ADAU1701 EVAL Board Speaker Sound Cracking.

Hello,

The eval board has its SSM2306 amp set up with 13K ohm input resistors, which works out to a linear gain of 6. The ADAU1701 DACs output 2.5 Vp-p full scale. Multiplying these yields 15 Vp-p speaker output. Since the amp cannot possibly output more than 10 Vp-p with a five volt supply, evidently there's excess gain in the system. The amplifier will clip at audio levels near DAC full scale -- and this will get worse if the power supply drops under five volts under load. Thus your observed clipping is likely normal. To get the most un-distorted output, make sure you have a full five volts at the SSM2306 at its maximum possible output.

Best regards,

Bob

Hello ,thanks for reply.

Checked voltages across Capacitor C7 , with USBi its 3.9volts and drops to 3.6 while on full volume and sound clipping . Powered with 5V1A power bank , voltage is 4.5Volts but the clipping is still there at the same Volume level.

i am using 4ohm 3W speakers.

Is there something wrong with the board.

Hello Rsain216,

Do you have a voltmeter? Can you carefully check the voltage across C28? It is a small ceramic cap located near the upper right corner of the ADAU1701. Near the U3 label.

Thanks,

Dave T

Hello Rsaini216,

Were you able to find the problem?

Dave T