The Transformer hum sound in audio amplifiers is a common issue and is caused by the mechanical vibrations of the connected transformer. These vibrations occur due to the magnetic fields generated by the transformer windings when current flows through it. In this article I will explain the possible reasons for transformer humming and its solutions. Let’s check out the common problems and solve them quickly.
Common Causes for Transformer Hum
- Magnetic Saturation of Transformer Core
- Loose Windings or Lamination of Copper Wires
- Operating Frequency
- Load Imbalance
- Defective Components
Magnetic Saturation of Transformer Core
The magnetic saturation is when the magnetic core material ( E core and I core) has reached its limit in carrying magnetic flux and can no longer increase its magnetic field strength, even with increased input. This will create an excessive vibration. This issue happens due to the overloading or the error in designing the transformer.
Loose Windings or Lamination of Copper Wires
The copper wire is wounded on the core in the proper manner. If the winding of copper is not proper or tightened this may cause the humming sound. The second one is proper lamination, failing to provide proper lamination on the transformer core is another reason for humming.
Operating Frequency of transformer
In normal condition the transformer will slightly produce a humming sound at 50 to 60Hz frequency. However, if the humming is louder than usual, it could indicate a problem with the transformer.
Load Imbalance
The output stage is rated as 8 ohms or 4 ohms speakers. The transformer gets strained If the output stages of the amplifier are imbalanced and this will cause it to hum. This may be due to a faulty output stage or incorrect biasing.
Defective Transformer
If the transformer is not working properly or the output voltage is less than the mentioned by the manufacturer is considered as a defective transformer. This type of defective transformer can produce excessive hum sound.
How to reduce Transformer Humming Sound
- Check Transformer
- Mounting Use Soft Mounts or Rubber Grommets
- Check for Overloading
- Upgrade or Replace the Transformer
- Shielding
- Check Grounding
- Balanced Power Supply
Checking the Transformer
Tre transformer produces a small amount of vibration in normal condition. So you must ensure that the transformer is securely mounted and isolated from the amplifier’s chassis to avoid humming sound. Loose mounting of the transformer leads to vibration and hum..
Use Soft Mounts or Rubber Grommets
When tightening the transformer, adding soft mounts, rubber feet, or isolators can reduce the transmission of vibrations to the amplifier’s chassis which can help to reduce the hum.
Check for Overloading of Amplifier
The Amplifier required high current for working with low frequencies audio signals. Eg subwoofer amplifiers. So you need to verify that the transformer is not overloaded and the transformer is able to handle the amplifiers required power usage.
Upgrade or Replace the Transformer
Replacing it with a higher quality one If the transformer is old, damaged, or poorly designed. A transformer with better shielding or a more stable core design might also reduce the hum.
Shielding of Transformer
Reduce the electromagnetic interference of other components when placing a transformer near to the amplifier board. So you need to use a magnetic shielding around the transformer.
Check Grounding Connections
The ground loop or poor grounding can often cause unwanted hum or buzz. So make sure that the amplifier’s ground connection is properly connected.
Conclusion
After trying all the given solutions, the hum sound is severe or persists. You might want to consult an electronic technician who can diagnose the transformer and check if the problem is due to the transformer or if other issues in the circuit are contributing to the hum.
