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Focusrite Scarlett 8i6 3rd - strange RMAA results

Giuse

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Mar 27, 2021
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Hi, I just bought a Scarlett 8i6 3rd generation and put it under test with RMAA.
I noticed three weird issues:

1) input 1/2 (the ones that have the mic) collects traces the sound being sent to the output even if no cable is inserted into them and gain is set to zero. In more details, when RMAA is outputting its 1 KHz test signal to output 1/2, if the DAW output 1/2 is routed also to output 3/4 with Focusrite Control... RMAA is getting a -108 db 1 KHz signal incoming from input 1/2... Similar effect if the volume of the headphones is set to very high levels. Like a "crosstalk" between input 1/2 and some other circuitry.... I'd be interested to know if others can confirm, it's not a good thing...

2) I then tested the interface connecting output 1/2 to input line 1/2 (the ones with pre-amp) and measured a good but not impressive 95 dB of dynamic range: the noise/distorsion of ADC (around 110 dB as specs) is summed to the noise/distorsion of the DAC (108 dB as specs), is it a normal value?

3) I repeated the test connecting the outputs to line input 3/4, with output volume set at 3 pm and actually got a better dynamic range of 103 dB but... the graph shows a large band
1-headphone-out-dynamic.png


and infact the IMD test result is very bad:
2-headphone-out-imd.png

where there is ton of distorsion, especially in the left channel, even though I lowered the output volume so that the test signal in the pre-test check was -11 dB instead of the required -1 dB.
I think it's still a problem of clipping, so I repeated the test lowering the volume as much as possible (-12 dB), the lowest level that allows the test to be successful, getting a less worse, but still bad, result:
3-out-imd-low.png

Similar results using the headphone output instead of the line outputs.
So it seems it's not possible to get a good physical loopback result in RMAA using the line inputs?

Thanks a lot for your feedbacks

Giuse

PS. I read the interesting Scarlett 2i2 3rd generation test of amirm
 

sergeauckland

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I've had similar results with RMAA with my various interfaces. I'm much more suspicious of RMAA than I am of the interfaces.

Try using another piece of software, REW I've found to work well, or ARTA.

If you get similar results, then it's possible for the Scarlett to be the cause, but I would not rely on RMAA as definitive.

S.
 
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