I ordered this same board and encountered the same problem. First thing I noticed when hooking up the board was the single ground wasn't tied together at all. I ran a jumper wire between the two grounds on the signal input and this greatly reduced the hum. It is still audible when the amp is powered on and volume is all the way down but you cannot hear it once you turn it up. So, the ground between the audio input not being shared is my best explanation for this problem. I will muster up a better fix shortly.
I am about to purchase this board but saw this thread and now rethinking. Someone in his/her review says this: note: (you need to use the isolation transformer on the input or else you will get a nasty hum)
What kind or power supply/transformer did you guys use?
Yuan-Jing TA2022 2 x 180W Audio Power Amplifier Board
What kind or power supply/transformer did you guys use?
Yuan-Jing TA2022 2 x 180W Audio Power Amplifier Board
As far as I can see, one AC source is serving two separate rectifiers and capacitors. This is a reliable problem to get hum into two amps (one stereo amp). As soon as you connect a input source, you connect both grounds, which will hum like crazy.
Use only one rectifier for both set´s of capacitors, turning the board into a stereo amp with one power supply for both channels. I only have seen a picture of this board, so here is advise that has to be checked with knowledge of the actual board!!!
Best would be one rectifier bridge which connects to the input of the amp (check polarity before powering up!!!) and the build in rectifiers shorted and /or removed.
Maybe just connecting + - and ground of both power supplys with reasonable wires will do it as well.
PS why this dual power supply, one transformer configuration gives such hum has not been explored by me, I just fix things. It might be some different potentials at the two rectifier bridges, that are connected over the input ground when a source is connected. If you use only one input, there is no ground connection..
Use only one rectifier for both set´s of capacitors, turning the board into a stereo amp with one power supply for both channels. I only have seen a picture of this board, so here is advise that has to be checked with knowledge of the actual board!!!
Best would be one rectifier bridge which connects to the input of the amp (check polarity before powering up!!!) and the build in rectifiers shorted and /or removed.
Maybe just connecting + - and ground of both power supplys with reasonable wires will do it as well.
PS why this dual power supply, one transformer configuration gives such hum has not been explored by me, I just fix things. It might be some different potentials at the two rectifier bridges, that are connected over the input ground when a source is connected. If you use only one input, there is no ground connection..
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There are some other solutions *here but I am mad at myself for getting this board with this problem. I should have known better. I will/can do some things but to a certain point since I am not an experienced DIYer.
* Yuan-Jing TA2022 2 x 180W Audio Power Amplifier Board
* Yuan-Jing TA2022 2 x 180W Audio Power Amplifier Board
With the link to parts express you provided, there is an additional input board with two audio transformers. This will isolate the inputs from the rest of the amp and prevent ground issues which come from the two dual power supply´s. A really stupid work around, because good audio transformers are expensive. So you reduce the potential sound quality of this chip to that of some cheap transformers with might or might not be linear from 20-20000 Hz.
These are Penny parts, not Lundahl high end parts as used in some amplifiers.
These are Penny parts, not Lundahl high end parts as used in some amplifiers.
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