.
Sometimes this single connection is direct, or else can be a special ground loop breaker network.
https://sound-au.com/earthing.htm#s9
Thank you very much for answering. So as I understand from your answer, the only 2 connections to the chassis are the IEC ground wire and one signal wire coming from the preamp for example. There will be no connecting the individual power supplies or the amplifier stages to chassis.
However, where do you propose the speaker ground will go to ? Should it be connected to the amplifier's ground that goes into its power supply and center tap, with no chassis link, or should it be connected directly to chassis ?
However, where do you propose the speaker ground will go to ? Should it be connected to the amplifier's ground that goes into its power supply and center tap, with no chassis link, or should it be connected directly to chassis ?
Rather, for each chassis, the audio common web of connections, among the sub-systems, must be properly worked out.
Then the single appropriate node of that common system should be connected to the chassis as in post #2.
This is done for each individual chassis. It helps if you avoid using the term "ground" which is misleading.
Here is one example for a power amplifier from our member profdc9 :
Then the single appropriate node of that common system should be connected to the chassis as in post #2.
This is done for each individual chassis. It helps if you avoid using the term "ground" which is misleading.
Here is one example for a power amplifier from our member profdc9 :