After building a number of transformers and amplifiers we tested these monsters. They sounded very good but some people like numbers and facts.

The transformers gave away the following facts: Leakage inductance is:

prim to sec: 8.3mH
½ prim to ½ prim 7.8mH
½ prim to sec 4.05mH

The starting inductance was over 100H at 5 volts, The maximum inductance is expected to be over 600H Core material was VM111-35 Din with Carlite insulation, EI 130B weighing 3.1Kg.

Impedance= 9000 to 8 ohms Winding is sectional with 6 primary coils interleaved by 5 secondary coils in each section. DC resistance over the total primary is between 120 and 130 ohms (varies with each roll of copperwire). DC resistance secondary is (calculated) 0.14 ohms.

With a generator with Ri=0 ohms the frequency response was flat from 7Hz to 100KHz, with a generator with Ri=2000 ohms freqencyresponce fell 3dB at 100KHz..

The amplifier we tested was equipped with the double driver stage as proposed in the driver stage chapter and a pair of EL34 in the powerstage. The overall feedback was 9.5 dB. The value of the capacitor C10 was 200pF. Frequency response feel 3dB at 95KHz. The square waves showed a risetime of 4 microseconds and an overshoot that lasted 4 microseconds. The overshoot ripple was 1/12 of the preceding rising line high. The rising line was very straight. The square wave at 40Hz was not so straight as the one of the "Conrad Johnson Premier 11A" but much better as many of the very expensive commercial constructions as the "luxman 38S".

Harmonic distortion remained till 8 watt output power as low as 0.025% rising to 0.25% at 14watts. Clipping point was between 11 and 12 volts at 8 ohms as was to be expected.