SPDIF Level Help

zerolight

Inspired
Hi guys, hope you can help. First time using the SPDIF out on a Fractal. I expected the volume level to be fixed line level, but it is linked to output 1. If I crank the output 1 level on my FM3, and max the input level on my Focusrite 8i6, I'm getting my input level is low - it's around -7db, way way lower than the USB audio coming in. Sure, I can balance that by reducing the level of the computer input, but surely I should be able to get my FM3 input hotter? Am I doing something wrong?
 
I've noticed the same, SPDIF level is too low. I'm not using the FM3 USB audio, but SPDIF is WAY low compared alongside analog output into my Presonus interface.

Following...
 
Switching between -10 and +4 has no affect on the SPDIF level. I notice that using Output 2 is the same, with the output cranked, the level is low. I assume (but I have no way to try) that the XLR outputs at +4db probably make a difference. But I want to use SPDIF.
 
I've noticed the same, SPDIF level is too low. I'm not using the FM3 USB audio, but SPDIF is WAY low compared alongside analog output into my Presonus interface.

Following...

When I said USB audio, I meant all within my Scarlett. The Scarlett USB audio level is as you'd expect, the SPDIF and Output 2 from the FM3 are around -7db.
 
So I've done some more experiments:

- You can use the Output 2 EQ to apply gain to get the SPDIF level up, however what I find when I do that is that whilst the input level is fine on my Focusrite, the higher input level seems to clip the outputs on the Focusrite. At least I get little red alerts appearing (that I can double click to clear) so I assume that is what it is saying. I don't hear any clipping.

- iTunes music played through the focusrite appears to clip its outputs too, but pulling that down to -6db resolves that.

I'm sure it's an issue really. I'll play some more tomorrow. As it stands, with output 2 maxed, output EQ on defaults, my input level from SPDIF is -7db and I end up pulling iTunes down by the same amount. I haven't properly spent time playing with the output slider in Focusrite to see whether or not that resolves anything.

ps: Should I have my interface use it's internal clock or SPDIF (which I presume is FM3 clock)? If I use the SPDIF clock then I can't use my interface to listen to audio from my Mac unless the FM3 is switched on. Are there any drawbacks to using the internal SPDIF instead?
 
It is apparently good practice to record at -7db with SPDIF so I’m just ignoring this now.

I don’t have an Axe3. When I had a 2 I used it as an interface rather than spdif to a different interface so can’t compare.
 
SPDIF is at its optimal level. I recommend Bob Katz: Mastering Audio as a reference for for how audio works from a science and engineering perspective.
 
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dB values are always relative to some known reference and 0 dB on that scale corresponds to the value of that reference.

0 dBFS = highest value that can be recorded in the digital format (sort of like all 24 bits are 1, so it can't go any higher)
0 dBV = 1 volt RMS signal level
0 dBu = 0.7746 volts RMS signal level

dBu and dBV allow for positive values so recording at 0 dBu usually still leaves some headroom for peaks. How much varies from device to device. With digital, there are no positive dBFS values, only negative. Anything above 0 dBFS is hard clipped/limited, which sounds awful. If you want to leave headroom on the dBFS scale, you have to set your average input level a few dB below 0 to make room.

Most DAWs give you options to adjust the way your VU meters are displayed. You can usually offset the display's 0 dB value if you prefer to see an analog style meter setup where 0 dB is your general target and there's a bit of headroom above. Reaper for example defaults to a 14 dB offset for it's VU meters. That means 0 dB on Reaper's VU meters is actually at -14 dBFS for the digital signal.

Another one that often throws people is the difference between Pro and consumer line level.

Pro line level = +4 dBu (1.228 volts RMS or 1.782 dBV)
Consumer line level = -10 dBV (0.316 volts RMS or -7.782 dBu)

Pro and consumer line level are not 14 dB apart but rather 11.782 dB apart because of the difference in their dB scale reference (dBu vs dBV)
 
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Hi guys, hope you can help. First time using the SPDIF out on a Fractal. I expected the volume level to be fixed line level, but it is linked to output 1. If I crank the output 1 level on my FM3, and max the input level on my Focusrite 8i6, I'm getting my input level is low - it's around -7db, way way lower than the USB audio coming in. Sure, I can balance that by reducing the level of the computer input, but surely I should be able to get my FM3 input hotter? Am I doing something wrong?
I just got my FM3 hooked up and am going through it and I noticed the same thing with the low level output. It's not a big deal, just a little lower than my Kemper head.
 
I have to have my output cranked to get any kind of level with my FM3 into spdif input of my focusrite 18i8. And it's still very low.
 
I'm using my FM3 S/PDIF output into a Presonus 1824c and it works perfectly.

The trick for me was to make sure I configured the 1824c to accept external clocking @ 48kHz from the S/PDIF clock generated by the FM3. In my case not doing that produced 'clicks & pops' in my signal. Don't know what the effect is on Focusrite gear.
 
I'm using my FM3 S/PDIF output into a Presonus 1824c and it works perfectly.

The trick for me was to make sure I configured the 1824c to accept external clocking @ 48kHz from the S/PDIF clock generated by the FM3. In my case not doing that produced 'clicks & pops' in my signal. Don't know what the effect is on Focusrite gear.

I've had this focusrite for a long time. Time to upgrade I think. I just ordered a Presonus Studio 68C. I'll let you guys know if the results are any diff...

 
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