Hi
I build a 3 way multi channel amp (low mid high) for direct drive of ribbons.
Each amp has it's own power supply and transformer.
From the power supply the pos neg and gnd go to the pcb pos neg and gnd.
From the pcb gnd it goes to the speaker neg and to the chassis the input cinch is floating.
All 3 amps wired the same.
When I connect the inputs to the crossover I get humm.
If I disconnect from the mid and high amp the wire from gnd to chassis the humm is gone but then only the low amp is connected to the chassis and the other two are floating.
Is there another solution for this problem ore just let it float?
Rob
I build a 3 way multi channel amp (low mid high) for direct drive of ribbons.
Each amp has it's own power supply and transformer.
From the power supply the pos neg and gnd go to the pcb pos neg and gnd.
From the pcb gnd it goes to the speaker neg and to the chassis the input cinch is floating.
All 3 amps wired the same.
When I connect the inputs to the crossover I get humm.
If I disconnect from the mid and high amp the wire from gnd to chassis the humm is gone but then only the low amp is connected to the chassis and the other two are floating.
Is there another solution for this problem ore just let it float?
Rob
Yes, sounds like a ground loop problem. I would guess that you have three separate RCA interconnects leading to the amp. You can test the ground loop theory by moving these around - the hum should increase as the cables are separated in space.
You can alleviate this problem by inserting a 4.7R resistor between the amp pcb line level ground and the power supply main audio ground point.
You can alleviate this problem by inserting a 4.7R resistor between the amp pcb line level ground and the power supply main audio ground point.
Use a Disconnecting Network from each Channels Main Audio Ground to the Chassis, three required.
To maintain the isolation achieved with the three transformers, you MUST isolate every channel from every other.
The input will have another two wire connection. This must go to the crossover board. The crossover board must be referenced to the Main Audio Ground of every Channel. That's where the ground loop can occur. This is where YOU must ensure just ONE link in each channel to the crossover board.
To maintain the isolation achieved with the three transformers, you MUST isolate every channel from every other.
The input will have another two wire connection. This must go to the crossover board. The crossover board must be referenced to the Main Audio Ground of every Channel. That's where the ground loop can occur. This is where YOU must ensure just ONE link in each channel to the crossover board.
Hi AndrewT
Gona try to use a bridge with a 10 Ohm resistor and 100n cap.
I don't understand the second part.
The filter used 2 pcb's for left and right.
Do you mean I have to connect only one ground of the three outputs?
Rob
Gona try to use a bridge with a 10 Ohm resistor and 100n cap.
I don't understand the second part.
The filter used 2 pcb's for left and right.
Do you mean I have to connect only one ground of the three outputs?
Rob
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