Advantages and Disadvantages of SMPS for Field Audio Amplifier

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 Today, the use of SMPS power supplies for field-class audio sound systems still raises a lot of questions among beginner audio lovers like me.  What are the advantages of SMPS for a large watt sound system?… Can it last for hours on end?….  is it not quickly damaged, etc.  Switching power supply technology or SMPS has actually been known for a long time, since it was first introduced to an application in 1970. So far, we may know that SMPS is widely used in home electronic devices such as VCD players, desktop computers, computer monitors, both flat screens/CRT tubes, to  cell phone chargers etc.  SMPS is known for its light weight, small dimensions, and high efficiency despite some drawbacks.  Also read: Linear Regulated Power Supply Vs SMPS, Which is Better?

 The popularity of SMPS is unquestionable, however, there are still many questions about its durability when applied to high-power audio amplifiers.  SMPS or people also call it AC-MATIC because of this wide input voltage range, there is no doubt about it, including its much lighter weight and smaller dimensions when compared to ordinary transformers.

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 About SMPS advantages and disadvantages compared to ordinary transformers, especially for large watt audio amplifiers

 Can SMPS Power Supply be used for Power Amplifiers with large power, for example for Field Sound Systems?

 About SMPS Advantages and Disadvantages Compared to Ordinary Transformers, Especially for Large Watt Audio Amplifiers

 Get to know what SMPS is at a glance

 Before discussing the advantages and disadvantages, it would be nice to get acquainted more closely with this SMPS.

 SMPS stands for Switch Mode Power Supply, is an electronic circuit that converts power using a switching device, i.e. that is turned on and off at high frequencies.

 How SMPS Works

 The high-voltage AC input voltage from the grid is converted to DC through a rectification process using a rectifier and a filter.  This unregulated DC voltage is then fed to a large filter capacitor or PFC (Power Factor Correction) circuit to correct for the affected power factor.  After that this high DC voltage is activated by switching (switching) very high speed (thousands of times/second) using a MOSFET.

 The mosfet works as a high speed on / off switch, which produces output in the form of a series of pulses on and off periodically at high frequencies – usually between 50 kHz-500 kHz.  MOSFET transistors have low resistance and are able to withstand high currents.  This switching frequency is controlled and driven using feedback current using a PWM oscillator.

 The AC voltage is then fed to the ferrite core transformer to step down the voltage.  Then, the output of this transformer is rectified and smoothed using rectifier and filter components.  The SMPS design topology uses a feedback circuit to control the output voltage by comparing it to the input voltage.  This Feddback circuit makes the SMPS output voltage stable and has a wide range.

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 SMPS Vs Ordinary/Linear Power Supply

 SMPS works at a much higher working frequency of 50 kHz-500 kHz.  It should also be noted that the higher the frequency, the more efficient it will work, so SMPS with the same output as a linear power supply have a much lighter weight and a much smaller transformer.

 SMPS Has High Efficiency

 The output shock on the linear power supply (iron transformer) depends on the tap of the existing transformer.  For non-regulated power supply types, the output voltage varies depending on the load current.  But for a regulated linear power supply, the process results in excessive transistor power dissipation or heat, which reduces efficiency.  Iron core transformers also produce considerable power losses, which in the end can only produce between about 30 or 40% efficiency.

 In SMPS, the output voltage is easily set at any voltage and at any current according to capacity without being affected by dimensions and weight.  Switching system on SMPS, voltage regulation can be obtained only by adjusting the pulse width, that is, by means of the mosfet transistor working completely off or fully on - so the heat and power losses generated will be minimal.  This causes the SMPS power supply to be cooler, which means less power is wasted.  Leveling diodes are a major contributor to power loss in SMPS – but even then they can still produce typical efficiencies of between 60 – 80%.

 SMPS Stability

 SMPS has a wide tolerance input voltage range.  The input voltage varies, namely between a DC voltage of 150 - 300V or an AC voltage between 90 - 265V, SMPS is still able to provide a stable output voltage, aka not easy to drop.  Thus SMPS is also often referred to as AC MATIC;  which means that although the input voltage drops very low to 90V, this does not affect the output voltage which can remain intact or not drop when given a load.  It's different from a linear power supply, where when the AC input voltage from the mains drops, for example, up to 90v (normal grid voltage is generally 220V), the output will also drop a lot, even to the point of not being able to turn on the equipment being supplied because it can't meet the working voltage.  .  ️

 The working temperature of the SMPS is also colder than the linear transformer, while the working temperature of the linear transformer is much hotter.  A hot transformer temperature in a linear transformer will reduce the voltage, while this does not happen in SMPS.  In conclusion, the SMPS transformer never drops as long as the input voltage remains stable.

 SMPS Doesn't Get Hot Easily

 One of the disadvantages of iron core transformers is that they have a high working temperature, which causes the voltage to drop.  SMPS is different, the ferrite core transformer in SMPS is not easy to heat so that the output voltage is relatively stable.  For this reason, SMPS is very suitable and widely applied to equipment that requires a continuous supply of voltage for a very long time, for example 24×7, aka ON continuously.

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 Cheaper SMPS Treatment

 SMPS, if damaged most often is a mosfet or maybe a small resistor and diode.  While the power supply is linear, it is the iron core transformer that often burns or leaks.  The price of the mosfet is of course much cheaper than the price of even the smallest 500mA iron core transformer.  A burnt iron core transformer can indeed be re-rolled, but the cost is still more expensive than the price of a mosfet.  Can a SMPS ferrite core transformer not be damaged?… Yes, of course it can, but this rarely happens, and even if it is damaged, it can also be re-rolled but at a much cheaper cost than iron core transformer winding services ~ you can even wind it yourself.

 Other advantages of SMPS

 SMPS can be equipped with a protection system, so if there is a short circuit or an error in use, the SMPS will activate the protection system so that the output voltage becomes 0 and does not harm the electronic circuit.

 Isolation from the grid is much better, so that high voltage leakage is rare which causes electric shock in the supplied circuit block such as audio.  Iron core transformer very often occurs leakage between primary and secondary, which in many cases has caused people to be electrocuted by the line voltage;  besides that, a leaky transformer can also cause distortion/noise, especially if it is used in an audio amp.

 Main Disadvantages of SMPS

 SMPS is a unit that is not easy to assemble by beginners because it is more complex and requires high accuracy.  In addition, it is also necessary to rectify the high voltage 220VAC from the grid which will turn into 300VDC.  Thus, it is very dangerous if you are not careful when assembling it yourself without adequate knowledge of SMPS – Unless you buy a ready-made kit, SMPS is not a serious problem for beginners, like me... hehe.

 Another drawback is that if the SMPS assembly and parts, especially ultra fast diodes and filter capacitors are of poor quality or KW, then the stray/harmonic frequencies at the output may not be muffled properly, so that eventually it will cause noise interference which is quite disturbing to the audio.  This is because SMPS operates using high frequency pulse voltages.  The effect of noise on audio when using SMPS can also be caused by the ripple voltage which is higher than that of a linear power supply.

 Requires a better voltage regulation system, otherwise the audio quality will be poor/defective.

 SMPS is actually very vulnerable to damage, especially if it has to carry a large power load.  This usually happens in high frequency FETs or diodes, if they are not strong they will usually heat up and eventually die so that the SMPS output voltage is also 0V or totally dead.  This is the quality of the circuit and the type and quality of components, especially FETs and diodes, greatly determine the resistance of SMPS.

 If there is a work failure, then the output voltage can be very high than expected which can make transistor leaks, capacitors explode, even all components are damaged so that SMPS becomes difficult to repair.

 Conclusion: SMPS designs are made very simple or not done properly, and the results may even be worse than linear power supplies/iron transformers especially for audio equipment.

 Can SMPS Power Supply Be Used For Power Amplifier With Large Power For Example For Field Sound System?

 SMPS has higher efficiency including having a wide input voltage range.  This means that it can be more stable when the input voltage is up and down.  However, for very large workloads such as thousands of watts of audio power, the input voltage must still be stable.

 With SMPS we can make POWER AMPLI units with large power but with a small size and very light weight.  Oops Don't drool dong….  haha.

 When paired with power class D, it will be very suitable because both adopt a switching system and both have high efficiency.  Then you will have a giant sub-bass power but with a very thin size and very light weight and more energy efficient.

 The drawback is if SMPS is for large watt audio, for example power class A/B;  SMPS uses FET transistors as pulse generators.  It is feared that this MOSFET transistor could die suddenly because it is unable to supply a large amount of power when the power amplifier reaches its peak power – it could be due to poor quality or lack of specs.  The rectifier diode is also quite prone to breaking if the quality or specs are not proportional to the large load.

 This can be overcome, for example: Strengthening the TR Mosfet in parallel, using a FET or diode type suitable for large power and or using 2 SMPS units for 1 mono power amplifier unit.

 The good news, when the mosfet is dead or short, this will not damage the power amplifier driver at all.  It's just IMPORTANT!!!  If the mosfet is short, the electricity can be tripped ~ for that the use of a suitable fuse is very important to protect the SMPS circuit from fire due to a high voltage short circuit.

 Suggestions don't use SMPS for giant power above 1000 watts if you are not sure about the quality of the SMPS you are using.  If you are still in doubt, you can use 2 units of SMPS/1 unit of mono power.  But before you buy an SMPS, ask the seller about its capabilities – for example, can it be given a load of a few watts of power.

 In my personal opinion, SMPS is safer for supplying class D power only – not for class A/B power.  This is because class D power does not consume a lot of electrical power, aka shock-efficient, so that the SMPS load will be lighter – this is different from the A/B power class which wastes electricity so that SMPS is more prone to breakage.

 And try to use SMPS products that are well designed and have been proven in the field.  so much