Technical details

The transformer is housed in a Mu-metal shielding can that measures 51 mm in diameter x 60 mm in height, excluding the connecting leads. The input and output connections are made via mil. spec. silver plated Teflon insulated copper wire.
The secondary (output) winding offers 23 taps allowing the following attenuation values:
0 dB, -3 dB, -6 dB, -8 dB, -10 dB, -12 dB, -14 dB, -16 dB, -18 dB, -20 dB, -22 dB, -24 db, -26 dB, -28 dB, -30 dB, -32 dB, -34 dB, -36 dB, -38 dB, -40 dB, -44 dB and -48 dB. The primary (input) winding has a 0 dB and +1 dB taps.

Combining the switching of primary and secondary taps with the built in microprocessor firmware and the miniature reed relays (50 pcs) we get the volume range between +1 and -48 dB in altogether 45 steps!

With this smart, new method the volume step is only 1 dB over the majority of the range which is much smaller than the commonly acknowledged limit of audibility (3dB), giving a sufficiently fine control over the volume, when compared to continuous controls. Obviously, any attenuation is reliably repeatable.

The full primary has around 400 Ohm DC winding resistance. The resistance of full secondary is 530 Ohm. The primary inductive reactance at 20 Hz is in excess of 100 kOhm (1100 H primary inductance) and thus provides an input impedance of more than 138 kOhm across the audio band if the secondary load is infinite.

The primary winding has a +1 dB tap which allows the very smooth 1 dB step of volume control.

Noise and distortion measurement


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