Re: firewire galvanic cable isolation?
« Reply #20 on: February 13, 2020, 04:15:13 AM »
In more than 15 years using a firewire cable to connect a computer to a soundcard,

Thanks for message
Can you be more precise please about your setup ?
I talk about a hybrid setup so there is a mixing desk with 16 cable from  audio interface , a lot of gear connected to the desk
all in star ground sheme

If I use the stereo out of soundcard ( WDM or ASIO )  NO problem It s black background
But when use Asio with 16 tracks out  / 2 in ( for the return of desk ) that amplifie the ground loop more






Newmarket

Re: firewire galvanic cable isolation?
« Reply #21 on: February 13, 2020, 05:22:28 AM »
You are wrong in my opinion
But when i read completly the manual of my console ( Soundcraft serie 600 ) , they mention the grounding sheme for a professional studio
pin one is remove sometime at receiver end , sometime at transmitter end ( that why there is terminal ) , depend of what design electronicaly used ( that why there is terminal on XLR , to have choice / other people can add 100ohms resistor and 10 to 100nF capacitor en // instead off cut it " in the air "

take a look if you want >>>page 37 to 40 of the PDF attached ...write maybe by genious designer of soundcraft circuit :-) ?
yes , i already study the pin 1 problem 5 years ago , isn 't the problem, because my studio is dead silence , volume max > just the amplification hiss of old 80's circuit , no hum ./ no buzz with no computer
So the ground sheme is valuable


JR is correct and I believe that it's now generally accepted by AES etc.
The fact that ground lifting has / is commonplace and documented in product literature doesn't mean that it's the 'correct' way - but it can be a solution in cases where the shield is allowed to affect the audio signal ground eg the infamous pin 1 issue where it's connected to the audio ground typically on a pcb. etc etc unbalanced connections etc etc
Worth noting that as the rfi / electromagnetic environment becomes ever more 'noisy' and with higher frequencies then problems are more likely to be experienced with OEO shield connection.
If it works for you then no problem.  You'll lose 'ground noise / loop' issues and if you're not picking up 'rf hash' etc then okay.
But looking at it more generally this is worth a read:https://www.resolutionmag.com/wp-content/uploads/2016/02/The-correct-way-to-bond-shields.pdf


« Last Edit: February 13, 2020, 06:25:21 AM by Newmarket »

Re: firewire galvanic cable isolation?
« Reply #22 on: February 13, 2020, 05:42:19 AM »
Just read the document , i m a agree 100% when it s a "simple" setup

The conclusion of the document you show it's :

In conclusion, bonding the shields of balanced
cables at only one end only achieves good noise
performance for complex installations after a great deal
of costly ‘fiddling about’, and also wastes a low-cost
EMC resource


So yes , i what i talking about too :)

Re: firewire galvanic cable isolation?
« Reply #23 on: February 13, 2020, 07:59:53 AM »
I find a document
They say that USB shield is only at one end too, don t know if I can transpose on the IEEE1494 cable ...
http://www.hardwarebook.info/Universal_Serial_Bus_%28USB%29

Whoops

Re: firewire galvanic cable isolation?
« Reply #24 on: February 13, 2020, 12:07:45 PM »
Can you be more precise please about your setup ?

"And I'm talking about a lot of different setups, different gear involved over time and different locations"

Not only my setup, not only one setup, not only in one place.
Yes Hybrid, with a console and outboard, pretty familiar, at least 3 places were like that.
In bigger studios I've worked they always had PT HD systems, only the Mid/small studios had firewire sound cards.
Soundcards were 002, 003, RME Fireface, UAD Apollo. Consoles were Studer 900, Soundtracks, Amek BCII, in those studios outboard is too big and varied to list.

Your problem is not the Firewire connection
« Last Edit: February 13, 2020, 12:11:39 PM by Whoops »

Re: firewire galvanic cable isolation?
« Reply #25 on: February 13, 2020, 03:38:50 PM »
See a lot of thread about ground loop and not only for firewire , often people resolve it because of the ground loop created beetween monitoring and soundcard ...
A lot of studio don't care for a minimal ground loop , nearly "inaudible "...too much time and money , or they have money to use only linear power supply
And , i suppose they have a big isolation transformer and earth only for studio ...so yes it minimize things to a tiny level

 if i unplugged the connection between PC & soundcard , the "small " groundloop disappears, so yes it's arround the firewire and because it s the only shield keep connected 2 chassis ground  together  in my studio , so the problem is related to the firewire grounding I think
My initial question is : Can cut the shield on Firewire cable at one end  , not Pin 1 to 9 , just the braided shield after the first layer

In USB cable is already a  " practive  "as described here

http://www.hardwarebook.info/Universal_Serial_Bus_%28USB%29#Shielding

Hardware Book says USB devices must
not connect the shield to their own ground.


Newmarket

Re: firewire galvanic cable isolation?
« Reply #26 on: February 14, 2020, 04:51:47 AM »

My initial question is : Can cut the shield on Firewire cable at one end  , not Pin 1 to 9 , just the braided shield after the first layer

In USB cable is already a  " practive  "as described here

http://www.hardwarebook.info/Universal_Serial_Bus_%28USB%29#Shielding

Hardware Book says USB devices must
not connect the shield to their own ground.

Short answer - yes  you can cut the braid shield.
The USB case is 'interesting' in that I think the USB standard does call for one end only screen connection.
But it's known to be poor EMC practice.

Re: firewire galvanic cable isolation?
« Reply #27 on: February 14, 2020, 06:52:53 AM »
Short answer - yes  you can cut the braid shield.
The USB case is 'interesting' in that I think the USB standard does call for one end only screen connection.
But it's known to be poor EMC practice.

Many thanks to confirm !
I just open the case of my computer to add 2 usb port ( front of tower )
And when i take a look carefully , i see that the shield of 2XUSB connector from front panel  connect shield at one end !
Check the photo attached . No metal connect the motherboard . It s avoid the possibily to have a ground loop

This afternoon , i will cut that shield on my firewire cable
You recommande to put a 100nF caps at the end or just cut ?

If you have choice you will cut at receiver or transmetter ?
My idea was to cut just before the audio interface

Thanks again !

Whoops

Re: firewire galvanic cable isolation?
« Reply #28 on: February 14, 2020, 07:17:58 AM »
Quote from: Seabstudio
If you have choice you will cut at receiver or transmetter ?

In an USB and FireWire data cable there's no receiver or transmitter end.

All connected devices transmit and receive

Re: firewire galvanic cable isolation?
« Reply #29 on: February 14, 2020, 07:21:40 AM »
In an USB and FireWire data cable there's no receiver or transmitter end.

All connected devices transmit and receive

Maybe i should say : ..... at "Host" or "Device " if you prefer :)


Re: firewire galvanic cable isolation?
« Reply #30 on: February 14, 2020, 09:05:13 AM »
 ;D ;D ;D WOW Sucess !!

After remove the shield & foil on one end of my Firewire cable ....
NOISE DISSAPEAR

Just to be sure , I test with a multimeter
And the firewire cable keep the necessary ground to work , multimeter show there is always a ground connection , but the digital side on groundplane so the multimeter "beep"

I'm really happy NOW :)
Thanks for all


Newmarket

Re: firewire galvanic cable isolation?
« Reply #31 on: February 14, 2020, 12:23:19 PM »
Many thanks to confirm !
I just open the case of my computer to add 2 usb port ( front of tower )
And when i take a look carefully , i see that the shield of 2XUSB connector from front panel  connect shield at one end !
Check the photo attached . No metal connect the motherboard . It s avoid the possibily to have a ground loop

This afternoon , i will cut that shield on my firewire cable
You recommande to put a 100nF caps at the end or just cut ?

If you have choice you will cut at receiver or transmetter ?
My idea was to cut just before the audio interface

Thanks again !

Not much in it where to cut. I'd say just do it where most convenient.
Since you're problem is 'computer noise' rather than 'mains hum' (?) then I'd suggest just cut. And leave at least 2mm gap between. See how that works.

I accept no liability of course :-)

btw the USB screen at one end only doesn't necessarily remove a ground loop possibility depending on the detail. There is still a 0V connection in the USB wiring and this may form part of a ground loop. But it's less likely to involve the audio 'ground' 0V.
It's all in the detail.
I've experienced 'noises' with a USB output ('earthed' PC) into a consumer DAC where the has been a common 0V.
The power ('from an unearthed 'wall wart' not itself grounded separately) was supplied separately but the 0V still had to be connected to the USB wiring.




Whoops

Re: firewire galvanic cable isolation?
« Reply #32 on: February 14, 2020, 08:55:01 PM »
Since you're problem is 'computer noise' rather than 'mains hum' (?)

Hi Newmarket, I don't see where Seabstudio says he has "computer noise' rather than 'mains hum"...

It seems to me he had a ground loop in his setup, firewire cable was not the culprit.
But hey a loop can be broken in a lot of different places, if you want to break it in the less logical place and are happy with it, that's completely fine.
have fun

 ;D

Re: firewire galvanic cable isolation?
« Reply #33 on: February 15, 2020, 05:14:44 AM »
Hi Newmarket, I don't see where Seabstudio says he has "computer noise' rather than 'mains hum"...

It seems to me he had a ground loop in his setup, firewire cable was not the culprit.
But hey a loop can be broken in a lot of different places, if you want to break it in the less logical place and are happy with it, that's completely fine.
have fun

 ;D

hi
yes i was a noise ( like cpu activity / 8khz maybe )
no hum


it can t be another place Whoop
because the firewire cable was  the last in "all " my studio that link 2 chassis ( with eart connected )
all my xlr / jack balanced have shield lifted
all gears have a wire return  to a star ground

if i remove all power from all gears and try to test with multimeter
no chassis touch another in the studio

so if not the firewire cuript
who is it :) ?

Re: firewire galvanic cable isolation?
« Reply #34 on: February 15, 2020, 06:37:35 PM »
In more than 15 years using a firewire cable to connect a computer to a soundcard, I never had that problem due to the firewire connections themselves. And I'm talking about a lot of different setups, different gear involved over time and different locations.

I also never had anyone with that problem.

There can be ground loop problems in a studio situation, also mains interference or bad power supplies, but those are solved at the source and not at the firewire cable itself.
Your problems lies elsewhere and not in the firewire cable connections

Just my 2 cents

+1

Newmarket

Re: firewire galvanic cable isolation?
« Reply #35 on: February 17, 2020, 04:57:36 AM »
Hi Newmarket, I don't see where Seabstudio says he has "computer noise' rather than 'mains hum"...

It seems to me he had a ground loop in his setup, firewire cable was not the culprit.
But hey a loop can be broken in a lot of different places, if you want to break it in the less logical place and are happy with it, that's completely fine.
have fun

 ;D

Re-reading it I see that the OP (not Seabstudio) mentioned 'computer noises'. But it seems Seabstudio had a similar thing - computer related 'noises' rather than mains hum and harmonics.
Anyway, breaking the screen connection might not be my preferred solution but I was answering the question directly.


 

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