TDA2050Pro – Bench Testing

TDA2050Pro – Bench Testing

The TDA2050Pro is meant to be housed inside a loudspeaker. Such speakers are known as Active Speakers. They can be used for Nearfield Recording Monitors, BGM (Back Ground Music) and others.

The input is fully balanced, hence the “Pro” designation. Balanced lines are necessary when running long interconnects otherwise you’ll pick up all sorts of noise. The TDA2050Pro power transformer is a 12-0-12Vac. Supply rail voltages are +/-16Vdc. I chose this lower voltage because I want the TDA2050 chip amp to be able to power 4Ω speakers.

One advantage of using +/- 16V is I don’t have to buy another transformer for the op amp. I simply tap the psu output to a 7812 and a 7912. All measurements below are with a 4Ω dummy load. 

Full Power into 4Ω

1kHz Full Power into 4Ω 1kHz Clipped Waveform into 4Ω

The plot on the left is the TDA2050Pro at 1kHz Full Power into 4Ω. This display is just before clip. The maximum voltage swing recorded is at 8V RMS. That works out to 16 Watts into 4Ω. Not too bad for a tiny chip.

The plot on the right is the TDA2050Pro driven into clipping. The top and bottom clipped waveforms are symmetrical with no signs of instability.

10kHz and 20kHz Square Wave into 4Ω

10kHz Square Wave into 4Ω
Rise Time = 1.6us | 10Vp-p
20kHz Square Wave into 4Ω
Rise Time = 2.4us | 10Vp-p

The TDA2050Pro has a beautiful Square Wave response. The display on the left is at 10kHz into 4Ω. Very clean. Rise time is at 1.6us. On the right is 20kHz into 4Ω. Rise time is 2.4us. There are no signs of oscillations in either plots.

TDA2050Pro Specifications

Power Output = 16W into 4Ω
Input Sensitivity (@ 1kHz before Clip) = 0.22V RMS (Bal) | 0.45V RMS into 4Ω (UnBal)
Input Impedance = 33K
Rise Time = 1.6us at 10kHz Sq into 4Ω
Voltage Gain = 30dB

Power Supply Specs
Power transformer = 12-0-12Vac
Supply Rails = +/- 16Vdc
PSU caps = 6,600uF / 25V


I didn’t expect such a high performance from the TDA2050. The square wave responses are absolutely gorgeous. Power is rather limited but it’s quite reasonable coming from a small chip amp. If one has ever worked with a 100V line distributed system, you’ll agree that 16Watts per speaker is pretty loud.

The trick to using low power chip amps is to be aware of where it clips. In other words, know it’s limitations and use it below the max. That way, they’ll sound great and last a long time.

The TDA2050Pro pcb is only 2.7″ x 2.25″. This is the smallest power amp pcb I have in the series. All that’s required is a 12-0-12Vac power transformer and a heatsink for the TDA2050 amplifier and you have an active speaker. When I have the time, I will convert one of my designs to an active speaker using this TDA2050Pro.

Lastly, this TDA2050 chip amp doesn’t need a phase lag compensation capacitor in the feedback. One of those rare birds. In fact, having one caused oscillations.