As in : Too stupid not to realize earlier on ...
Working on our Linear Power Supply, at some stage I noticed strange things; very adverse to earlier findings. Examples :
- Albums which showed the most silky previously now sounded the most snappy;
- Albums which sounded the most snappy previously, now sounded very silky (which quickly is perceived as too silky);
- The Silverstone card previously was needed to make al sound more realistically. Now the Silverstone card is not to be used because it makes the sound a sort of "bad" (say that suddenly you are unable to find a good sounding setting).
Yesterday for the first time all (for the LPS) was officially assembled in a case, meaning that all was screwed and bolted and everything needed to, say, ship it. Call it the final test to see whether all could really fit like I anticipated and of course that nothing gets hot in its final position.
But nothing sounded right to me. Or say that last night I had no real pleasure in the music.
I survived the night with good sleep because I also changed back to a 47000uF capacitor of which I earlier on had the idea it was too large to be good in its particular place (but also to see whether the PSU would still fit in its final place with that on it). So I blamed the capacitor ...
When one is working on a prototype, this often goes in some wooden box, just to be able to carry it back and forth between the test location and the soldering bench.
When one, like me, is not using protectice earth explicitly for some means of grounding, and only uses that for safety and say connect PE to the case only, in such a wooden box setup there is no connection with PE; you wouldn't know what to connect it to (wood really is quite useless now
).
When the setup becomes final, in its intended (kind of) final case, we must think of protection and thus blindly connect PE to the chassis. Blindly means : you really don't even consider it. Well, at least I didn't when I received the question (this really happened yesterday) : to what point in the chassis shall I connect the PE lead.
So now you think where I am going to, right ?
I don't think so.
This morning, in bed with my eyes half open, I recalled that one of the last things I suddenly noticed last night, was the again hammering emphasis of Windows 10 10586.0 "distortion" sound. You know, that sound I could take out with the Intona and after which 10586.0 suddenly was the best of them all.
I am sure that back at the time I described that sound as "too much of the Silverstone". IOW, it is an on/off sound which can do things right in the highs (it makes cymbals more realistic) but when too much of it, it is sheer distortion (which I think it is anyway, but alas). Now :
I don't know the real combination of matters yet, but it is now obvious that the past 10 days or so I had been listening to no PE connection at all - that the Silverstone had to go out, and that the PE connection now back in place destroys much of what has been for the better since my LPS. But it must go very sneaky ...
That Audio PC already was not connected to PE. BUT - and this is with all my audio gear - it connects to the PE lead of each device. So envision I have this power block and while it is not connected to PE, internally it has the PE leads connected among the sockets. So what I'm actually doing is connecting the chassis' of each device, as long as the power cord (and connector) used, carries a PE lead.
The sound with the LPS in use, generally is inmensely more lean. Think super light-footed and this is also where the vast amount of additional detail comes from. This is also how (again) the slightest disturbance in the sound becomes obvious.
So what actually may have happened with my two types of connections - prior to the LPS and when using it of which we know I removed the Silverstone (which btw was because of too black sound) ?
SMPSa. Chassis of PC connects to (e.g.) Chassis of NOS1a via PE leads and power block.
b. In NOS1a PE is not used further.
c. In PC I never investigated really, but we do know that the ground of USB connects to PE hence connects to the PC chassis.
d. We use an Isolated Silverstone card, meaning that we don't allow at least the shield of the USB cable to connect to the PC chassis. What happens further with that is up to the PC (again I didn't investigate and I don't know).
e. We use an Intona which isolates the USB concection itself.
f. We use an NOS1a which means another level of isolation, this time between the USB receiver and the i2s interface.
The famous "black wire" is disconnected in order to prevent a back door gnd connection to the PC (which again would be the PE lead connection).
LPS without PE connected to the PC chassisA. We do not use the isolated Silverstone - just the USB3 MoBo connection.
B. There is now no connection to PE at all, because the PE lead just is not connected. There is thus also no PC connection to any of the other devices. This is also because of :
C. We use an Intona which isolates the PC from the NOS1a.
D. We use an NOS1a which means another level of isolation, this time between the USB receiver and the i2s interface.
The famous "black wire" is disconnected in order to prevent a back door gnd connection to the PC (which again would be the PE lead connection).
Important side note :
I once observed something like the case of the NOS1 being able to act as a capacitor; it charges and discharges through air. Do notice though that this is explicitly without PE connection (so to the real protective earth (pin)), or otherwise this would not happen.
Do also notice that the say 1 meter of PE wire length in your mains cord, already is a capacitor which is very tough to discharge (read : it takes 30 minutes to do that). I am now talking about the situation that the power cord is connected to the NOS1(a I did not check back at the time because it did not exist) and that I can read a voltage between (IIRC) the output and the chassis (which is the PE wire - which wire is NOT connected at the other side, but obviously sits in between a hot and neutral mains wire (induction ?).
With the knowledge that "signal" travels through air and is radiated by the one device while captured (antenna) by the other, all sorts of things happen we can not see and most probably don't like either. Measuring it almost goes by coincidentally seeing it - to keep it in mind and hopefully utilize it later.
Could be today.
The crux is somewhere in the above two lists;
Because of what I observed yesterday, which now accidentally is with the reference of that not being present the past 10 days (no PE used towards the PC), I suddenly hear USB backfiring onto itself. This is high stipulation, but something like that which also would suit the connection of USB gnd to PE, which thus via the huge backdoor again connects to the NOS1(a), although outside of the real protective earth (and possibly crucial : with a same beat it has interently, but now with different timing (think 20ns because iof power cord lengths). Not using the PE connection in the PC now makes any USB connection impossible (?).
Mind you please, prior to the Intona we could not think like that. Also not because of the "a" version of the NOS1, because when the USB cable entered the case, at that moment a connection to the PC is still there and easily think now
some elements start at least to act as a capacitor (like ground itself, in front of the isolation of the "a"). This should at least influence the working of the USB connection (inherent jitter or something) which could be taken out by means of the Intona.
What remained tough - at least in my situation, is that the USB gnd plane which bounces up and down in the PC itself, fires back via the PE leads on to the NOS1(a) chassis, which again is going to be a capapacitor (but a very small and fast reacting one, which exactly could be the culprit).
Now before you all think that you won't be suffering from this because you do not use such power block and you really don't have the PE leads connected anywhere, think twice. You 100% most certainly will be using that power cord with PE lead in it. This is fine, as long as it does not connect to any chassis, or otherwise it is there (the PE lead) where your capacitor is charging and discharging (I am pretty sure of that). Sadly it now is a bit difficult to solve because the standard connector which goes into our devices, has that lead connected. Easiest would be to break off the PE pin ?
So notice that in-NOS1 you are able to disconnect the PE wire by means of the bolt it is connected to, but with your PC you can not do this while I am not even sure you should attempt this (over here the situation is easy because the LPS is all mine and I know what is happening).
Eureka ?
Peter