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Post by misterc on Dec 28, 2021 11:01:17 GMT
Here is an industry paper on the nasties that smps can deliver IF not properly controlled
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Post by lurch on Dec 28, 2021 13:48:43 GMT
Well that fried my brain within 30 secsonds, think I will leave it to the experts.
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Post by hifinutt on Jan 1, 2022 17:03:57 GMT
yes thanks tony . perhaps one day you can interpret it into very simple english for me !!
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Post by misterc on Jan 3, 2022 10:18:33 GMT
yes thanks tony . perhaps one day you can interpret it into very simple english for me !! Hello Phil
Not a problem, will break it down in a non Rhode & Schwarz manner .
SMPS are all about three main benefits over tradition linear power supplies:
Power density factor (Grunt per square mm) Power output Vs size smps are far more powerful per 'real estate' than LPS in that I can generate 20 amps in a far smaller package (No big transformer required)
Cost factor, using components which are cheaper and easier to mount on smaller circuit boards, cheaper to produce.
Size is on the whole much smaller and compact easier to site within a box or case
Virtually everything uses smps now, very widely available 'off the shelf' psu's for almost any application.
One of the big advantages for SMPS is speed?, what really? well yes this equates to much smaller storage / smoothing capacitors sizes.
A UK LPS has just 50Hz (50 cycles a second) to work with so basically the recharge time for the capacitors is quite long therefore necessitating the need for much larger capacitors to hold the charge longer until to the next charge cycle occurs, compare to say a basic SMPS which can switch (charge the capacitors) anything from 20Khz (twenty thousand times a second) upwards. So basically the recharge time on to the capacitors is much, much smaller so the 'sag' between the charges is hugely reduced which in turn leads to MUCH smaller capacitors required to deliver the same power.
Hence why the cap sizes on SMPS are significantly smaller along with smaller transformers etc.
Downsides to smps supplies:
RF noise due to the higher switching frequencies which are required to 'chop up' rectified dc into much smaller segments.
Not ideal for big power reserves unless you have multi smps units power a full capacitor super storage bank.
Careful placement and understanding of how a SMPS works and how the 'high side' must be totally isolated from the 'low side'
For sensitive noise application much more work must be applied to reduce the power rail noise to acceptable levels for sensors/audio/RF applications much more indepth work on a/c filtration plus DC noise suppression filter banks.
To sum up this section:
For
SMPS cheaper/easier/mass production simpler/greater choice/smaller footprint
Against
Noise generation both a/c harmonics and common mode (if poor incoming filtering techniques used) DC power rail integrity needs attention for more sensitive applications
Extra sheilding required to help with above noise issues so more space required
Critical placement of smps within chassis as not to upset any other rf susceptible components.
They are a few more that would bore you Phil
Next part on how it works simply
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Post by hifinutt on Jan 3, 2022 16:06:28 GMT
thanks tony
nicely put , appreciated
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Post by sq225917 on Jan 3, 2022 16:54:00 GMT
Be fair, as far as domestic use goes the placement is no more onerous than keeping that big traffo out of the way.
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Post by misterc on Jan 3, 2022 17:55:27 GMT
Be fair, as far as domestic use goes the placement is no more onerous than keeping that big traffo out of the way. Its just cheaper and uses less iron and space Simon, when we have the meet I will bring along the PA3000 and we can see how much noise they dump back into the mains grid.
Putting Tx's in the vast majority of domestic applicances is not worth the effort absolutely agree, otherwise you wouldn't be able to obtain that 10Kg tumble drier for under £300!
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Post by sq225917 on Jan 3, 2022 18:50:56 GMT
No arguement from me on the crap they put back onto the mains...
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Post by misterc on Mar 23, 2022 17:42:31 GMT
I saw this article in What caravan eariler this afternoon, I tried hard not piss myself laughing but you have admire his staunch company line towing policy, however John Franks has been careful to place a remote 100Kva probes on either of his testicles at press conferences I suspect.
To replicate anywhere near lps quietness you would need to go to full space fairing psu's / ulratrick T&E style power and uber medical varients but a wall wart really 
Why do most Chord Electronics DAC products use what appears to be cheap wall-wart power supplies?
Because the units themselves have internal power regulation and RF filtering. Adding ‘better’ power supplies will either make no difference or make it sound worse (brighter) – so superficially more impressive but actually worse due to increased RF noise from big linear PSUs.
Comments gentleman please
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Post by sq225917 on Mar 23, 2022 18:05:55 GMT
Because they've decided its all they require to give the sound quality that they think commensurate with their price and blingyness.
And because anyone who likes Chord amps is after a hard, forward sound anyway so it'll be right up their Strasßße anyway.
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Post by macca on Mar 23, 2022 20:51:01 GMT
They are never going to say it could be better with an lpsu as that would cost them sales.
And they can't really switch to LPSU now since that's admitting all the DACs they've sold to date are compromised when they told the buyers that the SMPS was fine.
Likewise they can't sell aftermarket upgrade supplies for the same reason (I know Naim get away with it but that's Naim).
Or they could be quite correct in that there's nothing wrong with SMPS. Certainly you can't fault the measurements, no power supply noise at all on any of them. If it is a problem, it's well hidden.
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