Hi-Fi Preamp

Nice

Yes, i was surprised that the THD level was down to the uV with such a simple topology.

Only from THD the curcuit could be even more simple http://everycircuit.com/circuit/6725607352172544

Yes, rob elliott has some very good circuits. When i first dabbled in amplifiers i took much knowledge and ideas from him. There are many ways to get the THD very low. From what I've learned the key moments are: 1. Whenever you can replace a resistor with a constant current source - do it. 2.Try to keep it simple, but not too simple. Just avoid many stages. 3.Put as many feedbacks as you can and of any kind you can. 4.Keep the gain per stage low. 5. Avoid output capacitors, and capacitors as a whole. They tend to introduce phase shift distortion, which by itself isn't harmful, but as far as a complete negative feedback is concerned, a phase shift could easily turn a negative feedback into a positive one. That should be avoided at all costs. 6.Try not to strain the amp with too much gain and try not to have an impedance mismatch. 7.For preamps, the power supply is essential. Use the best filtering you can. 8. Ground loops should be avoided at any cost. 9. Using high quality components is recommended. 10. The component layout is the least important, but should be mentioned as well. Parasitic capacitance may cause instability and increased THD.

The last year you learned a lot of new things. Keep it up for 2016!

The last 5 years have been such a journey. I wish you all a splendid 2016.

Happy 2016!

I'd say the frequency response is is good at 10hz-40khz.