Tl072 preamp and TDA2050 amp


Joined Jun 17, 2016
The first thing you need to do is reduce the gain of the first stage. As shown, it has a gain of 12 (22k/2k+1), and any input over ~650mV RMS will cause the input stage to clip. Try replacing R11 & R17 with 10k.

Also remove R13 & R19 (100k) at the opamp outputs, as they reduce the signal level before the volume pot and serve no useful purpose. Replace the resistors with links or 100 ohm resistors.

C15 & C17 should be no greater than 220pF. They are there to reduce RF interference. The previously suggested 2.2nF (or 1.5nF) are too high if the source has a significant output impedance. HF attenuation is via the two caps, but also includes R9/R15 in series with the output impedance of the source. Some sources have low output impedance, but not all do, and it's unwise to assume that the resistor/capacitor networks in your circuit are the only impedance present.

Delete C4 (2.2nF) on both channels - they will seriously affect the HF response when the volume pot is centred.