0db: What does it mean?

[MusicFirst]

Can someone tell me what the 0db volume setting refers to?
I thought it might refer to the full output power of the amp in question,
but it still can be increased to positive dbs without clipping.

[f1eng]

It is the point at which full digital modulation generates the rated power.
I don't know what Devialet do to the output if a fully modulated digital signal is encountered when the level is set at 0dB. Maybe the instantaneous power will be more than rated, it usually is, or maybe they engage soft clipping to protect the tweeters.
On a conventional analogue amp full power at rated input will typically be around half the volume control travel, allowing low output sources to be turned up loud enough, but meaning sources with an output close to the rated amp input to be clipping if the volume control is much above half way.

[MusicFirst]

So how is full digital modulation determined for, say, a S/PDIF input?  Are there variable voltages between digital sources?  I find some digital sources and even different CDs on the same source sound louder at the same volume setting on the DEV.  How is this possible and accounted for?

Thanks

Kerry

[f1eng]

So how is full digital modulation determined for, say, a S/PDIF input?  Are there variable voltages between digital sources?  I find some digital sources and even different CDs on the same source sound louder at the same volume setting on the DEV.  How is this possible and accounted for?

Thanks

Kerry

The average sound level has risen as recordings have ben increasingly compressed to make things easier to hear in cars and on earbuds. The full dynamics of music is almost never left on non-classical CDs any more.
Full modulation is when all bits are "1", but should never be actually encountered if the recording engineers are competent. 1111111111111110 should be maximum

Really high quality recordings always need the volume setting a lot higher than the compressed dross for the same apparent loudness, but then the dynamic peaks are much more real...

It is possible to monitor this on the Devialet display.
Hold down the right hand remote button until the information display comes on, 2 short presses on the left button will then show you the level display. On a good quality recording the orange will just light on peaks, with the red only on the very loudest peaks. Any recording where it is orange/red a lot has suffered from "loudness wars" compression and is not as high fidelity as is possible on CD. This is disappointingly common over the last 5 years or so.

[PhilP]

I have noticed the same as MusicFirst reports - playing the same file via different digital inputs results in different levels of loudness. So music sounds as loud at -15dB on one input as it does at -20dB on another. No idea why...

[f1eng]

I did not understand the OP to mean that the same file had different loudness on different inputs (that would mean a fault or strange configuration), just that different CDs sound different loudness even on the same CD player, the reason for which I tried to explain.

[PhilP]

I did not understand the OP to mean that the same file had different loudness on different inputs (that would mean a fault or strange configuration), just that different CDs sound different loudness even on the same CD player, the reason for which I tried to explain.

Maybe I misunderstood - If you look at the OPs second post then I think that's what he means - though obviously CDs are recorded at different levels.

"Are the variable voltages between digital sources? I find some digital sources and even different CDs on the same source sound louder at the same volume setting on the DEV"

When previously comparing iMac/AIR to Naim NDX/coax the comparison was made difficult because latter was definitely louder. I haven't tried this comparison with the v 8 firmware.

[f1eng]

I did not understand the OP to mean that the same file had different loudness on different inputs (that would mean a fault or strange configuration), just that different CDs sound different loudness even on the same CD player, the reason for which I tried to explain.

If you look at the OPs second post than that's what he says:

"I find some digital sources and even different CDs on the same source sound louder at the same volume setting on the DEV"

Quite. That is what I tried to explain. Nowhere has he mentioned the same file on different inputs sounding a different loudness. 

[PhilP]

Sorry I think you replied whilst I was editing my post.

A thought- although the the files I was using were the same the processing was different: AIFF iTunes from the Mac and AIFF transcoded on the fly to 24-bit WAV (using Minimserver) through the NDX. I don't see why the loudness should be different? But it definitely was.

[BjornWiman]

"0dB" means that the amplifier do not amplify, nor damping the incoming signal of the connected source.


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