matthias Posted October 7, 2018 Share Posted October 7, 2018 Leedh Processing, the "lossless" digital volume control, has been implemented into Soulution DACs and there are rumours that Audirvana will get it as well. Are there any news about this topic? Matt "I want to know why the musicians are on stage, not where". (John Farlowe) Link to comment
mansr Posted October 7, 2018 Share Posted October 7, 2018 Is there anything to suggest it's not just a standard digital attenuator wrapped in technobabble and deep-fried in snake oil? Link to comment
matthias Posted October 7, 2018 Author Share Posted October 7, 2018 17 minutes ago, mansr said: Is there anything to suggest it's not just a standard digital attenuator wrapped in technobabble and deep-fried in snake oil? According to this review there seem to be advantages: http://www.6moons.com/industryfeatures/munich2018/9.html Matt "I want to know why the musicians are on stage, not where". (John Farlowe) Link to comment
mansr Posted October 7, 2018 Share Posted October 7, 2018 9 minutes ago, matthias said: According to this review there seem to be advantages: http://www.6moons.com/industryfeatures/munich2018/9.html I'd expect nothing less from 6moons. The trouble with these claims is that no matter what you do, the result of the processing must ultimately be sent to a DAC chip as, at best, 32-bit integer samples, only about 21 of which actually matter due to unavoidable noise. If the signal level is reduced by half, the topmost bit will go unused, or in other words, the softest details will be lost below the noise. There is no way around mathematics. tmtomh 1 Link to comment
alec_eiffel Posted May 27, 2020 Share Posted May 27, 2020 Here's the patent interesting but somehow disappointing. Link to comment
Patatorz Posted June 4, 2020 Share Posted June 4, 2020 A link to give perhaps more insights to a disappointing patent : https://www.processing-leedh.com Soulution (yes yes Soulution), Lumin, 3dlab : who’s next ? Blog / Forum Link to comment
matthias Posted June 4, 2020 Author Share Posted June 4, 2020 2 hours ago, Patatorz said: A link to give perhaps more insights to a disappointing patent : https://www.processing-leedh.com Soulution (yes yes Soulution), Lumin, 3dlab : who’s next ? The conclusion from the second paper: So the Leedh Processing Volume offers perfectly lossless performance down to -30dB for 16 bits digital signal with a 24 bits DAC and more than -30dB with a minimized level of loss by truncation. Matt "I want to know why the musicians are on stage, not where". (John Farlowe) Link to comment
matthias Posted June 4, 2020 Author Share Posted June 4, 2020 So if I understand the papers correctly there must be a headroom of at least 8 bits, that means a 24bit DAC works with 16bits only or a 32bit DAC works with 24bits only and the Leedh VC is NOT lossless when the attenuation is more than 30dB. Matt "I want to know why the musicians are on stage, not where". (John Farlowe) Link to comment
alec_eiffel Posted June 6, 2020 Share Posted June 6, 2020 @matthias, yes The trick of the Leedh processing is to only allow volume gains leading to a "lossless" representation the signal over a 30dB range, even with only 8 bits of "room of manoeuver" (use case : 16bit CD quality source, 24bits DAC). It's clever and also very efficient against more advanced techniques involving complex dithering. I struggle to see the interest for 32bit DAC though, when "room of manoeuver" is 16bits, for example using software DSP such as in Roon or HQPLayer : 16 bits --> 64bit float --> reduction of XX dB --> conversion to 32 bit --> DAC 32bits It should sound identical to Leedh volume control even for large XX values, especially with good dithering techniques TPDF or other noise shapers. If you convert 16 bits to 64 bit float, apply 30db reduction, convert to 32 bits, convert to 64bit float, apply 30dB gain, convert to 16bits, you'll get the source signal bitperfect, no information is lost, no "need" for the trick of the LP. matthias 1 Link to comment
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