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Audio Power Supplies - PART3 - SMPS, LPS. SuperCap, Battery, DIY route. New devices opens up new options.

Discussion in 'Computer Audio' started by rb2013, Oct 5, 2016.
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  1. rb2013 Contributor
    Ok Now things well get more interesting - here I want to explore the LPS solutions available - focusing on the less expensive options (under $250).  But first a quick primer on the last main component of these LPS units - the filter capacitors.
    LPS Capacitors:  There are many types of capacitors, but linear power supplies generally use electrolytics, due to their ability to withstand high voltage spikes and reasonable performance.  These caps are rated for voltage, and capacity, as well as expected life, temperature rating and physical size.  But other important criteria is the caps ESR rating, PSRR and impedance - more on this in a bit.  Generally the aluminum electrolytic types are preferred.
    "The basic unit of electrolytic capacitors capacitance is the microfarad (μF, or less correctly uF)", that and voltage are two main parameters for use.
    "Electrolytic capacitors are polarized capacitors and generally require an anode electrode voltage to be positive relative to the cathode voltage.   To minimize the likelihood of a polarized electrolytic being incorrectly inserted into a circuit, polarity has to be very clearly indicated on the case, see the section headed "Polarity marking".
    Now for some details on why these capacitors are used in a LPS and how to select the better versions:
    It's my understanding that a lower impedance is generally better for use as a filtering cap.

    ESR and dissipation factor tan δ:

    Here a lower value is generally better.

    Ripple current:

    Here again higher is better.
    I have had good success replacing the stock capacitors on inexpensive LPS's.  I look for long life - 10,000 hours preferred (most of the cheaper LPS from China use 2,000 hr or less rated caps), low ESR, high PSRR and low impedance for the respective capacitor value.  I also try and find capacitors rated for 105C temperature, if possible.  The cost for these better caps is minimal compared to the overall cost of the LPS.  One note more and larger filter caps in a LPS will give a higher level of AC noise or ripple rejection - all other things being equal.  The larger number and size will slightly increase the noise fed back into the local AC mains (still orders of magnitude less then a SMPS). 
    Here is a TeraDak X1/X2 with the stock Panasonic FC 25V 1500uf caps (rated at 5000 hrs, 105C Temp) - from Digikey (although they show a different color) Impedance: 30mOhm,
    Ripple: 1.55A@120Hz, they do not show an ESR rating for these.
    With Nichicon HW  25V 1500uf - 10,000hr (105C), low impedance: 16mOhm, Ripple 1.56A@120Hz.
    Other possible caps I could have used that are excellent:
    United Chem KZ (5000hr - 18mOhm, 2.7A) $1.00each
    Pannasonic FM (7000hr - 15mOhm, 2.55A@120Hz) $1.40each
    Pannasonic FR (10,000hr - 18mOhm, 2.08A@120Hz) $1.01each
    I have the FMs and may switch the caps in this little unit at some point - more on this LPS later.
    Existing LPS available for low cost  - under $250:
    Just a note on linear power supplies - they do come in both regulated and unregulated versions.  Typically the unreg will be cheaper wall wart looking devices.  Do to the lack of regulation they are not recommended, their voltages can swing by wide amounts and even damage some equipment.  All the following are of the regulated variety.
    In PART 1,2,and 3 we have explored the three main components of a linear power supply:  the transformer, the regulation circuit, and the power filtering capacitors.  So what to look for?  Well for me I really like the R-Core transformer for it's AC noise (ripple) rejection superiority over toroidal or EI transformers.  A high quality LDO with low DC noise and high current capacity (an issue with many of the ultra low LDO's available). 
    You have to look at what your current and voltage needs are, when choosing a replacement power supply.  If you're powering a USB DAC or DDC - is 500mA enough?  Many draw in excess of this - the PUC 2 Lite for example with a 800mA draw.  Most external XMOS DDC's will draw less and abide by the 500mA USB std.  I would prefer a LPS that can provide at least 1A 5VDC(the std USB voltage).
    Many LPS's also have adjustable voltage pots - so their voltage can be changed as needed.  Some of the external USB gizmos like the Regen and Recovery need a higher voltage then the std USB +5VDC, as they have their own on board LDO regulators that will then step down the required voltage to 5VDC - in the case of the Regen 7-9V is optimal and the W4S Recovery needs 9VDC.   Feeding a USB DDC like the F-1 can be done with a split USB cable (the data and power leads are separate), taking the power from the LPS and the data from the PC's USB.

    As for capacitors - not as big of an issue for me as they are fairly easy and cheap to upgrade.  But it would be nice to have the better Panasonic, Nichicon, or Chemcon caps.
    So here are a few I own, or look interesting to me.
    First I want to discuss a neat little gadget:
    iFi DC iPurifier:
    This attaches to the end of the DC feed cable before the device and filters the DC power by many factors.  I have had very good success using one of these with a low cost LPS bought on Ebay.
    iFi claims tremendous DC noise filtering from this unit - 316X under 1Khz, up to 100,000x above.  They claim they are able to achieve this with an active noise canceling circuit used in military radar.  I wonder if this type of circuit isn't being used on chip for these >1uv LDO IC's to get the DC noise levels down?
    They are not cheap - around $80 from Music Direct:
    But the big question is - do you need an ultra low noise regulator (>4uv) in your LPS if you use one of these?
    As you'll see there are many decent and cheap LPS's on Ebay - some for less then $100.  If one uses the LT1083 or LT1084 LDO regulators (see Part 2 for a comparison of LDO's) with 180uv of DC noise - but that then gets filtered down by a DC iPur at least 317 times - that would leave less then .5uv of noise to the device!  This is the lowest noise level I have seen in a plain IC LDO. So for around $160 you can have a nice ultra low noise package.  That is if the DC iPur works as advertised.
    OK On the LPS's:
    Generic R-Core LPS:
    This unit I own uses the LT1083 regulator mounted on a nice large heat sink - uses one 50V
    3300uf filter cap, 4 of the new Vishay B560 Ultra Fat, Ultra Low Loss Rectifiers, and a 12V R-Core transformer.  The LT1083 does not have very good noise numbers rated at 180uv, and lowly PSRR.  But with an R-Core maybe high PSRR is not as necessary?  With the iFi DC iPur - the DC noise can be reduced to virtually nothing.  This is a high current unit - and not appropriate for a USB device - the lowest setting is 9V(3A) and can go as high as 24V(1A).  So if high current and voltage is needed this looks like a great low cost solution. Note the iFi DC iPur is rated to just 24VDC - and over heated when I tried it this unit at that voltage, but has worked well at much lower voltages.
    $77 Delivered.
    I will explore the DIY option in a later part 4.  But this could be the 'bones' for just such a project.  Just replace the LDO with some thing like this (the existing board is 75X50mm):

    Ultra low noise LT3042 .8uv - very high PSRR 79dB @ 1Mhz.  This board is rated at 6-12V input and 1.5A 5VDC output.  So the existing R-Core could be used.  The size is 69x47mm - so it would fit as well.
    $60 shipped.  So with a little effort this could be a killer good USB DDC or DAC power supply.  The voltage is non-adjustable.
    TeraDak X1/X2 LPS:
    Neat little unit  - EI transformer - LT1084 LDO (180uv 30dB PSRR)- Panasonic FC caps 25V 1500uf (8 total), AC common mode filter coil, MOV surge protectors, etc... $80 shipped.
    Upgrade the caps - as pictured - or use the stock caps and add a iFi DC iPur and you have a neat low cost LPS solution.
    Nice feature - has two DC power ports - one a USB set for 5VDC and the other a 2.5mm barrel which has adjustable voltage.

    Product Specification​

    1. Output : 8.5V DC + USB-A 5 VDC Port @ ~ 1A
    With a total of 1A 5VDC - I would not use both power ports simultaneously.  But 1A for 5VDC is more then adequate for XMOS USB DDC use.
    TeraDak DC-30W (old design):
    Nice copper shielded R-Core transformer, likely the LT1084 LDO's 180uv, 30dB PSRR, Panasonic FC caps 25V 1500uf (10 of them).
    With the R-Core transformer and it's excellent inherent PSRR - the low LT1084 PSRR may not be as important as when it's used with a toroidal transfomer (see PART 1 on transformers).
    Rated at 3Amps 5VDC and 1.5A for 12V and with an adjustable voltage  - more then enough for almost any DAC or DDC.  Great for powering the 7-9 VDC Regen or 9VDC Recovery USB reclockers.
    TeraDak DC-30W (New design):
    Nice copper shielded R-Core Transformer, looks like two NPN devices used for power regulation, mine had the Panasonic FC 25V 1500uf caps 3 total and two larger 25V 3300uf Panasonic SU caps (low 2000 hr life), EMI common mode filter and MOV surge protection on board.
    I see the latest versions have the better Panasonic FC 25V 3300uf caps vs the SU.  (On mine I swapped the SU's for 25V 3300uf Nichicon HW's.  This made a noticeable improvement in SQ.)
    $139 shipped.
    This new design has high current capability - rated at 2.5A @ 9VDC.  Also with adjustable voltage - so at say 5VDC plenty of power for any USB DDC and then some.  Plenty for the Regen and Recovery etc...
    I could only find the marking of D44H11 on the regulation devices - there are two.  I identified them a NPN devices (OnSemi?) - but was not able to find any DC noise figures on this power supply.  Imagine less then 50uv with excellent PSRR.
    I use mine with a iFi DC iPur to excellent effect on both my modded BURL B2B DAC and with the Singxer F-1 XMOS USB DDC.
    MEIYAN Ultra Low Noise - High Current LPS:
    This unit I found on Ebay has me really intrigued - very low noise - 13uv @24VDC - low noise at lower voltages, very high current capability:
    $192 shipped.
    We have following several kinds voltage for choose (Output voltage / current)

    1. 5V /6A

    2. 9V /5.7A

    3. 12V /5.5A

    4. 15V /5.3A

    5. 18V /4.4A

    6. 19V /4.2A

    7. 24V /3.3A

    Nice copper shielded R-Core transformer - excellent low noise.
    One downside is the voltage is not adjustable.  But it is available in a range of voltages - I will likely order one at some point to try out.  Update:  The DC voltage is adjustable in a range of 5VDC to 24VDC.
    So that completes the low cost LPS's I have found - now a few expensive ones:
    Paul Hynes SR2 & SR3:
    These highly regarded LPS's are excellent designs - but not cheap the SR2 is approx $250 ($195 English Pounds) and the SR3 $381 (300 English Pounds):
    For the SR3, I have seen 5uv @10-100Hz quoted for the SR3 and PSRR of 80dB @ 0-300Mhz!
    On his Z100A Shunt regulator he quotes 110dB of PSRR from DC to 20kHz! 
    The SR2 used to be much more expensive - and maybe this is the best lower cost LPS to get.  The one issue is very long back order que from what I have heard - I'm sure with the recent devaluation in the British pound - maybe even more so today.
    Note these PS's need to be built to spec as the DC voltage is not adjustable.
    Teddy Pardo - Teddy Cap PS -
    These made a name for themselves replacing the NAIM power supplies.  Available in a range of voltages - $369 for a 5VDC version.
    I have not seen noise or PSRR numbers for these power supplies.
    Uptone JS-2 -
    $925  Wow!  This is a beautifully totl LPS - with multiple DC outputs that have various voltage settings:
    R-core transformer!  The choice of the R-core here speaks volumes:
    Have not seen DC noise or PSRR numbers for the JS-2 but I bet they are very good.

    OK R-Core Transformer  - nice.  But...the LDO regulator used is the Linear Tech LT1083.  High noise of 180uv and only  30dB PSRR at high frequencies - not great for a $395 PS.  Says low ripple and 'void of high frequency noise' what ever that means.  Any numbers?

    I'd prefer going with a TeraDak DC-30W or the MEIYAN for much less money and adding a DC iPur.  Or get in line for a Hynes SR3.
    Next Part - the new SuperCap PS's and Batteries.
    kazsud likes this.
  2. rb2013 Contributor
    I received this in a PM good stuff:
  3. rb2013 Contributor
    I wanted to add some of the information I found about the latest generation of USB gizmos - like the Regen and W4S Recovery - the Schiit Wyrd as well.  Both the Regen and the Recovery make powering your USB DDC (like the Singxer F-1) easy with the simple DC external barrel plug usually provided with the LPS.
    All three devices filter the USB 5VDC power that then powers the attached DDC or DAC - the Regen and Recovery have external DC power ports  - the Wyrd is AC driven (by a linear power module - not sure if it's regulated or if the regulation occurs on the Wyrd board).  So here is the info:
    W4S Recovery -

    The Recovery uses a 9VDC input that is then further regulated to output 5VDC on the USB lines.  The low noise regulators in the Recovery product 13uv of noise ( I have been trying to find the exact one they use - will open mine up and take some closeup photos).  The Recovery prefers 9VDC - but can accept 7-10VDC.
    Uptone Regen -

    The Regen likewise has an ext DC power port - so makes using a LPS to power the 5VDC USB lines easy.  Like the Recovery it also has on board LDO regulators - filtering the inbound DC (from 7-9 VDC - 7.5 preferred) to 5VDC out.  Uptone does sepecifiy which LDO they use  - the TI TPS7A4700 - it has 4uv of noise.  Very nice!
    Schiit Wyrd -
    This may be a great lower cost power solution for USB devices - up to 500mA of clean linear power.  Using LM723 regulators - with 2.5 uv of noise - this unit for a direct power feed to a USB DDC may be a great solution.  I prefer the Recovery - with an external LPS - and a iFi iPurifier 2 in between (less the 1uv of noise).  But that is a more costly route.  Speaking of iFi
    iFi USB3.0 Nano -
    Another fairly inexpensive solution for USB audio.  The $200 iUSB 3.0 Nano - claims .5uv of noise when fed by it's included iPower 9VDC SMPS.  Being a SMPS - the iPower will produce much higher levels of noise back into the AC mains - possibly effecting other components - like your DAC.  But I have tried the iPower both directly and feeding the Regen and Recovery (and a older iUSB 2.0) to very good effect.  I'm sure this would be made even better with the Nano - a true bargain - as it's technology is the same as the iPurifier 2 - $109 on it's own.  For me I still prefer the LPS route through the Recovery and an iPur2 inbetween.  But certainly for $200 this is a very viable turnkey solution.
  4. rb2013 Contributor
    Found this interesting discussion of the 'John Linsley Hood Ripple Eater' circuit.
    Looks similar to the stage 1 in the MEIYAN LPS:
  5. occamsrazor
    Some other LPS options.....
    Qualia Physic
    I read some good reports of these used with a Mytek Brooklyn DAC
    Wyred 4 Sound PS-1 modular LPS:
    Just announced at RMAF 2016. Seems a bit expensive to me but a nice idea and design.
  6. wushuliu
    I Believe the Meiyan is really an Amb sigma 11 which can be bought custom built from ymb if you want to be assured of quality control.
  7. rb2013 Contributor

    Thanks for that- the AMB webiste gives more detailed information the MEIYAN LPS.
    I would say for less then $200 shipped thefully assembled MEIYAN looks pretty good.  Nice quality of parts from what I can tell.
    I like the attention to low impedance.
  8. rb2013 Contributor

    I saw the W4S PS-1 announcement.  Nice they are using an R-core.  But no mention of noise or PSRR.  $499 for a single module version, $125 to add additional voltage modules.  Will be looking forward to more information on this one.  The power supply wars are heating up!
    I did come across the Qualia Physics 271 SV - but wasn't to impressed.  Use of a toroidal transformer - number 1.  They quote:
    But in their specs quote:
    Well .0027% equates to approx 140uv of noise - not much better then the LM317 or LT1083 (.003% - 180uv).  And they only quote 10-10kHz not 10-100Khz like most other LDO datasheets.  As for PSRR - they claim 72dB but give no freq range (which usually varies widely - and drops significantly at high freq) - or supply a PSRR vs Freq chart like most LDO datasheets.  With the use of a toroidal the job of the regulation circuit is even more critical for PSRR.
    I bet it's not cheap too.
  9. rb2013 Contributor
    More info on the MEIYAN 100W LPS:
    Similar DIY board:
  10. astrostar59
    I can vouch for the HDPlex unit. I have used mine for over a year and great performance. I nearly bought the Uptone Audio unit but as they told me, they couldn't make the HDPlex for double the price just in parts. The R-Core in both are the same unit. And the HDPlex has a 3 year warranty, you won't get that from many of the others.
    It also has 4 outputs not one.
  11. rb2013 Contributor

    Uptone said that the JS-2 uses the exact same R-core transformer?  The four outputs is a nice feature - but the LDO regulator they use has very high noise, and poor PSRR - it's an old design.  You'd expect better for the $395.
    But if it works for you - great!
    Here is the R-Core in the HDPlex:
    And the JS-2:
    They sure don't look the same.
  12. astrostar59
    Here is the correct HDPlex photos. The unit you show is the wrong model. See the larger amount of Elna caps and the R-Core is the same apart from the copper shield. 

    Not sure if the regulators are 'noisy'units, but that is part of the story, the caps also impact the noise and ripple reduction. The unit comes with CE approval and 4 other standards.
    Where does it say LT1083, I can't see that quoted on the HDPlex site?
  13. rb2013 Contributor

    Thanks for the photos!  
    See the beginning page of this thread -I'll repost it again.  Taken directly from their website under 'SPECS'
  14. rb2013 Contributor
    It does have a nice bank of caps - but the ELNA's are not the best at PSRR.  They are fine caps for SQ - I have used the SILMIC II ELNA's inmy DAC60 mod project and in a pre-amp mod that I did.
    Wouldn't use them in a PS filtering  - the Pannie FC's and FM's are better  - same for the Nichicon HW's.  Lower impedence and higher PSRR.
  15. rb2013 Contributor
    See my PART 2  - I go over the more common LDO IC's
    Not only do they have high noise - but poor PSRR.
    It's the same ones used in this $80 LPS:
    IN contrast the MEIYAN has 13uv of noise at 24VDC and lower at lower voltages.  Very high PSRR as well.  Can deliver 5.5A at 12VDC - copper shielded R-Core transformer.
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