Graham's Blog Archive

Discrete Versus Opamps: Should We Reinvent The Wheel?

Posted by Graham
July 12th, 2014

I’ll not go into the pros and cons of wheels – many have tried to reinvent them over the last 5,000 years or so – but we still use them today.

Opamps are several semiconductor junctions, resistors and small value capacitors fabricated onto a sliver of silicon. Their origins were arrangements of discrete components. They have shrunk in size with technological advancement.

There are many different types – some suitable for audio – some suitable for other uses.

If you were to study amplifier design in depth you would recognise certain important things about circuit behaviour and why some configurations work in audio, and others simply don’t.

Doing it discretely requires an awful lot of knowledge and then some. Recognising the limitations of discrete circuits you add to them and reconfigure them until the circuit behaves impeccably, which is also the point where it wows you with its musicality.

At that point you stand back and take stock of your achievement… and realise that you’ve reinvented the wheel, and that the result is a wheel!

However, you have wasted lots of your life, perhaps a relationship or two in the process, and did it make you any richer? It may surprise you to know that most went bust – nobody queued-up to buy!

60, or soon to be 70 years, if it isn’t already, have passed by and in that time the opamp designers have done far more than any individual audio designer is capable of.

As a designer you have to realise that you are not the first to have designed the circuit you are so proud of. That you could have spent less of your life and researched opamps instead – and have been able to conclude that it’s already been done.

However, maybe your circuit may not be so complex? It has a unique sound and more clout maybe? But there is something nagging at you because it doesn’t have that deep sound stage extending beyond the room boundary, and you so wanted to do that (this being just one example).

I remember reading lots of articles by the late great JLH. He did some clever discrete audio circuits, especially on power amps, but when it came to a full preamp design, he knew when to throw in the towel . . . and use opamps.