eBay LM1875 Audio Amplifier Kit Test 

Sonic, I appreciate your comment critical or not, it helps me understand how my content comes across your end. The numbers show the output in a way the ear can not hear. Referring to the FFT with even and uneven harmonics anything under -60db is inaudible to us so noise below there doesn't really count as an issue. Even harmonics 2, 4, 6kHz etc sound nice, tube like. Uneven 3, 5, etc sound bad, distortion. Looking at the 0.01% signal injected into frequency range 20Hz - 20kHz audio range at 4.5kHz (between even and odd) its measured and expected. We could look at that as 0.01% of distortion in relation to the rest of the range. Anything below that would be below 0.01% distortion. That will sound nice. Next we look at the response of a signal across the whole range 20Hz to 20kHz to see if it deviates. A flat even response is good it shows that the amplifier does not gain or lose power/amplitude within our 20Hz - 20kHz audible range. The power test increases the power output until a desired distortion level, in this case 1%. Looking at the result we can see where the amplifier overloads and get a measurement visually of output power. Fearing I have bored you, I will save the power supply for a video explaining how it is set up and why ; )

Thank you so much for the further explanation! It helps me understand other technical videos too. I'm getting a pretty good handle on it now. You are definitely not boring me lol. I really appreciate your sharing of knowledge. It seems my brain has a pretty strong resistor across the information input but you're installing a really good capacitor downstream. Thanks again amigo.

Hi John, cheers for the tips. I've just rebuilt the board with film bypass caps so will check that out now. As for the IC, yes it has scoops, I didn't really think it was genuine as the price doesn't reflect that. I have swapped it out for store (RS Components) bought, testing atm. Results so far look promising.

Nah its not that technical really.. the physics and maths# behind the curtain pertaining to this subject is. We don't need that here. Glad you watched anyway, thanks for that. The 60 Watt amplifier I built can be bridged for double the output. It is a good amp and not that difficult to build. Sleep well.

@@Elecifun oh okay. I didn't get a very good education and I went to 14 different schools which made it very difficult later in life. That's one of my biggest hurdles. I taught myself English to some extent which was pretty bad up until my 30s. I watch to boost your google stat's. I few more likes and views helps your channel. A few dollars more means you can buy more goodies. 👍 Even comments helps your channel as you already know. The 60 watt amplifier oh okay. I wish I knew more about why my mates amp had so many components. It looked like a computer mainboard except for some really big capacitors. If IRC it took him quite a long time to build. It definitely wasn't an overnight project. Weeks maybe months. I'm trying to remember whether it was two amps not one. I think he had a pre-amplifier and and another amp. The first one had everything attached to it. Like receiver, turn table, etc. I remember going into the city of Melbourne Douglas Hifi to get the speakers which were Sony 14" or 16" bass drivers. It also had tweeters and mid range speakers. I remember him building the cross overs. I remember when the speaker boxes arrived which he had built. He filled them with something like insulation and then of course the speakers. The amp had a big enclosure with just a light and flick switch. Inside hundreds of components. In those days I had no idea what resistors, caps, inductors, triodes, transistors, and other components did. I can vaguely remember him talking about pnp transistors. The only thing I can clearly remember was that it was 100W per channel RMS. Anyway, I'll go now and grab a coffee. I'm feeling a bit rough. I don't sleep very well. I had a beer last night which I don't normally drink. Cya! Dec.

Yup I know that feeling.. have a drink take it easy.

@@Elecifun I'm okay now amigo ! 😃😄

Christmas is tradition here and more for some. I not sure about the woman you speak of. I guess Marks and Sparks might be expensive.

@@Elecifun very posh name but the irony is its probably full of Chinese junk. Not the fault of the Chinese entirely. 😄

@@Elecifun If you have heating then itsca lovely white Christmas 🎄 Here it's like 38°C ha ha 😂

@@Elecifun I'd love to experience a white Christmas like in America or England where it snows.

@@Elecifun I just soldered another light chaser and it looks pretty cool. 😎