Hi Peter,

Thanks for explaining. I measure 104k ohm from the usb shield connection point  on the NOS input (the port on the outside of the case) to [ EDIT  the NOS signal ground at the RCA output ground or the velaman psu ground]. This measurement is taken with mains cord, interconnects and usb cord all disconnected from the nos.

I know the whereabouts of the 104 k resistor an it is bypassed with a cap meaning that for ac, pe and signal ground are connected. I have not changed anything electricaly in the ground layout. I cannot see any point where the usb sheild is "lifted" in the cable between the nos port and the card.

I have just broken the shield pe (using tape) after the point that the pe wire runs back to the chassis but before the shield connection reaches the interface. What a difference to SQ.

 Is this the intended arrangement ?

Thanks,
Nick.

Ps 09-z9 sounds MIGHTY, MIGHTY  fine 

A few thoughts, and a question.

Be careful isolating your pc from PE, beyond the obvious safety points, I did this a long time ago and found that the singnal ground in the pc rose to 79v as the smps drifted upwards. As soon as the pc was connected to PE via another component the voltage dropped but this would have been due to a ground loop. The other thing is that if a ground was connected to the pc (eg monitor d connector) it would give a very feeble spark as the voltage was pulled down to earth.  You pc smps many not behave the same but put a meter from the signal earth of the pc to PE before you try using a disconnected PE as a diagnostic.

I arrived at the star earth signal ground to PE set up in the balanced amp after trying a few permutations. Its a little counter intuitive but it gave the best results here.   

I think the gainclone hum I have here is due to an out of spec tranformer, it humed before it was put into the amp and I have an RMA from the supplier to have it replaced. Even with 103db speakers the hum is not bad and its actually as loud coming from the transformer inside the amp.

As I mentioned by mail I think  Paul, I would try reversing the mains phase of one transformer first. They are very close to one another and the flux runs in opposite directions at their closest point. Assuming the windings have the same direction reversing the phase will make the fields run in the same direction. This may work like stacking the transformers. It a quick arrangement to test and may help. Otherwise Im with Peter regarding the position  of the transformers.

Im planning to take a close look at the ground set up when my new oscilloscope arrives is a couple of weeks.

Peter,

Am I right saying that the NOS is signal ground is connected to PE on the interface via a 100k resistor and a cap in parallel with the resistor  (i'm unsure of the cap value) ?

These components sit between the usb cable shield connection (which routes off to the nos case ground) and the signal ground of the usb lead which in turn sets signal ground....I think.

Cheers nick

Peter hi,
I like the conclusion in the last post that tuning of the passive supply filtering needs to be understood. I don’t know how much research the makers of the card already applied but it may be that our requirements are different to those tested. It could be a big undertaking though.
 
About resonance from a bypassed capacitor network, I certainly agree with your comments about the THD+N performance of 1 2 and 3 caps. I would add to this that when I think about using bypassed signal coupling caps in the past, more often than not the effect has been to fix one problem in the sound only to introduce another (usually smaller) problem elsewhere. You may remember I commented that the x-Sound cap values seem to be unusually chosen in an earlier post. The common start point for PSU bypassing values, is to select values between 1/100th  to 1/1000th of the larger cap as a sensible starting point to minimise resonance caused by combined caps. But it’s never perfect, and the X-Sound boards don’t seem to do this anyway for what ever reason. So I’m with you on the point that the X-Sound or any other bypass capacitor networks has the potential to introduce its own characteristic resonance noise.

I still think that the RC network of the card will lower the noise spectrum of the PCIe supply rail over the effective range determined by the card cap values. The response of the RC filter must be limited by the performance of caps (ESR and response frequency etc, which will also all change as the caps burn in) and card trace lengths. My assumption would be that over some frequency range the card will be effective in reducing noise already on the PCIe supply rails. However as you say the card may well present its own resonances back onto the rails. But if  the card is reasonably designed though, surely the resonance spectrum should be secondary to the filter effect ?

Thinking about the PCIe bus and what needs to happen to the supply rails, I think there is some evidence that transfer jitter as data moves over the bus (maybe as block transfer timing or even a bit timing level) has an impact on sound quality.

(The PCIe “jitter” idea might be evidenced by the effect that PCI latency BIOS setting has on SQ on older MoBos. I wonder also if one of the reasons that the Adnaco card was not as successful as hoped was that in the Adnaco system PCI data has to traverse something like 5 PCI to PCI bridges before it reaches the remote USB chipset of the Adnaco card)

My guess, and it is only a guess, is that there are there are probably two main requirements of the PCIe bus power rail filter. The first would be to reduce the noise on the supply rails across some [edit: frequency] range that is useful to audio replay (but key here is understanding the range ?). And the second might be to lower the effective impedance of the supply over a frequency range to improve transient response of the DC supply to support transient On / Off signalling of different devices on the bus.

Now I’m layering guess on guess here but also I think the DC noise filtering might need to be effective from a low frequency in the <10hz range as audio frequency power supply induced errors in digital data patens have a habit of cropping up in the sound via some digital domain coupling process within the signal after the DAC.

Don’t take this too seriously it’s just the ramblings of a non-engineer who probably knows "just enough to be dangerous"  .

At least we know one thing and that is that the x-Sound card shows that messing with the PCIe power rails has the potential for significant impact (?improvement?) on sound so it seems worth pursuing.

Best,

Nick.

PS might it be that whilst a test with 5 x 47000uf caps would result in very good low frequency rail smoothing, that the caps will probably have much too high an ESR at the higher PSU frequencies needed by buss components and this might result in the “Supper Bass” effect that we discussed when I tried large caps on the Adnaco card. Fingers crossed anyway.

Paul,

It's looking very nice, not far to go now ! Really looking forwards to having a listen to your finished amp. There are subtle differences in our builds, will they be audible I wonder ?

Cheers,

Nick.

Peter hi,

Great !

The card is not subtle in what it does that's for sure. Personally I think there may just be the slightest loss of air in the presentation, as others have mentioned as well but the positive effects are overwhelminging worth the very very small trade off. The card is a key part of my setup now with a spare standing buy just in case :-)

EDIT - now that i have read Peters W8 update.

Very good to hear also that W8 is so much improved, i can't wait might have to give that a go again !

Cheers nick.

Ps sound WILL improve with burn in over the next week or so.

Hi,

I was lucky enough to spend last Saterday at Paul's place, with Paul and his family, listening to Paul's system.

It's a while since I last listened to Paul's music system which had improved again with Peter's latest significant release of XXHE and Paul adding an X-Sound PCIe card in to his PC. I always love the sound and as usual it drew us into some very enjoyable listening with its strikingly real portrayal of musical events.

One of the reasons for my visit was for us to try my newly built bi-amped and bridged gainclone amplifier in Paul's system. After a nervous hour getting out ears "into" the system playing through Pauls single ended bi-amped gainclones we swopped in my new bridged gainclone amp.

It was one of those "one note demo" situations we just felt immediately that things had fundamentally improved. Stand out changes were the significant improvements I substance, presence, stage size (I didn't think that was possible given the starting point) control and the effortless flow and  super fast dynamics.

A violin solo played using the single ended gainclone amp was really wonderfully portrayed but didn't quite cure my aversion to reproduced violin music. There was still just too much cat gut in the sound and not enough resonance from the body of the instrument. With the bridged amp in place the resonance of body coupled with strings was simply mesmerising, a real first for me.

Paul summed up the amp change by saying that he had been wishing for an amp that could provide more body, control and detail without losing out on the great points of his single ended bi-amped gainclones. The is exactly what the bridged gainclone amp manages to do. The rest of the afternoon passed listening to track after track smiling like idiots and remarking on elements of the musi's portrayal. I suspect that Paul has found his new wished for amp and for me the new bridged amp is a keeper, no question.

Thanks to Paul and family for putting up with a hifi nut for the day and for such such wonderful hospitality.

Kind regards,

Nick.



 

Hi Flecko,

The ifi psu It looks interesting and sounds like it can be heard :-). Nice specs on the 5v psu.

Which dac are you using the ifi box with ?

Cheers,

Nick.

Hi,

I have now had some time to do A B comparisons on the use of 1 or 2 X-Sound cards fitted on my PCIe bus.

I find that using one card I still hear the positive change in sound quality that I described earlier in the post compared with not having as X-Sound card fitted.

When a second X-Sound card is added, the prominence of high frequencies drops and there is a corresponding loss of presence and detail. The sound is slightly dull relative to the using one card.

Regards,

Nick.

Bob Juan hi,

I have two of the fractal design cases in the link from Juan above. One is used for my main audio pc. The are very well built and tick the boxes for an audio pc that Juan mentions. Very nice kit.

Regards,

Nick.

Brian hi,

We have the same mother board etc and I am not getting the symptoms you describe, could the problem could be unrelated to the x-sound card ? Does the sound get back to normal if the card is removed  ?

I received my second card in the post today, I fitted it and i think there may be a cumulative improvement. I need to a b sound quality with the second card to check its effect however because a lot of other stuff has been changing with my new amplifier build.

Regards,

Nick.

Sounds like fun Mani, that would be great.

From the internal shots of Berts amps its looks like there are some very fine components in them. It will be really interesting to see how Berts parallel bridged design with input buffering (I think) compares to the Bii-amped bridged approach I have taken.

I am sure there will be some nice sounds 

Regards,

Nick.

PS could you bring any balanced interconnects along that you rate ? At the moment I am using a set I make up for the new amp which are loosely based on a VH Audio diy recipe that Paul put me onto, but I'm keen to hear other good cables.

Paul hi,

Regards the heat it runs warmer but not that much. The playing at -30db out of the NOS (which is louder because of the balanced design compared to single ended) the amp just gets warn, say 40 deg C on the case sides. The copper heat sink arrangement in the Modu case seems to work very well so the chips are the same temp as the case.

The NOS1 appears to have no problem driving 8 amp modules. I think using your Black gates as input caps would be a good move, the Mondorfs I have are only 5.8uf and are driving two amp modules per capacitor so they are theoretically marginal for the -3db low pass point, but I have to say that listening the much stronger, snappier base is a big feature of the sound so the 5.8uf caps are ok for now.

I would be tempted to build new a new amp myself. It would be worth having a chat off line, I spent quite a while working out the details of the signal earth, heat sink and setup the case work / wiring. If you use the same layout I can help with some ideas and pointers on materials etc.

Besides the sound quality, the amp behaves in a very civilised way, absolutely no clicks or pops turning on and off and very very quiet (save for a small amount of transformer hum from one of the transformers, need to think if this is worth changing out the transformer for).

The amp has a very valve like warmth and presence but with detail and extension at both ends. I guarantee you will not regret building one for your system (except the hours and hours it takes ha ha  ).

Happy to pop down with it if you want to try it in your system.

Speak soon,

Nick.

Thanks Peter,

It ended up looking a bit more "complex" when the input caps went into the centre between the amp modules, but the sound is in another league which has made the effort worth it  .

Nick.

Hi I spent 18 hours wiring up the Mk II Bi-amped bridged gainclone amp this weekend, I was determined to get it finished.

IT LIVES ! 

 

I'll post some pictures of the build the finished amp together with thoughts about sound quality soon, but for now first imprisons are VERY good,, a game changer, and that is with just a couple of hours ruining in. Definitely worth all effort.

Time to sit down with a glass of wine and listen to some music   

Nick,

Brian,

That's great, they do seem to take a day or three to burn in, so more improvements on the way. Let us know know what you think to the sq  when you have some hours on the  card 

Nick.