CNO project 2010

I've done some measurements on this Pre-Amplifier, to check the quality. This is done in a conventional way, so no PC-measurement software.

Used equipment;

-Fluke oscilloscope PM3380B 2-channel 100MHz combiscope

-Hewlett Packard HP 339A Distortion measuring set

-Fluke PM6680B timer/counter

-Fluke PM5139 Function generator

-Sennheiser UPM 550 analoge AC mV meter

First of all I've measured THD+n distortion (Total Harmonic Distortion, including noise) at the HP 339A meter.

THD+n;

Measurement at a 1kHz signal ( Hi-Pass 400Hz filter on )

THD+n = -78dBv or 0.015% ( @1Vrms out )

THD+n = -70dBv or 0.030% ( @2Vrms out )

THD+n = -69dBv or 0.032% ( @4Vrms out ) Max. input voltage for the end-stages

Voltage gain;

24dBV (Volume adjustment in 64 steps of 1dBV/each)

Frequency response;

This is measured with a 0.47uF output capacitor installed in the amplifier (Audio Note), in 100kOhm out resistor.

9Hz - 96kHz ( -3dB )

18Hz - 48kHz ( -1dB )

25Hz - 33kHz ( -0.5dB )

Signal to noise level S/N;

88dBv ( unweighted )

Measured @ the CD standard of 2Vrms output voltage.

Output impedance;

200 Ohms (@ 1kHz )

The concepts of signal-to-noise ratio and dynamic range are closely related. Dynamic range measures the ratio between the strongest un-distorted signal on a channel and the minimum discernable signal, which for most purposes is the noise level. SNR measures the ratio between an arbitrary signal level (not necessarily the most powerful signal possible) and noise. Measuring signal-to-noise ratios requires the selection of a representative or reference signal. In audio engineering, the reference signal is usually a sine wave at a standardized nominal or alignment level, such as 1 kHz at +4 dBu (1.228 V_RMS). (source "Wikipedia")

Mechanical spec's of this amplifier;

Weight; approximately 15 kgs.

Width x Depth x Height = 43 x 38 x 11 cm