How much dynamic range is possible in a simple stereo recording?

[esldude]

Hear ye, hear ye, please listen and testify. 

 

With two microphones and a stereo recording how much dynamic range is actually possible? We'll assume using more than two microphones is a treasonous perversion of the stereo medium. 

 

What say ye?  And yes be prepared to defend your opinions.  If you've only anecdotal listening impressions, you're entering a gunfight with a knife.  

 

Is dithered 16 bit digital all anyone needs for distribution of recordings? If not why not?

[STC]

Room noise floor is around 40dB. So far the loudest in listening room at insane level the peak hit 113dB. On average 70dB is more than enough. Yes, for playback 16bit is enough but for recording I would not go for anything less than 24bit.

[Miska]

46 minutes ago, STC said:

Room noise floor is around 40dB. So far the loudest in listening room at insane level the peak hit 113dB. On average 70dB is more than enough. Yes, for playback 16bit is enough but for recording I would not go for anything less than 24bit.

 

You have quite loud room! I've measured around 30 dB!

[STC]

32 minutes ago, Miska said:

 

You have quite loud room! I've measured around 30 dB!

 

Average room. Mine used to around 32dB without the air conditioner.  Last week, visited all Triangle Art room measuring 55dB!  The Master Reference TT is more than my total system cost and yet they have no qualm of 55dB!

[sandyk]

Quote

Frank Stearns  <[email protected]> wrote:
>A top-notch studio with double walls, floating floors, special HVAC and doors, etc,
>can approach -80 but not much more. And you can bet that LOTS or money was spent to
>get that low. Many that sell themselves as top-notch are more like -60 to -65. But
>that's certainly workable.

-65 dBA is not good enough for distant-miking a clavichord.... I found this out
the hard way.

 

>While ambient noise is an important consideration, I'm always much more worried
>about any weird reflections or other acoustic problems in the space; small rooms
>being the more difficult "problem children."
>
>If given the choice between a sweet room that has a noise issue versus an ugly room
>sound that is noise free, I'll generally go for the former.

Amen, brother!
--scott
--
"C'est un Nagra.  C'est suisse, et tres, tres precis."

 

 

https://groups.google.com/forum/#!topic/rec.audio.pro/B0e1NVfLjLY

[Arpiben]

 

Digital Noise Floor 16 bit dithered -> -84dB (1.5-2bits used for noise shaping)

 

Acoustic and Analogue (Mics + analogue devices noise) Noise Floor -> around - 50 dB.

 

[Miska]

4 hours ago, esldude said:

With two microphones and a stereo recording how much dynamic range is actually possible? We'll assume using more than two microphones is a treasonous perversion of the stereo medium. 

 

About 18 - 20 bit worth.

 

4 hours ago, esldude said:

Is dithered 16 bit digital all anyone needs for distribution of recordings? If not why not?

 

I think it would be good to preserve original dynamic range of the recordings.

 

4 hours ago, esldude said:

And yes be prepared to defend your opinions.

 

I picked two hires recordings at random. And for example for these cases 16-bit resolution limits dynamic range compared to original.

 

Here's 2L-111 original 24-bit DXD:

Same dithered to 16-bit:

Keeping the sample rate and using noise shaping the 16-bit would preserve all information though.

 

One DSD256 recording, converted to 88.2 kHz 24-bit PCM:

Same dithered to 16-bit:

 

 

It is not very straightforward to say whether 16-bit is enough because it also depends on sampling rate if you use noise shaping. At high enough sampling rate 1-bit is enough.

[esldude]

15 hours ago, Miska said:

 

About 18 - 20 bit worth.

 

 

I think it would be good to preserve original dynamic range of the recordings.

 

 

I picked two hires recordings at random. And for example for these cases 16-bit resolution limits dynamic range compared to original.

 

Here's 2L-111 original 24-bit DXD:

Same dithered to 16-bit:

Keeping the sample rate and using noise shaping the 16-bit would preserve all information though.

 

One DSD256 recording, converted to 88.2 kHz 24-bit PCM:

Same dithered to 16-bit:

 

 

It is not very straightforward to say whether 16-bit is enough because it also depends on sampling rate if you use noise shaping. At high enough sampling rate 1-bit is enough.

What range do you have set for the spectrogram here? As in how many db Range?

[esldude]

I had in mind starting with the event and proceeding thru the chain of recording and reproduction. 

 

I'll assume a two mic recording of no more than 120 db SPL for the recorded event. 

 

A good quiet LDC has a few db self noise.  I'll use 4db as an example.  

 

The sensitivity and range of mic pres would mean you'll need about 25 db of gain so that 120 db SPL puts the ADC near 0 dbFS.  The amplified self noise will sit at 29 db FS.  Leaving you only 91 db of max signal to noise ratio.  This is before counting any ambient noise of the venue which one has to think is going to be at least 30 db which also will be amplified by the microphone preamps.  Meaning you may only have 65 db of signal to noise ratio.  

 

Of course our ears can in the most sensitive range (3-5khz) hear some 15 db into noise.  Plus in that range in ERB units the noise floor is likely some 20-25 db lower.  So we regain some of the range our microphone preamps took away in the range we hear with best sensitivity.  Plus few, few recordings, less than 1% are recorded in this manner, and without compression of any kind.  

 

Either way, dithered 16 bit will get you around 120 db effectively with tpdf dither (more if heavier noise shaping is used).  

[Le Concombre Masqué]

I read 28 dBC on my iPhone app right now (still night ; countryside). I don't think I ever read it over 93 DB. When I had a calibrated mic plugged and REW on I've seen it's easy to see instant peaks above 100+ but it read silence in the 30+

 

I believe 2.5 x 24 bits is worth it. Explanations still welcome but after extended experimentation with MCH (hence a roughly 2.5 x,  what's being covered by LFE not being in Central)) played stereo, I'm definitely convinced there's more to think about bits than dB range derived from 16 or 24. Although, I'm pretty sure 2.5 x 16 bits would be better than 24 to produce that live like dynamics and controlled articulated energy in the upper lows that I hear (and never but with MCH played ST my amplifiers dedicated to that range lit their half charge diodes)

[fas42]

1 hour ago, Le Concombre Masqué said:

...  to produce that live like dynamics and controlled articulated energy in the upper lows that I hear ...

 

Yes, it's the 'subjective' dynamics that do it for the hearing - so, how does one correlate that with measurements, and number of bits?

[esldude]

6 minutes ago, fas42 said:

 

Yes, it's the 'subjective' dynamics that do it for the hearing - so, how does one correlate that with measurements, and number of bits?

With dither we can get more or less 120 db dynamic range with 16 bit audio.  Do you need more?

 

LP's would lead me to think with the right kinks in the transfer function you don't need that much for subjectively good dynamics. 

 

The use of tasteful compression leads me to the same conclusion. 

[Miska]

5 hours ago, esldude said:

What range do you have set for the spectrogram here? As in how many db Range?

 

144 dB, gain 0 dB, 4096 points, Blackman window

[Miska]

1 hour ago, esldude said:

With dither we can get more or less 120 db dynamic range with 16 bit audio.  Do you need more?

 

Well, not dynamic range, but you can resolve signals to -120 dB or lower. If you use noise shaping and high enough sampling rate, you can resolve signals at -200 dB or lower (of course not through real converter, but in digital domain). 16-bit has dynamic range of 96 dB.

 

[Le Concombre Masqué]

1 hour ago, fas42 said:

 

Yes, it's the 'subjective' dynamics that do it for the hearing - so, how does one correlate that with measurements, and number of bits?

maybe as simply as roughly 2.5 more information at a given point of the dynamic scale  ; but no one has committed on a technical explanation, Miska, if I recall correctly from my thread MCH shining in stereo, simply stating that the surround mixes bring different perspectives. I'm damn sure there's room from a new format and that, say, a 20/96 "Triple Feed" that would be aggregated as Stereo by the players such as HQP would beat 24/192 easy with a comparable footprint on our drives. Not to mention how it would crush mqa...

[Miska]

2 hours ago, fas42 said:

Yes, it's the 'subjective' dynamics that do it for the hearing - so, how does one correlate that with measurements, and number of bits?

 

For that purpose there are couple of calculation standards (dynamic range ratings) and listings like here:

http://dr.loudness-war.info

Also see: https://tech.ebu.ch/loudness/

 

But what we are talking about how quiet and loud signals can be fit together on a recording using single stereo mic pair. It is also related to another similar aspect called signal to noise ratio but these are measured in a different way. SNR (THD+N) contains also distortion products of high level signal.

 

Microphone manufacturers also typically list some figures. Like DPA 4041 has 118 dB dynamic range. And one of the mics most used for hires recordings, DPA 4006 has 124 dB dynamic range. DPA used to have also fancier (better performing) 130V phantom power version which is used by many for hires recordings. Sennheiser and Neumann have similar figures. Best figure I found was 127 dB, which is very close to 21-bit worth (just slightly over 21 bit).

 

[Arpiben]

Digital dynamic range is defined by the range between the peak signal level and the digital noise floor.

Digital noise floor is determined by the amount of quantisation error.

Quantisation error can be randomised (dithered). Noise-shaping algorithms can significantly reduce the digital noise.

Typical digital dynamic range of 120 dB (or much more) can be achieved within the audible frequency bandwidth.

Nevertheless:

 

Noise-shaping has no effect on the noise-floor of the analogue or acoustic signal.

The noise floor of the recording, the self noise of the mics and other analogue equipment in the recording and reproduction chains is still all there.

What defines practically the dynamic range of digital recordings is the acoustic and analogue noise floor.

From what I read that floor is at least 30 dB greater than the digital noise floor of a 16 bit dithered ( 120 db within audio bandwidth).

 

Unless dealing with digitally produced audio rare should be the cases where a 16 bit properly dithered digital have not enough digital dynamic range to reproduce an acoustic recording.

 

Feel free to correct.

[The_K-Man]

As far as measuring dynamic range goes, tools such as TT DR Meter or Foobar 2000 measure only certain aspects of the sound - such as crest factor or peak to average ratio.  There is short-term dynamics, typically percussion, and long-term dynamics, such as crescendo in orchestra or the swell of  a chorus.  Gaps of silence in a composition, followed by bars of melody or lyrics, count as dynamics also.  How does one measure those?

 

Dynamics in music is so subjective.  For instance, Charlie Puth's recent hit 'ATTENTION', sounds as clear and dynamic as any late-'70s to early-'80s funk piece, yet returns a measurement of only DR6 on one of the tools I mentioned above.  Imagine Dragons' 'RADIOACTIVE", at a similar DR value, is practically unlistenable for me, compared to the Puth example!   Something comparable to 'ATTENTION', such as by Kool and The Gang from 1980, yields DR12 or higher.  

 

So what is it about Puth's effort that makes it sound so clear, and as 'crank-it-up!' good as Kool's measurably far more dynamic 'GET DOWN ON IT' from nearly 40 years prior, compared to that disaster by Imagine Dragons - arrangement, different stylistic intenstions?  I am told that certain DR apps measure only certain apsect of a track, such as the second highest peak, etc, as they are looking for the effects of certain mastering practices.  

 

A circa 2012 article on loudness and dynamics in Sound On Sound Magazine covered a project that measured various aspects of thousands of recorded popular songs, from WW2 to that year.  Somehow the article was able to reach the conclusion that yes, although the average music recording has definitely gotten louder over a 60 year period, that recorded music is actually MORE dynamic now than it was during any decade before.... !

[esldude]

We are not talking subjective dynamic range. I want to stick with measured dynamic range. We already know the two don't correlate with each other.

[esldude]

A Lewitt LCT 540 subzero has 132 db of dynamic range. 4db self noise and 136 db max with no padding. It also is a little more sensitive requiring a bit less gain.

[The_K-Man]

3 hours ago, esldude said:

We are not talking subjective dynamic range. I want to stick with measured dynamic range. We already know the two don't correlate with each other.

 

I'm genuine surprised to hear that from someone in an Audiophile forum.  Just remember that there are more than one way to measure the dynamic range of a song.

 

That Sound On Sound article https://www.soundonsound.com/sound-advice/dynamic-range-loudness-war    describes but a few.  Crest factor and PLR(Peak-to-Loudness Ratio) are two of them.

[mansr]

The lowest sound level that can be captured is determined by ambient noise and self-noise of the microphone. The upper limit is likely set by the microphone as going too loud will cause severe distortion and can even damage it. You'll have to check the specs to get accurate numbers, but I doubt you'll find many offering more than 100 dB of usable dynamic range. A good 24-bit ADC will have no trouble recording this.

[esldude]

31 minutes ago, The_K-Man said:

 

I'm genuine surprised to hear that from someone in an Audiophile forum.  Just remember that there are more than one way to measure the dynamic range of a song.

 

That Sound On Sound article https://www.soundonsound.com/sound-advice/dynamic-range-loudness-war    describes but a few.  Crest factor and PLR(Peak-to-Loudness Ratio) are two of them.

Well for this topic I'm interested in physically possible dynamic range that can be recorded. To keep from mixing subjective range and the various ways of ranking recordings I wish to leave that for another topic.

[The_K-Man]

32 minutes ago, esldude said:

Well for this topic I'm interested in physically possible dynamic range that can be recorded. To keep from mixing subjective range and the various ways of ranking recordings I wish to leave that for another topic.

 

You want maximums then. Ok.

 

In purest terms, 16bit = 96dB, 24bit = 144dB, 32bit float = 192dB?  I can't add 2+2, so someone check that last one for me.

[esldude]

36 minutes ago, The_K-Man said:

 

You want maximums then. Ok.

 

In purest terms, 16bit = 96dB, 24bit = 144dB, 32bit float = 192dB?  I can't add 2+2, so someone check that last one for me.

So which microphone and recording venue gets us to 144 db?  The answer is none of them. So then the question is how close do we get?