Here’s a list of equipment we used to adjust, optimize and evaluate the performance of this amp. It is unlikely that the ultimate performance could be attained if any of these instruments (or equivalents) are not available. Most of the instruments are currently connected on a GPIB bus and controlled remotely over a TCP/IP network. We developed proprietary software that allows remote measurements, to avoid any interference with the the development phase. It should be understood that measurements around 0.0001% THD imply measuring microvolt levels and a very large dynamic range (over 120dB). Therefore, the measurements should be as much as possible automated and performed as much as possible in reproductible conditions, including the wiring (don’t change the wiring between measurements, take care and avoid any ground loops, etc…) and ambient (don’t measure while the dryer, dishwasher, electric oven or any other large power AC appliance is on). Some of the performance data below were measured rather than taken directly from the data sheets.
Dual Channel Spectrum Analyzer: HP3562A

Frequency range: 64uHz to 100KHz
Noise floor: -129dB
Resolution: Span/800 in linear mode
Dynamic range: better than 87dB
Filter synthesis capability
Advanced FFT math operations.
Frequency synthesizer: Philips/Fluke PM5192

Frequency range: 1mHz to 20MHz sine and square waves
Sine wave harmonic distortion: -65dB 10KHz to 100KHz
Square wave rise and fall times: better than 10nS 10KHz to 100KHz
Phase noise and jitter: -80dB, 3mrad
Digital oscilloscope: Tektronix TDS540A

Maximum analog bandwidth: 500MHz
Digitizing (sampling) rate: 1 Gigasample/second
No. channels: 4
Analog oscilloscope: Tektronix 2336YA

Bandwidth: 100MHz
Delta Time measurement
Distortion and Noise Measuring System: Amber 5500

Sine oscillator

Frequency range: 10Hz-100KHz
THD: -106dB (10Hz-20KHz)
Max output level: 10Veff


Frequency range: 5Hz-600kHz
Residual noise (narrow band, 1KHz): -126dB
THD+N range: -10dB to -120dB
THD+N display resolution: 0.1dB or 2 LSB
Fundamental rejection: better than -128dB
The Ultimate Audio Amp
From Genesis to Revelation

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