[drez]

  Hi Alex - Nice to see you back here!  We may have had our battles, but I always respect your knowledge and input.  Good info on the 575 - strange Digikey did not show a version with the Tri-state feature, or maybe I missed something.  Or maybe it's not as important as Audiobyte says?  That is the ability to disable the unused audio clock.
 
As you can see a few talented folks here are working some very interesting mods to the F-1.  Maybe Uptone could do a Uber-F-1?  That would be very interesting.
 
Nice!  Your concurrence is appreciated.  I can see the use of a toroidal in a small one unit case design - due to the EMI issues.  But that can easily be a non-factor with an ext LPS box.
 
Researching yesterday I came across this comment:
http://www.stereo.net.au/forums/topic/55835-why-a-torroidal-instead-of-an-r-core-transformer-in-digital/
 
Also looked at shielding materials - came on this - looks like copper is pretty good.
http://www.ets-lindgren.com/pdf/emctd_1293_weibler.pdf

 
I was agonising over transformer selection for this power supply.  I think the inductive coupling issue is real when it comes to rejecting line noise, and also possibly noise between secondary windings.  The thing is though the transformer is not the only way to reduce line noise.  You can also use a line filter, although I am not sure how these compare in terms of strengths, weaknesses, tradeoffs etc.
 
I was not able to find an appropriate R core for this build unfortunately.  Not many with 5V secondaries.  Especially in bigger transformers which have better voltage regulation.  The secondary voltage seems to vary a lot over different load especially on the smaller units which might have been an issue with my power supply in that the voltage would have been a bit high at the load I would be using.
 
The shielding seems a good idea.  I was looking at a shielded O core, or using mu-metal.  For me the other thing is humming, which R cores are very low hum.  The potted toroidals might be good also.  I might still end up using the mu-metal as this PSU will sit right on top of my DAC digital circuits.  Actually the EI core I bought for prototyping might be pretty bad for that as well as radiated EMF.  I am keen to minimise vibrations as they seems to work their way back into the signal through microphonic components.

 

[wakka992]

 
So far the best of the Chinese LPS I have tried is the R-Core TeraDak DC-30W.   I modded with Nichicon HWs.
 

 
Hi rb2013,
would it be possible to power an iFi iPurifier or Singxer F-1 with this Teradak DC-30W even if the output is 5V 3A instead of the classic 5V 0,5A of the usb bus?
 
If yes what cable do you use? if I understand correctly the DC-30W comes with a DC Cable only
 
thanks!

 

[ccschua]

this is a very frequent question asked by the user. 
 
its like asking can I use 5000cc car instead of a 800cc compact car running on a highway.

 

[rb2013]

   
I was agonising over transformer selection for this power supply.  I think the inductive coupling issue is real when it comes to rejecting line noise, and also possibly noise between secondary windings.  The thing is though the transformer is not the only way to reduce line noise.  You can also use a line filter, although I am not sure how these compare in terms of strengths, weaknesses, tradeoffs etc.
 
I was not able to find an appropriate R core for this build unfortunately.  Not many with 5V secondaries.  Especially in bigger transformers which have better voltage regulation.  The secondary voltage seems to vary a lot over different load especially on the smaller units which might have been an issue with my power supply in that the voltage would have been a bit high at the load I would be using.
 
The shielding seems a good idea.  I was looking at a shielded O core, or using mu-metal.  For me the other thing is humming, which R cores are very low hum.  The potted toroidals might be good also.  I might still end up using the mu-metal as this PSU will sit right on top of my DAC digital circuits.  Actually the EI core I bought for prototyping might be pretty bad for that as well as radiated EMF.  I am keen to minimise vibrations as they seems to work their way back into the signal through microphonic components.

Good question on the noise rejection issue.  I have to say the more I experiment with power filtering - both AC and DC - the more I'm interested in maximizing this aspect of audio.  This applied to digital - as my analog systems seemed much more immune to line noise.  The beating heart of the entire digital chain are these femto clocks - and they appear to be quite sensitive to noise.
 
So even with a pretty good AC line filtering chain: Teslaplex>Audience Rp1 (AC line conditioner and balancer)>Art Audio PB4X4Pros (common mode and differential mode AC filtering and isolation - separate ones for DDC, DAC and PC) - I have still noticed an improvement with the better LPS's.  None of the TeraDak's I have make any discernible transformer vibration or noise.  I still use BB boxes on top with vibration isolation underneath each - as with all my gear.  Vibrating control is a whole other issue.  I keep my TeraDaks a foot away from the F-1 (suing the Recovery in between).  Vibration is another reason I like to have the PS external.
 
But here is my ranking for PS's feeding the F-1 and Recovery:
1) TeraDak DC-30W (modded with Nichicon HW caps) + DC iPur
2) TeraDak DC-30W (modded with Nichicon HW caps)
3) TeraDak DC-30W (stock caps) + DC iPur
4) TeraDak X1/X2 (modded with Nichicon HW caps) +DC iPur
5) TeraDak DC-30W (stock caps)
5) TeraDak X1/X2 (modded with Nichicon HW caps)
6) TeraDak X1/X2 (stock caps) + DC iPur
7) TeraDak X1/X2 (stock caps)
8) iFi iPower
9) stock SMPS
 
Note the DC-30W has a copper shielded R-core transformer.  The Nichicon HW caps have a higher PSRR then the stock caps (and a 5x longer life, lower impedance)

   
Hi rb2013,
would it be possible to power an iFi iPurifier or Singxer F-1 with this Teradak DC-30W even if the output is 5V 3A instead of the classic 5V 0,5A of the usb bus?
 
If yes what cable do you use? if I understand correctly the DC-30W comes with a DC Cable only
 
thanks!

No problem - just be sure the voltage is set properly. You can get DC plug to USB Female adapters.  I would recommend using a Regen or Recovery (or an iUSB 2.0 or iUSB 3.0 - with the USB3.0 no need for the DC iPurifier as it's built into the new design) - they each have ext DC inputs and additional power filtering.  With the iPurifer and iPurifer2 (much prefer the latter, big leap in performance over the original), is just takes the power feed off the USB 5VDC.
 

  this is a very frequent question asked by the user. 
 
its like asking can I use 5000cc car instead of a 800cc compact car running on a highway.

Yes  - no problem at all.

 

[drez]

I gave up on the LT3042 PSU I bought.  Not sure it will be the best fit for what I have in mind (as a pre-regulator to the isolated section of the Singer F-1).  
 
Too many headaches so I am going with Sjostrom super regulator and bring my own rectifier and filter cap.  Hopefully I can use 9V R-core I bought in error.  Maybe order custom wound, potted and shielded O-core later.  I think the R core has some shielding, but not sure what % effective.
 
Seems I will be doing a lot of point to point wiring despite investing in the crimping tool.  I guess it will come in handy for the AC wiring.

 

[wakka992]

 
1) TeraDak DC-30W (modded with Nichicon HW caps) + DC iPur
 
 
No problem - just be sure the voltage is set properly. You can get DC plug to USB Female adapters.  I would recommend using a Regen or Recovery (or an iUSB 2.0 or iUSB 3.0 - with the USB3.0 no need for the DC iPurifier as it's built into the new design) - they each have ext DC inputs and additional power filtering.  With the iPurifer and iPurifer2 (much prefer the latter, big leap in performance over the original), is just takes the power feed off the USB 5VDC.
 
 

Thanks for the answer.
 
wouldn't it be better a good LPS such as the TeraDak DC-30W+iPurifier 2 instead of Regen/Recovery/iUSB that have external DC input? 

 

[rb2013]

  I gave up on the LT3042 PSU I bought.  Not sure it will be the best fit for what I have in mind (as a pre-regulator to the isolated section of the Singer F-1).  
 
Too many headaches so I am going with Sjostrom super regulator and bring my own rectifier and filter cap.  Hopefully I can use 9V R-core I bought in error.  Maybe order custom wound, potted and shielded O-core later.  I think the R core has some shielding, but not sure what % effective.
 
Seems I will be doing a lot of point to point wiring despite investing in the crimping tool.  I guess it will come in handy for the AC wiring.

Interesting project - looking forward to your results.
 
Paul Hynes also sells some nice regulators:
http://www.paulhynesdesign.com/page6.html

 

[rb2013]

  Thanks for the answer.
 
wouldn't it be better a good LPS such as the TeraDak DC-30W+iPurifier 2 instead of Regen/Recovery/iUSB that have external DC input? 

Actually they work together very well.  The Regen and Recovery have no power of their own - but need a higher voltage then the +5VDC than USB provides.
 
The Recovery uses 9VDC and the Regen a range from say 7-9VDC.  This is due to their own low noise regulators - than then step down the voltage to +5VDC to the USB power leads after filtering.

 

[rb2013]

Another choice for LPS is the Teddy Pardo - using the 'Super Teddy Reg' scheme.
 
ww.teddypardo.com/powersupplies/underthehood.html
 
$400 for a USB version - not cheap!
http://www.teddypardo.com/powersupplies/usb-psus.html

 

[wakka992]

Thanks rb2013 for your advice!
 
Thing is there's this cheap "TeraDak DC-30W 12V/1.5A FPGA Linear Power Supply" on ebay, I contacted the seller and it seems he'll ship me the 5V/3A version if asked to. In any case, should the seller "forget" about me and shipping the 12V/1.5A version is there any screw inside the case to adjust voltage/amp?
 
thanks as always

 

[rb2013]

  Thanks rb2013 for your advice!
 
Thing is there's this cheap "TeraDak DC-30W 12V/1.5A FPGA Linear Power Supply" on ebay, I contacted the seller and it seems he'll ship me the 5V/3A version if asked to. In any case, should the seller "forget" about me and shipping the 12V/1.5A version is there any screw inside the case to adjust voltage/amp?
 
thanks as always

Yes both the DC-30W and the X1/X2 have voltage adjustment pots inside.
 
WARNING: LETHAL VOLTAGE INSIDE - I adjust mine 'hot' with a meter on the DC outputs.  That pot screw is very small. Best to have an experienced tech do the adjustment for you.
 

 

[rb2013]

Interesting info from the Teddy Pardo website on power supplies:
 

Linear power supplies, such as those used in Naim power supplies are based on a transformer, rectifier, smoothing capacitors, and a linear regulator. When the AC at the output of the transformer is rectified and smoothed, a ripple is still present on the DC rail. This ripple has the form of a saw tooth which translates into noise at all audible frequencies and has a negative effect on the sound quality. The better the power supply can filter this ripple the better the sound will be. To get an idea of how much the power supply can affect the sound quality suffice to mention that almost all Naim preamplifiers are based on the same amplification circuitry and differ in their ability to connect more or better power supplies.​

The amplitude of the ripple mentioned above decreases with the size and quality of the smoothing capacitors being used. Naim Audio uses a brute force technique for the HiCap; they use a 500VA transformer and rely on large low ESR capacitors.​

 

 

 

The most common way to reduce ripple is to use a linear voltage regulator such as the LM317. The core of a linear regulator is an operational amplifier which monitors the output voltage and correct it using feedback. In order to reduce cost, most monolithic linear regulators, including the LM317 used by Naim for their power supplies, make use of a simple operational amplifier which generates its own additional noise. According to the LM317 datasheet it has a typical output noise of 0.003% of the output voltage. For an output voltage of 24V the output noise will be 0.72mV, not negligible...​

In addition, all linear (feedback) regulators, including the superior Jung SuperRegulator, have a limitation which is inherent to the way they operate, they can only fix a problem after it occurs. Since the speed in which they can fix the problem (regulate) is constant, their ripple rejection capability decreases with frequency. The LM317 has a ripple rejection of around 80db at 50Hz, which drops to merely 20db at very high frequencies (note that a -60db difference means x1000 times less!!!).​

Switch mode power supplies, such as the small wall-wart power supplies provided with the Logitech Squeezebox or with many popular DACs, are based on switching technology rather than transformer/rectifier/bridge combination. The idea behind these power supplies is to charge a coil/capacitor at high frequency and use the energy they store. The advantages of this technology are numerous which makes them very popular. They are small, efficient, low cost, and they are readily available from many manufacturers (mostly in China). The main drawback of these power supplies is that they are noisy, very noisy... Not only do they have a high level of high frequency noise on the DC, but they often inject high frequency noise to the mains which may impact performance of other hi-fi equipment. In short, less than optimal for high-end audio equipment.​

 

[wakka992]

 
Yes both the DC-30W and the X1/X2 have voltage adjustment pots inside.
 
WARNING: LETHAL VOLTAGE INSIDE - I adjust mine 'hot' with a meter on the DC outputs.  That pot screw is very small. Best to have an experienced tech do the adjustment for you.
 

 
Is it the really small golden screw on the blue parts?
 
Anyway, how can they have such difference in prices?
- TeraDak DC-30W-TOUCH DC5V 3A = 120USD
- TeraDak DC-30W 12V/1.5A FPGA = 60USD
 
Are there more DC-30W model?? I've asked the seller for clarification.... 

 

[rb2013]

   
Is it the really small golden screw on the blue parts?
 
Anyway, how can they have such difference in prices?
- TeraDak DC-30W-TOUCH DC5V 3A = 120USD
- TeraDak DC-30W 12V/1.5A FPGA = 60USD
 
Are there more DC-30W model?? I've asked the seller for clarification.... 

Yes the brass screw - and yes there are a few different versions of the DC-30W.
 
Here are two I have:

 

[rb2013]

Super Teddy Reg - interesting for $59
 
http://www.teddypardo.com/diy/superteddyreg-37.html