Soundcard calibration on REW, with a SSL2

Hi everyone, this is Mat....I'm confused with the calibration testing on REW using a Solid State Logic SSL2.

The most tutorials I've seen, indicate that you need send a 1kHz tone to set the levels of the measurement signal and the interface input volume, and you must equal both at -12 dbFS by turning the output and input knobs manually. Here's an example:

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.

Well...in my own testing. First of all, I put balanced cable into my audio interface from "Input 1" (mic) to "Output L" (speaker), by creating a loopback.



Then, in the "Soundcard Preferences" on REW. I selected both as "Input 1" and "Output 1" respectively.



In "Calibration Soundcard", by keeping all the knobs on zero, I send a 1kHz tone at -12 dB and then I tried to match levels turning the output knob ("monitor level") and the gain doesn't increase at all...not so when I use the input knob, which does decrease / increase proportionally each time when I turn it. This prevents me reach the minimun gain level for the required measurement, so the test is invalid (I only get almost -60 dBFS, so far from -12).



But doing some changes, when I select the input field as "Loopback L" instead "Output 1", the level matching adjusted automatically at -12 (without the need to adjusting input and output knobs manually).



Like this:

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After that, I could calibrate the soundcard and get a perfect flat frequency response of my audio interface. Similar that showed the last video.

What is the correct way to use?. Why the output knob doesn't respond when its turned up or down? (in speaker monitoring it works perfectly).

Thank in advance, I hope you could help me.

Make sure mix is turned all the way to USB and you have set input 1 as Line. Loopback L is a driver software loopback as far as I know, so doesn't go through the interface.

John Mulcahy said:

Make sure mix is turned all the way to USB and you have set input 1 as Line. Loopback L is a driver software loopback as far as I know, so doesn't go through the interface.You save my day. I could resolve the issue. The mix was in the USB mode, but he input wasn't configured as a line.This make all the difference.

Thanks!!!

Click to expand...

Oh thanks, you save my day. I could resolve the issue after a couple of days of failed attempts.

Effectively the mix was in the USB mode, but the input wasn't configured as a line.This make all the difference.

Do you know is necessary to set a double loopback (input 1 and 2) with a timing reference output and a loopback input as I've seen in some tutorials, or is just one enough?

The soundcard cal uses a loopback from the measurement output to the measurement input to measure and compensate for the interface response. It is removed after performing soundcard cal. A timing reference loopback would be from another output to another input to provide a reference for the timing of measurements. Whether you need that depends on whether you need to compare phase or relative timing between different measurements.