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Everything posted by OAudio

  1. Have you tried simulating the dual choke CLCLC configuration? I had not spotted the move to CLCLC. Modelling that configuration closes the gap somewhat :-)
  2. @Nenon Wow, 5uV = ~-135db of rejection ( assuming a ~30v rail ) ! I have been playing along in the background for a while using simulations of an unregulated supply based on the component choices in your earlier posts. With components listed and tweaking components parameters to near ideal performance levels its hard to get <3mv pk - pk @ 1 amp constant load. 5uV is exceptional. Can I ask how you measuring the ripple and and under what test conditions ? Thanks.
  3. Hi @StreamFidelity, That is an interesting writeup thanks for posting. Its sound as thought the DC ATX is working very well in your system. The measurement you quoted is interesting, did you make it directly yourself ? If so I wonder if you can say what the conditions of the measurement were ? eg with a DVM an oscilloscope or analyser, and what were the load conditions for the measurement ? Thanks, OAudio.
  4. Yes mind blowing, makes you wonder how on earth it can all work out as it does when listening to music Regarding the trace size, the physical geometry its critical, but larger would not really help. Most of the lines between say a CPU and other systems such as memory another CPU or PCie for example run at muti Gb/s serial speeds. Even over very short board distances they have to be impedance matched to manage insertion loss and reflections otherwise signal integrity is not good enough for reliable transmission. The physical geometry of a traces dimensions are the way
  5. I have working with some c621 board schematics and fab files for a project where I would like to understand the routing of some traces across a motherboard. If you have ever wondered what fiendish complexity sits inside the motherboard of the PC that's generating your music (probably lost at least 95+% of people with that sentence ) take a look. Above ~3600 traces fanned out from LGA3647 CPU sockets, to memory / DMI / PCIe Lanes and chipset etc. 8 layers are needed for the fan out, most of the traces are just 0.15mm. Just staggering design !
  6. No argument there Marcin and full credit. Like a good wine I think it has aged well and is still an excellent choice. I was very close to going with the ASM3142 which I think you also use I just checked your card also has the high end black and gold "house" scheme to that's a full house
  7. Hi Dev, Haha you have some thing there. The Taiko, Core Audio (very nice looking design) and my card have all settled on the same USB host controller chipset and the "house" colour scheme for high end USB cards of black and gold :-). The card pictured was built in January this year after 5 months of very intensive development work, but pulls heavily on earlier ideas I had and projects going back a number of years. There was a lot I wanted to packed into the card so its actually had to be larger than the other designs I think and uses a full size PCIE blade. It has been
  8. Indeed exciting times, thanks Rob, Yes that's correct it is intended to be part of my music server and was developed primarily for use in single and dual core c621 systems. There were a number of iterations pro of concept and prototypes to confirm the way the card should be designed. Voicing will obviously be spot on with c621 systems but in other servers its been remarkably consistent as well.
  9. Matt hi, Perhaps I should offer some additional information that might help understand why I have a least a little confidence that a linear everywhere to the motherboard supply system of the right performance level can defiantly hold its own. Before the lock down my server with its power system was in a very high end audio system for some fun back to back comparison with a Taiko extreme and another leading server. Using this as a reference point I am reasonably sure that unless the Taiko DC-ATX generates sound quality of a standard greater than their premium extreme server product,
  10. Hi, This is the OAudio RealStream USB card which I hope people will find interesting. It's designed and constructed without compromise for what I think might be the ultimate in USB sound reproduction. Sound quality is best simply described as "next level". A few details: Highly developed master USB RealStream clock subsystem incorporated onto the card. 12 LDOs for people that count, many more commonly found in applications like top end RF test equipment. Two user configurable USB ports Both ports No1 and No2 can have USB chips
  11. Hi Matt, I am defiantly familiar with these two posts, I spotted them some time ago and to be honest they contributed to why I said this. There are some interesting points made in these two links but there a few tangents and assumptions that appear to be there, in order to make the argument that linear supplies can not supply the current levels needed by a music server without descending into mush :-). This explanation is lifted below for instance which is just a nonsense argument. The math is correct, but no one would be stupid enough to apply a
  12. @Nenon, All, I really would not want this pass into forum folk law, without putting an alternate view and note of caution forward. I think using higher current headroom as key parameter to select a power supply is akin to using amplifier wattage alone to compare sound quality of power amplifiers. It might not be a very good idea. Here is some of what I found designing supplies for c621 servers and why I say this. Important to remember first that there isn't anything mystical about c621 boards, they are just incrementally slightly larger then previous Xeon architecture
  13. My conversations with Alex were with a true gentleman who had a passion to understand what makes music sound good. He was the type of enquiring person that makes a forum a interesting and fun place to hang out. He will be sadly missed. RIP.
  14. They are very nice looking boards in your pics. I had noticed the UPD's 😉 thanks for confirming. Looks like you are also using the 701s with ROM which is the way I went as well. I have some 711s I might have a look at them again. My understanding was that they are for embedded use where BIOS writes the firmware blocks to the chipset at boot time. That "industrial" comment has me wondering if I missed a way to use these ?
  15. Renasus UPD720202 from the package and circuit's pin out. The -711 variant is the -40 deg C temp range otherwise not sure what would attract the "industrial" commet if not this, there are only two variants.
  16. From experiance, in an engineered approach the main levers that need to be pulled on are: Timing (inc usb and upstream PCIe clock quaility), Signal integrity (inc usb transmission, detection cable effects and upstream PCIe comms), PSU quality and matching (inc differential noise between PSU systems in the USB card, PC and DAC) Managment of conducted noise, PC to DAC. Chipset selection Lesser items such as EMI and vibration also need to be covered off. I put the linked post up in a thead about USB not being bit perfect. It dosent frame all of th
  17. Hi al2813, I have developed a USB PCIe card using the UPD720202 and am familiar with the firmware options of the chipset. I don't have a JPlay card but I think the card is laid out so that the that port shut off by firmware is the top port furthest away from pcie connector on the card. You will not be able to determine if the 2nd port has been disabled by firmware. The one / two port options are set as part of the chipsets "vendor settings" firmware block by toggling a couple of bits of the image. Unfortunatly the UPD720202 will not dump this port setting b
  18. Looks very much like it uses the same host controller I also alighted on when screening available chipsets, the μPD720202.
  19. They are nice looking units but perhaps not very well suited to powering a quality DC ATX. The PSU's spec's show droop rate performance under load and in particular the ripple and noise specs would be a concern. And there can also be combined noise issues with an SMPS followed by DC ATX buck conversion. The specs on the supply linked show: Droop Rate (-xDx-R suffix) 50 mv/A Ripple & Noise 400 mv (Both for the 28v version). They are big figures for feeding a DC ATX in a server that's focused on sound quality. I spent quite some time a few yea
  20. Intel "client" level Optane SSDs go end of life this month. Just a heads up for anyone considering using an Optane drive and who has not heard about Intel's change of market strategy on Optane. I got a distributor bulleting late last year to saying some Intel SSDs were to go end of life in Q1. In the announcement recently are all of the "client" level 900p and 905p series Optane devices are withdrawn this month (Feb). Going forward the available high capacity, none hybrid, Optane drives are all to be "data centre" units which are significantly more expensive than the withdrawn 900
  21. GPU cooling is not a priority for the server builds I am working on, but the engineering of the GPU cooling system in the linked article looks really nice :-)
  22. Hi kyoya78, What a difference to the radiator on the other CPU. That's a nice looking CPU block !
  23. Hi VHS, Thanks for the interest, yes things have moved forwards. I wanted to see if the cooling system performed as per the thermal design I did. I couldn't wait any longer so I did do a trail fit a week ago. They are just about bang on the thermal design which was really nice to see and they look absolutely superb in the chassis. The coolers were made by an engineer with decades of work for a jet engine manufacturer, and it really shows. Its such a shame to shut them away inside the server chassis. They are back out of the server again and the fans are back in for n
  24. Hi Rossb, There is a lot of dogma about fans which really makes me 🙂sometimes. You would think they are a complete disaster the amount of attention that "fan-less" setups get, however the truth is that if you: run them slow so you are happy / can live with the with the sound noise levels, isolate them from the servers sensitive power (don't connect via the mother board headers), make sure that the fans ground is not referenced to the servers supplies, run fan wiring well away from the servers wiring and the motherboard etc, the sound quality
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