Introduction
The Fender Mustang LT40S is a versatile and user-friendly guitar amplifier designed for practicing and jamming at home. It delivers 40 watts of stereo power through a pair of high-fidelity, full-range 4-inch speakers. Featuring a simple user interface and a full-color display, the LT40S offers a wide array of built-in presets covering various electric guitar tones. Its robust signal chain includes high-quality onboard amp and effects models, enabling a broad spectrum of sounds. Users can also connect to the free Fender TONE LT Desktop app to edit, store, and manage presets on a Mac or PC. This amplifier provides a fun, flexible, and accessible experience for guitarists of all levels.
Setup
Before operating your Fender Mustang LT40S amplifier, please follow these steps to ensure proper setup and functionality.
1. Unpacking and Placement
Carefully remove the amplifier from its packaging. Place the amplifier on a stable, flat surface. Ensure adequate ventilation around the unit to prevent overheating. Avoid placing it near heat sources or in direct sunlight.

The Fender Mustang LT40S Guitar Amplifier, showcasing its compact design and front grille.
2. Power Connection
Connect the supplied power cord to the amplifier's power input jack and then to a suitable AC power outlet. Ensure the power switch is in the OFF position before connecting to power.
3. Connecting Your Instrument
Plug your guitar cable into the instrument input jack on the front panel of the amplifier. Use a high-quality instrument cable for optimal sound transmission.

A person playing an electric guitar, with the Fender Mustang LT40S amplifier visible on the floor, demonstrating a typical setup for practice.
4. Initial Power-On
Once all connections are secure, turn the amplifier's power switch to the ON position. The display will illuminate, indicating the amplifier is ready for use. It is recommended to start with the Master Volume knob set to a low level.
Operating the Amplifier
The Mustang LT40S features an intuitive control panel and a full-color display for easy navigation and tone shaping.
Front Panel Controls

A detailed view of the Fender Mustang LT40S amplifier's control knobs, including Volume, Gain, Treble, Bass, and Master, along with the preset selection knob.
- Volume: Adjusts the input gain, affecting the amount of distortion.
- Gain: Controls the overall loudness of the amplifier.
- Treble: Adjusts the high-frequency response.
- Bass: Adjusts the low-frequency response.
- Master: Controls the overall output volume of the amplifier.
- Preset Knob/Display: Used to select from the 30 built-in presets and navigate menus on the full-color display.
Preset Selection and Editing
The LT40S comes pre-loaded with 30 diverse presets. Rotate the Preset knob to browse through them. To customize a preset or create your own, you can adjust the amp models (20 available) and effects (25 available) using the control knobs and the display interface. Your changes can be saved to one of the available memory locations.
Fender TONE LT Desktop App
For advanced editing, storing, and managing your presets, download the free Fender TONE LT Desktop app. Connect your amplifier to your Mac or PC via USB to access a comprehensive interface for deep customization of amp models, effects, and signal chain routing.
Maintenance
Proper maintenance will ensure the longevity and optimal performance of your Fender Mustang LT40S amplifier.
- Cleaning: Disconnect the amplifier from power before cleaning. Use a soft, dry cloth to wipe down the exterior. Do not use abrasive cleaners, solvents, or waxes, as these can damage the finish.
- Storage: When not in use, store the amplifier in a cool, dry place away from direct sunlight and extreme temperatures.
- Ventilation: Ensure that the amplifier's ventilation openings are not blocked during operation to prevent overheating.
- Transportation: When moving the amplifier, use the integrated handle and ensure it is securely placed to prevent damage from drops or impacts.
Troubleshooting
If you encounter issues with your Mustang LT40S, refer to the following common problems and their solutions.
| Problem | Possible Cause | Solution |
|---|---|---|
| No Sound Output |
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| Distorted or Poor Sound Quality |
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| Amplifier Not Powering On |
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Specifications
| Feature | Detail |
|---|---|
| Model Name | Mustang LT40S |
| Output Wattage | 40 Watts (Stereo) |
| Speakers | Two 4-inch Full-Range Fender Special Design |
| Amp Models | 20 |
| Effects | 25 |
| Presets | 30 (User-editable) |
| Connectivity | USB (for Fender TONE LT Desktop App) |
| Display | Full-Color LCD |
| Item Weight | 14.65 pounds |
| Product Dimensions | 14.4 x 8.3 x 8 inches |
| Power Source | Corded Electric |
Warranty and Support
The Fender Mustang LT40S Guitar Amplifier comes with a 2-Year Warranty, ensuring peace of mind regarding manufacturing defects and performance issues under normal use.
For detailed warranty information, technical support, or service inquiries, please visit the official Fender support website or refer to the full user manual available for download.
Official User Manual (PDF): Download PDF
Fender Support: For additional assistance, please visit the Fender Support Page.





