Peter Maes

audio visual productions

AL500 (DIY)

The AL500 started after the need for a good autolevel audio processor for livestream or broadcast productions.

The analog circuit is designed with premium grade electronic opamps. Several options are available if you want to exchange opamps, and if desired the input opamp can be exchanged by an input transformer. The differential output stage is based on a DRV134 driver originaly made by Burr Brown. It can be replaced by THAT1646 with improved performance.

The PGA2311 device is a high-performance, stereo audio volume control designed for professional and high-end consumer audio systems. The PGA2311 uses an internal high-performance operational amplifier to yield low noise and distortion.

The theoretical specifications are :

  • maximum input level : +20dBu
  • maximum output level : +20 dBu (limited by rack power supply)
  • variable attenuation or gain : -95.5dB … +31.5dB (127 dB range)
  • firmware upgradable via mini USB (Arduino Nano V3)

Feel free to ask any questions or features you would like to see on this item. The behaviour and features can change in the future as the leveling process can be updated by firmware.
DIY kits (all electronic components + printed circuit boards + alu front panel) are available for purchase.

Part List – Display PCB

U101, U102MAX7221PUMaxim
D102, D103, D104, D105DC10EGWAKingbright
R101, R10247K0 SMD 1206optional
C101, C102, C106, C107, C108100nF X7R SMD 1206
C103, C103, C104, C10947uF 10V X7R SMD 1206

Part List – Main PCB