OK339 Karaoke Pre Amplifier Board with Dual Microphone Input
The OK339 Karaoke Pre Amplifier Board is a DIY audio front-end module designed for building or upgrading karaoke amplifier systems. It provides microphone input, audio mixing and adjustable echo functionality before sending the processed audio signal to a suitable external power amplifier.
The board supports two wired microphone inputs, making it suitable for karaoke setups where two people need to use microphones simultaneously. The microphone section includes controls for adjusting the microphone volume and echo effect.
This module is intended to work as a pre-amplifier/control board, rather than as a standalone speaker power amplifier. Its output should therefore be connected to an appropriate power amplifier or powered audio system.
Dual Microphone Inputs
The OK339 provides two microphone inputs, allowing two compatible wired microphones to be connected to the karaoke system.
This makes the board useful for karaoke applications involving duets, small events, home entertainment systems and DIY audio projects where two microphone channels are required.
The microphone inputs use 6.35mm (1/4-inch) jack connections on documented versions of the OK339 board.
Adjustable Echo Control
One of the main features of the OK339 Karaoke Pre Amplifier Board is its adjustable microphone echo effect.
The board uses the PT2399 integrated circuit for echo processing. The echo control allows the user to adjust the microphone effect according to the desired karaoke sound.
This can add an echo/reverb-style effect to vocals instead of producing a completely dry microphone signal.
Microphone Volume Control
The board provides control over the microphone signal level, allowing the microphone volume to be adjusted independently as part of the karaoke setup.
This is useful when balancing microphone vocals against the music source.
Audio Pre-Amplifier Function
The OK339 is designed to process and mix low-level audio signals before they are sent to a power amplifier.
The documented board provides an audio input for music and an output carrying the mixed music and microphone signal.
This makes it useful as the front-end section of a DIY karaoke amplifier.
Important: It Is Not a Speaker Power Amplifier
The OK339 Karaoke Pre Amplifier Board should not be confused with a complete power amplifier module.
It does not directly provide the high-power speaker output required to drive passive speakers. Its output needs to be connected to a suitable external power amplifier or compatible powered audio system.
This distinction is important when building a karaoke system.
PT2399 Echo Processing
The board uses the PT2399 for echo processing. The PT2399 is commonly used in audio echo and delay circuits and provides the processing required for the OK339’s adjustable microphone echo function.
This makes the module particularly useful for DIY karaoke systems where adjustable vocal effects are required.
TL074 Audio Processing
Documented OK339 versions use a TL074 operational amplifier in the audio section. This is used for input audio amplification and processing before the signal is sent through the rest of the circuit.
Music and Microphone Mixing
The board is designed to combine the microphone and music signals into an audio output.
A compatible music source can be connected to the board’s audio input, while the microphone inputs provide the vocal signal. The resulting mixed audio signal can then be sent to an external amplifier.
This makes the OK339 useful for building a karaoke system where music and microphone audio need to be combined.
Power Supply
Documented OK339 specifications indicate a 12–15V dual AC power supply for the board. Some listings also describe provision for an additional 12V output and a 5V output for connecting compatible auxiliary decoder modules.
Important: Follow the exact power requirements of your supplied board. Do not connect an arbitrary power supply simply because it has a similar voltage.
Optional Bluetooth Decoder Connection
Some OK339 versions include a 5V output intended for connection to a compatible Bluetooth decoder board. This can allow the karaoke system to incorporate Bluetooth audio through a separate decoder module.
This does not mean that every OK339 board has built-in Bluetooth. The Bluetooth function depends on adding a compatible decoder module where supported.
Key Features
| Feature | Feature |
|---|---|
| OK339 model | Dual microphone inputs |
| Microphone volume control | Adjustable echo control |
| PT2399 echo processing | TL074 audio processing |
| Music + microphone mixing | Pre-amplifier output |
| DIY karaoke application | External amplifier required |
Common Applications
| Application | Application |
|---|---|
| DIY karaoke amplifier | Home karaoke system |
| Audio system upgrades | Karaoke machine repairs |
| Custom sound systems | Electronics projects |
| Small event audio setups | Microphone echo projects |
How the OK339 Works in a Karaoke System
A basic setup can follow this signal path:
Music source → OK339 audio input
Microphones → OK339 microphone inputs
OK339 mixed output → External power amplifier → Speakers
The OK339 handles the microphone pre-amplification, audio mixing and echo processing, while the external power amplifier provides the power required to drive the speakers.
Technical Specifications
| Specification | Details |
|---|---|
| Product Type | Karaoke Pre Amplifier Board |
| Model | OK339 |
| Microphone Inputs | 2 |
| Microphone Connector | 6.35mm / 1/4-inch jack |
| Echo IC | PT2399 |
| Audio Op-Amp | TL074 |
| Power Requirement | 12–15V dual supply on documented versions |
| Audio Input | 3-pin header |
| Audio Output | 3-pin header |
| Output Function | Mixed music + microphone audio |
| Bluetooth Expansion | 5V output for compatible decoder on documented versions |
The exact board revision should be checked before publishing dimensions or any additional electrical specifications. Documented versions vary slightly in descriptions and power terminology.
Who Should Buy the OK339?
The OK339 Karaoke Pre Amplifier Board is suitable for:
- Electronics technicians
- DIY audio builders
- Karaoke-system repairers
- Audio hobbyists
- Amplifier builders
- Students working on audio projects
- Custom sound-system installers
It is especially useful when you already have, or plan to build, a separate power amplifier and need a front-end board for microphone mixing and echo control.
Buy OK339 Karaoke Pre Amplifier Board in Kenya
The OK339 Karaoke Pre Amplifier Board provides a practical front-end solution for DIY karaoke and audio projects. With dual microphone inputs, adjustable microphone volume, PT2399 echo processing and mixed audio output, it allows you to add karaoke functionality to a compatible amplifier system.
Remember that this is a pre-amplifier/control board, not a speaker power amplifier. It should be connected to a suitable external amplifier before driving passive speakers.
Order the OK339 Karaoke Pre Amplifier Board from Viroh store Kenya for DIY karaoke amplifier builds, repairs and custom audio projects.
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