USB to PC chassis ground ? (noise) - The biggest change ever !

[PeterSt]

General remark, counting for my consistent setup as of now :

By now I am pretty sure (not 100% yet) that the higher NOS1 Driver Control Panel buffer setting (like 16ms) invokes the "harder" sound. This is not bad but music can be too "pressing" because of it.
When I engage 2ms the highs become more silky and music becomes more background music like; it encourages more for turning up the volume.

Notice that it is not said that a setting in the middle (e.g. 8ms) tunes the silky vs. hard into the middle of the both, which is related to how W7 behaves (I'm thus talking about W7 in this situation). But I didn't try that.

Peter

[juanpmar]

Today I used again my previous amp, the one I was using before I disconnected the black wire inside the NOS1. No hum here. So, testing it with the same amp I can confirm that there is less hum with one or the two sides isolated (almost imperceptible hum in both cases) than with the USB non isolated in any of the two sides.

Juan

[BertD]

Not that I know of, athough it seems to derive from logic (of the posts). It *is* true though that in my situation the only thing which can be connected to PE is the PC, while that measures better. So can indeed is must - in my situation.

In my situation isolating both sides of the USB card is a no go... you should hear the noise when I turn on my TL lights!

 

Best situation would then be to NOT isolate the USB card in the PC but DO isolate the USB wire inside the NOS which  seems the best compromise for me...

Keep the noise in the PC and lead it directly to PE from there.

[PeterSt]

Bert,

Then in your situation something is wrong I'd say. What about your "power conditioning" transformer ?

but DO isolate the USB wire inside the NOS which  seems the best compromise for me...

That is up to you of course, but at least *that* would be an inconsistent situation. If it sounds better, then it does, but I would be very careful with that.

Peter

[boleary]

Several days ago I disconnect the usb ground in the NOS1 just to see what it sounded like. I use the MB usb connection so no isolation on the PC side. I thought it sounded a little bit smoother but needed to let it play for more than a few hours. That same night I woke up at 3 a.m. to the sound of rumbling pops coming from the music room. Freaked me out. Ran to the music room and turned the amp off and went back to bed. Next day "that" noise only went away when I reconnected the NOS1 usb ground wire. I was so glad nothing was destroyed!

[Scroobius]

you should hear the noise when I turn on my TL lights!

This is an excerpt from an interesting article about grounding and TL lighting:-

For example, as much as 20% (or more) of the power used by fluorescent ballasts is reflected back onto the power grid in the form of reactive or harmonic currents -- now that’s a lot of distortion. In the late 80’s, a 40-plus-story office building in Los Angeles actually burst into flames because of these reactive currents. Incredibly, the origin of the fire was determined to be from excessive harmonic distortion in fluorescent lighting circuits which created a high-frequency current overload and literally a meltdown of the electrical wiring system. The First Interstate Bank fire in Los Angeles in May of 1988 was the event dubbed by the media as "The Towering Inferno" a la the Hollywood movie.

Single phase derived from three phase is particularly bad.

The level of interference created when a three-phase wye system is split up and used as three single-phase circuits is truly something to behold.

Apparently balanced supplies were adopted to minimise this problem. Balanced transformers were used to isolate the incoming supply from the load suppl. So a balanced transformer secondary allows PE to be connected to the 0 on the secondary (115 0 115). The result is cancellation of noise that is induced equally(ish) on the +115 & -115 resulting very low noise on PE.

So if you turn on the lights and your NOS1 bursts into flames at least you know what probably happened.

I seem to remember that the supply to Nick's house is 3 phase and so his mains is single phase derived from it.

Paul

[CoenP]

A little usb isolation tweak update that I like to share:

I reconnected the "black wire from the USB connector" to the groundingpoint of the NOS1 powersupply for two reasons:

First I have been missing some subtlety in the 'reference' sound of familiar tracks lately. I've been undoing a number of tweaks to get back to the sound of the 8e setting. Though not ultimaltely the best its the one I remember well. The ground connection brought a lot of the realness back that was also noticable on 1.168 at the expense of a little liveliness. That last might very well have been a synthetic effect of noise, anyway I like the original connected setup soundwise better.

Secondly I disconnected the NOS1 USB cable from the pc while the whole system was powered like I am used to (in order to reorganise cables). The NOS produced a rythm of loud pops that scared the hell out of me. Reconnecting the usb cable made them disappear instantly. I am glad everything seems still to work well but I am rather 'safe than sorry' with the wire connected.

Regards, Coen

[AlainGr]

A little usb isolation tweak update that I like to share:
Secondly I disconnected the NOS1 USB cable from the pc while the whole system was powered like I am used to (in order to reorganise cables). The NOS produced a rythm of loud pops that scared the hell out of me. Reconnecting the usb cable made them disappear instantly. I am glad everything seems still to work well but I am rather 'safe than sorry' with the wire connected.

Hi Coen,

Last year, while I was trying to get rid of my ground loop problem, something similar happened. There was a series of pops getting louder and louder... I jumped on the "mute" button of my preamp, but the preamp and power amp had already entered in protection mode... This scared me to death...

It could have been a stupid move on my part (it was probably just that), but all my cables were connected between the components... The only thing I was doing was shutting off a component (while volume was muted), raise the earth (or the contrary) on that component, then put back the volume... But what I learned from this was never brutally raise the volume of the preamp, just in case...

This is the part I hate: not knowing exactly what I am doing, or assuming it should be harmless...

Regards,

Alain

[acg]

Coen, I would bet that if you had the light on for the DC Offsets on your NOS1 you would have noticed that they were jumping around (not fixed) when the pops were happening.  I had a similar thing happen when testing my cable loom configurations (remember the flouro light sending things crazy?) and in the end I would mute the amplifiers and just look at the DC Offsets to see if my ground connections between the PC and NOS1 had been disturbed during the testing. 

I concur that it is not a nice sound, but I think that it is related to the USB lock between the computer and NOS1, although I may be wrong.

Anthony

[PeterSt]

Hey Coen,

Secondly I disconnected the NOS1 USB cable from the pc while the whole system was powered like I am used to (in order to reorganise cables). The NOS produced a rythm of loud pops that scared the hell out of me. Reconnecting the usb cable made them disappear instantly. I am glad everything seems still to work well but I am rather 'safe than sorry' with the wire connected.

You seem to say that with the wire connected all is well again and no plops will occur at disconnecting the USB cable.
Well, I don't think so and the USB cable always has to be connected or otherwise the plopping just happens or can happen (not today then tomorrow). I think this is even mentioned in the Install Guide.

Personally I never saw a change in behaviour regarding this after disconnecting that black wire. BUT I 100% sure see different behaviour/sounds at using different amps or other apparatus.

Indeed (as Anthony suggests) you will see DC Offset not being stable in such a situation. But to my belief, what you actually see is the DC change behaviour of PE under influence of USB but now from the PC. So, an indirect groundloop and this is shortcut by means of the USB cable itself.

The black wire sure *is* there (explicitly !) for better control of this but now think that things can be unstable otherwise even with the USB cable connected. This very much depends on household situations and even mains setup means (very different in many countries and also different setups in the same country exist).
Keep in mind that to my belief the wire being disconnected is consistent with the isolation at the PC side, BUT this is only theory and not much theory applies here were it for all the situations. The wire disconnected while the PC side is NOT isolated would be illegal (also theory).

Anyway and summarized, I am sure that everybody here at some times experienced the plopping (in different variations when things in the chain changed), and if you never experienced it Coen, it is sheer coincidence OR you just changed something what now makes it happen.
And about cable cleanup, don't underestimate what a loose mains cord but connected to the mains already can do.

Regards,
Peter

[CoenP]

Hi Peter,

Thanks for the elaboration.

I've never noticed this rhythmic plopping before when changing or rerouting the USB cable. In the course of time things have changed, some of which I already forgot and there are unconnected cables in the powerstrips... Maybe the isolated usb card is part of this phenomena.

regards, Coen

[CoenP]

Fyi:

I double checked with some powercables in and out the strip, but with the black usb wire connected there are never any plops when usb cable is pulled out of the usb3 card.

Regards, Coen

[PeterSt]

Thank you for the feedback on this Coen.
Here no plops either but I always switch off the amps when I pull the USB cable. Well ... not really any more, because with the new (Orelo etc.) amplifiers the plopping is soft or not existent.
So yes, all matters. But don't ask me what exactly.

Regards,
Peter

[pedal]

Gentlemen,

My Silverstone SST-EC04-P arrived today. (The same version as Peter.St has).

So what to do?
-Install it as is, or reading through these 18 pages trying to understand the essence of how to isolate it by DIY means?

 

[PeterSt]

Ha !

Unscrew the bracket from it for your first attempt so it will be isolated from the PC's chassis. Be very careful with it because it will be very loose in there so don't try to plug/unplug the USB cable when the PC is running.

Further, see picture in here : http://www.phasure.com/index.php?topic=2838.msg30188#msg30188
for the wire in the NOS1 to be separated from where it's now. It is not soldered, only fixed under that bolt.

Happy weekend and take care of your woofers !

Peter


PS: And later ask your wide to be creative so a plastic bracket is made from some bottle. http://www.phasure.com/index.php?topic=2838.msg29883#msg29883
But more solutions are shown around that post.