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Author Topic: SD vs R2R madness (to suck or not to suck)  (Read 2219 times)

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madaboutaudio

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #20 on: September 02, 2015, 05:00:43 AM »

Dsd/class d in theory is not lossy, but in real world application it is.

Dsd is explained here:
http://www.thewelltemperedcomputer.com/Lib/SACD.pdf

Class d:
http://www.extron.com/company/article.aspx?id=ts122001

Class D is band/duty cycle limited by the speed of switching power supply. Also The faster the switching power supply is, the more switching noise is generated. It's paradoxical in a sense. You want faster switching, but you also don't want more noise.

There is a reason why class d amps are typically used only in low frequency subwoofers and why class A and A/B is used for higher frequency. Just check out JBL studio monitors for example.
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ultrabike

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #21 on: September 02, 2015, 05:42:36 AM »

Yes. 1-bit DS has issues, that are substantially mitigated in more advanced multi-bit DS designs.

I'm not going to argue about Class D amplifiers because that's not something I have direct experience with. But I believe Class-D amplifiers are not multi-bit Delta Sigmas.
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jacal01

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #22 on: September 09, 2015, 02:01:34 AM »

...28 miilion taps or DSDx666 not withstanding.

funny.
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Solderdude

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #23 on: September 09, 2015, 05:00:15 AM »

I'm not going to argue about Class D amplifiers because that's not something I have direct experience with. But I believe Class-D amplifiers are not multi-bit Delta Sigmas.

I thought class T is closer to DS.
Class D is just PWM based on the input signal.

Could be wrong though... I never got an interest in class-D or T designs.
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ultrabike

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #24 on: September 09, 2015, 07:05:13 AM »

Seems like so from some wikipedia articles. I doubt they are very sophisticated DS designs though. Likely 1-bit DS, and who knows what random order and topology. I honestly don't know.

Lately, for DACs, it seems that folks at TI are using hybrid (segment) DACs where the upper bits are sort of R-2R like while the lower bits are multi-bit (5-level, 2.32... bit) 3rd order Delta Sigma. Or so it seems with the PCM1794A (datasheet page 24):

http://www.ti.com/lit/ds/symlink/pcm1794a.pdf

Not sure what the DWA stuff is. And dunno if the PCM1794A sounds awesome.
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Solderdude

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #25 on: September 09, 2015, 07:36:11 AM »

Yes, most likely 1 bit 'DS'.

When Sony came out with their first 1 bit DAC's they did not even mention this.
The datasheet of that player simply mentioned ... 18 bits resolution or something like that.
It was in the time that the bitrace began ... 18 bits... 20 bits etc and guess Sony did not know how to 'defend' going to 1 bit.
Technics, at the same time, came out with MASH converters and made a big deal of those.
Lots of 'technical info' on how it worked was available (I got a 2 day course in this technology when I worked for Technics)
These already were 4 bit 'ladder' DAC's that used these 4 bits in 'DS' for the smaller bits.
Talking about >20 years ago already.
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bixby

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Re: SD vs R2R madness (to suck or not to suck)
« Reply #26 on: September 09, 2015, 04:27:57 PM »

I like the sound of my Class T amps.  They use a control system similar to ds.  I think some class d amps might even now be using ds.  Regardless I like the sound of my Bel Canto Tripath chip based EVO4.  It replaced another tripath based Bel Canto Evo 2.  Running the EVO4- 4 channels in bridged mode gives me lots of power and very nice sound indeed. 

My second system also uses a tripath chip in a simple yet very good sounding Virtue Audio integrated amp.  The sound of this amp is quite reminiscent of some tube monoblocks I had from Rogue.  Even when I had a simple 10 watt per channel Trends Tripath chip based amp it handily beat a 100 watt Emotive power amp.   A number of friends in the Denver area with speaker based systems have chucked their class a or ab amps for class d, especially some of the modder types who have taken some Pascal amps and modded them with very good results.

 
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