ATTO is the attenuator for the ultra low distortion oscillator PC board described in the Pro Audio Design Forum.

ATTO provides 600Ω balanced or two 300Ω unbalanced outputs with 10 dB steps from -70 to +10 dB along with a 49.9Ω/leg direct output for levels greater than +20 dBu.

Construction and assembly information for for ATTO is included in the ULDO-Nacho documents which can be found here: Ultra Low Distortion Oscillator and Notch Filter Assembly Instructions And Test

A Mouser Project Manager parts list is also available.