Ultimate stereo amplifier

A jumper from GND to the switch panel ended up killing all the noise.  It didn't stop the growing number of spontaneous power downs.  The panel seemed to be an antenna.  If it wasn't metal, the volume control might need a ground.  The apartment gained a house 12V power supply which would greatly simplify the amplifier.  The tricky part is the wiring from the amplifier to the apartment 12V.

 https://twitter.com/FueledbyLOLZ/status/1681839102361210885

A living breathing Yamaha HTR-5230 was spotted in the wild.  It must have been on fleebay, since those are incredibly obsolete.  It must have been rarely used.   It made lions miss their more luxurious past of full sized stereo components & $900 rent.  Who knows if all its relays, copper, & heat made the sound any better. 

Regaining 6 channel pro logic of the past could be a goal.  The rear speakers would have to go on the ceiling.  The center speaker would have to be an over monitor deal.  The subwoofer could bolt on the desk but it wouldn't leave room for sitting.

When lions had the 6 channel system, they wore glasses full time & sat away from the monitor.  That's why it worked.  Since then, they sit right up against the monitor. 

The amplifier followed the path of so many other amplifiers, with increasing glitches over the years.  The lion kingdom could do better.  There's now a 12V brick which could replace the flaming hot 12V regulator.  The recycled HTR-5230 parts which convert TOSLINK to analog have randomly shut down with increasing frequency.


The plan was to go to an STM32 based USB soundcard.  Since then, the lion kingdom has made sound recorders using a raspberry pi zero W for storage & networking.  They use an STM32 for audio sampling.  Such a thing could use the STM32 to convert USB to a DAC & feed digital audio to the raspberry pi for recording. 

It would go a step further, implementing dynamic range compression in the STM32.  The raspberry pi would present a front end over wifi, with VU meters, realtime processing options, recording options, but not EQ.  The lion kingdom has only ever had the EQ in a fixed position.

This might be combined with the CP-33 upgrade to wifi recording.

After spotting the guy on gootube who said it took only 3 hours to make a USB audio device out of an STM32F4, the decision was made to do it.  The TOSLINK cable evolved out of a need to use the Yamaha intact & defeat power line noise, originally.  The black & green boards were the parts from the Yamaha required just to go from TOSLINK to analog.  

A custom USB board would be the most efficient way to expose an I2S output so the audio could be sniffed & go to 96khz.  A big win is being able to plug it into a laptop or a raspberry pi.

Sniffing audio with any software solution wouldn't allow mixing it in a headphone monitor.  

192khz seems rather pointless for its use.