Above 0DB What does it really mean?

the 0.0 dB value on the Sonar meters can't really be 0.0 dBFS, as you say, since 0.0 dBFS is the maximum digital signal strength possible. It's certainly possible to venture into positive (red) values in the Sonar mixer, and the world doesn't come to an end, as it were. The question is... what exactly is the headroom between "Sonar 0.0" and 0.0 dBFS? I think it must be in the manual, but I don't have it handy at the moment...

NYSR:

Ok, I'll bite on this one..... 8bit / 16 bit / 24 bit / 32 bit / 64 bit all have a full scale right? Isn't 0db the full scale regardless of wordlength/bit depth? It seems your saying that 0db in Sonar is maintained in a 32 bit space but measurements are reported in 24 bit? I can wrap my brain around that thought - though not sure the advantage would be.

So then what is full scale in Sonar +6db red hot?

I think I'm more confused - I appreciate your assistance.

-D

Jonas? Oh Jonas? Where is that boy when we need 'im?

fac nailed it!

Thanks!

a.

I like this thread! I'd never thought about the meter's scale before. Let me see if I have some of it right...

Any A-D/D-A converter has a maximum input voltage it can process. Staying with 16bit, the converter assigns a value of 32767 (or -32767) to this maximum voltage. This voltage is the converter's 0dBFS reference. Different makes of converters process different ranges of voltages, so 0dBFS is just a statement about the maximum voltage a particular converter can process.

If an A-D converter is provided with a higher input voltage than the maximum, it can still only assign a value of 32767, which alters (clips) the signal until it drops down to a workable voltage again.

During tracking Sonar recognises the 32767 value as maximum for 16bit and places it at 0dB on its meter scale. In the case of a clipped signal (still a 32767 value), Sonar can't possibly know by how much it clipped, which is why the input meter does not read above zero.

During mixing however, Sonar can manipulate the numeric values without the constraint that the converters have (they have to work with real voltages, but Sonar is just juggling numbers), so the Sonar meters are constructed to read up to +6.

But +6 what? Here is a supposition:

The scale is logarithmic and zero represents the maximum voltage that any converter can process (ie. For a zero reading Sonar will provide the converter with the number 32767, and the converter will change that into the maximum voltage that it can produce). So doesn't that mean the meter is measuring decibel-volts (dBu), but rather referencing 0dBu to the usual 0.775V(rms) like the VU meters do, the 0dBu in Sonar is actually a reference to the convertor's dBFS voltage (whatever that may be... it will be different for each converter)?

If that is the case, above 0dB is like saying 'this signal is +X dBu above the maximum voltage any D-A converter can process'.

What d'ya think?

> My guess is that Sonar will clip those samples to 0db *before* sending them to the DAC.

Of course that's true. I took it for granted that the maximum value Sonar will pass to a 16bit converter would be 32767, just as the maximum value Sonar receives from a 16bit converter is 32767.

But the original question is what does a +dB reading relate to?
It isn't dBu in the normal sense of VU meters, nor dB-SPL, nor dBV, or any other dB measurement I've come across. So I always assumed it was a completely arbitrary measurement, and they'd just labelled it dB because it was logarithmic. But if the zero reading is based on a maximum voltage of the DAC, then surely that means that the meters are measuring dBu, but using a different zero reference voltage than the standard. Infact everyone's meters will measure voltage uniquely, because the reference depends on the DACs they are using!

So if you knew the 0dBFS reference voltage of your DAC, would you be able to work out what +3dB in the Sonar meters actually was in terms of voltage? And instead of just saying 'the signal is 3dB too loud' and not really knowing what that meant, could you more accurately say 'the signal is 3 decibel-volts more than the DAC I am using can process'? I know it doesn't matter that much in practical sense, but I would like to know what it is I'm looking at in the meters! Thanks for helping me understand it.

Hmm. I'm still not clear. I thought that in the mix meter, +6db is 0dbfs and 0db means 6dbu below 0dbfs. Now I'm totally confuse, how can you have +db if 0 is 0dbfs.

Thanks for that Yep. I, for one, was getting huge headache trying to understand the practical "bottom line" lesson-to-be-learned from this discussion.

ORIGINAL: yep

ORIGINAL: micv

Hmm. I'm still not clear. I thought that in the mix meter, +6db is 0dbfs and 0db means 6dbu below 0dbfs. Now I'm totally confuse, how can you have +db if 0 is 0dbfs.

No. 0 in sonar's meter=0dbfs.

WITHIN Sonar's virtual world, you can safely run tracks quite far "in the red" and it is almost impossible to cause clipping WITHIN Sonar (32bit floating point audio has something like 300dB of dynamic range). But the minute you try and send your audio projects out into the real world, they have to be below 0dbfs or they will clip when they get converted to analog.

So your individual tracks and busses can go over, but your main out must not, unless you want clipping.

Cheers.