AC M-690 High-End Professional Karaoke DSP Processor
The AC M-690 is a high-end professional karaoke DSP processor designed for premium home KTV systems, dedicated karaoke rooms, restaurants, lounges, clubs, and professional karaoke installations.
Built to serve as the audio control center of a separates-based karaoke system, the M-690 provides detailed processing for music, two independent microphone channels, Echo/Reverb effects, Main L/R, additional L/R, Center, and Subwoofer outputs.
A typical system can be configured as:
Karaoke Player / TV / Audio Source → AC M-690 → Power Amplifier → Speakers
The M-690 combines advanced karaoke vocal processing with detailed system tuning, independent output control, professional XLR connections, real-time front-panel level monitoring, Bluetooth 5.0, USB and Wi-Fi control, dynamic EQ, precision limiting, and audio/video delay adjustment.
It is designed to deliver cleaner vocals, lower noise, stronger dynamics, better speaker control, and more flexible professional tuning in one compact processor.
Key Features
- High-end professional Karaoke DSP processor
- Front-panel real-time signal level meters
- 121dB microphone signal-to-noise ratio
- 118dB music signal-to-noise ratio
- 15-band Music Parametric EQ
- Dual independent 20-band Microphone Parametric EQ
- 3-band Dynamic EQ
- Advanced Stereo Echo and Stereo Reverb processing
- 7-band PEQ for each effect section
- Independent Main L/R output processing
- Independent additional L/R output processing
- Independent Center output processing
- Independent Subwoofer output processing
- 10-band PEQ for each output section
- Precision compression and limiting
- Independent HPF / LPF crossover control
- Up to 150ms Music Delay
- Up to 50ms output delay
- Digital microphone noise gate
- 4-level microphone feedback suppression
- Automatic audio source selection
- Bluetooth 5.0
- Optical digital input
- Coaxial digital input
- Dual stereo RCA analog inputs
- ±7-step Key / Pitch Control
- Driver-free USB PC control
- Wi-Fi wireless DSP control
- Real-time spectrum analysis
- Up to 16 editable DSP configurations
- Software password and control-lock functions
- 6 professional balanced XLR outputs
Real-Time Front-Panel Level Meters
One of the most useful features of the M-690 is its built-in front-panel level meter display.
Input and output signal activity can be monitored directly from the processor, allowing users and installers to quickly check operating levels without opening the PC tuning software.
This makes it easier to:
- Confirm incoming signals
- Monitor microphone and music levels
- Check output activity
- Identify excessive signal levels
- Troubleshoot the system during installation
For professionally installed karaoke systems, real-time level monitoring makes setup and daily operation much more intuitive.
High Dynamic Range & Low-Noise Performance
The M-690 is designed for clean signal processing with excellent dynamic range and low background noise.
Microphone Signal-to-Noise Ratio: 121dB
Music Signal-to-Noise Ratio: 118dB
The processor also supports:
Maximum Music Input Level: 7Vrms
Maximum Microphone Input Level: 730mVrms
Maximum Output Level: 7Vrms
The high input and output headroom makes the M-690 especially suitable for systems using professional power amplifiers and higher-output speaker systems.
15-Band Music Parametric EQ
The Music section provides a dedicated 15-band parametric EQ for detailed system tuning.
Each band can be adjusted for:
- Frequency
- Q
- Gain
- Filter Type
- Bypass
Additional music processing includes:
- High-Pass Filter
- Low-Pass Filter
- Input Level
- Source Selection
- ±7-Step Key / Pitch Control
- Music Limiter
- Dynamic EQ
- Music Delay
This allows the music response to be optimized for different speakers and room acoustics without changing the microphone tuning.
3-Band Dynamic EQ
The M-690 includes an independent 3-band Dynamic EQ.
Unlike a conventional EQ that applies the same correction all the time, Dynamic EQ can change the amount of processing according to signal level.
Adjustable parameters include:
- Frequency
- Q
- Gain
- Threshold
- Attack
- Release
- Ratio
- Above / Below Threshold Processing
This provides an additional layer of control for frequencies that become excessive only when the system is played louder.
150ms Music Delay for Audio / Video Sync
The M-690 provides up to 150ms of adjustable Music Delay.
Modern TVs, projectors, streaming devices, and video processors can introduce video latency. The adjustable delay allows the audio signal to be synchronized more accurately with the picture.
This is particularly useful when the same system is used for both karaoke and TV entertainment.
Dual Independent 20-Band Microphone Processing
MIC 1 and MIC 2 each provide their own independent 20-band parametric EQ.
This gives installers precise control over:
- Vocal warmth
- Clarity
- Presence
- Brightness
- Harsh frequencies
- Low-frequency buildup
- Different microphones
- Different vocal characteristics
Additional microphone processing includes:
- Digital Noise Gate
- 4-Level Feedback Suppression
- High-Pass Filter
- Low-Pass Filter
- Input Limiter
- Attack
- Release
- Ratio
- Independent Input Level
This extensive microphone processing allows the M-690 to produce vocals that are clear, natural, powerful, and comfortable to sing through.
4-Level Feedback Suppression
Microphone feedback is one of the most common problems in karaoke systems.
The M-690 provides four selectable levels of feedback suppression, allowing the system to be adjusted according to:
- Speaker placement
- Microphone position
- Room acoustics
- Singing volume
- Overall system gain
Combined with the 20-band microphone PEQ, noise gate, filters, and limiter, the M-690 provides multiple tools for controlling feedback while maintaining strong vocal output.
Advanced Stereo Echo & Reverb
The M-690 features advanced multi-engine karaoke vocal effects using Stereo Echo and Stereo Reverb processing.
The effect sections provide detailed adjustment including:
- Effect Level
- Direct Vocal Level
- Pre-Delay
- Delay
- Repeat
- Stereo Delay Relationship
- High-Pass Filter
- Low-Pass Filter
- 7-Band Parametric EQ
Each effect can be tuned independently, allowing the vocal sound to range from clean and natural to full, wide, smooth, and immersive.
The separate effect processing also makes it easier to add space and depth without covering up the clarity of the original vocal.
Precision Compression & Limiting
The M-690 provides detailed dynamics processing throughout the system.
Output channels include adjustable limiter controls for:
- Limit Level
- Attack
- Release
- Ratio
The tuning software provides a visual interface for adjusting these parameters, making system protection easier to understand and configure.
When correctly matched to the connected amplifier and speakers, the limiter can help control excessive peaks before they reach the speaker system.
This provides an important layer of protection for:
- High-frequency drivers
- Karaoke speakers
- Woofers
- Subwoofers
while still allowing the system to maintain strong usable output.
6 Independently Adjustable Output Channels
The M-690 provides six independently processed balanced outputs:
- Main Left
- Main Right
- Additional Left
- Additional Right
- Center
- Subwoofer
Each output section provides independent control over:
- Music Level
- Microphone Level
- Echo Level
- Reverb Level
- Mute
- 10-Band Parametric EQ
- High-Pass Filter
- Low-Pass Filter
- Crossover
- Delay
- Limiter
This allows different speaker groups to be tuned according to their position, purpose, and frequency range instead of forcing every speaker to use the same settings.
Independent Main L/R Processing
The Main Left and Right outputs provide the final tuning stage for the primary speakers.
After Music, Microphone, and Effects have been adjusted individually, the Main Output processing can be used to correct the final interaction between:
Speakers + Room + Complete Sound System
This makes it much easier to adapt the same M-690 to different speaker brands, room sizes, and installation environments.
Flexible Additional L/R & Center Outputs
The additional L/R and Center outputs provide their own independent:
- Level
- EQ
- HPF / LPF
- Delay
- Limiter
- Mute
These outputs can be used for additional speaker coverage in larger rooms or for custom multi-speaker karaoke installations.
They are independently configurable speaker outputs and are not dependent on a fixed speaker layout.
Dedicated Subwoofer DSP
The Subwoofer output has its own complete DSP section.
Available processing includes:
- Independent Level
- Music / Microphone / Effect Mix
- 10-Band Parametric EQ
- High-Pass Filter
- Low-Pass Filter
- Crossover
- Delay
- Limiter
- Mute
This allows an active subwoofer or dedicated subwoofer amplifier to be matched accurately with the main speakers without requiring an additional external crossover processor.
A properly configured subwoofer can provide deeper bass, stronger impact, and greater system dynamics while reducing unnecessary low-frequency load on the main speakers.
Professional Balanced XLR Outputs
The M-690 provides six professional balanced XLR outputs for connection to professional power amplifiers or compatible powered speakers.
Balanced XLR connections provide better resistance to hum and electrical interference than conventional unbalanced connections, especially in:
- Equipment racks
- Longer cable runs
- Commercial installations
- High-performance audio systems
Bluetooth 5.0 + Multiple Audio Inputs
The M-690 supports a wide range of audio sources.
Available connections include:
- Bluetooth 5.0
- Optical Digital Audio
- Coaxial Digital Audio
- 2 × Stereo RCA Analog Inputs
Automatic source selection helps simplify operation when multiple playback devices are connected.
The M-690 can be integrated with:
- Karaoke players
- TVs
- Streaming devices
- Media players
- Smartphones
- Tablets
TV Audio & 2.1 Support
The M-690 can receive audio from a compatible TV and play the sound through a 2.1 stereo audio system using the Main Left / Right speakers and Subwoofer.
This allows the same audio system to be used for both karaoke and everyday TV or movie playback.
Driver-Free USB PC Control
The M-690 can connect directly to a Windows computer through USB for professional DSP tuning.
The control connection does not require a dedicated USB driver installation, helping simplify setup and reduce compatibility problems.
Wi-Fi Wireless DSP Control
The M-690 also supports Wi-Fi wireless DSP control.
This allows installers to adjust the system from the actual listening position rather than remaining beside the equipment rack.
EQ, crossover, delay, limiter, microphone, effect, and output settings can be adjusted while listening to the changes in real time.
Real-Time Spectrum Analysis
The PC tuning software includes a graphical Spectrum Analysis function.
It provides a visual reference for:
- Frequency response
- Problem frequencies
- Feedback areas
- Tonal balance
- System tuning
Combined with the M-690’s PEQ and Dynamic EQ functions, spectrum analysis makes professional room tuning faster and more intuitive.
Up to 16 Editable DSP Configurations
The M-690 software supports up to 16 editable DSP configurations.
Different configurations can be stored for:
- Different rooms
- Different speakers
- Different singers
- Different vocal styles
- Karaoke playback
- Music playback
- Different installation requirements
This allows professionally tuned configurations to be saved and recalled instead of rebuilding the complete DSP setup every time.
Software Password & Control Lock
For professionally installed or commercial systems, the M-690 includes security functions such as:
- Software connection password
- Front-panel control lock
- System lock functions
These features help prevent unauthorized users from accidentally changing professionally tuned system settings.
M-690 vs. M-590 — What Has Been Upgraded?
Both the M-590 and M-690 are professional Karaoke DSP processors with detailed Music, Microphone, Effect, Main, Center, Subwoofer, and multi-output tuning.
The M-690 builds on the M-590 platform with several significant upgrades.
Front-Panel Level Meters
The M-690 adds real-time front-panel level meters, allowing users and installers to monitor signal activity directly from the processor.
Higher Signal-to-Noise Performance
The M-690 provides:
121dB Microphone SNR
118dB Music SNR
for lower noise and greater usable dynamic range.
Higher Input & Output Headroom
The M-690 supports up to:
7Vrms Music Input
7Vrms Output
compared with the M-590’s 4Vrms maximum input/output level.
This provides additional headroom when working with professional power amplifiers and higher-output systems.
Bluetooth 5.0
The M-690 adds Bluetooth 5.0, allowing convenient wireless music playback from compatible phones and tablets.
Coaxial Digital Input
In addition to Optical and RCA audio inputs, the M-690 adds a Coaxial digital input for greater source flexibility.
Music A/V Delay
The M-690 adds up to 150ms of Music Delay for correcting audio/video synchronization when using TVs, projectors, or video equipment.
Enhanced Dynamics & Speaker Protection
The M-690 places greater emphasis on visual compression and limiter control across the system, making it easier to configure output protection for different speakers and amplifiers.
USB + Wi-Fi Control
The M-690 supports both driver-free USB PC control and Wi-Fi wireless tuning, allowing professional adjustments to be made directly from the listening position.
More Convenient System Monitoring
The combination of front-panel meters, spectrum analysis, wireless tuning, advanced dynamics control, and higher signal headroom makes the M-690 easier to monitor and tune in demanding installations.
For customers who want the most advanced processing, control, and system-protection capabilities in the AC M-Series, the M-690 is the premium choice.
Technical Specifications
Brand: AC
Model: M-690
Product Type: High-End Professional Karaoke DSP Processor
Music EQ: 15-Band Parametric EQ
Music Dynamic EQ: 3-Band
Microphone EQ: Dual Independent 20-Band Parametric EQ
Microphone Feedback Suppression: 4 Levels
Microphone Noise Gate: Yes
Vocal Effects: Advanced Stereo Echo + Stereo Reverb
Effect EQ: 7-Band Parametric EQ per Effect Section
Output Channels: 6
Output EQ: 10-Band Parametric EQ per Output Section
Output Processing: Level, Mix, Mute, HPF/LPF, Crossover, Delay and Limiter
Maximum Music Delay: 150ms
Maximum Output Delay: 50ms
Analog Audio Inputs: 2 × Stereo RCA
Digital Audio Inputs: Optical + Coaxial
Bluetooth: Bluetooth 5.0
Balanced Audio Outputs: 6 × XLR
2.1 Support: Main L/R + Dedicated Subwoofer Output
PC Control: Driver-Free USB
Wireless Control: Wi-Fi
Spectrum Analysis: Yes
DSP Configurations: Up to 16
Software Password: Yes
Control Lock: Yes
Maximum Music Input Level: 7Vrms
Maximum Microphone Input Level: 730mVrms
Maximum Output Level: 7Vrms
Microphone Signal-to-Noise Ratio: 121dB
Music Signal-to-Noise Ratio: 118dB
Dimensions: 19.1 W × 8.7 D × 1.75 H in
(485 × 220 × 44.5 mm)
Net Weight: 8.6 lb (3.9 kg)
Shipping Weight: 9.9 lb (4.5 kg)
Ideal Applications
- High-End Home Karaoke
- Premium Home KTV
- Dedicated Karaoke Rooms
- Karaoke + TV Entertainment Rooms
- Private KTV Rooms
- Restaurants
- Bars & Lounges
- Clubs
- Multi-Speaker Karaoke Systems
- Commercial Karaoke Installations
Frequently Asked Questions
Is the AC M-690 a power amplifier?
No. The M-690 is a professional Karaoke DSP processor / preamplifier. It connects to separate power amplifiers or compatible powered speakers.
How many microphone EQ bands does the M-690 have?
MIC 1 and MIC 2 each provide an independent 20-band parametric EQ.
How many Music EQ bands does it have?
The Music section provides a 15-band parametric EQ plus an independent 3-band Dynamic EQ.
Does every output have independent DSP?
Yes. Each output section provides independent level, EQ, HPF/LPF, delay, limiter, and mute control.
Can the M-690 help protect my speakers?
Yes. The M-690 includes adjustable compression and limiter processing. When correctly configured for the connected amplifier and speakers, it can help control excessive peaks before they reach the speaker system.
Can I connect my TV to the M-690?
Yes. Compatible TV audio can be connected to the M-690 and played through a 2.1 stereo audio system using the Main Left / Right speakers and Subwoofer.
Can it correct audio/video synchronization?
Yes. The Music section provides up to 150ms of adjustable delay for correcting audio/video synchronization.
Can I tune the M-690 wirelessly?
Yes. The M-690 supports both driver-free USB PC control and Wi-Fi wireless DSP control.
What is the main difference between the M-690 and M-590?
The M-690 adds front-panel real-time level meters, higher 121dB/118dB signal-to-noise performance, 7Vrms input/output headroom, Bluetooth 5.0, Coaxial digital input, Music A/V Delay, enhanced dynamics and limiter control, and USB/Wi-Fi tuning capability.
Who should choose the M-690 instead of the M-590?
The M-590 already provides extensive professional Karaoke DSP control. The M-690 is better suited for customers and installers who want higher signal headroom, lower noise, real-time monitoring, wireless tuning, Bluetooth connectivity, A/V synchronization, and more advanced system-protection tools.
