The core part of the transformer is installed with “EX Type” 78% permalloy core having superb inductance property, achieving to create a wide performance range. Likewise, the shield case chose to use the same material in order to aim for the decrease in the noise components. “Damping material, Sorbothane” carrying high vibration absorbing characteristics located on the transformer support, effectively works to improve the distortions of the sound.
https://www.etsurojapan.com/product/transformer for detail.