16 versus 24 bit files

[Rothchild]

I want to try this, can someone direct me to a recording that was dead-cert made at 24 bit and where the same master was used to generate the cd and the hi-rez version?

Alternately, I have access to a reasonable recording facility does someone want to come up wiht a sensible experiment whereby I can capture the same recording / performance at both bit depths and I will happily post the results - I can't for now work out how to get my studio machine to record both 16 and 24 bit files at the same time....

[lurcher]

Nick/Stan, that is an interesting idea - you would ideally have different audio signals such as speech combined at differnent levels,say -40db, -60db, which are then truncated to different bit depths and then padded into a 24bit format to see how integlligability is affected by reducing the bit depth. Is this easily achievable?.

Don't see why not, though you could get a -40dB signal by taking a CD and adding 8 bits of zero (sign extended) to the MSB.

[User211]

In theory increasing the bit depth should only improve the SNR but I've just recorded an LP track at 44.1Khz in 16 and 24 bit and compared the Spectrogram plots in Audacity. At first glance they look the same (they are not perfectly time aligned) but looking more closely there are some differences in the plots! What the cause is I have no clue! Its big so just the link:

http://s94.photobucket.com/user/_NRG...11323.png.html

Try recording the same track again at either sampling rate. Does it look the same as the original? That'll tell you whether it is just variance in the analogue domain - or not. If not, then interesting

[NRG]

I understand where you are coming from and will try it but I cant think what would change so significantly in the analogue domain in such a short time. The Phono stage had warmed up, the deck was not stopped in between, the loading was the same and the tracks recorded within a minute of each other...

[User211]

I'd like to see the result Neal. But now things really have changed I guess - ambient temperature, warm up time etc.

So just do two at 16 or 24 bit one immediately after the other?

[Richard Kimber]

It seems to me that it depends what you are recording. I'm not convinced you'd notice much difference if it's just someone playing a guitar. On the other hand, if it's a large symphony orchestra playing Wagner, then I think you would.

- Richard

[Stratmangler]

Well, not entirely. If you listen to enough hi-res recordings and enough CDs it's possible to form a judgement about whether there is a tendency for hi-res to sound better.

- Richard.

It's also possible to have CD seem to have greater detail by making the overall level higher, thus making low level sounds become more apparent.
This is not the same as what's been taking place in the loudness wars, where dynamic limiting and compression have been misused.

The thing about comparing high resolution files to CD spec files is that often high resolution transfer is done some years after the CD release, so it isn't mastered from the same production transfer.
In between times the ADCs in the studio may have changed for something that is much better resolving.

[WOStantonCS100]

That's all well and good, but you don't think that a record company goes to the effort of recording at different resolutions for different formats, do you?
They don't, they have the studios number crunch things down.

Precisely my point. In order to get a real idea of how higher bit depth and/or sampling frequencies benefit what is heard, you have to sidestep the record companies most of the time. But, that doesn't mean that the technology doesn't have worth or doesn't do what it is designed to do. No need to throw the baby out with the bath water, so to speak. There are and will be companies (the majors will have to get the "ok" from the bean counters first) that will avail high res, properly.

As for upsampling, how can you add data that isn't in existance at the start point.
All that upsampling can do at best is add loads of redundant zeros.
The additional bits might fool the logic cicuit of a DAC into using a different output filter, but nothing more.

Again, that was my point. If the source is a 16/44.1 file, be it on a hdd or a cd-da, then it doesn't really matter if the increase in bit depth is done with software or hardware. So, in my opinion, do it on the fly and keep your CDs or your original file (save space and time) and let competent hardware deal with it.

[WOStantonCS100]

We seem to be drifting off a bit here. My question was with regards to 16 versus 24 bits. I have intentionally left out comparing sampling rates. Otherwise we have two variables to deal with, namely bitrate and sampling rate. It's difficult enough as it is for many to distinguish between the two. Putting both of them into the mix so to speak only helps yo muddle the waters.

What I have been able to hear is a larger dynamic impact with 24bit. I can also hear more clarity in low level signals. The most appropriate test for this is live sessions with people talking in the background. Murmurs in 16bits tend to turn to understandable speech with 24bits.

That infamous AoS thread drift...

Yes, I'd agree. Anytime one can increase the S/N ration, theoretically, it should render low level information more articulately, increase dynamic range. Wasn't that the purpose of going to 24 bit?

The thing is, aside from a computer program, I know of few DACS that only up the bit rate. Maybe I'm just ignorant on this (a distinct possibility). My experience is that most DACS that will increase the bit depth also want to up the sampling frequency at the same time. Ironically, my DV-RA1000HD will NOT copy a CD as 16/44.1 It extracts audio from a CD at 24/44.1 For all practical purposes it is a "24 bit" machine that is backward compatible so as to read a 16/44.1 disc. Obviously Tascam don't think 16 bit is a worthy format for a master recorder.

[Reffc]

The theoretical argument for 24 bit is fine and the technology widespread these days. In practice however, it's not a huge audible margin between the two if we're being honest. The main reason being that there's far greater divergence between recording (mastering) qualities of music than there is significant audible differences between the bit rates. As there is still no de-facto industry standard to address this, then the argument imho becomes somewhat pointless to a lesser extent. Just buy and enjoy music in either format. A well recorded 16 bit piece of music still offers a thoeretical 90dB dynamic range which is above human hearing perception anyway. Sampling rates at 44.1 are also adequate if properly implemented and it would be interesting to see how many people could pick out 88 or higher in blind listening tests. I have heard some superbly recorded high res files that would knock spots off most of my 16 bit CD recordings, but equally, I have some CD recordings that are impossible to distinguish between their hi-res counterparts. I did this comparison using the Astell and Kern A100 hi-res player loaded with hi-res versions of some of my 16 bit albums and tracks.