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Aug 2018 in progress
I have started the
measurements on my projects in the year 2003 with the
Clio system 6
Audiomatica, this was a PC PCI audio card
(16bit 44KHz) with an external unit.
After some year these has been upgraded to the version 8 using the M-Audio Transit USB as audio card (24bit 96KHz).
The Clio system was designed for loudspeaker measurements but it can be used also to test amplifiers with some limits.
I have destroyed 2 times the input circuit of the Clio system during tube amplifier measurements.
To overcome these problems I have designed the EMU input project able to measure 1000Vrms like the anode of a 845 tube.
This project use the M-Audio 0404 USB audio and the Arta software.
Also if the M-Audio 0404 USB have 192Khz A/D converters the limit is 20KHz for the measurements.
To increase the frequency band and the distortion resolution are necessary 3 different systems for distortion, frequency spectrum and loudspeakers.
It is necessary an ultra
low distortion sine generator like the
board with an harmonics typically about -150dB.
MEASURE OF DISTORTION
Measure the distortion with
very good resolution is not possible with normal audio card so the my choice is
the Olivine 2 an USB Analog To Digital Converter by
In order to purchase this USB ADC contact Alexander Torres by contact page.
Follows the measurement of the Victor ultra low distortion sine generator with Olivine 2 unsing Arta software, the result is very good 0.0003%.
To power the Victor 1kHz board I have used a LM317-LM337 module and a 18V-0-18V r-core transformer.
MEASURE OF FREQUENCY RESPONSE
To measure frequency spectrum I suggest an USB oscilloscope with minimun 12bit ADC and at least 1MHz band.
It s a portable lab with 12bit ADC and 12bit DAC designed for university students
Two general-purpose analog inputs:
Differential, ±25 V, 1 MΩ || 30 pF, 12-bit, 100 MSPS ADC with 25 MHz bandwid
Two general-purpose analog outputs:•Single-ended, ±5 V, 50 Ω, 12-bit, 150 MSPS DAC with 30 MHz bandwidth
Two variable power supplies•0 V to 5 V, –5 V to 0 V, 50 mA
16 digital input or output pins•3.3 V, 1.8 V, 100 MSPS, 5 V tolerant
Two digital triggers•3.3 V or 1.8 V, 100 MSPS, 5 V tolerant
The BNC adapter module for Analog Discovery could be used also for the ADALM2000 but I don't suggest to use it because it does not have differential analog (scope) inputs.
One input channel (1+) will be used as reference
and output is measured on the second channel (2+).
There are 2 software to use with this product:
In the webpage https://wiki.analog.com/university/tools/m2k/common/firmware you can find the procedure to upgrade the firmware to the last release.
In the webpage
https://wiki.analog.com/university/tools/m2k/scopy you will find 3 download
links for Scopy, one for the latest release, and two for the latest nightly
builds (one for 32-bit systems and one for 64-bit systems)
Select the second or third installer depending on your system, you should use the Scopy v1.1.1.
Here the frequency response of a pair of RC filter.
Here the frequency of the Gainclone amplifier using LM3875 chip using Scopy Network Analyzer with automatic voltage gain.
Here the frequency of the my PF2019 amplifier high voltage gain on 8ohm, output cap. 4700uF and driven by 6072 pre-ampl.
In order to create a final product to use I have put the ADALM2000 inside a chassie with standard connectors.
This is miniDSP UMIK-1 Omni-Directional USB Measurement Calibrated Microphone
Special features such as calibrated SPL measurement enabled under free Room EQ Wizard (REW) software
Frequency response: 20 Hz - 20kHz +/-1dB with calibration loaded
Resolution & Sample rate 24bit ADC @ 48kHz
Max SPL for 1% THD @ 1kHz 133dB SPL @ 0dB analog gain setting
USB Audio: USB Audio class 1.0 Driverless interface for Windows, Mac & Linux
Power USB Powered (5V) -Blue LED indicates unit under Power
All UMIK-1 are calibrated with a unique calibration file
Power Follower 2019