Littelfuse fuses for audio equipment, electronics and repairs

A good fuse is often the smallest component in a device, but it plays a crucial role in the safety and reliability of the entire system. With Littelfuse fuses, you choose a globally renowned manufacturer known for high-quality circuit protection for consumer electronics, industrial applications, medical equipment and high-end audio equipment.

Whether you want to replace a blown fuse in an amplifier, speaker processor, DAC, tube amplifier or power supply, or safely protect a new design: Littelfuse offers reliable solutions that comply with international safety standards such as IEC 60127 and various UL certifications. Littelfuse produces both fast-acting fuses and time-delay / slow-blow fuses in different sizes, including the widely used 5x20 mm and 6.3x32 mm versions.

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Why choose Littelfuse?

Littelfuse is one of the best-known manufacturers of fuses and circuit protection in the world. Its products are used in thousands of electronic devices and are known for:

- High reliability and consistent quality

- Compliance with European IEC standards

- Availability of fast-blow and slow-blow versions

- Ceramic and glass fuses

- RoHS-compliant and lead-free production

- Use in audio, medical and industrial electronics

For sensitive audio electronics, Littelfuse fuses are often used because of their mechanical strength, stable characteristics and reliable opening behaviour. Several Littelfuse 5x20 mm series are specifically developed for audio and video electronics.

When should a fuse be replaced?

A fuse is designed as a protection component. When excessive current occurs, the fuse interrupts the circuit to prevent damage to components, wiring or users.

- Common situations in which a fuse needs to be replaced:

- An amplifier no longer powers on.

- An active speaker remains completely without power.

- A subwoofer amplifier has suffered a power-supply fault.

- A tube amplifier has had a faulty output tube.

- A DIY audio project is being powered up for the first time.

- An old amplifier from the 1970s, 1980s or 1990s is being restored.

Important: a blown fuse is often a symptom and not always the cause of the problem. If a new fuse blows immediately again, there is usually an underlying fault that must be resolved first. Repair specialists within the audio community also point out that a fuse is intended to prevent damage and fire when a fault occurs inside the device.

Fast-blow or slow-blow fuse?

One of the most frequently asked questions is the difference between fast-acting and time-delay fuses.

Fast Blow (F)

A fast-acting fuse responds almost immediately to overcurrent. It is used for sensitive electronics where components need direct protection against current spikes.

- Typical applications:

- DACs

- Digital electronics

- Test and measurement equipment

- Signal processing

Slow Blow (T)

A slow-blow or time-delay fuse can tolerate short inrush currents without blowing immediately. Many power supplies and amplifiers temporarily draw a higher current when switched on.

Typical applications:

- Amplifiers

- Toroidal transformers

- Switch-mode power supplies

- Tube amplifiers

- Active speakers

Littelfuse produces various time-delay series specially designed for equipment with high inrush currents.

How do I choose the right replacement fuse?

When replacing a fuse, the original specifications should always be followed.

Check:

- The size (for example 5x20 mm or 6.3x32 mm)

- The current rating (amperes)

- The voltage rating (volts)

- The type (fast-blow or slow-blow)

- The material (glass or ceramic)

Never use a fuse with a higher current rating than specified. An oversized fuse can allow components to become damaged before the protection activates.

In audio equipment, 5x20 mm fuses are most commonly used. Littelfuse supplies both fast-acting and time-delay versions for this size, compliant with international IEC specifications.

Frequently asked questions about Littelfuse fuses

Which fuse is usually found in an amplifier?

Many hi-fi amplifiers, power amplifiers and active speakers use time-delay (T) 5x20 mm fuses to handle transformer inrush currents.

Can I replace a slow-blow fuse with a fast-blow fuse?

No. The fuse type is part of the device’s safety design. Always use the same type specified by the manufacturer.

What does T2A or F3.15A mean?

- T = Time Delay (slow-blow fuse)

- F = Fast Acting (fast-blow fuse)

- The number indicates the rated current.

Examples:

- T2A = 2 ampere slow-blow fuse

- 15A = 3.15 ampere fast-blow fuse

Why does my new fuse blow immediately again?

This usually indicates a fault in the device, such as a defective power supply, short circuit, faulty transistor or faulty tube. Replacing only the fuse will not solve the underlying problem.

Are Littelfuse fuses suitable for audio equipment?

Yes. Several Littelfuse series are specifically used in audio and video electronics, including home audio systems, amplifiers, power supplies and other sensitive electronic equipment.

Order Littelfuse fuses at SoundImports

At SoundImports, you will find an extensive range of Littelfuse fuses for repair, maintenance and new-build projects. From fast-acting glass fuses to high-quality ceramic slow-blow versions for amplifiers and power supplies.

With original Littelfuse fuses, you choose reliable circuit protection according to international safety standards, helping your audio equipment continue to operate safely and reliably.