My retro project would take me back to my high school days (late 60's, early 70's) when I built a discrete color organ.  The color organ used 4 different discrete bandpass filters with analog power amps to drive the red, green, yellow and blue 120 Vac light bulbs.  I would still use analog bandpass input circuits into the analog inputs of a single board computer (SBC).  The SBC would process and convert the signal amplitudes into PWM outputs to a LED arrays on a display panel.  Output constant current power amps could be added depending upon the requirements of the LED arrays.  Four analog inputs and four digital PWM output would be needed, one for each frequency/color band.  Raspberry PI (RPI) SBC could be eliminated due to the lack of analog inputs, unless a separate multi-channel ADC chip/module was added to interface with the RPI's GPIO port(s).  So that would point to the Arduino family.  At the simplest level an 8-bit MCU should work fine.  A minimum of 4 analog inputs and 4 PWM output ports would be needed pointing to a variety of Arduino boards (i.e. 101, LilyPad family, pro, mini, etc.).  The need for output amps could be reduced and/or eliminated by splitting the outputs into multiple sub-segments per color band.  As an example, the Arduino MKRZero has 12 PWM outputs so each color band can be divided into 3 sub-segments with lower power output requirements.  Beyond the vintage feature of a 4 color organ, with the MKRZero's higher processing speed and sound library additional feature, such as DSP input filtering, special effects and a separate audio output.  In addition, shields could be added for more feature, like wireless connections or environmental monitoring (i.e. LED could change color as the temperature or humidity change).  But enough for now.

Stay Well - Stay Safe,  Gordon

My retro project would take me back to my high school days (late 60's, early 70's) when I built a discrete color organ.  The color organ used 4 different discrete bandpass filters with analog power amps to drive the red, green, yellow and blue 120 Vac light bulbs.  I would still use analog bandpass input circuits into the analog inputs of a single board computer (SBC).  The SBC would process and convert the signal amplitudes into PWM outputs to a LED arrays on a display panel.  Output constant current power amps could be added depending upon the requirements of the LED arrays.  Four analog inputs and four digital PWM output would be needed, one for each frequency/color band.  Raspberry PI (RPI) SBC could be eliminated due to the lack of analog inputs, unless a separate multi-channel ADC chip/module was added to interface with the RPI's GPIO port(s).  So that would point to the Arduino family.  At the simplest level an 8-bit MCU should work fine.  A minimum of 4 analog inputs and 4 PWM output ports would be needed pointing to a variety of Arduino boards (i.e. 101, LilyPad family, pro, mini, etc.).  The need for output amps could be reduced and/or eliminated by splitting the outputs into multiple sub-segments per color band.  As an example, the Arduino MKRZero has 12 PWM outputs so each color band can be divided into 3 sub-segments with lower power output requirements.  Beyond the vintage feature of a 4 color organ, with the MKRZero's higher processing speed and sound library additional feature, such as DSP input filtering, special effects and a separate audio output.  In addition, shields could be added for more feature, like wireless connections or environmental monitoring (i.e. LED could change color as the temperature or humidity change).  But enough for now.

Stay Well - Stay Safe,  Gordon