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What's up with ADH?
#1
l'll talk a little about ADH (Analog Digital Hybrid) one of Devialet's fundamental technologies. ADH is part of all Expert amplifiers and all Phantom speakers. ADH was part of D-Premier, the first amplifier Devialet marketed back in 2011. Most of the early adopters understand how ADH works, but some newcomers may not. Devialet is using clever techniques to achieve good sound quality. A classic class-A amplifier connected in parallel with a modern class-D amplifier.

A link to a white paper (which also describes SAM, another important Devialet invention) https://data.heimkinowelt.at/d/devialet-white-paper.pdf posted by @Confused in another thread reminded me of something John Atkinson of Stereophile said in the measurement section of his review of Devialet's D-Premier back in 2012/13.

The D-Premier has been updated and improved several times since the Stereophile review and is today the Expert 250 Pro CI. This is the current top of the line stereo amplifier and two of those makes the D1000 mono block amplifier. I show three images, one with some explanatory text and two measurements. (NOTE you have to be logged in to see the images)

The two D-Premier items actually represent most of what one needs to know about why ADH sounds good: no switching noise from the class-D stage and no (visible) distortion on the speaker output. The third image is an identical measurement of a different (mono block) class AB amplifier. I'm not revealing the brand and model of this amp as it's not my intention to bash other designs here.
While the lower part of the measurement of the class AB is quite spiky and uneven, repeating itself relative to the sine wave, the D-Premier measurement is just noise without any specific pattern.

The spiky and uneven shape from the class AB amplifier is actually the shape of the distortion of this design. The distortion is of course very low in level, about the same as D-Premier which has 0,0022% THD+N (Total Harmonic Distortion + Noise). But the distortion product in D-Premier is benign in comparison.


I recommend reading both the white paper and the complete Stereophile review.


   
   
   
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Devialetless!
Roon, ROCK/Audiolense XO/Music on NAS/EtherRegen/RoPieee/USPCB/ISORegen/USPCB/Sound Devices USBPre2/Tannoy GOLD 8
250 Pro CI, MicroRendu(1.4), Mutec MC-3+USB
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