Published Date 2/2/07 5:53 PM
At the moment SoundExpert (SE) testing engine is ready for listening tests of analogue audio circuits. Most probable contenders to start with are digital audio players [DAP] or just mp3 players.
In general case such testing needs DA converter for feeding analogue device under test with SE reference samples (signals) and AD converter for digitizing the device output. Further preparation of SE test files for listening tests is similar to the one usually performed for high-bitrate audio codecs – time alignment and sound artifacts amplification. In case of DAPs first DA conversion is not necessary because SE samples can be easily transferred to DAP in digital form.
As sound artifacts amplification (SARTAMP) is sensitive towards phase inaccuracy of reference/output signals the use of high precision and clock synchronized AD-DA converters is highly desirable.
Basic features and specifications required
- Simultaneous input and output conversions with synchronized clock
- Standard balanced and unbalanced analogue inputs/outputs
- USB or FireWire digital input/output
- Sampling frequency (fs) up to 96 kHz
- Total [D+A] accuracy of both conversions:
- THD+Noise: < -100 dB
- Frequency response: ± 0.1 db within 0…1/2fs
- Amplitude accuracy: ± 1% within 0…1/2fs
- Phase accuracy: ± 1.0 degree within 0…1/2fs
Best laboratory instruments of such kind on the market are quoted around $10 000 which is not affordable for SoundExpert indie-project. So we would be thankful for any recommendations on similar converters (new or used) around $2000.
BTW, if some research organization would like to grant such equipment to SoundExpert we are ready to discuss terms and conditions …