Car audio fuse types fall into four families with 14 fuses between them. Bolt-down fuses include ANL, mini-ANL, MIDI and MEGA, glass-tube fuses include AGU and AGC, and plug-in blade fuses include regular ATO/ATC, MINI, low-profile MINI, MICRO2, MICRO3 and MAXI, while classic cars add Bosch torpedo and Lucas fuses. Amplifier power cables use bolt-down fuses rated from about 30 to 500 amps, and car radios and the onboard fuses on many amplifiers use blade fuses, typically 10 to 40 amps. Each type fits only its own holder, so two fuses with the same amp rating are not interchangeable across formats. A fuse protects the cable, so its rating comes from the wire and the equipment, which the fuse sizing steps for amplifier wiring cover. This guide is for anyone identifying a blown fuse or choosing the right format for new audio wiring.
Table of Contents
Bolt-Down Car Audio Fuses
Bolt-down fuses are the standard type of car audio fuse for amplifier power cables because their bolted terminals carry high current with very little resistance. Each one sits in a holder with two studs, and the nuts clamp the fuse ends against the cable terminals.
1. ANL Fuse
An ANL fuse is a large bolt-down fuse with a flat metal element between two slotted ends, commonly sold from about 35 to 300 amps for car audio and up to 500 amps for very large systems. It's the most common main fuse on 4 AWG and 1/0 AWG amplifier power cables.
Most automotive ANL fuses are rated for 32 volts DC or higher, and their wide terminals spread the clamping force well. The drawback is size, since an ANL holder takes noticeably more room than a MIDI or mini-ANL holder.
Best for: main amplifier fuses on 4 AWG to 1/0 AWG power cable.
2. Mini-ANL (AFS) Fuse
A mini-ANL fuse is a smaller version of the ANL with the same bolt-down design, commonly sold from about 30 to 150 amps. AFS is a closely related compact audio fuse, and many distribution blocks and fused holders from audio brands use one of the two.
Mini-ANL and AFS dimensions vary slightly between makers, so a similar label does not guarantee a fit. Match the fuse to the part number the holder maker lists.
Best for: 8 AWG and 4 AWG runs and fused distribution blocks where space is tight.
3. MIDI Fuse
A MIDI fuse is a compact bolt-down fuse with a plastic body and a window over the element, made in ratings from about 30 to 200 amps. Littelfuse sells it as MIDI, and the Eaton Bussmann equivalent is the AMI.
MIDI fuses are common in factory power distribution and make a tidy main fuse for audio feeds up to 200 amps. A mini-ANL can look similar, but the two can differ in body and terminal dimensions, so check the fuse type printed on the holder or its instructions.
Best for: compact main fuses and battery-terminal fuse blocks up to 200 amps.
4. MEGA Fuse
A MEGA fuse is the largest common bolt-down automotive fuse, typically rated from 100 to 500 amps. Littelfuse calls it MEGA, and the Eaton Bussmann equivalent is the AMG. Many vehicles use a MEGA fuse on the alternator output, and the same format suits large audio systems running 1/0 AWG cable.
Best for: very high-current main feeds and protecting the alternator cable during a Big 3 charging wire upgrade.
Glass-Tube Car Audio Fuses
Glass-tube fuses use a glass body with metal end caps, and the element is visible through the glass. They clip or screw into holders sized for their exact length and diameter.
5. AGU Fuse
An AGU fuse is a large glass-tube fuse measuring about 10 × 38 mm (13/32 × 1-1/2 inches), common in older amplifier wiring kits and distribution blocks in ratings up to about 80 amps.
AGU holders rely on spring clips or set screws touching the end caps, and that small contact area can heat up and discolor under heavy current. For a new install drawing more than about 60 amps, we recommend an ANL, mini-ANL or MIDI holder instead.
Best for: like-for-like replacement in existing AGU holders and moderate current runs.
6. AGC Fuse
An AGC fuse is a smaller glass-tube fuse measuring about 6.3 × 32 mm (1/4 × 1-1/4 inches), also called a 3AG fuse, and is usually rated up to 30 amps. It appears in inline holders on older head unit power leads, in some equalizers and crossovers, and in older amplifiers.
AGC is a fast-acting fuse, and time-delay fuses in the same body size carry a different code, such as MDL. Replace it with the same size and the same speed so a normal power-on surge does not open it.
Best for: low-current radio and accessory circuits in older installs.
Blade Fuses Used in Car Radios and Amplifiers
Blade fuses have a plastic body and two flat metal prongs that plug into a socket. Car radios, many aftermarket amplifiers and the vehicle's own fuse box use them. The body color shows the amp rating, but the color code is shared only by the regular, MINI and MICRO families, so a red MAXI fuse is 50 amps while a red regular blade is 10 amps.
Figure: Different Blade Type Car Fuses
Amp rating | Regular, MINI and MICRO2 color | MAXI color |
|---|---|---|
5 A | Tan | Not made |
7.5 A | Brown | Not made |
10 A | Red | Not made |
15 A | Blue | Not made |
20 A | Yellow | Yellow |
25 A | Clear or natural | Not common |
30 A | Green | Green |
40 A | Orange (amber) | Orange (amber) |
50 A | Not made | Red |
60 A | Not made | Blue |
7. Regular Blade Fuse (ATO/ATC)
The regular blade fuse, sold as ATO or ATC, is about 19 mm wide and comes in ratings from 1 to 40 amps. ATO fuses leave the element open on the underside, while ATC fuses are fully sealed, and both fit the same socket.
Many aftermarket head units carry a 10 or 15 amp ATC fuse on the back of the chassis or in the power lead, and the fuse rating for a car stereo depends on the model. Many amplifiers also use two or more 25 or 30 amp ATC fuses on board instead of one large fuse.
Best for: head unit power leads, onboard amplifier fuses and older vehicle fuse boxes.
8. MINI Blade Fuse (ATM)
The MINI blade fuse, also called ATM or APM, is about 11 mm wide and covers 2 to 30 amps. It has been the most common fuse in vehicle fuse boxes since the 1990s, and it protects the factory radio circuit in many cars.
Best for: factory radio and accessory circuits in the vehicle fuse box.
9. Low-Profile MINI Fuse
The low-profile MINI fuse has the same width and terminal spacing as a MINI but a shorter body that sits almost flush with the fuse box. It's rated from 2 to 30 amps. Check whether your fuse box was designed for the shorter body before mixing the two, and keep a fuse puller handy, since there is little to grip.
Best for: newer fuse boxes that list low-profile MINI fuses on the lid diagram.
10. MICRO2 Fuse
The MICRO2 fuse is a narrow two-prong blade fuse about 9 mm wide, rated from 5 to 30 amps and used in many newer vehicles. Its prongs are thinner and closer together than a MINI's, so it does not fit a MINI socket even at the same rating.
Best for: radio and accessory circuits in newer vehicles that specify MICRO2.
11. MICRO3 Fuse
The MICRO3 fuse has three prongs and protects two circuits from one fuse body, with ratings from 5 to 15 amps. A MICRO2 cannot replace it, since the third prong and the two-circuit layout are part of the design.
Best for: vehicle fuse boxes that use MICRO3 positions, never added audio wiring
12. MAXI Fuse
The MAXI fuse is a large blade fuse about 29 mm wide, commonly rated from 20 to 80 amps, with larger sizes from some makers. Vehicles use it on high-current circuits, and some fused distribution blocks and battery-terminal blocks use it for moderate amplifier feeds.
Best for: amplifier feeds up to about 80 amps where the holder is rated for MAXI fuses.
Legacy Fuses in Classic Cars
Classic cars often use fuse types that predate blade fuses. For an added audio system, we'd leave those original circuits untouched and run the amplifier from its own modern fuse on a separate power feed.
13. Bosch (Torpedo) Fuse
A Bosch fuse, also called a torpedo or continental fuse, has a ceramic or plastic body with a metal strip along one side and cone-shaped ends. Though they've largely been superseded by blade fuses in new vehicles, they remain relevant in classic cars and specific European models.
Standard torpedo colors are yellow for 5 amps, white for 8 amps, red for 16 amps and blue for 25 amps, so a color means something different here than it does on a blade fuse.
14. Lucas Fuse
A Lucas fuse is a glass cartridge fuse used in older British cars, usually 1-1/4 inches long with a paper label inside the glass. Lucas fuses were marked with their blow rating instead of their continuous rating, so a fuse labeled 35 amps carries only about 17 amps continuously. Swapping in a modern 35 amp fuse roughly doubles the current the circuit can carry before it opens, which can let a fault overheat the original wiring.
Circuit Breakers as a Fuse Alternative
A circuit breaker opens like a fuse during an overload but can be reset instead of replaced. Car audio breakers are usually manual-reset (Type III) units rated from about 50 to 300 amps, and many double as a power switch for working on the system.
Breakers usually react more slowly than fuses on a dead short, and low-quality units can trip early or fail to trip at all. We prefer a fuse at the battery for the main protection, with a breaker used only where its rating and trip curve are published.
Car Audio Fuse Types Compared
This table sets all the car audio fuse types side by side, along with the connection style that decides which holder each one needs. Exact dimensions for every family are published in the Littelfuse automotive fuse catalog, which is the safest reference when two fuses look alike.
Fuse type | Connection | Common rating range | Typical audio use |
|---|---|---|---|
ANL | Bolt-down | 35 to 500 A | Main amplifier power fuse |
Mini-ANL / AFS | Bolt-down | 30 to 150 A | Distribution blocks, mid-size amps |
MIDI (AMI) | Bolt-down | 30 to 200 A | Compact main fuse |
MEGA (AMG) | Bolt-down | 100 to 500 A | Alternator and very large feeds |
AGU | Glass tube, clip | Up to about 80 A | Older amp kits and blocks |
AGC (3AG) | Glass tube, clip | Up to 30 A | Older radios, inline accessories |
Regular blade (ATO/ATC) | Plug-in | 1 to 40 A | Head units, onboard amp fuses |
MINI (ATM) | Plug-in | 2 to 30 A | Factory radio circuit |
Low-profile MINI | Plug-in | 2 to 30 A | Newer vehicle fuse boxes |
MICRO2 | Plug-in | 5 to 30 A | Newer vehicle fuse boxes |
MICRO3 | Plug-in, three prongs | 5 to 15 A | Dual circuits in newer fuse boxes |
MAXI | Large plug-in | 20 to 80 A and up | Moderate amp feeds, vehicle circuits |
Bosch torpedo | Clip, cone ends | 5 to 25 A | Classic European cars |
Lucas | Glass cartridge | Blow-rated | Classic British cars |
Circuit breaker | Bolt-down studs | 50 to 300 A | Resettable main protection |
Which Fuse Type Is Best for Car Audio?
The best fuse type for car audio depends on the circuit it protects. For an amplifier's main power cable, an ANL, mini-ANL or MIDI fuse in a covered holder is the best choice, because bolted terminals handle 50 to 300 amps without the heating clip-style glass holders suffer. For an aftermarket head unit, use the blade fuse type and rating the radio maker specifies, usually a 10 or 15 amp ATC. The vehicle's own radio circuit keeps the MINI, MICRO2 or other format already in the fuse box.
Running more than one amplifier adds a second layer of protection, a fused distribution block with a smaller fuse for each branch cable, and the guide to running two amplifiers from one power wire walks through the layout. Planning the whole system first, with the comparison of car audio system types, tells you whether you're fusing a single radio circuit or a multi-amp build, and the power and wiring components list shows every part that sits on that power path.
How Do You Identify and Replace a Car Audio Fuse?
Car audio fuse types are easiest to identify by shape and terminals first, then by the printed amp rating, and a replacement should match both the type and the rating.
You'll need the vehicle owner's manual or the equipment manual, a fuse puller or needle-nose pliers, a multimeter or test light, a wrench or socket for the battery terminal and holder nuts (10 mm is common), and a replacement fuse of the same type and rating. It's a one-person job.
1.Turn the ignition off and remove the key, so the radio and amplifier circuits are not live when you pull a fuse.
Turn the ignition off and remove the key, so the radio and amplifier circuits are not live when you pull a fuse.
- Disconnect the negative battery terminal before opening an amplifier's main fuse holder, because that holder sits on a cable connected straight to the battery positive.
- Find the fuse using the fuse-box diagram in the manual, the back of the head unit, the inline holder on the radio's yellow or red lead, the amplifier's fuse bay or the main holder near the battery.
- Leave yellow connectors and yellow-sleeved harnesses alone while tracing radio wiring, since yellow marks airbag circuits.
- Remove the fuse with a puller, or loosen the holder nuts on a bolt-down fuse.
- Test the fuse out of the circuit with a multimeter set to continuity or resistance, where a good fuse reads close to 0 ohms and a blown one reads open (OL).
- Read the type and rating printed on the fuse body, then pick a replacement that matches both.
- Inspect the holder for melted plastic, discolored contacts or loose nuts, because a damaged holder can overheat even with the correct fuse.
- Fit the new fuse and tighten bolt-down terminals to the torque the holder maker lists, since a loose terminal creates resistance and heat under load.
- Reconnect the battery and test the system at low volume before turning it up.
What if the new fuse blows again?
A replacement fuse that blows immediately points to a short circuit, most often a power or speaker wire pinched against metal, a failed amplifier or a head unit with an internal fault. A fuse that blows only at high volume points to an amplifier drawing more current than the circuit was designed for, or to an impedance load below what the amplifier supports.
Never fit a larger fuse to stop it blowing, because the rating exists to protect the cable. Our standard is to find the short or overload before fitting another fuse, then confirm the rating against the amplifier fuse rating calculator.
Questions people usually ask (FAQ)
What kind of fuse does a car radio use?
A car radio usually has two fuses. One is a MINI, MICRO2 or regular blade fuse in the vehicle fuse box, and most aftermarket radios add a 10 or 15 amp ATC blade fuse on the back of the unit or in its power lead. The owner's manual and the radio's installation manual list both ratings.
Are ANL and AGU fuses interchangeable?
Not quite. While both are built for high-current protection, they differ in size, shape, and mounting style. Always double-check compatibility with your fuse holder before swapping one for the other. Moving from AGU to ANL means replacing the holder as well.
Can you use a higher amp fuse than the one that blew?
No. A higher-rated fuse lets more current through the wire than it was sized for, which can overheat the cable before the fuse ever opens.
What is the difference between ATO and ATC fuses?
ATO and ATC fuses share the same size and amp ratings. An ATO fuse has an open element on the underside, while an ATC fuse is fully sealed in plastic, which suits damp locations better.
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