Sig Gen and Interfacing with the QA402

Just received the new 402 and really excited to mess around with it. I should preface that the reason I bought it is to test some audio equipment I’ve built as well as use it for client gear repairs. My goal is to be able to to make measurements and check over all frequency response. After only playing with it for a few hours I had a few questions. I noticed on my end that when I run the software signal generator out of the 402 to a line amp to monitor it it seems to be pulsing and not a solid signal. When the idle option is engaged when I stop it I get a solid tone. I saw that at the bottom of the software it jumps between streaming and processing at the rate the tone cuts in and out. Is there something on my end I’m doing wrong to be getting the pulse instead of a solid tone out of the unit?

In addition, I’d like to be able to use a signal generator that can produce white noise from an external audio interface from a Daw (in my case protools with an UA Apollo) I hooked up the output of the Apollo to the input of the 402 and wasn’t able to get any readings. I’m using some custom bnc to xlr cables. I am using both +/- jacks on the 402 going to a single xlr wired using both +/- independently to the respective plus and minus BNC connectors. I will add that I tested the cable by going out of the 402 and back in. Is there a way to use the Apollo to send signal into the 402? Would I need a separate asio driver perhaps?

Hi @Rompstomp89, it is correct that measurements are pulsed. If you need a solid tone for some reason (eg to make measurement with a DVM to verify a signal level) then the idle tone option is what you want.

If you are pushing white noise into the QA402, then it should measure that. Note that there’s a bug in 0.992 and earlier where left and right channels are swapped for noise generation at higher sample rates. Not sure if that might be what you are seeing, but be aware. To rule that out at this stage, just stick to 48K

Can you first try a constant tone from your DAW? Just set the DAW to generate 1 kHz at full scale, and then probe to make sure it’s correctly going into the QA402. The QA402 uses bursts on output to measure, but it doesn’t care if constant input from another source.

I’d also start single-ended just to make sure that potential source of confusion is put aside initially.