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Old 6th January 2013, 09:11 AM   #41
marce is offline marce  United Kingdom
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Oh when cascading PSU's generaly you will have a on board SMPS for the main supply (say 3V3) then quite often small local LDO's are used for isolated derived voltages (such as a local 3V3 for a clock etc). AQ lot of new main SMPS's are now employing spread spectrum and multphase design topology. But as a technology the PC is not exactly new, I've been using one to do my job since 1985.
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Old 6th January 2013, 09:13 AM   #42
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As to sptraying the room with RF, get somthing thgat has been designed properly and dosn't spray the room with rf, thats common sense.

May you, kind and knowledgeable Sir, suggest a class D amp that doesn't supply a volt or so of 500kHz carrier at the output?
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Old 6th January 2013, 09:25 AM   #43
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But as a technology the PC is not exactly new, I've been using one to do my job since 1985.

And so have i and that proves, what?

Otoh, 1985 was indeed a very different time and i believe audio systems at the time sounded in many ways much better than they sound today. Around that time British audio mag reviewers had an obsession with front panel LEDs. I think it was Jimmy Hughes who first started disabling such devices and claimed improved sound. What in '85 was a potential source of RF, today is among the audiophile's favourite voltage references, commended for it's low noise. The irony



It is, of course, speculation, but one explanation for the sonic preference for linear supplies is that switched mode regulators integrated into mother boards have negligible effect on RF pollution compared to off-board power supplies. Ground planes and the absence of long wires certainly do make a difference. The (anecdotal indeed) effect of sata filters points in the same direction.
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Old 6th January 2013, 10:22 AM   #44
marce is offline marce  United Kingdom
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What worries me about a class D is that it is transmitting noise into the envoironment, if it is a commercial piece of equipement it should be EMC compatable, the noise spectrum is already bad enought with all the wireless devices and mains borne noise as it is.
Either a linear or a SMPS designed correctly will do the job, but my belief having been involved with the design of lots of various systems over the years is that iif you are worried about PC noise then isolate the DAC stage galvonicly. Myslef I use squeezeboxes, and have a PC exclusivly for running squeezbox server, thats all it does, bare minimum running, players isolated either wirelessly or via an therenet connection.
My reference to PC's was that they are not new, the digital transmission side of things is way more stable than then, I run quite power hungry CAD systems and PC crashes are a rare event these days, whereas that has not always been the case. Many years of research and development have given us digital devices that are stable and just keep working.
I am all for reducing noise in any circuitry and have a big interest in said noise. One of the main concerns with commercial gear is the ever increasing demand for low cost, as consumers we have got use to reasonable prices, and the cost cutting has an effect of the designs, and compramises are made. I think with a PC with a realy well designed SMPS will be no different from one with a linear supply.
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Old 7th January 2013, 04:01 AM   #45
kp93300 is offline kp93300  Malaysia
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Hi kp93300

Nothing particularly surprising in your findings. I know nothing about Atom boards but quite possibly you can take this a step further by disabling on-board switching regulators one by one and supplying your own regulated voltages. Are you able to identify the regulators and the corresponding circuits they supply?
Hi
I do not have the expertise to do this but i am planning to get a refurbished and cheap motherboard for this purpose !
may be i can learn a thing or two.
cheers
kp93300
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Old 7th January 2013, 06:27 AM   #46
marce is offline marce  United Kingdom
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How will you stop the digital noise generated by the digital circuitry switching.
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Old 7th January 2013, 06:29 AM   #47
qusp is offline qusp  Australia
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dont you know thats distinctly different and less important then SMPS switching?
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Old 7th January 2013, 07:04 AM   #48
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That's why I'm using an 8086 CPU. And it sounds so much better at Normal mode (5Mhz) than at Turbo mode (8Mhz)! Switching is bad, M'Kay?!

Quote:
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I think it was Jimmy Hughes who first started disabling such devices and claimed improved sound. What in '85 was a potential source of RF, today is among the audiophile's favourite voltage references, commended for it's low noise.
Should give you a good indication of how nonsensical those claims were...
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Last edited by TheShaman; 7th January 2013 at 07:08 AM.
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Old 7th January 2013, 09:15 AM   #49
marce is offline marce  United Kingdom
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switching may be bad but it is basicly what digital is, so you design your boards and decoupling, power planes etc to cater for the high dI/dt switching circuitry requires. Provided the designs are with certain parameters using linear of switchmode does not affect the digital signals in anyway, though I have heard comments regarding digital such as passing through numerous servers can add low level distortion!!!! The poster refused to discuss this further.
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Old 7th January 2013, 02:21 PM   #50
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...though I have heard comments regarding digital such as passing through numerous servers can add low level distortion!!!! The poster refused to discuss this further.
Yeah, we should design a routing protocol that favors audiophile servers running on linear supplies and SSDs.

The most .... absurd thing I've read (and "absurd" is me trying - really hard - to keep it civil) is that files play worse the deeper they are in the directory structure. So if, say, you reproduce a file directly from D: it'll play better compare to the same file in D:\folder1\folder2\music.

I know, I know... I feel dumb even reproducing this stuff and I'm afraid too many people (i.e. more than 0) reading this will go ahead and try it, but I'm sure many more will have a good laugh.

If any of you don't believe someone would seriously write that stuff in public, I can name and shame.
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Last edited by TheShaman; 7th January 2013 at 02:24 PM.
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