Hi Peter,

I am edging along but it now sounds like I should pick up the pace.  I built one 5A supply and it tests fine but now I need to get in and build the rest of them as well as the motherboard control circuit for ATX startup and shutdown.  All of the parts are here except a proto board for the control board, which after two months in the post has been forsaken and refunded as of yesterday so I need to chase down another of those to really get the project happening.

How is the W10 expiry going?  I will design the LPSU to best suit the latest hardware so if W10 has not expired I should get you to send out a HDD so I can work with the os running in Ramdisk.

Cheers,

Anthony

Would be nice to shorten/eliminate those dc cables or provide a second round of regulation at the motherboard just to see what happens.

Thanks for the reports Peter.  Have we found a new rabbit hole to go down?  There are several ways to build a good power supply and some guys are doing some interesting stuff over here with choke filtered unregulated supplies such as you would see in a valve amp.

More processes probably shut down when you press play. 

Then it is perplexing if your other sources work fine.  The unintelligibility thing is quite an extreme symptom and it seems as though something is definitely amiss.  Is there someone nearby that can loan you a XXHE pc for a while just to see if the problem is computer hardware related?  I would send you mine (no playback at the moment  ) but I doubt we are even in the same hemisphere let alone the same country.

Hi Coen,

I love reading your posts about the various Windows versions and your experience with them.  It makes me wonder why your experience is so different to many others?  Obviously you have a keen ear for what you like and knowing "musical structure" and understanding "nuance" are very important things that I don't think everyone gets.

Personally, I liked W7 for a while but eventually W8 won out because of the extra nuance and better tonal shading, which is completely the opposite of your experience!  Based on the impressions you have made in the various threads I have this idea that what you are liking or not liking emanates from the upper-bass/lower midrange, say 100Hz - 1000Hz, which is where warmth and tone and fullness are really set by your speakers.  Would you say this is accurate?  I ended up not liking W7 in this range because is made things a little unfocused or muddy in my system but you are the opposite. 

Could the differences be speaker/amplifier related?  I notice you use a 16" high efficiency Altec woofer for this frequency range and I wonder if there is some interaction problem with the 0.8W SET amplifier you are using, be that by back EMF, clipping, OPT core saturation or some other mechanism?  Just putting it out there, I am really not sure and no-one is more familiar with your system than you, but it is something that I thought about when I read your signature.

Cheers,

Anthony

Yeah 15uV which is quite an astounding noise level really for that amperage.  It is one thing to have a supply that carries that much noise at its outputs, but it is another thing to keep that low noise for the load which may be down a meter or more of cable.  A tricky part will be laying out the supplies inside the computer case so that there are either no leads (as in directly plug in the power supply to the sockets) or the leads are very short, say 10cm or thereabouts.  Of course the lower noise supplies are physically larger because of paralleled regulators and lots of capacitance so they are going to be more difficult to snuggle up next to the things that we want to power.

Ideally I will need a custom computer case to make room for these things...but we will see if it comes to that.

Hi Todd,

Those Acopian supplies look fine, so I will be quite keen to hear how you go getting your motherboard to start and of course how everything sounds.


Cheers,

Anthony

Well, with nothing happening on this front since I learned about the computer immunity of the NOS1a.  However, considering a few anecdotes of improvements from a computer LPS and Peters half-enthusiasm due to his workload with the NOS2 I have decided to revisit this project.  But the scope has changed a little with the technical advancements of both the Phasure system and linear regulators in general.  Ultimately, I want to find out just what it is about a linear power supply for the computer that can influence sound with our dacs, so I plan to go about things from two angles:

• An ATX LPS similar to those already on the market using the same voltage regulators, but in what is probably a better, lower noise way.
• An ATX LPS with new technology that surpasses existing supplies in terms of low noise, ripple, psrr, impedance et cetera.

Obviously this means that I will have to make at least two power supplies with different technology and see if they cause the system to sound different.  With the new technology I should be able to keep noise around 100 times lower than the tech. used in the commercially available power supplies.  Will this make a difference?  Is it the noise/ripple/psrr that makes a difference or is it simply about lowering the amount of noise fed back into the mains supply?  Is there a difference at all and is it work going all-out with the power supplies?

Anyway, I have been busy lately and am working on the module that will interface with the motherboard and control the power supplies.  I am quite confident that I can get it to work and once I do I can then play with the "good" power supplies (say 1mV RMS noise @8A and 4.5uV RMS noise @ 1A) and the "great" ones (say 15uV RMS noise @8A and 0.4uV RMS noise @ 1A).


Cheers,

Anthony

Yowser!

28 bits x 3 resistors per bit (from photo - not sure if this is true) x $15 = $1260 per board.

I know it is off topic but a similar things happened to me this week.  I sent some gerbers to China for some pcb's for the ATX Linear psu project and about 30 minutes after I got the email that they had been put into production I realised that I should have added a snubber in one of the power supply boards...oh well...at this stage I just want to get the thing working...I can fine-tune it later.

This is important.  Those Vishay Dales are expensive little fellows especially in the 0.1% variant and at the number you will probably buy them they are like 40c each.  But there are a number of good low noise resistors to choose from, so it will be interesting to see what you come up with.  Var-Z Foil for about $15 each will make the dac very, very expensive, but perhaps they will be just what the doctor ordered!

Need a bigger case?

Looks rather good by the way.  Thanks for the update.

Arjan mentioned a positive change last year in the LPS thread.  That was with a simple LPS into a picoPSU.