On Wednesday, March 10, 2010 5:52 AM, Parker Dinkins wrote: > on 3/9/10 8:42 PM US/Central, Eric Jacobs wrote: > >> Transfering FLAT will cost you about 6-7 bits of dynamic >> range - an audible loss. EQ in the digital domain will >> not recover that lost dynamic range. > > For a different conclusion, you might want to read > > Filter Reconstruction and Program Material Characteristics > Mitigating Word Length Loss in Digital Signal Processing- > Based Compensation Curves used for Playback of Analog > Recordings > > By R.S. Robinson, Channel D Corp., Audio Engineering Society Paper > 7185, Oct. 2007. I'm not sure that the conclusion is different, but rather candy-coated to some degree... Keep in mind that the entire paper and its arguments are built around modern vinyl LP media. On Page 3, under "4. Program Characteristics", it reads: "In the high frequency region of the spectrum, the degree of extra headroom needed for recording uncorrected program material will depend on the frequency balance of the program material. The amplitude of program content above 1 kHz is critical, because that frequency range is pre-emphasized and will impact the effective dynamic range of lower frequencies. Therefore, it's useful to know about the frequency balance of typical, actual music LP recordings that have been emphasized with the RIAA compensation curve." Keep in mind that shellacs and older recordings when transferred FLAT have a frequency balance that is significantly biased above 1 kHz when compared with a modern LP due to their high frequency noise content. Therefore, the dynamic range of lower frequencies on older recordings is going to be more impacted than on a modern LP. On Page 7, under "7. Upper Bound of Treble Headroom", we find: "For the exceptional example (Bob Marley and the Wailers) among the recordings surveyed, and shown here, this was a maximum of 17.5 dB (2.9 bits). There also is the possibility that other, more extreme such examples exist and could be located, but they will be uncommon." More extreme examples among LPs probably are uncommon, but among shellacs and transcription discs, more extreme examples are the norm with their clicks, crackle, and pops. "Given the results from the variety of recordings surveyed (most of which aren't presented here), and considering that the above figure represents an upper bound, a more likely typical loss of digital dynamic range due to treble emphasis, from the peak responding / peak hold analysis, is less than one bit (6 dB). It appears to be unlikely, in practice, to exceed this figure with LP music recordings on a consistent basis." Again, all references in this paper by Robinson are vinyl LP. Shellacs and transcription discs, with their noise characteristics, will likely result in more than one bit of loss. And 6 dB is audible. On Page 8, under "6. Conclusion", it reads: "The reconstructive properties of digital de-emphasis filtering, as shown here, in conjunction with the characteristics of most program material, will cause a typical overall bass resolution truncation of only one bit or less..." And again, this one-bit loss is what you'll find with LP program material. I would expect more with pre-LP grooved media. Finally, the article states: "Exceptional, uncommonly encountered program material may cause a worst case bass truncation of approximately three bits, which is negligible considering the 24 bit resolution capability of modern analog to digital converters." This statement just glosses over the fact that losing three bits in the bass (18 dB) is actually audible - not sonically negligible. "In cases where bass word length truncation does occur, the disadvantage is balanced by the complementary enhancement of digital resolution, due to treble preemphasis, in the frequency range where human hearing is at its most sensitive." Does increased treble really make up for bass loss? This really seems like a non-sequiter. But the article is called "Word Length Loss *Mitigation*" - and mitigation is different from recovery. This paper argues that for modern vinyl LPs, that digital EQ can come very close to the very best analog EQ for less cost. It does not say, or even imply, that digital EQ can match or exceed the best analog EQ. It only says that the shortcomings of digital EQ are relatively minor (for vinyl LPs). The gap between analog and digital EQ is greater for pre-LP grooved media due its greater high frequency noise component. Food for thought anyway. <smile> Eric Jacobs The Audio Archive, Inc. tel: 408.221.2128 fax: 408.549.9867 mailto:[log in to unmask] http://www.TheAudioArchive.com Disc and Tape Audio Transfer Services and Preservation Consulting