Lab Measurements with the Audio Analyzer APX555 from Audio Precision
Since we own in our Lab the flagship Audio Analyzer APX555 from Audio Precision, we publish some measurement results from commercial devices.
Please note, that we offer measurements from your devices in our LAB. You will get world leading measurement equipment plus our experienced engineering. The results from an audio analyzer APX555 from Audio Precision are worldwide recognized as a reference. We can do small series batch testing as well. Please do not hesitate to contact us.
An almost “ultra-low distortion generator”
You can buy this board on various trading platforms. It is advertised as an “ultra-low distortion generator”. The technical specifications vary somewhat, but the board is now often only advertised with a distortion factor of <0.1%.
You can also find the circuit diagram. It is basically an active RC oscillator. In principle, purely analogue generators can be significantly much better than any digital solutions with a DAC. Such a tunable RC oscillator is built into the APX555, with a very complex and tricky circuit. However, its performance is world reference.
Measurement results
Even after careful adjustment, the circuit is by no means “ultra-low distortion”, but at least “low-distortion”.
- THD is 0.006311%
- Output level 7.658 Vrms
- THD+N 0.007540%
- Frequency 1.00081 kHz
Further links on this topic
- Ultra-Low Distortion Sinewave Oscillator by Tom McKay and Rod Elliott
- DIY ultra low distortion generator
- An ultra low-distortion oscillator with THD below -140 dB Vojtěch Janásek, www.janascard.cz
- Low-Distortion Sine Wave Oscillator with Precise RMS Amplitude Stability by Cheng-Wei Pei
- some useful threads with links from diyaudio.com
