Typical Frequency Responce

[MoogRick]

Hello,

I just purchased an Audio Express.
My main use for it will be not be for recording but for SINAD and Frequency response measurements of devices. I picked this device due to DC response.

I'm getting very good results but not perfect. I'm wondering what is normal. I suspect some of what I am seeing is from ARTA and some are from the Audio Express itself.

Using ARTA I seem to have a 0.5dB peek that starts around 7k and maxes out around 21k. It then starts a very steep rolloff around 30k. I'm guessing what I am seeing here is peeking in the Audio Expresses Anti Alias filter from a high Q filter. This is not bad, but a well designed filter should not have this broad a peek, even at high Q.

On the low end I only see response down to about 1.5Hz. That is probably Arta. it is flat to about 10Hz then starts to roll off fast.

Is all this normal, especially the peeking at the top? 0.5dB is just enough to be a pain, but not enough to bother me that much.

BTW, if anyone is interest ed i am seeing about 126dB SNR (hard to be exact) and 700Hz THD = .001% THD+N = .0038% Very good.

This is from line out 3 to line in 3.

Rick