I am about to attempt make my first audio amplifier (beyond an LM386 amp). I chose the TDA2030A (dataheet http://www.st.com/web/en/resource/technical/document/datasheet/CD00000128.pdf). Since its a dangerous thing to do I chose an smps power supply, which is 24V and 2A. I have been training for this task for the last month and a half, learning to make PCBs etc. Yet realizing the nature of electronics, where there is always some piece of knowledge that is hiding in the bushes and that I wasn't aware of, I decided to ask the community some questions that will help me make this amplifier without killing myself in the process. Just for background, Electronics has been a hobby for the last 3 months and I am an Industrial Engineer myself.

  1. If you look at the circuit diagram, the amps use pin 1 as their non inverting input. In this diagram taken from the datasheet, the amp on the right has its non inverting connected to a resistor that is connected to ground. Both amps drive a single speaker. My question is that if I connect the right amp to the right audio channel and the left of the left audio channel, unlike shown in the diagram, can I drive two speaker? I don't see why it cant be done.

  2. For proper grounding, I create ground planes on my pcb. Then I need to make a hole in my PCB on the ground plane and connect it via wire to the Ground on the smps. Right? (am asking stupidly obvious questions just to know if I am right). Proper grounding seems the key to any proper functioning electronic circuit.

  3. Do I need to have a complex filtering system like capacitor for ripple etc? I ask this because this is smps purchased from the market, it would already have the required components.

  4. What is the V ADJ pin on my SMPS? How do I use it?

Thank you. Any help will go a long way in insuring a long life for me.

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  1. Yes, but not with that circuit set up. You'd need a different one, and large capacitors. Edit: More explaining is necessary. The circuit you have provided is a bridged topology for only one channel. You can either double this circuit and have one copy drive each channel separately OR you can use one amplifier with the circuit at the top of the data sheet you yourself have provided (and hopefully read). That circuit in the datasheet is a single ended configuration. The Large capacitor is what would sit between the amplifier and the speaker so that you don't have a DC short from 12V (mid-rail) to ground. If you want a single ended amplifier without a capacitor then you need a bi-polar supply.
  2. Ground planes are generally bad for audio amps, introduces too much coupling. I prefer routing the power and ground directly under each other to maximize the capacitance on the lines for high frequency AC shunting. Also, most importantly, star ground. Edit: Star ground information can be found very easily by using the power of the internet. A brief explanation: Current flows through ground just like all wires. Large currents, such as those experienced by power amplifiers, will cause a voltage drop on the ground wires enough so that the "ground" connection of different components will not be at the same potential. This can cause all sort of inaccuracies. But seriously, there are a thousand and one examples elsewhere.
  3. It doesn't hurt you per say to not have them, but if you have a scope with an fft and can find the harmonic frequency you can filter better. Also, since that's a chip, it should have been made with some PSSR (power supply rejection ratio) look that up and figure out how much the noise from the power supply will get in. Edit Just looked at datasheet. Yes you want to filter that, there's no frequency/rejection chart. Who knows what will make it in, but 50dB is not great.
  4. Vadj, lets you adjust the voltage output up and down from 24V. Not too far either direction, but enough that you can compensate for load variations and such (or run at 26V if that's what you wanted, with a drop in current capacity of course [it's a power supply, i.e. you get 48W no matter what voltage it gives]).
  • \$\begingroup\$ Thank you for your reply Dave. Why would I need a different circuit set up for two speakers (is it because this current circuit is set up in a negative feedback loop? They need to be separate independent circuits?) And the large capacitors you are referring to are at the power (+-) input terminals from the smps? Also what do you mean by star ground? \$\endgroup\$ – Kunal Verma Feb 8 '16 at 12:39
  • \$\begingroup\$ @KunalVerma, I'll adjust for the answer. \$\endgroup\$ – Dave Feb 9 '16 at 5:35

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