Hi guys, I wired up my 100as2 icepower board for single ended use, and it's fine off my laptop or phone, but as soon as they get plugged into power then I get hum, which I assume is a ground loop. And I get a hum from any mains powered source.
The manual says a bit about curing ground loops, but it assumes I'm using a front end PCB, which I'm not. Should I just be attaching the negative signal pin to ground in this case? And should it be GND or AGND (which has a 22ohm resistance to the general ground)?
Here's the relevant bits of the manual.
Thanks in advance, Tim 🙂
The manual says a bit about curing ground loops, but it assumes I'm using a front end PCB, which I'm not. Should I just be attaching the negative signal pin to ground in this case? And should it be GND or AGND (which has a 22ohm resistance to the general ground)?
Here's the relevant bits of the manual.
Thanks in advance, Tim 🙂
What is the power supply for the amplifier? Has it a own grounded plugged into the wall outlet? If the laptop is also grounded the same, thus the grounding wires close the (unfortunate) loop.
The PSU is part of the board and it's just 2 pin. So no ground and I'm using a figure 8 power connector, I could swap to a kettle plug to give me a mains ground if that would help?
Now I understand. If you are using a SMPS, thus they have Y2 capacitors to the earthed pin. But as your SMPS is not earthed, the return of such capacitors may be the negative side of the secondary. Thus it isn't a loop, is direct amplification of the 50/60 leackage though this capacitors. Try using the laptop running from battery, unplug it a moment and listen if hum goes away.
Yep, as I mentioned, there's no hum off my phone or laptop, until either is plugged into the charger.
Thus you need either a grounded charger (2 live plus earthing) or use the laptop from battery or to take an independent grounding wire for the amplifier.
The laptop is irrelevant, it was just a diagnostic tool, the amp will be used on my main system, and it hums with that too.
Should I be connecting the grounded base plate of the amp to the ground pin of the mains supply? And should the negative signal line be connected to the audio ground, or the general ground, or the general ground with a low value resistor in series?
Should I be connecting the grounded base plate of the amp to the ground pin of the mains supply? And should the negative signal line be connected to the audio ground, or the general ground, or the general ground with a low value resistor in series?
Ground the chassis where you can: a metallic duct (water or vapor, never to gas duct or lightning rod discharge wire). Perhaps a bar in the structure of your building, etc. Any large metallic part that is in contact with the earth.
The earting wire may be used by keep attention to not accidentally confuse it with one of the live ones.
The earting wire may be used by keep attention to not accidentally confuse it with one of the live ones.
You should, for safety reasons. The high-voltage switching transistors/diodes could potentially fail; any high voltage that could find its way to the metal plate must be drained to the ground to ensure the RCCB will trip as soon as possible.
As per figure 24 in section 12. Here, you should follow the manufactures instructions.
Figure 24 implies I have a pre-amp with a ground to connect to, my pre-amp is my PC. Can I assume that if I connect signal negative to ground through a 100 ohm resistor, and that my amp is grounded to the mains earth, and my pc is grounded through mains earth too, that this will in effect be the same?
And should I be grounding the signal negative to GND or AGND?
(I'm not very experienced with electronic circuits, please respond as if I were a 10 year old 😂)
And should I be grounding the signal negative to GND or AGND?
(I'm not very experienced with electronic circuits, please respond as if I were a 10 year old 😂)