A Gainclone challenge? Why not? Solid state? Why? Why? Why? Why? Why? Wise man says ask “Why” five times. But I think I will end up with same answer 😉 Sorry! Just consider this as a small killing time, boredom destroyer project uh…
But remember, we are on crisis, so no budget!!! So, I also don’t want to spend any budget… Well, small budget is ok, but really-really small.
Let’s straight to the point and back to the topic: I want to try a LM1875 Gainclone Amplifier. This is not my first time building a Gainclone, but first time with LM1875. Gainclone becomes famous because this “simple chip amplifier” could sound beautiful – in 47 Laboratory 4706 Gaincard (retail price near US$ 3000) and Jeff Rowland Concentra (retail price around US$ 6500). FYI, Gainclone family has some models, like LM1875, LM3875, LM3886, etc. Each has different specifications, especially for power rating and speaker load impedance – but all amplifier with this chip will be called as “Gainclone”.
I’ve received the PCB from my friend at local DIY forum. Now, it’s time to pick my “agents” – I mean my components 😉
“As always, should you or any of your IM force be caught or killed,, the Secretary will disavow any knowledge of your actions. This tape will self-destruct in five seconds. Good luck, Jim.”
Well, just suddenly remember those classic Mission Impossible warning on every end of its mission tape. Now I’m starting to pick my agents. Let’s open my shelves and see what I can find. A Gainclone only need very small amount of components, around 10 pcs each channel. I think I still have some in my drawers.
Some capacitors on my drawer. Umm… I’ve collected these for quite long time.
Hmmm… after 30 minutes of digging around, finally I finish picking the “agents”. Here is the “agents” below.
Those soldiers above are ready to fight. What do we have here? Let’s take a closer look.
What do we have here? The yellow Auricap, the MUR860 diode, the Rubycon ZL, Elna Cerafine, Rubycon ZA, Elna Silmic, and K40Y Russian PIO. Not a bad result, eh? Two PCBs on the back, one for LM1875 signal section and one is for Power Supply section. I don’t do Point-to-Point/Hardwiring, because I want this amplifier looked good (I hope it will be looked good!).
Some more here, Vishay S102 resistor, Dale resistor, WIMA MKP10, Eagle/Madisound resistor, Vishay L4C resistor, Black Gate F Series, Refco caps (what he is doing here?) and Siemens old PIO caps.
Enough? We will continue with assembling and soldering process soon. I need to order the main transfomer first!
Added 14 December 2008:
My oh my, look what I’ve just bought (I broke my own promise not to spend any money for this amp). Two Shinkoh Tantalum Resistor 0.5 Watt that cost more than the LM1875 itself! We’ll see what this magic “highly praised” resistor could do…
Added 9 January 2009:
I got some additional items, perhaps it will be useful on this project. Don’t ask me when I will start this project. Simply I’m to busy to start soldering and I simply can’t start something when I don’t have the “mood”. So? 😉
The first is the BHC Aerovox 680uF 100VDC. Well, good place for this item is on the power supply. Now, I’m getting confused how to put all of them in a row. Who should go first? The Elna? Rubycon ZL? BlackGate? Oil Caps? or the Aerovox? Some Copper Obbligato will be used as bypass.
The second is the Solen 22uF 630VDC. Few months ago, I planned to use this capacitor as my other tube Power Supply project, but I forgot why I didn’t use it. Ok, forget it. The 22uF is a good size for Gainclone feedback-to-ground capacitor. So, let’s try it.
Finally, some small Obbligato for bypass purpose. I plan to use some extra cables to connect the big capacitor, so a bypass capacitor perhaps will be needed.