Thanks for your input Peter.  Yes, it is hard to know if modding computer power is a valid path now or at another stage.  I know it works in other systems and have seen a reasonably cheap and easy solution feeding three rails (12v, 5v, 3.3v) into the motherboard for a solid improvement in sound quality, but the question becomes whether it is all worthwhile. 

I think that I will play around with it a little.  How I plan to approach it is to get a good quality linear lab supply with 3 rails and poke power into different things and see what happens.  I have a feeling that directly feeding the ram will have a good impact (because I use a RAMdisk) but that requires some de-soldering on the mobo so I will leave that one alone for a while at least. 

If I can find a reasonable improvement using the lab supply then I will build or have built a higher quality supply for the computer.

I plugged my XXHE PC back into the UPS and re-ran my power draw numbers:

Power On                (minimised o/s) 88w  (normal o/s) 88w
Idle with XXHE open (minimised o/s) 58w (normal o/s) 78w
Playing Music           (minimised o/s) 49w (normal o/s) 58w
Shutting Down         (minimised o/s) 68w (normal o/s) 98w

Note that my UPS only updates the display about once a second so there may be peaks that I missed.  To try to counteract this I repeated each process several times.

Anthony

PS:  I think that this is a particularly good exercise for XXHE/NOS1 users because I think we mostly use the same mobo.  If there is someone else that wants to duplicate these experiments and possibly give some corroboration please put your hand up.

PSS:  Peter, should I start a new thread about developing an XXHE PC linear supply?

No problemo!

OK.  I've just measured my XXHE pc power draw by plugging it into my office UPS. 

Startup 88w
Idle with XXHE open 58w
Music playing in unattended mode 49w
Shutdown 68w

If I was to experiment with a linear psu for this pc a Hynes 10A continuous voltage regulator feeding a 24v 160w pico type dc-dc converter would provide oodles of headroom.  Even a Hynes 5A reg should feed the dc-dc converter enough juice to run the XXHE pc.

Has anyone measured draw using the i7-3930k processor?  That would be an interesting comparison.

Anthony

Yeah, the JPlay pc was minimalist compared to the XXHE pc but is still much more powerful than what many use for computer audio (i7-3770?, mini server board, server core 2012 etc.).  I ran the dual PC JPlay config that worked rather well but I think the XXHE approach is much more sensible in that one pc is used for both tasks, it just takes a little bit of time to switch between library and playback.

I have read elsewhere from guys such as John Swenson that once the USB is galvanically isolated and a FIFO buffer is used within the dac that usb cables fail to make much of an impact on sound quality, but that power supply on the computer does still make a difference.  My understanding of how Peter has isolated the USB input is that it is NOT galvanically isolated, but is a grounding arrangement (or some such thing).  The big unknown for me is whether this different approach still allows improved PC power to make an impact.

Cheers,

Anthony

Hi Coen,

I think the i7-3930K will use a lot more than its 135w TDP...I have seen a figure around 170w somewhere or other.  My JPlay PC (when I had it) would draw less than 2A when running but would peak somewhere around 5A when shutting down (only 4A as startup).  Most PC's use more power shutting down than starting up, which seems strange.

Anthony

Correct about the Xeon cpu Peter.  It is sold as an "Engineering Sample" but may well be a clone of some type, I really don't know.  It is cheap, low powered, and seems to run cool and work very well.  The real bonus is the low power:  if we all start to mess with linear supplies down the track then this psu uses a fraction of the current that the big i7-3930K uses so the likelihood of powering it directly by linear psu is much easier and much cheaper.

Anthony

Hi Peter,

In my pre NOS1/XXHE days I played with a linear psu and it did make a difference on the PC.  Is it your position that it could make a difference?  Or is it your position that if it does make a difference that something else is wrong?

When selecting the SMPS psu for my XXHE PC I followed your recommendation for the BeQuiet L7 530w because you had measured it somehow and determined that it does not spew too much hash back into the mains (I read that on this forum somewhere).  If we have a SMPS that works like that, where do you think the gains of linear supplies for a PC may lie?

Or is that a can of worms you would prefer not to open?

Regards,

Anthony

Hi Alain,

A fellow has loaned me a set of these single ended cables to compare with my expensive interconnects.  Note the Blue Jeans LC-1 capacitance of 12.2pF/ft (a third of the capacitance your cable claims).

I have not had a chance to spend much time with the loaner cable but I will throw it in now and let you know what I think.

EDIT:  The Blue Jeans cable is very good.  It is uncomfortably close to my high priced interconnect.

Cheers,

Anthony

Hi Alain,

Of course I cannot know what the pre-amp did for you in your system, but since getting my NOS1 a couple of months ago I have had a steady stream of dacs through to compare to it in my own system (due diligence for the NOS1 purchase if you like).  Included in these are the fully optioned MSB Analogue and Playback Designs MPD-3 and I must say that when compared to the NOS1 both of these dacs cannot produce the accuracy of reproduction nor generate for me the same emotional connection to the music.  The NOS1 soundstages at least as well as the MSB (and better than the PD) but outshines them both in speed, dynamics and detail retrieval, which are three of the things that infuses life into the music.  So when you say that the music sounds 'kind of lifeless' I know that the NOS1 should not be at fault.

My first thought would be your balanced cables.  One of the things I learnt from a thread on my local forum that Peter was kind enough to join is that the NOS1 will play nicely with very low capacitance interconnects.  Perhaps there is something to be gained there?

Anthony

EDIT: I should say that I have never used a preamp with the NOS1

Interesting Paul.  I hope the solution holds for a while and you have solved your problem!

I had an interesting one today...the midrange got all hazy and harder to listen to than I am used to, not a great deal but noticeable.  I remembered that I had left the Ethernet cable in the back of the XXHE pc while transferring music to the HDD so I pulled it out and things are back to normal.  In the last few days I have moved the NAS into the ceiling with its own UPS and about 15m of cat5e cable which at first glimpse seems to be acting as an antenna for something or other.

Cheers,

Anthony

I agree Alain.  My first thought was that it might have been some o/s process like a screen saver or turning off the monitor or usb or PCIe power management because it seemed to happen about the same time into playback.  I only put up with it three or four times and did the o/s trick I mentioned above after a simple restart did not fix the problem.

Regards,

Anthony

Hi Coen,

Just yesterday I had that same weird situation of the music stopping and then only restarting once I touched my mouse.  I just assumed that it was a windows update issue because I had left the ethernet cable in place after transferring some music to the library on the XXHE pc (normally completely removed from the network - I should turn off automatic windows updates).  All I did was 'un-minimize' the o/s then minimized the o/s again.  I assumed that the restore point that is used to un-minimize the o/s would get rid of any windows updates.  Of course I did not think too much about it but it did work a charm.

I do find that win8 sometimes needs a second boot.  Sometimes, and it seems random to me, a little pop-up is displayed at windows log-in that says something along the line of "Failed to log-in to a windows service" with a heap of text after it.  Whenever I see this I just restart the pc and then I don't see the message again.

Not a lot of help here Coen, but a little commiseration.  Perhaps try un-minimizing and then re-minimizing the o/s and see if that counters the playback stall.

Regards,

Anthony

I think your way is more elegant than mine Alain, so I will change my BAT file accordingly.

Anthony

Alain, I just added them in the order that I want them to execute, so I put the batch file in first, then I did XXHE.  On my system it looks like both the batch file and XXHE are starting together, but if we really wanted to make sure the batch executed first we could just start XXHE from the batch file.

Anthony

Hi Juan,

Create a duplicate shortcut on your desktop for the programs that you wish to add to windows startup.  Drag the duplicate icon over the windows start button (in your win7 shell) - don't let go - then hover over "All Programs" - don't let go - hover over the "Start-Up" folder and drop the shortcut in there.

You can enable or disable the startup shortcuts using the "Start-up" tab in Task Manager.

Hope this helps.  There are other ways to do it, but I found this the simplest.

Anthony