Linear Power Supplies - any improvement in sound?

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Re: Linear Power Supplies - any improvement in sound?

Postby bertie » 23 Apr 2017, 12:45

I'm quite interested in this topic and had tentatively reached the conclusion from digesting hundreds of websites that moving away from a switchmode supply was a no-brainer for all the digital signal devices in my hifi.

Sad to say, though, when I recently connected my raspberry pi (with DigiPro hat) and its wired harddrive (self-powered) to two separate power packs I could not (definitively at least) hear any difference. This was an initial test to find out whether it was worth buying 3 linear power supplies (including another one for my DAC).

Now, these lithium devices have quite high internal resistance (apparently) compared with, say, a nickelhydride battery or 'supercapacitors" so my result isn't conclusive. Also, my SMPS devices always run off a power conditioner that reconstructs a sine wave at tightly defined voltage (overkill but is the result of previously blowing a preamp), so 'mains' noise was never an issue for me (though I thought the whole point of the exercise was to remove noise created by the SMPS devices themselves).

Of course my sound system may not be sufficiently resolving (fairly likely) or my abused 50year old ears may not be up to the job (very likely). Anyway, while I'm always looking for the next item to buy, at this stage I'm leaning to the idea that SMPS devices have become adequately quiet for my purposes - indeed some websites claim to have recently tested off-the-shelf SMPS adaptors and found essentially zero noise.

Bottom line is I will look to upgrade my DAC or speakers before worrying about power supplies.

Might I just toss in that the Rune audio software is fantastic and I am so appreciative and in awe that the Rune team put together an image for the DigiPro so quickly.
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Re: Linear Power Supplies - any improvement in sound?

Postby bertie » 29 Aug 2017, 12:04

Four months later I would like to retract my previous 'null' result. I have since replaced my external dac (dacmagic plus) with a dac costing twice as much and then hooked the raspberry/Digi+Pro up again to a lithium battery pack as the power supply. Definite improvement, including a noticeable reduction in glare. Have since purchased a 25W linear power supply to preserve the improvement, without having to recharge every two days! Count me as a convert, with the caveat that one does actually need a 'half-decent' system for it to make any noticeable difference.
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Re: Linear Power Supplies - any improvement in sound?

Postby dirtylarry » 20 Dec 2017, 18:35

Im curious to what batteries can be used for clean power? Id like to pick one up for at work listening via headphones.
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Re: Linear Power Supplies - any improvement in sound?

Postby rastus » 11 Jan 2018, 12:44

dirtylarry wrote:Im curious to what batteries can be used for clean power? Id like to pick one up for at work listening via headphones.


Any battery... that supplies around 5v 2a...
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Subjects covered: Hardware setup for the Raspberry Pi as a digital streamer. Digital music, artists and thier albums or CDs. More will be added in the coming weeks.
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Re: Linear Power Supplies - any improvement in sound?

Postby rastus » 11 Jan 2018, 12:47

bertie wrote:Have since purchased a 25W linear power supply to preserve the improvement, without having to recharge every two days! Count me as a convert, with the caveat that one does actually need a 'half-decent' system for it to make any noticeable difference.


Yep, got myself a LPU that feeds my Raspberry Pi and my DSpeaker Anit-Mode 8033 sub eq at the same time.... works a charm, and my system would be deemed 'half-decent'.... sound awesome, to me.
You are invited to participate in my new forum, Rastus' Rants: http://rastus.tk
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Re: Linear Power Supplies - any improvement in sound?

Postby nic » 04 Feb 2018, 13:05

I tried a few different 5V 3A lump-in-line switchmode power supplies but now I have a linear power supply feeding my Kali/Piano DAC . It uses a conventional 25VA split bobbin mains transformer rather than toroidal for good isolation . This is followed by a bridge rectifier of SB560 schottky diodes , 0.47uF film cap , a pair of 5mH chokes (one in the + , one in the - rail) running choke input and 10,000uF of capacitance feeding an LM1085-5 . The reg chip is bypassed with tantalum caps . It's just a pre-regulator to get rid of the original switchmode but a subtle difference and noticeable after a few minutes listening . I will eventually build a similar supply for the Raspberry Pi main board but I doubt this will be as effective

Probably overkill and slightly pricey but I had the chokes already . This is a worthwhile way of wringing out that little bit extra :)

cheers

Nic
Pi3 with dual PSU , Kali , Piano 2.1 ----6E5P plate choke loaded linestage---BUZ900P choke loaded source follower---Beyma 15XT in 230l cabinets/TPL150H AMT
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Re: Linear Power Supplies - any improvement in sound?

Postby Stephane » 04 Feb 2018, 13:18

After a few minutes your ears accomodate so it is more likely that your brain wants to ear an improvement !
If there is a real improvement you can hear it as soon as you power up the system. And it can be measured.

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Re: Linear Power Supplies - any improvement in sound?

Postby nic » 08 Feb 2018, 20:16

I know what I hear and my ears are not easily fooled , I build a lot of audio equipment and after soldering , there is a lot of listening :) I use a hybrid tube / mosfet amp which takes a while to settle so for me after a few minutes is what it takes

In a switchmode supply , all that is between the mains and their amp etc is the enamel wire insulation and inter-section tape insulation within the flyback transformer . That has got to couple more crud from the mains than a split bobbin EI transformer . probably the reason for better sound . I used a search coil a few years ago and found some cheap Chinese power supplies emitted a lot of nasties

With the choke input supply , far lower peak current so reservoir capacitors are less stressed . Same goes for the mains transformer , I have not powered down the supply since it was built , the transformer is hardly warm at all . Benefits all round...

cheers

Nic
Pi3 with dual PSU , Kali , Piano 2.1 ----6E5P plate choke loaded linestage---BUZ900P choke loaded source follower---Beyma 15XT in 230l cabinets/TPL150H AMT
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