Jump to content
IGNORED

Lavry Engineering Paper on Hi-Res


Recommended Posts

Interesting thread. In this one and the one on "24/192 Downloads ... and why they make no sense?" a very significant question is raised. In both threads there are a lot of answers, but in my view it is not quite clear which question these answers refer to. I don't believe they are relevant to the question at hand (192/24 vs. 44.1/16). My conclusion is that everyone in the two threads claiming to hear differences between 192/24 and 44.1/16 is probably correct, But whether these differences are actually caused by going from 44.1/16 to 192/24 is very open question to me.

 

Please bear with me, this will take a moment.

 

My journey in music reproduction has been a most enjoyable one over a few decades. I also play music with passion. This question of whether hires is better than CD is an intriguing one. Going from vinyl to CD, I was unsatisfied with CD (harsh sounding, the lot). Moving on to a Berkeley Alpha DAC Series 1 a few years back, I discovered how good 44.1/16 could sound. Hearing the Weiss DAC202 was another veil lifted. Changing speakers a month ago revealed a new world of detail (still in 44.1/16). While I can hear differences between reproduction of 44.1/16 and 192/24 material, I find the differences between recordings much greater than any systematic difference I could detect. There are CDs that I vastly prefer to certain 192/24 material.

 

In this thread two data points raised my interest:

- An AES article claims that the insertion of a 44.1/16 A/D D/A loop into a high resolution signal cannot be detected (in that specific test setup) http://www.aes.org/e-lib/browse.cfm?elib=14195

- Barry Diament says that only 192/24 can reproduce the mike feed. Keith O. Johnson has a similar view

 

I believe both views are correct. I have great respect for both Barry D. and Keith J. and I am sure the differences they hear are for real. I have my doubts however that they are singularly caused by going from a lower bit rate / bit depth to 192/24. The recording / reproduction chain's performance is the end result of the interaction of a long chain of components. Microphones, recording equipment, mastering, player, amp, speakers or headphones, cables, ears, brain, all contribute. If one component produces ringing, jitter, transients, it will go through the chain and be modified by the following components. Same thing with acoustic background noise (which is way above the noise floor of 44.1/16), electrical supply noise, cable microphony etc. Not to speak of the imperfections of the ear and the processing that happens in the brain (listeners bias, we hear what we want to hear).

 

Given there are so many variables in the chain, the differences heard by Barry D. and Keith J. and many others (including myself) could very easily be caused by other factors than purely by the difference between 44.1/16 and 192/24 (i.e. higher quality amps, cables, power supplies etc.). As others have pointed out, it is extremely difficult to construct a test setup that ONLY tests the difference between 192/24 and 44/16 and nothing else.

 

Dan Lavry argues that due to noise, there is an inherent limit of time / amplitude resolution product for a given technology. One can either record / reproduce very small amplitude differences with a low time resolution (by averaging several samples) or record / reproduce very small time differences with a low amplitude resolution. Similar to Heisenberg's uncertainty principle, but not quite at Heisenberg's resolution level. This limit seems to be below 100khz sampling rate for 24bit resolution. If we sample higher (192/24) the theoretical resolution limit of the system would be masked by electrical noise (acoustic background noise in the best studio being several orders of magnitude higher).

 

On the other hand I have no doubt whatsoever that for editing / mastering higher sampling rates / bit depths are better and improve accuracy. Here we are purely in the digital domain and we are not real time. Hence Dan Lavry's time / amplitude limit does not hold and the higher accuracy is not masked. If after the high bit rate mastering we down sample to 44.1/16, we get a better CD, than if the mastering had been done at 44.1/16. No contradiction to theory here.

 

I think we need to think about what question it is we want ot answer.

 

Is it better to record at 192/24 than at 44.1/16? I don't know, I am not a recording engineer. I would suspect that Dan Lavry's limit will kick in at some point, but I have no clue where. Barry D. or Keith J. could probably answer this one, or an experiment could be devised to test this (true resolution limits of the microphones and the A/D converters).

 

Is it better to master at 192/24 than at 44.1/16? Certainly, no theory would contradict that.

 

Is it better to reproduce at 192/24 than at 44.1/16? With all the information at hand, I would suspect that given current technology, the "optimum" would be somewhere around 96/24. Dan Lavry's argument would suggest the point of diminishing returns to be a bit (no pun intended) below that. As technology progresses, the limit will increase, but whether the ear and the brain can detect the difference I have no clue. Looks like more testing is needed.

 

My conclusion is that everyone in the two threads claiming to hear differences between 192/24 and 44.1/16 is probably correct. But whether these differences are actually singularly caused by going from 44.1/16 to 192/24 is very open question.

 

For the time being I am quite happy to rediscover my CD collection through my new Piega 90.2s

 

 

Link to comment

Thank you all for the great debate over the last two days. I have learned a lot about the different approaches (Peter's NOS DAC for example). From what I gather, the state of the art has moved on a bit since 2004 (60khz/24bit) but not a quantum leap. True 192khz/24bit seems to be more like 20bit. But then, who needs >120db of dynamic range at 20khz, when most of us seem to be older than twenty and our hearing is going downhill.

Thanks also to the mastering artists, who produce wonderful music with this technology. After all to me it is all about technology becoming inaudible (Barry's mic feed) and the soul of the music coming through.

 

 

 

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...