Originally Posted by SoNic67
Distortions produced by speakers and headphones at mid levels (before saturation) are fairly natural, linear progression, the brain is not bothered by them.
False and misleading claim.
Nonlinear distortion is characterized by order and magnitude. The ear all by itself does not know or care how the nonlinear distortion comes to be, it is only sensitive to order and magnitude. It is possible for both speakers and headphones to have high order distortion at mid levels (before saturation) due to common faults such as a rubbing voice coil.
This also does not relate to the basic fact that the distortion in transducers is orders of magnitude larger than that in even mediocre modern DACs.
However, I said many times that any test that uses speakers as final transducer is almost worthless. Only a good pair of headphones can reveal true differences.
For example, here is a technical report on highly regarded $1200 headphones:
We can see that THD is in the -40 to -60 dB range, much the same as I showed for fine high performance loudspeakers in an earlier post. Your claim that headphones are so superior to loudspeakers in terms of linearity that tests based on loudspeakers are "worthless" is thus falsified
The data also falsifies similar claims related to frequency response should you wish to make them. Friendly advice: Don't go there! ;-)
This information was obtained from the following well known and highly credible web site:
Inspection of that site will show that I did not "cherry pick" my results. They are typical. Your post appears to be uses invented and false facts to support your erroneous arguments.
Better results may be obtained using headphones, but the reasons are reduction of problems with room acoustics and external noise sources. International standards body recommendationis relating to l sitening tess such as BS 1116 and BS 1534 still recommend the use of loudspeakers.
That's not the case with the not-linear harmonic products of a DAC - those can be heard easily, they don't fit in the musical program.
That is true of the obsolete R-2R DACs that you seem to favor, but it is not true of the Sigma-Delta DACs that are now the industry standard for mainstream audio.
For example the critical need for precise trimming in R-2R DACs is shown here:
"Resistors used with the more significant bits must be proportionally more accurate than those used with the lower significant bits; for example, in the R-2R network shown above, inaccuracies in the Bit4 MSB resistors must be insignificant compared to R/32 (i.e., much better than 3%). Further, to avoid problems at the 10000 to 01111 transition, the sum of the inaccuracies in the lower bits must be significantly less than R/32. The required accuracy doubles with each additional bit—for 8 bits, the accuracy required will be better than 1/256 (0.4%). Within integrated circuits, high accuracy R-2R networks may be printed directly onto a single substrate using thin-film technology, ensuring the resistors share similar electrical characteristics. Even so, they must often be laser trimmed to achieve the required precision. Such on-chip resistor ladders for digital-to-analog converters achieving 14 bits accuracy have been demonstrated. On a printed circuit board, using discrete components, high precision resistors of 1% accuracy may be employed for a 5 bit circuit, however with bit counts beyond this the cost of ever increasing precision resistors becomes prohibitive. Even for a 5 bit circuit, to achieve high accuracy, it will be necessary to select matched resistors or to adjust individual resistors to a common value by adding high value resistors in parallel."
In fact all by themselves Sigma-Delta DACs have no known mechanisms for nonlinear distortion. Try Googling for "nonlinear distortion in Sigma Delta DACs" You'll come up empty! Such distortion as they have is due to associated analog circuitry which is not an inherent problem of the basic technology. In my tests poorer Sigma Delta DACs (that are still orders of magnitude better than loudspeakers or headphones) demonstrate primarily elevated noise floors.
Here is a relevant white paper on the topic:
Figure 6.42 asserts my claim that Sigma Delta technology has "Inherently High Linearity". It is possible to use precise and expensive trimming to achive good linearity with R-2R DACs, but it is costly, time consuming and subject to human errors such as lapses in quality control.