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How can i generate 1kHz clean audio input ?

Canan Simsek1
Prodigy 80 points

Hi all,

I want to do audio measurement with an Audio codec and  I have audio analyzer sys2522. I need a clean input source, because i want to see jitter effect on dynamic range of the audio.  My audio codec has 3.5 mm stereo jack input, first I fed my codec with 1kHz wav input from my phone but i had %3 THD ratio.

Now I am thinking to fed codec from audio analyzer, but the problem is that. analyzer has BNC connection, audio codec has 3.5 mm jack input. So i have to cut cable and solder the input of the audio codec.  I have couple of questions

1 - ) Is there any easy way to generate 1kHz clean input source ? I checked frequency generators but most of them do not support to generate 1kHz input signal.

2 - )Will soldering BNC cable to jack input is good idea ? and do you think it will also add jitter  ?

3 - ) According to A - weigted curve frequency response of 1kHz and 12.5 kHz sinusoidal signal is same. Is it possible to use 12.5 kHz instead of 1kHz ?  

Thanks & Regards

Canan Simsek

 

  • 0
    TI__Mastermind 46195 points

    Hi Canan,

    You need a very clean sine generator with THD < -90dB, SNR > 110dB or so to be able to measure accurately. Typically we use the analog output generator of the Audio Precision for these kind of tests.

    Regards,

    J-

     

  • 0 in reply to J-
    Prodigy 80 points

    Hi Mr.Arbona,

    I used Audio generator output but even with PLL i have 5% THD . I can not see what is wrong with my setup.

    Regards

    Canan 

  • 0 in reply to Canan Simsek1
    TI__Mastermind 46195 points

    Canan,

    Refer to the datasheet test setup as a guideline. First, the full-scale of the device is 500mVrms, single ended. 500mV = ~0dBFS. To have good performance, you need to set the amplitude of the generator a bit lower, for example -1dB relative to 500mVrms.

    1. The setup is simple. Connect the PSIA's MCLK, BCLK, WCLK, DOUT to the USB-MODEVMs J14 header.

    2. Configure SW2 USB MCLK and USB I2S to the right (OFF). This will make AIC3254 as I2S slave. Even if your setup is different, I suggest to start this way to ensure you get good performance first and go from there.

    3. In PSIA setup, set RECEIVER as output and its master clock to Rx out. Click the large I2S button.

    4. Use the AP analog generator to generate a -1dB signal relative to 500mVrms (or -7dBV).

    5. Configure codec using AIC3254 CS with High performance recording preset. This will make it an I2S slave.

    6. Connect analog signal to IN1 jack of AIC3254EVM.

    7. Measure amplitude, THD+N in digital analyzer, etc.

    Regards,

    J-