Gold-A502 2x30W Bluetooth 5.0 Audio Stereo Digital Power Amplifier Board

Key Features

• 2.0-channel stereo amplifier

• Maximum 30W + 30W output

• 60W total maximum claimed output

• Class-D digital amplification

• Bluetooth 5.0

• AUX audio input

• USB flash-drive playback

• TF/microSD card playback

• Integrated volume control

• DC 8V–24V operating range

• DC 12V–24V recommended

• 4Ω–8Ω speaker compatibility

• 
  

  90% efficiency

• Bluetooth range up to approximately 10–15m in open conditions

• Integrated heat sink

• Multiple playback modes

• Suitable for complete DIY speaker systems

Amplifier Specifications

Power Specifications

Speaker Specifications

Audio & Playback

Bluetooth Specifications

Physical Specifications

Protection Features

The current RoboGears listing specifies protection functions including:

• Overvoltage protection

• Undervoltage protection

• Overheating protection

• Short-circuit protection

• DC detection

Protection implementation can vary between manufacturing revisions, so correct power supply, polarity and speaker wiring should always be maintained.

Understanding the 30W + 30W Rating

The maximum advertised output is:

30W + 30W

under suitable operating conditions.

RoboGears recommends approximately:

24V / 3A–5A

for applications intended to approach the board's higher output capability.

Lower supply voltage will reduce the maximum available amplifier output.

Compatibility

The Gold-A502 is designed for a:

2.0-Channel Stereo Speaker System

consisting of:

• 1 × Left Passive Speaker

• 1 × Right Passive Speaker

Speaker Compatibility

Supported impedance:

4Ω–8Ω

For higher-output operation, use speakers with adequate power handling.

For a system intended to approach maximum amplifier output, approximately 30W or higher per speaker is recommended.

Power Supply Compatibility

Supported:

DC 8V–24V

Recommended practical range:

DC 12V–24V

For higher-output applications:

24V / 3A–5A

is recommended.

Do not exceed 24V DC.

Bluetooth Compatibility

Bluetooth 5.0 enables wireless audio from compatible:

• Android smartphones

• iPhones

• Tablets

• Laptops

• Computers

• Other Bluetooth audio-source devices

Actual wireless range depends on the installation environment.

AUX Compatibility

AUX input can be used with compatible:

• Smartphones with analogue output/adaptor

• Computers

• TVs with analogue audio output

• MP3 players

• Audio decoder boards

• Other line-level audio sources

USB Playback

The A502 supports compatible USB flash-drive media playback.

This allows the amplifier to operate as a standalone audio player without requiring a continuously connected smartphone.

TF Card Playback

The board also supports compatible:

TF / microSD cards

for stored audio playback.

Required for a Complete System

You will generally need:

• Suitable DC power supply

• Left passive speaker

• Right passive speaker

• Speaker wires

The audio source can then be:

• Bluetooth device

• AUX source

• USB flash drive

• TF/microSD card

Before Purchase

Channels: 2.0 Stereo

Speaker Load: 4Ω–8Ω

Supply: DC 8V–24V

Bluetooth: Built in

USB Playback: Built in

TF Card Playback: Built in

AUX: Supported

Dedicated Subwoofer Channel: No

Applications

• DIY Bluetooth speakers

• Desktop stereo systems

• Bookshelf speaker projects

• Portable speaker projects

• Home audio systems

• Multimedia speakers

• Workshop audio systems

• Custom wooden speaker cabinets

• USB music players

• TF-card music players

• Computer speaker systems

• Educational audio projects

• DIY amplifier boxes

• Wireless stereo systems

• Audio prototyping

Suitable For

• DIY audio enthusiasts

• Electronics hobbyists

• Speaker builders

• Engineering students

• Makers

• Audio technicians

• Electronics laboratories

• Custom speaker projects

📦 What's Included

❌ What's Not Included

Unless specifically offered as part of another bundle, the standard package does not include:

• DC Power Supply / SMPS

• Left Speaker

• Right Speaker

• Subwoofer

• Speaker Wire

• AUX Cable

• USB Flash Drive

• TF / microSD Card

• Smartphone / Audio Source

• Complete Speaker Cabinet

• AC Power Cable

Important Purchase Note

This product is an amplifier and audio playback board, not a complete ready-to-use speaker system.

For a basic Bluetooth speaker system, you will generally need:

DC Power Supply + Gold-A502 + Left Speaker + Right Speaker + Speaker Wiring

Because Bluetooth is already built into the A502, a separate Bluetooth receiver is normally not required.

Standalone Media Playback

For stored music playback, compatible media can be connected through:

• USB Flash Drive

or

• TF / microSD Card

Product Variation

PCB colour, heat-sink appearance, control-knob style, connector design, capacitor brands and minor component placement may vary between manufacturing batches while maintaining the intended A502 functionality.

Getting Started

Step 1 — Identify the Connections

Before applying power, identify the connections printed on the actual PCB, including:

• DC power input

• Left speaker output

• Right speaker output

• AUX input

• USB port

• TF/microSD slot

• Volume control

• Playback / mode controls, where provided

Always follow the labels on the actual board.

Step 2 — Select the Power Supply

Supported range:

DC 8V–24V

Recommended practical range:

DC 12V–24V

For higher-power operation:

24V / 3A–5A

is recommended.

Never exceed 24V DC.

Step 3 — Select the Speakers

Use passive speakers within:

4Ω–8Ω

For high-output applications, use speakers capable of safely handling the amplifier's available output.

Step 4 — Connect the Speakers

Connect:

Left Speaker → Left Output

Right Speaker → Right Output

Check all connections before applying power.

Step 5 — Reduce the Volume

Turn the onboard volume control down before first startup.

This prevents unexpectedly high speaker output.

Step 6 — Connect Power

Verify:

• Correct voltage

• Correct polarity

• Sufficient current capacity

• Secure power connection

Then apply power.

Step 7 — Bluetooth Playback

For wireless playback:

1. Power on the A502.

2. Enable Bluetooth on your phone, tablet or computer.

3. Search for the amplifier's available Bluetooth device.

4. Connect to the A502 audio device.

5. Start music playback.

6. Increase volume gradually.

Bluetooth device naming can vary between board/decoder revisions.

Step 8 — AUX Playback

Connect a compatible line-level audio source to the AUX input.

Start with low source and amplifier volume.

Increase gradually after confirming clean audio.

Step 9 — USB Playback

Insert a compatible USB flash drive containing supported audio files.

Use the board's available playback/mode controls as applicable.

Step 10 — TF Card Playback

Insert a compatible TF/microSD card containing supported audio files.

Select the appropriate playback mode if required by the board revision.

Step 11 — Test Both Channels

Verify:

• Left speaker output

• Right speaker output

• Bluetooth playback

• AUX playback

• USB playback if required

• TF-card playback if required

• Volume adjustment

Basic Bluetooth System

Smartphone

↓

Bluetooth 5.0

↓

Gold-A502

↓

Left Speaker + Right Speaker

and

DC Power Supply → Gold-A502

USB / TF Standalone System

USB Flash Drive / TF Card

↓

Gold-A502

↓

Left Speaker + Right Speaker

High-Power Setup

For applications intended to approach the advertised output:

24V DC / 3A–5A + Suitable 4Ω–8Ω Speakers

provides a practical configuration.

Actual output still depends on the complete system.

🔧 Prototyping and Engineering Tips from RoboGears

1. Use 24V for Higher Output

The amplifier operates across DC 8V–24V, but maximum available power depends strongly on supply voltage.

For applications intended to approach the maximum 30W-per-channel output, use a suitable:

24V / 3A–5A regulated supply

2. Don't Expect 30W + 30W at 8V or 12V

Lower supply voltage significantly reduces the maximum available amplifier output.

The 30W + 30W specification should therefore not be treated as the output at every operating voltage.

3. Match the Speakers Correctly

Use:

4Ω–8Ω passive speakers

For high-volume operation, use speakers with sufficient power handling.

4. Use a Clean Regulated Power Supply

Poor-quality power supplies can introduce:

• Hum

• Buzz

• Switching noise

• Distortion

• Bluetooth interference

A good regulated supply can noticeably improve system performance.

5. Keep the Bluetooth Area Clear

Metal around the Bluetooth antenna area can reduce wireless range.

When designing an enclosure:

• Keep the Bluetooth antenna area away from large metal surfaces

• Prefer plastic or wooden enclosures around the antenna area

• Avoid placing the antenna directly beside high-current wiring

6. Don't Assume 15m Indoors

The published Bluetooth range of approximately 10–15m applies to favourable open conditions.

Actual range may decrease because of:

• Walls

• Metal cabinets

• Wi-Fi/Bluetooth interference

• Antenna orientation

• Nearby electronics

7. Keep AUX Wiring Short

For wired analogue audio, keep AUX/signal wiring away from:

• Speaker-output wires

• High-current DC cables

• Switching power circuitry

This can help reduce unwanted noise.

8. Maintain Heat-Sink Airflow

The board includes a substantial heat sink.

Do not completely cover it inside a tightly sealed enclosure during sustained high-power operation.

9. Reduce Volume if Clipping Occurs

If audio becomes harsh or distorted at high volume:

• Reduce amplifier volume

• Check supply voltage

• Check available supply current

• Check speaker impedance

• Check source level

10. USB and TF Playback Are Useful for Standalone Builds

Because the board incorporates media playback, it can be used without a dedicated external Bluetooth/MP3 decoder board.

This can simplify:

• Portable speakers

• Workshop audio systems

• Standalone music boxes

• DIY stereo cabinets

11. Use Proper Speaker Wire

At higher output levels, undersized wiring can introduce voltage loss and unnecessary resistance.

Use appropriately sized speaker wire for the installation.

12. Test Every Input Before Final Assembly

Before permanently installing the board into an enclosure, test:

• Bluetooth

• AUX

• USB

• TF card

• Left speaker

• Right speaker

• Volume control

This avoids dismantling the enclosure later.

Troubleshooting

Bluetooth Does Not Connect

Check:

• Amplifier power

• Bluetooth enabled on source

• Distance from board

• Previously connected devices

• Interference

• Current playback/input mode

Bluetooth Range Is Poor

Check:

• Metal enclosure

• Antenna obstruction

• Board position

• Nearby wireless interference

USB / TF Card Does Not Play

Check:

• Media installation

• Audio files

• Selected playback mode

• Card/drive condition

Because supported formats and storage capacities can vary between decoder revisions, test the media with the actual board.

AUX Has No Sound

Check:

• AUX cable

• Source output

• Source volume

• Input/playback mode

• Amplifier volume

One Speaker Does Not Work

Check:

• Speaker wiring

• Speaker itself

• Left/right output

• Audio source

Swap speakers between channels to isolate the problem.

Distortion at High Volume

Possible causes include:

• Insufficient supply current

• Low supply voltage

• Amplifier clipping

• Excessive source level

• Speaker limitation

Amplifier Gets Too Hot

Check:

• Speaker impedance

• Supply voltage

• Output level

• Ventilation

• Heat-sink clearance

Engineering Principle

A reliable stereo system requires correct matching of:

Audio Source + Power Supply + Amplifier + Speakers + Wiring + Enclosure + Cooling

The amplifier's wattage rating alone does not determine final sound quality.

FAQ

1. What is the Gold-A502?

The Gold-A502 is a compact 2.0-channel Class-D stereo amplifier and audio playback board with Bluetooth, AUX, USB and TF-card support.

2. What is the output power?

Published maximum output:

30W + 30W

under suitable operating conditions.

3. Is it stereo?

Yes.

It provides:

• Left channel

• Right channel

4. Is it a 2.1-channel amplifier?

No.

The Gold-A502 is a 2.0-channel stereo amplifier without a dedicated amplified subwoofer channel.

5. Does it have Bluetooth?

Yes.

The board supports:

Bluetooth 5.0

6. What is the Bluetooth range?

Published range is approximately:

10–15 metres in favourable open conditions

Actual range depends on the installation environment.

7. Does it support AUX?

Yes.

AUX wired audio input is supported.

8. Does it support USB flash drives?

Yes.

The A502 supports USB-drive audio playback.

9. Does it support TF / microSD cards?

Yes.

TF-card audio playback is supported.

10. Does it require a separate MP3 decoder?

Not for its built-in Bluetooth, USB, TF-card and AUX playback functions.

These functions are already integrated into the A502.

11. What power supply does it require?

Supported range:

DC 8V–24V

Recommended practical range:

12V–24V DC

12. Which power supply should I use for higher output?

For higher-power operation, approximately:

24V / 3A–5A

is recommended.

13. Can I use a 12V adapter?

Yes.

12V is within the supported range, but maximum available output will be lower than with a suitable 24V supply.

14. Can I use a 24V adapter?

Yes.

24V is within the specified range.

Use a regulated supply with sufficient current capacity.

15. Which speakers can I use?

Published compatibility:

4Ω–8Ω passive speakers

16. Can I use 4Ω speakers?

Yes.

4Ω speakers are supported.

17. Can I use 8Ω speakers?

Yes.

8Ω speakers are supported, although obtainable maximum output can differ from a 4Ω configuration.

18. Does it have volume control?

Yes.

The current RoboGears listing specifies an integrated volume-control knob.

19. Does it have bass and treble controls?

Dedicated adjustable bass and treble controls are not specified for the standard Gold-A502.

An external tone-control/pre-amplifier can be added if required.

20. Does it have a dedicated subwoofer output?

No.

This is a two-channel stereo amplifier.

21. What are the dimensions?

Approximately:

80.5 × 67 × 35mm

22. Does it have a heat sink?

Yes.

The board incorporates a large heat sink for thermal management.

23. Can I build a Bluetooth speaker with it?

Yes.

A basic configuration is:

Gold-A502 + DC Power Supply + Left Speaker + Right Speaker

Bluetooth audio functionality is already built in.

24. Can it work without a phone?

Yes.

USB flash-drive and TF-card playback allow compatible stored music to be played without continuously using a smartphone as the audio source.

25. Is a power supply included?

No.

The standard package contains the amplifier board only.

26. Are speakers included?

No.

Speakers must be purchased separately.

27. Is the USB drive included?

No.

A USB flash drive is not included in the standard package.

28. Is a TF/microSD card included?

No.

A memory card must be purchased separately if required.

29. Which amplifier IC does it use?

The current RoboGears listing identifies the board as using dual TPA3116D2 amplifier ICs.

However, because generic A502 board revisions can vary, RoboGears recommends confirming the markings on the actual physical stock before using the exact IC count as a guaranteed specification.

30. Does 30W + 30W mean 60W continuous output?

Not necessarily.

The published 30W + 30W figure represents the board's maximum advertised output under suitable operating conditions.

Actual continuous output depends on:

• Supply voltage

• Available current

• Speaker impedance

• Input signal

• Thermal conditions

Important Safety Note

• Use DC power only.

• Observe correct polarity.

• Do not exceed 24V DC.

• Use 4Ω–8Ω speakers.

• Prevent speaker-output short circuits.

• Disconnect power before modifying wiring.

• Maintain airflow around the heat sink.

• Use a regulated supply with adequate current capacity.

Disclaimer

The 30W + 30W specification represents the published maximum output under suitable operating conditions and should not be interpreted as guaranteed continuous RMS output at every supply voltage or speaker impedance.

Actual output depends on power-supply voltage/current, speaker load, audio signal, wiring and thermal conditions.

PCB colour, heat-sink design, decoder components, IC revision, connectors and minor component placement may vary between manufacturing batches.