Helpful ReplyWhat dBu is 0dBFS?

Page: < 12 Showing page 2 of 2
Author
drewfx1
Max Output Level: -9.5 dBFS
  • Total Posts : 6585
  • Joined: 2008/08/04 16:19:11
  • Status: offline
Re:What dBu is 0dBFS? 2011/12/30 14:10:23 (permalink)
I tested it on 8.something with an alternating 1kHz sine/square wave and got the same results for both the sine and square, with matching results all around from the peak meters and markers.

So the only other thing I can think of is maybe there's a setting somewhere (or it piggybacks on some other setting)?

[EDIT: I forgot to mention my test waves were stereo (wouldn't want Jeff to get mad at me ). ]
post edited by drewfx1 - 2011/12/30 14:28:33

 In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
#31
droddey
Max Output Level: -24 dBFS
  • Total Posts : 5147
  • Joined: 2007/02/09 03:44:49
  • Location: Mountain View, CA
  • Status: offline
Re:What dBu is 0dBFS? 2011/12/30 14:37:36 (permalink)
It's what dBYou Want It to Be. We're all winners here today

Dean Roddey
Chairman/CTO, Charmed Quark Systems
www.charmedquark.com
#32
droddey
Max Output Level: -24 dBFS
  • Total Posts : 5147
  • Joined: 2007/02/09 03:44:49
  • Location: Mountain View, CA
  • Status: offline
Re:What dBu is 0dBFS? 2011/12/30 14:44:37 (permalink)
BTW, isn't the pan law going to be an issue if you use SONAR to send out a standard sine wave for measurement? If you have it set to -3dB or -6dB center, SONAR is going to drop it down since you'll have that track centered obviously. If you are using an external send insert to get the signal out and only using one side of it to go to a mono device, you'd have to be sure to press the Mono button so that it sums both signals going on in that case, or you'll end up with a reduced level.

Or, vice versa as well I guess or you'd end up with a too high signal if you have 0 center pan law but are sending both sides of a stereo wave file out to a mono device in some way.

Anyhoo, ways for things to go wrong to take into consideration.

Dean Roddey
Chairman/CTO, Charmed Quark Systems
www.charmedquark.com
#33
JeffinOz
Max Output Level: -90 dBFS
  • Total Posts : 15
  • Joined: 2011/12/27 21:16:44
  • Status: offline
Re:What dBu is 0dBFS? 2011/12/30 15:28:38 (permalink)
I could never get mad at you drewfx1 I don't get mad at anyone! I find it easier to just make stereo test signals and pan centre and just measure either the left or right output. (Analog outputs that is) Usually they are identical as they should be.

Tell you what can be interesting though is to do some polarity tests. Adobe Audition (ala Cool Edit Pro) can create a special test signal that is not the same above and below the line. (A sinewave is no good because a CRO will trigger on the one part of the cycle so you cannot tell) You need an oscilloscope but it is interesting to check the polarity of signals leaving your interface as well.

On a previous system I had two audio interfaces running under Logic. Although the waveforms appeared the right way up in the DAW one interface was inverting the signal. Not a big deal unless you had a stereo signal going across two interfaces which you would not do but it was interesting none the less.

Also interesting is to feed this polarity test signal out through a known poweramp which does not invert the signal of course and into a speaker that is moving the right way. Then I put every microphone I owned in front of the speaker, fed that signal into a preamp that was not inverting the signal (which it should not of course) and look at the output on a scope. I found some of my microphones were inverting the signal! It is also good to test multiple speakers in your room as well just to make sure. You can run the polarity test signal through various bits of outboard gear. (and pedals too) You will be surprised what you find.

Also if you are running multiple speakers in a large PA system this test is also invaluable for checking the polarity of all your FOH and monitor low and high frequency drivers. You will also be amazed at what you find.

post edited by JeffinOz - 2011/12/30 15:41:00
#34
drewfx1
Max Output Level: -9.5 dBFS
  • Total Posts : 6585
  • Joined: 2008/08/04 16:19:11
  • Status: offline
Re:What dBu is 0dBFS? 2011/12/30 15:49:47 (permalink)
JeffinOz


I could never get mad at you drewfx1 I don't get mad at anyone!  
I know Jeff - I was just playing.
Tell you what can be interesting though is to do some polarity tests. Adobe Audition (ala Cool Edit Pro) can create a special test signal that is not the same above and below the line. (A sinewave is no good because a CRO will trigger on the one part of the cycle so you cannot tell) You need an oscilloscope but it is interesting to check the polarity of signals leaving your interface as well.

On a previous system I had two audio interfaces running under Logic. Although the waveforms appeared the right way up in the DAW one interface was inverting the signal. Not a big deal unless you had a stereo signal going across two interfaces which you would not do but it was interesting none the less.

Also interesting is to feed this polarity test signal out through a known poweramp which does not invert the signal of course and into a speaker that is moving the right way. Then I put every microphone I owned in front of the speaker, fed that signal into a preamp that was not inverting the signal (which it should not of course) and look at the output on a scope. I found some of my microphones were inverting the signal! It is also good to test multiple speakers in your room as well just to make sure. You can run the polarity test signal through various bits of outboard gear. (and pedals too) You will be surprised what you find.

That's interesting. I may have to put some asymmetric signal tests on my list of things to do. I don't have a scope, but I can think of some other ways to test for it.

 In order, then, to discover the limit of deepest tones, it is necessary not only to produce very violent agitations in the air but to give these the form of simple pendular vibrations. - Hermann von Helmholtz, predicting the role of the electric bassist in 1877.
#35
aricajwalker
Max Output Level: -90 dBFS
  • Total Posts : 2
  • Joined: 2012/01/03 00:42:53
  • Status: offline
Re:What dBu is 0dBFS? 2012/01/03 01:21:13 (permalink)
Its typical question for me..
#36
Page: < 12 Showing page 2 of 2
Jump to:
© 2024 APG vNext Commercial Version 5.1