Some of people on the net says that Gainclone is one of the shortest amplifier in the world. Some people could make it less than 32 mm on the signal path. Check it here! But I don’t have any intention to match or compete with them. Remember, I do what people don’t, so don’t bother with what they are doing 😉
The parts, most likely, are my old stock. Most of the time, I use what I have on hand (and also buy some if I do really need that). So you can see a lot of mixed brand here. I try to pick the best from what I have.
The first thing that I do is, to install the input ground resistor. Not just because this is the most important, but simply because I need to put two resistor in a “not common” way. The picture below will explain more than what I can say. It’s Vishay S139 (similar with S102) Ultra-High Precision Bulk Metal Foil Resistors. It’s 0.01% tolerance 🙂 So 11K is 11K, not with additional value behind the dot. I need to use 22KOhm, but only have 11KOhm on hand, so I use two.
Not a genius job, just put two in series and they will do the job perfectly.
Another shoot of the resistor. and other components You will also notice 0.1uF/200V K40Y-9 PIO capacitor behind the Vishay S139. It’s for power supply bypass, 2 for each channel (for positive and negative rail), so total is 4 for stereo.
Behind them is a BlackGate F Series 680uF/65V on each section (for positive and negative rail). Total is 4 pcs for stereo. So, the PIO will bypass those BlackGate? I hope I’ve done it right…
Other components are Kiwame 1KOhm/5W for feedback to ground and a beautiful 20K Shinkoh Tantalum on feedback section.
The final PCB. So big, so long signal path, and so “out of tradition”. Really Jimmy, you do what people don’t.
What is that? It’s a “special gold edition” Nichicon PIO capacitor. The main idea is for input capacitor. I plan to change it to Mundorf Silver/Oil/Gold later. But for now, I will stick with this old capacitor.
Still remember 22uF feedback to ground capacitor? I’m thinking of 18 years old SCR capacitor (SCR is well know as Solen manufacturer). I don’t want to use electrolytic on my signal path, so this SCR should fit right to replace the electrolytic.
The final photo of my LM1875 Gainclone, without the power supply section. I will design the power supply later. And we’ll see, how this “out of tradition” Gainclone shall perform!