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Finally got enough time to make this writeup.
The Lapai Class-T T2020A+ amplifier is available on Parts Express for a measly $22.80. At 20W RMS x 2 channels, that's a lot of power for a very little money.
However, there's a reason these are so cheap, and this thread will show you how to modify these to improve output and sound quality.
From what I can tell, there are 2 major deficiencies with this amplifier.
Power Supply
First is the power supply, which cannot physically deliver the rated power, being only a 2 amp power supply at 12V. Assuming a 90% efficiency, that's only 21.6W of power when we need 40W. When playing harder bass beats, the unit's lights will dim and the unit will eventually shut down due to undervoltage. Below is a link for a more suitable power supply. I have since purchased four of these power supplies and they have all worked flawlessly.
Capacitors
These are all sorts of messed up. Quality control and consistency on these amplifiers is just short of depressing. The units will arrive with a variety of capacitors, some of which even appear to be used. While they do have the same ratings, they are certainly not the same. I previously received a unit with an input capacitor that was soldered with the polarity reversed. This resulted in smoke and electrolytic goop splattered inside the amplifier when I tried to use it. As a result, I recommend replacing the capacitors. However, be mindful of the polarity.
I have uploaded a few attachment images in this post for reference. I will refer to their filenames.
The first 4 images titled StockAmp* are what the amp looks like when you first open it. You will notice that in these two samples, the input capacitors look differnet. One looks either used or very heavily handled. In addition, the output capacitors look different, with one having small and red, and another having medium and red capacitors. A previous sample of mine had small and blue capacitors.
The last image is titled AmpDiagram. The capacitors are color coded for simplicity, and a link to the item on mouser.com is provided.
In Yellow is the input capacitor. This is a 16V 3300uf 20% capacitor. I have opted to upgrade this to a 16V 5600uf Low ESR capacitor.
In Red are the output capacitors. These are 63V .47uf +80/-20% capacitors. They have a very loose tolerance. I believe that replacing these made the biggest difference. The replacements are 450V .47uf 5% capacitors. You will need six. One thing to note: there are 3 holes for these capacitors to be soldered through; one on one side and two other other. The stock capacitors use the inner hole. You can use the outer hole to solder the upgraded capacitor, as they are wider.
In Magenta/Pink is a film capacitor. It is a 63V .1uf capacitor. I have no idea what it does, but I replaced it anyway because its only $0.68.
In Green are a bunch of electrolytic capacitors. These are rated as follows. Disregard the two in orange for now:
2 x 16v 100uf
1 x 16v 470uf
2 x 16v 220uf
2 x 50v 1uf
These were replaced with Nichicon Audio Grade capacitors. Just match the values on the old ones when you remove them with the new ones.
In Orange are two 50v 1.7uf capacitors. I had initially bought two 2.2uf capacitors to replace these, but after replacing them, I had a great deal of distortion and discovered that the value needs to be kept the same, so I put the stock ones back in. Unless you can find 1.7uf capacitors to replace them, leave them alone.
I will post pictures of the modded amps in the next post.
The Lapai Class-T T2020A+ amplifier is available on Parts Express for a measly $22.80. At 20W RMS x 2 channels, that's a lot of power for a very little money.
However, there's a reason these are so cheap, and this thread will show you how to modify these to improve output and sound quality.
From what I can tell, there are 2 major deficiencies with this amplifier.
Power Supply
First is the power supply, which cannot physically deliver the rated power, being only a 2 amp power supply at 12V. Assuming a 90% efficiency, that's only 21.6W of power when we need 40W. When playing harder bass beats, the unit's lights will dim and the unit will eventually shut down due to undervoltage. Below is a link for a more suitable power supply. I have since purchased four of these power supplies and they have all worked flawlessly.
Capacitors
These are all sorts of messed up. Quality control and consistency on these amplifiers is just short of depressing. The units will arrive with a variety of capacitors, some of which even appear to be used. While they do have the same ratings, they are certainly not the same. I previously received a unit with an input capacitor that was soldered with the polarity reversed. This resulted in smoke and electrolytic goop splattered inside the amplifier when I tried to use it. As a result, I recommend replacing the capacitors. However, be mindful of the polarity.
I have uploaded a few attachment images in this post for reference. I will refer to their filenames.
The first 4 images titled StockAmp* are what the amp looks like when you first open it. You will notice that in these two samples, the input capacitors look differnet. One looks either used or very heavily handled. In addition, the output capacitors look different, with one having small and red, and another having medium and red capacitors. A previous sample of mine had small and blue capacitors.
The last image is titled AmpDiagram. The capacitors are color coded for simplicity, and a link to the item on mouser.com is provided.
In Yellow is the input capacitor. This is a 16V 3300uf 20% capacitor. I have opted to upgrade this to a 16V 5600uf Low ESR capacitor.
In Red are the output capacitors. These are 63V .47uf +80/-20% capacitors. They have a very loose tolerance. I believe that replacing these made the biggest difference. The replacements are 450V .47uf 5% capacitors. You will need six. One thing to note: there are 3 holes for these capacitors to be soldered through; one on one side and two other other. The stock capacitors use the inner hole. You can use the outer hole to solder the upgraded capacitor, as they are wider.
In Magenta/Pink is a film capacitor. It is a 63V .1uf capacitor. I have no idea what it does, but I replaced it anyway because its only $0.68.
In Green are a bunch of electrolytic capacitors. These are rated as follows. Disregard the two in orange for now:
2 x 16v 100uf
1 x 16v 470uf
2 x 16v 220uf
2 x 50v 1uf
These were replaced with Nichicon Audio Grade capacitors. Just match the values on the old ones when you remove them with the new ones.
In Orange are two 50v 1.7uf capacitors. I had initially bought two 2.2uf capacitors to replace these, but after replacing them, I had a great deal of distortion and discovered that the value needs to be kept the same, so I put the stock ones back in. Unless you can find 1.7uf capacitors to replace them, leave them alone.
I will post pictures of the modded amps in the next post.
Attached Files
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