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The Future of Audio Amplification

I have recently paired an Audio Research DS225 Class D amplifier with an Audio Research tube preamplifier (SP8 mkii). I cannot believe how wonderful and lifelike my music sounds. The DS225 replaced an Audio Research SD135 Class AB amplifier. Perhaps the SD135 is just not as good as some of the better quality amps that are out there, but it got me thinking that amazingly wonderful sonance can be achieved with a tubed pre and Class D amp. I have a hunch that as more people experience this combination, it will likely catch on and become the future path of many, if not most audiophile systems. It is interesting that Audio Research has been at the forefront of this development.
distortions
atmasphere's avatar
atmasphere
11,936 posts
 
It would, since feedback is how the switching is controlled, without feedback, there can be no switching.
There are three main types of encoding. One is 'self oscillating' which requires feedback and the feedback sets the switching frequency. So for that type the above statement is true but for Pulse Width Modulation and Pulse Density Modulation the statement is false; the latter two can be operated without feedback.
The Technics model is different though. It uses digital signal processing to compensate for the speaker load, and then is a pure digital amp with no feedback ( I believe )
Its a class D (switching analog amp) with digital control. Bruno Putzeys, one of the top class D designers, has a nice article on why class D is analog and digital isn't:
https://www.hypex.nl/img/upload/doc/an_wp/WP_All_amps_are_analogue.pdf

coltrane1's avatar
coltrane1
805 posts
 
Saying Class D is as good as Class A is like those hyping Digital is a good as Vinyl. Are your ears truly that bad? Does a digital piano sound as good as an acoustic? No. End of story.
mapman's avatar
mapman
22,413 posts
 
Class D is not digital. 
erik_squires
16,369 posts
 
Saying Class D is as good as Class A is like those hyping Digital is a good as Vinyl. Are your ears truly that bad? Does a digital piano sound as good as an acoustic? No. End of story.

Someones feelings are hurt. NO no no. I meant to say that good Class D is better than several Class A amps.

Please stop comparing it to such inferior technology better suited for cold climates and drafty hallways.
erik_squires
16,369 posts
 
I find Brunos definitions kind of useless. 
Most Class D have no Analog to Digital Conversion (ADC) stage, but do have comparators. Hence the feedback required.

The Technics on the other hand, really does have an ADC, and once calibrated, the output behavior is deterministic.
Best,
E
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