Hardware audio visualizer with line-in, built-in microphone, and configurable display modes.

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An entirely on-chip hardware spectrum analyzer that displays frequency bins from either line-in or microphone input on an RGB LED Matrix display. Designed to work with HUB75 RGB LED Matrices, and scalable to any size. 14 bands across 40Hz - 16kHz are displayed in a variety of user changeable modes. Modes can be changed with the built-in button on the back of TeensyVisualizer and brightness can be adjusted with the onboard potentiometer. There are several display modes and color profiles to chose from, these settings are all non-volatile and stored into the Teensy's onboard EEPROM memory.

This PCB uses all hardware frequency analysis instead of software-based FFT like most Teensy-based audio visualizers. The two MSI MSGEQ7 Graphic Equalizer Display Filters compute frequency bins and decay at a logarathmic rate per sample, creating a much more realistic representation of audio than FFT. The onboard switch allows use of the built-in microphone or passthrough 3.5mm line input, both inputs feature adjustable gain through a dual op amp. A trick is used to offset the center frequencies of the 2 MSGEQ7 ICs by passing in two external clocks via the onboard SI5351A Clock Generator - this allows 14 independent frequencies to be sampled.

• Teensy 4.0 ARM MCU
• SmartMartix SmartLED Shield
• HUB75 64x32 P5 LED Matrix (scalable to any matrix size/pitch)
• 2x MSI MSGEQ7 Graphic Equalizer ICs
• Adafruit SI5351A Clock Generator
• LM358 Dual Channel Op Amp

• 14 Channel IC-Based Hardware Spectrum Analyzer
• Automatic scaling to any matrix size, supports daisy chaining
• Switch between 3.5mm line-in passthrough or built-in microphone
• Dual channel amplifier with adjustable gain
• Built-in 5V DC jack with on/off switch
• Onboard button to switch display modes
• Onboard knob to control display brightness
• Non-volatile setting storage
• Automatic dimming when no audio detected

PCBs can be purchased on Tindie here. Components can all be sourced on popular suppliers like Digi-Key or Mouser by following the Bill of Materials (BOM). Gerber files are also included if you want to fabricate the PCB yourself.

Full Kits include everything you need to build your own TeensyVisualizer, they are available for purchase through Tindie here.

The Bill of Materials can be found here: BOM. The Schematic can be found here: Schematic.

1. Solder all components to the PCB per the BOM. Make sure female headers are used for any ICs including the Teensy. Solder 2x14 male header pins on the reverse side of the PCB next to the Teensy, these will be inserted in to the display driver.
2. Cut the trace between VIN and VUSB on the back of the Teensy. This prevents back-powering your computer when connected to the Teensy over USB.
3. Insert PCB with male header pins into the SmartLED Display Shield, making sure it is fully seated. Insert the 2 PCBs with Teensy on top into the male port on the LED Matrix. The TeensyVisualizer board should be flush with the edge of the matrix and sitting on top of it.
4. Attach power cable to matrix and positive and negative to the terminal block on the TeensyVisualizer PCB, clamping them down.

1. Insert 5V DC Power Barrel into connector, use large switch to turn on power.
2. Smaller switch can be used to switch between line and mic input.
3. Run TeensyVisualizer through typical sound environment levels and adjust the two onboard trimmer potentiometers to desired gain. Each takes 25 turns to reach full gain. Mic circuit has default max 100x gain and line input has default max 2x gain. Mic and line gain ratio can be adjusted past these values by changing R7 and R3 respectively.
4. Use big potentiometer to change brightness. TeensyVisualizer will automatically dim the display if no audio input is detected.
5. Press the button to cycle color profiles, hold the button to cycle through display modes.

The 3D Printed Case is included with the Kit, or you can print it yourself. This case is designed for the standard 320mm x 160mm 64x32 P5 LED Matrix and requires six M3x30mm screws. STL Download.

Originally inspired by Mark Donner's 14 Channel Analyzer based off the ATMega2560 using FastLED. Circuit redesigned from the ground up around Teensy and 3.3V using SmartMatrix HUB75 panels and programmed from scratch.

The following open-source libraries are used:

• SmartMatrix
• SmartMatrix GFX
• FastLED
• MegunoLink
• SI5351MCU