Would a 32bit floating point dac/adc system remove the need for dither? - diyAudio
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Old 6th April 2012, 02:41 AM   #1
JZatopa is offline JZatopa  United States
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Default Would a 32bit floating point dac/adc system remove the need for dither?

So I was thinking about the current DAC/ADC system and how we are slowly moving towards lossless 24/96K + 24/192K recordings in the music industry. Before we just move on to the next best standard, shouldn't we consider making two steps forward and design a format that has as few limitations as possible? Some say that 24bit recordings are better then we could possibly need or want. While that was also said about vinyl, 8-track, tape, CD, color TV and HDTV. While the fact of matter is that progress is going to continue. ie. HDTV is already planned to be replaced by UHDTV by 2016-2020. 4k TVs are already in the consumer marketplace. Rather then drag our feet, why isn't the audio industry looking at designing an audio format that does away with as many limitations as possible? So how do we do this, IMO we jump straight to r 64bit floating point audio. We gain all of the benefits of floating point ie. accuracy, lower noise, higher dynamic range, greater resolution, the ability to record almost the highest level of dB possible on earth (192dB vs. 194db) at the cost of bigger files which will become a non-issue as data storage grows over the years. Aside from the fact that new hardware would need to be developed and that IC technology is not currently at the level of utilizing this whole range, yet, what would be the drawbacks of such a system? Once the media format stops being a limitation, what is the next limitation that would need to be worked on in the audio chain?

I predict that something like this will exist in the future. The final result will be losslessly compressed. My trademark for it is Audio Reality Recording . The file extension will be .arr so the pirates will adopt it quickly and make it the new standard. You heard it hear first folks.

I can't seem to find any data on a real world 64bit ADCs?. Is it possible to make one out of 2 32bit ADCs?



BTW please don't post in here just to say why this isn't worth the effort currently because of X. Imagine that we are 30 years in the future and X isn't a problem. A lot of things in audio/electronics/computers have improved greatly since 1982. Who is to say that the the problems of our current technology won't be mitigated in the near future. ie. 30 years ago TV was analog and had been color for only about 30 years, now we have 1080P and 4K.


Here is an interesting read related to the subject.
http://diwaves.com/tmp/sample_bits.htm

Last edited by JZatopa; 6th April 2012 at 02:54 AM.
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Old 6th April 2012, 03:31 AM   #2
jcx is online now jcx  United States
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human hearing noise floor isn't likely to change short of tech redefining "human"

thermal/Johnson noise, Browinian motion of air molecules aren't going to yeild to any tech advance - there will always be limits on transducer and electronics S/N


any rationally gain structured 24 bit system will be naturally dithered by the random noise in the recording mics, much less the room/venue noise of any "real" musical performance

Last edited by jcx; 6th April 2012 at 03:33 AM.
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Old 6th April 2012, 10:57 AM   #3
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You are making a confusion between the packets of data that travels inside the PC and the size of the captured frames.
The processing path inside the studio consoles is as wide as 40 bit floating point to provide room for calculations.
But at analog interfaces, you don't have available more than 20-22 bit of real resolution. Noise gets in the way, human hearing gets in the way. Musical instruments have a limited dynamic range.
PS: Dither is needed only when you truncate the 24 bit 96kHz to 16 bit 44.1kHz to sell it on CD format.

Last edited by SoNic_real_one; 6th April 2012 at 10:59 AM.
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Old 1st May 2012, 05:31 PM   #4
JZatopa is offline JZatopa  United States
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And yet we are progressing to 32bit.
HP-A8C | 32bit DAC Headphone Amplifier | Fostex

AK4399|Site of Asahi KASEI MICRODEVICES

SONIC_real_one - REAL resolution will improve with time, just as everything else does. Noise will diminish as we make newer and better designs. Musical instruments do have a limited dynamic range, electronic instruments theoretically don't. You sound like one of those people from the 60's who thought that vinyl, stereo and color TV was the end all be all, as we know that was a fallacy. Stop being stuck in the now and use a little bit of imagination.

Where will we be in 2042 audio-wise? At a minimum you can answer that linearly by saying, what has changed since 1982 and project that growth forward. The problem with that is that it doesn't take into account the move to the digital world which changes and grows at an exponential rate. Looking at this graph Click the image to open in full size. you can see we have increased the size of our hard drives by ~ 500,000 times in the past 30 years. In 30 years, as long as moore's law doesn't break down, a hard drive will be ~ 488 Petabytes.

Future | Computers | Internet | 2020 | 2030 | 2040 | 2050 | 2100 | 2150 | 2200 | 21st century | 22nd century | 23rd century | Far Future | Technology


I am trying to make an argument for us moving away from the universal shortsightedness that has crept into our culture because digital's rapid growth and to start thinking about developing standards that last the test of time. CD is dead, DVD-A and SACD are not going to supplant it, in fact all audio going forward will be digital transfered. MP3 is far from dead but the end is in sight, it has had a good 10 years but it will not have 10 more. FLAC or ALAC will be the next standard, or something that is similarly lossless. I just think that the next format needs to be designed for the future, not for planned obsolescence. As the internet has shown, planned obsolescence works great for the analog world, nothing really ever leaves the digital world.
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Old 1st May 2012, 06:02 PM   #5
DF96 is offline DF96  England
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Quote:
Originally Posted by DJNUBZ
Musical instruments do have a limited dynamic range, electronic instruments theoretically don't.
Theoretically do. Ever heard of Johnson/thermal noise? Or do you intend to cryo-treat your system but leave it in the cryostat for operation?
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Old 1st May 2012, 06:21 PM   #6
JZatopa is offline JZatopa  United States
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So we have -174dBm@1hz to -134dBm@10khz for our resistors as our noise limits correct?

In 30 years we may have room temperature super conductors. Is this still a problem then?

Since glasses can cause violations in the Fluctuation-dissipation theorem - who is to say that we may not find an amorphous metal alloy that violates the theorem, which could be used to make ultra low noise electronics?

What if someone devises a way to compensate for johnson/thermal noise in a circuit in the next 30 years?
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Old 1st May 2012, 09:38 PM   #7
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Quote:
Originally Posted by DJNUBZ View Post
SONIC_real_one - REAL resolution will improve with time, just as everything else does. Noise will diminish as we make newer and better designs. Musical instruments do have a limited dynamic range, electronic instruments theoretically don't.
Really? You will improve the human hearing?
How about the termal noise of the air molecules? You will listen your recordings in a freezer? That limits the "silence" end.
Humar ear also has a threshold of pain (some 130dB SPL).
Both those limits ear performance for music at not more than 22-23 bit of dynamic - in a perfect silent room. Of course, you can consider a jet-engine at 1m as "music" and extend that range to some 24 bit, but that is it...

Last edited by SoNic_real_one; 1st May 2012 at 09:50 PM.
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Old 1st May 2012, 09:45 PM   #8
DF96 is offline DF96  England
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Room temperature superconductors might not help much, as you will probably still need resistors in your circuits. I suppose resistors might be simulated by using switched capacitors but then you have all the usual issues of sampling rates etc.

When people talk about the fluctuation-dissipation theorem and glassy systems they are not necessarily talking about transparent stuff from which windows can be made. I suppose it is conceivable that some substance might be found which never reaches thermal equilibrium with its surroundings and so has lower than usual thermal noise. Somewhat more likely is spurious claims from snake oil merchants.

Realistically, I think we have to accept that for domestic electronics we are probably stuck with Johnson noise for the forseeable future. And of course at audio frequencies there is flicker noise - still only poorly understood which could be either good or bad: good because a breakthrough could occur, bad because until we understand it we probably can't design it away.
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Old 2nd May 2012, 03:12 PM   #9
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Just thought I would point out that the so-called 32-bit dacs linked above & mentioned from Asahi, ESS, etc., are NOT 32-bit dacs at all, but simply 24-bit dacs(arguable in itself in the AK4399's specs) with 32-bit digital filters included on-chip. All of thes 32-bit dac claims are ranging from misleading to downright fraudulent(e.g., Fostex's ad copy). Does an actual 32-bit dac for audio really exist? I haven't seen one.
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Old 2nd May 2012, 07:44 PM   #10
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Quote:
Originally Posted by DJNUBZ View Post
So we have -174dBm@1hz to -134dBm@10khz for our resistors as our noise limits correct?

In 30 years we may have room temperature super conductors. Is this still a problem then?

Since glasses can cause violations in the Fluctuation-dissipation theorem - who is to say that we may not find an amorphous metal alloy that violates the theorem, which could be used to make ultra low noise electronics?

What if someone devises a way to compensate for johnson/thermal noise in a circuit in the next 30 years?

To quote SY the second law is a bitch. A superconductor has 0 Ohms or it's not super anymore. In any case when the magic is found every device in the chain would have to use it.
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