Yamamoto Sound Craft
AT-03-1A Passive Attenuator

The overwhelming volume of information and the liveliness in the high frequency range characteristic of passive attenuators are complemented by a soft and warm tone. The sound is light, delicate, bright, and pleasant.

The AT-03-1A and AT-03-3A attenuators have a volume control function called "L type" that switches 28 points of resistors. The L-pad type has only two resistors that enter the signal source, minimizing the sound quality loss due to resistors. Losses due to passing resistors are minimized by the use of surface-mount resistors, and almost no noise is generated when switching contacts. The step interval of each switch point can be adjusted from 0 dB to -38 dB in 2 dB steps, allowing fine adjustment. The minimum volume can be reduced to -65dB, allowing for any level adjustment. The left/right level deviation at each volume setting is practically within 0.2 dB, successfully keeping the left/right level difference, a weak point of continuous-type volume units, negligibly small.

The impedance is set as 50kΩ, an impedance that can be connected to any equipment. The volume control switch and input switch of this unit are 45SD type made by Seiden Corporation, which has an established reputation for reliability and usability. For the resistors in the volume control section, 1W type surface mount resistors manufactured by DALE of the U.S.A. are used after numerous audition tests. For the internal wiring of the unit, 1.2mm-diameter high-purity 6N single copper wire was used for all wires. The wires are used in Teflon tubing with the best insulation properties.

Type	28-step volume control attenuator
Impedance	50kΩ
Input System Input	1 system only
Output systemOutput	1 system only
Input switch	None
Dimensions	200(W) 270(D) 97(H)
Weight	2.2kg

The extremely simple configuration may have contributed to the impression of a dry sound. However, the tone and range of the sound is soft and warm, with a gentle tone with a center of gravity in the midrange, similar to other Yamamoto Acoustics products. The piano has a round sound that evokes the warmth of wood, and likewise the violin and classical guitar have a woody warmth to their tones. Timpani and bass have a light tone that is not overly heavy, with just the right amount of persistence and extension. When natural sounds are played back, such as the sound of waves, birdsong, and the chirping of a brown-eared bulbul, they are pleasantly mellow while having a finely detailed quality that reveals details. The audible volume is slightly lower than that of AmTrans and Phasemation.