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Help with setting up Compressor with A/D D/A Converter
Old 11th November 2018
  #1
Gear Maniac
Help with setting up Compressor with A/D D/A Converter

I want to connect my SPL Compressor with my Metric Halo 2882 and calibrate them so I can switch back and forth and compare the signals.

The manual says:

Quote:
The Kultube is configured for a nominal level of +4dBu and can handle an input level of max. 25 dBu, with max. +23 dBu available on the output. It is recommended to drive the Kultube with a signal level of between 0dBu and 12dBu – this being the optimum drive range for signal processing in which also the signal-to-noise ratio is the best.
the SPL has a VU meter that goes from -20 to +5, so to optimal drive it the meter would actually always be 100% in the red when I'd be driving it betwen +5 and 12 dbu? What is the 0 here in reference to, it's very confusing

I also put the 2882 to ouput and input at +4db, so sending a 1000 Hz signal o 0dbFS should actually be at 0 on the VU meter right, or is 0dbFS at +4db +25dBu in that case?

edit:

Actually when I output a -20db signal the Compressors via the +4db Outputs and Inputs the VU is at 0. Does this mean when you put mixes through you're gear you should actually do this at this low a volume? I always thought that mixes should be around -6db when working on mastering, but does this mean engineers still have to lower the Volume a great deal to interface with outboard gear?


so confused right now

Last edited by dbot; 11th November 2018 at 06:03 PM..
Old 11th November 2018
  #2
Lives for gear
 
BT64's Avatar
Quote:
Originally Posted by dbot View Post
.. does this mean engineers still have to lower the Volume a great deal to interface with outboard gear?
Correct.
0dBFS is absolute maximum digital.

".. a nominal level of +4dBu and can handle an input level of max. 25 dBu.."
+4dBu is 0 vu.
25 - 4 woud make 0vu = - 20dBFS about right.
Old 11th November 2018
  #3
Gear Maniac
Quote:
Originally Posted by BT64 View Post
Correct.
0dBFS is absolute maximum digital.

".. a nominal level of +4dBu and can handle an input level of max. 25 dBu.."
+4dBu is 0 vu.
25 - 4 woud make 0vu = - 20dBFS about right.
Yep, seems true. I'm just confused because the level should be between 5 and 12db which both are not even on the VU Scale?

Also if the noise level at 0 VU is about -80db and you then have to actually raise the level 20db (without even any limiting) to get to 0dBFS, doesn't that make the noisefloor very audible (around -60)

Do proper Mastering Compressors have way better specs?
Old 11th November 2018
  #4
Gear Maniac
OK, I just realized I'm probably wrong assuming that if the VU meter is only hitting at 0 that this actually includes fast transients right? so just going a little into the red, probably means going a lot more into it with transients.
Old 11th November 2018
  #5
Lives for gear
 
BT64's Avatar
Quote:
Originally Posted by dbot View Post
Yep, seems true. I'm just confused because the level should be between 5 and 12db which both are not even on the VU Scale?
"It is recommended to drive the Kultube with a signal level of between 0dBu and 12dBu"
dBu.
That would be -4 and +8 VU. But VU is something like RMS, not peak.

Quote:
Originally Posted by dbot View Post
Also if the noise level at 0 VU is about -80db and you then have to actually raise the level 20db (without even any limiting) to get to 0dBFS, doesn't that make the noisefloor very audible (around -60)
Don't forget that 0VU is a avarage.
If it is audible (against the present signal) depends, but yes, you will raise the noisefloor to.

Quote:
Originally Posted by dbot View Post
Do proper Mastering Compressors have way better specs?
The Kultube has a S/N of 90dBu if I'm right.
Analog mastering compressors do, yes.
Old 11th November 2018
  #6
Gear Guru
 

Quote:
Originally Posted by dbot View Post
so just going a little into the red, probably means going a lot more into it with transients.
Yes, which is fine since you headroom. Use your ears; if you're in the red and hear distortion something is obviously wrong. If not... you're good.
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