Do Tubes take the edge off of Digital???

Wayne, the basic premise of your question lacks factual support. There's no inherent "edge" , square or otherwise, involved in digital sampling. Any material can have an edgy sound if the original performance was like that, or the recording process, whether analog or digital, was poorly done and introduced that coloration. Digital sampling, as long as there are at least two samples of the analog waveform taken(which happens when the sampling rate is at least twice the frequency of the sound sample)reproduces the analog waveform exactly after the DAC conversion, and we hear the same analog waveform coming out as went in before the digital sampling took place. This is simply(although not simple)mathematics: when at least two sample points are present to be mathematically analysed, only one possible waveform fits those points. No naive "connect-the-dots" type of analysis takes place where the more points there are, the closer the reproduction is.

A fairly brief explanation(including mathematical proofs which can be skimmed over)is found in these materials which have previously been cited here, which Dr. Lesurf originally prepared as introductory material for his students in electronics and physics. To quote the bottom line, the summary is that "You should also know that the amount of information in a continuous analog signal can be specified by a finite number of values. This result is summarised by the Sampling Theorem which states that we can collect all the information in a signal by a sampling rate 2B, where B is the signal bandwidth. Given this information we can, therefore, reconstruct the actual shape of the continuous signal at any instant 'in between' the sampled instants. It should also be clear that this reconstruction is not a guess but a true reconstruction".

This is basic technology which was proved mathematically by Nyquist and others about 80 years ago and which has since been used in practice in industrial, military and scientific fields where it's a little more crucial than in audio that what comes out of the digital sampling is precisely what went in.

John K. wrote: »

Wayne, the basic premise of your question lacks factual support. There's no inherent "edge" , square or otherwise, involved in digital sampling. Any material can have an edgy sound if the original performance was like that, or the recording process, whether analog or digital, was poorly done and introduced that coloration. Digital sampling, as long as there are at least two samples of the analog waveform taken(which happens when the sampling rate is at least twice the frequency of the sound sample)reproduces the analog waveform exactly after the DAC conversion, and we hear the same analog waveform coming out as went in before the digital sampling took place. This is simply(although not simple)mathematics: when at least two sample points are present to be mathematically analysed, only one possible waveform fits those points. No naive "connect-the-dots" type of analysis takes place where the more points there are, the closer the reproduction is.

A fairly brief explanation(including mathematical proofs which can be skimmed over)is found in these materials which have previously been cited here, which Dr. Lesurf originally prepared as introductory material for his students in electronics and physics. To quote the bottom line, the summary is that "You should also know that the amount of information in a continuous analog signal can be specified by a finite number of values. This result is summarised by the Sampling Theorem which states that we can collect all the information in a signal by a sampling rate 2B, where B is the signal bandwidth. Given this information we can, therefore, reconstruct the actual shape of the continuous signal at any instant 'in between' the sampled instants. It should also be clear that this reconstruction is not a guess but a true reconstruction".

This is basic technology which was proved mathematically by Nyquist and others about 80 years ago and which has since been used in practice in industrial, military and scientific fields where it's a little more crucial than in audio that what comes out of the digital sampling is precisely what went in.

If, what you say is accurate then why does a D/A converted signal sound different to me than a purely analog signal (assuming it is the same master recorded source)?

Greg

BlueFox wrote: »

You do realize don't you that a lot of recording has been digital for years, and it is converted to analog for the LP.

Yes, I do. Luckily most of the music I listen to was recorded prior to digital tape decks and hard drive recorders though (i.e. pre-1980's). That would be about 90% of the music I listen to.

Greg