Searching for a tone generator 1db step-1000Hz and THD Meter

Hi,
I'm in France-Eu and searching for these items to calibrate some gear,
could you please recommend me good affordable ones? (I can buy second hand)

Thanks for your advise!
best,
Julien

I have  HP 8903A Audio Analyser and TTI TG 315  Function Generator. Please PM me if it is of interest.

pm'ed

thekid777 said:

Hi,
I'm in France-Eu and searching for these items to calibrate some gear,
could you please recommend me good affordable ones? (I can buy second hand)

Thanks for your advise!
best,
Julien

Click to expand...

Although I still own venerable LEA stuff (generator with calibrated attenuator - 1dB steps from -70 to +22 and Qualiscope - THD meter with built-in tuning oscilloscope), I would recommend using the RMAA software. The only limitation is the soundcard; most soundcards are unbalanced and have limited input handling and output capability. If you can afford a good soundcard with balanced outputs, that would probably be the best long-term solution.

I think adding tuned filters to a sound card would give more than excelents results, going even further than the sound card capabilities, narrow bandpass at the output, narrow notch at the input, some boost at the input and you took up the THD measurements capabilities of the sound card quite a lot. If just aiming for 1kHz analysis not need for automatic tuned filters, once you get them there is good to go, and you only need some realizable filters to attenuate the fundamental so you can get better S/N ratio (the noise here is the original 1kHz) so you get much better headroom and then measurement capabilities than the sound card it self. Then DSP could manage to end the filtering.

For the calibration you do need an external calibrated source, not 1kHz because the filter, something like 4kHz is probably the best way since 2kHz may be just a bit off depending on the notch used.

JS