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mosc
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Joined: Jan 31, 2003 Posts: 18195 Location: Durham, NC
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Posted: Tue Feb 06, 2007 1:48 pm Post subject:
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OMG, what have I done. If I knew iPassenger looked like that I would have made a house call.
(Just kidding Ross. ) _________________ --Howard
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
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Posted: Tue Feb 06, 2007 1:52 pm Post subject:
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LOL...(gotta keep smiling.)
No way am I opening it up, that is one step too far. (for an idiot like myself)
I only bought it last week.!
Have returned to original un-doctored lead and all is well again, contact maintained. but noise is back.
I think I am gonna give it a rest for now (i need to eat), until someone has a solution that doesn't involve re-wiring the flat or the inside of my g2.
Thanks for all your help anyway. _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 2:02 pm Post subject:
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Actually, I once fixed a similar problem once for a friend of mine by doctoring a cheap hub. I did all the snips and voodoo stuff on the hub`s PCB. That worked fine. However, the hub was of course not a hub anymore. _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
Audio files: 5
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elektro80
Site Admin
Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 2:18 pm Post subject:
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PSU.. Probably not.. but who knows. Some high end hubs supposedly do disconnect and float shield/grnd or something. There was posh one make out there with a dip switch..a pink/red translucent thingie with an obnoxious logo and lotsa blinking led. You know.. the Pimp My USB variety...
Anyways, what I did was pretty much using the front part of the PCB with the connectors. The rest was removed.
I think we ended up with shield disconnected and grnd connected. _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
Audio files: 5
G2 patch files: 78
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Posted: Tue Feb 06, 2007 2:23 pm Post subject:
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In that case, r u saying that if i just bodged another lead, n this time, just disconnect the ground n the shield it might clear the noise but still operate as a useful lead? Or do these signals need to go somewhere hence the need for a hub?
Damn it I need to go back to college n try n suss this bloody electronics out, mind it lost last me last time, studios, recording kit, software ok, the insides of the boxes n the wires themselves n i am lost. _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 2:28 pm Post subject:
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Killing a hub seemed easier at the moment than killing 10 known good USB cables. YMMV. I´m getting old. My eyes are going. It seemed easier to mess with a PCB.
_________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 2:32 pm Post subject:
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Hey, see Jan´s comment in that other thread. He is also mentioning the grnd issue. He has a point. Don´t go wild.
One thing you really shouldn´t do is connecting the USB cable shielding to the nearest stanless steel kitchen sink. _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
Audio files: 5
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Posted: Tue Feb 06, 2007 2:37 pm Post subject:
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hehe...well as far as my 20/20 vision was concerned i only cut the earth n live (perhaps i shouldn't have cut the live) n separated the screening.
Don't really fancy wasting £10 or so doing it again for it not to work tho.
It was a cheap USB cable, maybe there were faults wit hit anyway.
Too many variables. _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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blue hell
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Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
Audio files: 277
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Posted: Tue Feb 06, 2007 2:38 pm Post subject:
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elektro80 wrote: | but it might be more productive to disconnect USB grnd inside the G2. |
Seems the most sensible thing to do IMO, I'll have look. _________________ Jan
also .. could someone please turn down the thermostat a bit.
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 2:42 pm Post subject:
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Blue Hell wrote: | elektro80 wrote: | but it might be more productive to disconnect USB grnd inside the G2. |
Seems the most sensible thing to do IMO, I'll have look. |
Take care! You are entering the domain of norse gods.
Welcome to USBhalla.
_________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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blue hell
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Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
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Posted: Tue Feb 06, 2007 3:19 pm Post subject:
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elektro80 wrote: | You are entering the domain of norse gods. |
Indeed
Next time I'll measure before I speak. Next time I'll measure before I unscrew a device. The USB shield is floating on the G2 side. Erm and now I have a lot of iron to reassemble, and I'll shut up
However this gave me a nice opportunity to see the PCB mistakes made by Mr Nordelius.
While I was at it I also checked the MIDI shields, MIDI in has a flaoting shield , out and thru have the shield connected to ground. This is as it should be.
So why ... is the USB interface not silent.
Well there is another ground loop of course,as soon as both audio and USB are connected to the computer, eventhough the item did get some designer attention. The USB GND signal (not the shield) is connected to the G2 GND through a resistor of about 10 Ohm. The G2 GND is the same as it's audio GND of course. So maybe this 10 E resistor could be replaced by an inductor to break the loop for HF signals. _________________ Jan
also .. could someone please turn down the thermostat a bit.
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seraph
Editor
Joined: Jun 21, 2003 Posts: 12398 Location: Firenze, Italy
Audio files: 33
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Posted: Tue Feb 06, 2007 3:29 pm Post subject:
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elektro80 wrote: |
One thing you really shouldn´t do is connecting the USB cable shielding to the nearest stanless steel kitchen sink. |
why not you could end up with a "sink in sync" _________________ homepage - blog - forum - youtube
Quote: | Don't die with your music still in you - Wayne Dyer |
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 4:17 pm Post subject:
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Ross, keep an eye on that other USB thread too. Jan came back with some vital information re the G2s wiring.
Trivia: In general I think a lot of project studio mess could have been sorted out by vendors having implemented a fully isolated and balanced audio path. When it comes to "expensive" electronic instruments with analog audio out intended for pro use, it simply does not make any sense to stick with unbalanced. _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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blue hell
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Joined: Apr 03, 2004 Posts: 24075 Location: The Netherlands, Enschede
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Posted: Tue Feb 06, 2007 4:45 pm Post subject:
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elektro80 wrote: | Jan came back with some vital information re the G2s wiring. |
Same info is in this thread BTW ... mostly Clavia did a good job as far as I can tell - maybe it could be improved a bit , I'll get me some inductors to see if it helps. The problem seems to be in having both audio and USB conected to a computer and this seems pretty hard to solve as the GND wire should be broken to break the loop, but that seems not to be allowed by the USB specs.
Better quality USB cable (read thicker wire for the GND) could better it a bit as the current flowing through it would give lessa (audible) voltage drop then. Shorter cables are better than long ones, but it's all pretty marginal probably.
Balanced audio outputs and/or transformer coupling would better it more. Or light pipes of course.
A computer having a ground connection tied to the ground connection of an amplifier or mixer will add yet another ground loop. Ground lifting might help there (but I've seen things getting worse on ground lifting as well). Why a laptop would need a ground conection is beyond me, the transformer should be properly isolated and that would be good enough.
Please do keep in mind though that for some equipment the ground actually is there for safety - I remember quite well hitting the ceiling after touching a PC and a central heating pipe at the same time. In a wet environment it would have killed me I guess - electricity in a bad mood is not something to joke about (in Europe even more so than in the US due to the higher voltage used). _________________ Jan
also .. could someone please turn down the thermostat a bit.
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Tue Feb 06, 2007 4:57 pm Post subject:
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Blue Hell wrote: | The problem seems to be in having both audio and USB conected to a computer and this seems pretty hard to solve as the GND wire should be broken to break the loop, but that seems not to be allowed by the USB specs. |
It just could improve matters to use a DI/balanced line driver and use a soundcard with a balanced input. _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
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Posted: Wed Feb 07, 2007 2:12 am Post subject:
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I have discussed this with a few people at work, one suggestion was to try placing a ferrite noise suppressing core arround the usb cable, like the ones, you have on a monitor cable, the usb keyboards we have at work have them on them, unfortunately they cannot be removed (for testing purposes).
What u think? _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
Audio files: 5
G2 patch files: 78
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Posted: Wed Feb 07, 2007 5:52 am Post subject:
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Right then. I have bought, on the condition that I can return it if it doesn't work, another usb cable with gold plated ends, good screening and a ferrite core on each end of the cable.
I'll let you know the results when I get home.
If this doesn't work, i was advised that I would need a power conditioner, which is gonna set me back around £40 or so.
So could really do with this working. (just a 10db drop would do)
Cheers
R (Yr resident test subject) _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Wed Feb 07, 2007 9:04 am Post subject:
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A G4? Which model? CPU speed, number of CPUs.. ? _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Wed Feb 07, 2007 9:05 am Post subject:
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Still connecting to the keyboard USB port?
Do you have a CRT or an LCD display? _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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elektro80
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Joined: Mar 25, 2003 Posts: 21959 Location: Norway
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Posted: Wed Feb 07, 2007 9:32 am Post subject:
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Are there any CRT displays near the keyboard? _________________ A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
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iPassenger
Joined: Jan 27, 2007 Posts: 1067 Location: Sheffield, UK
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Posted: Wed Feb 07, 2007 10:29 am Post subject:
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re-wiring studio from ground up to see if I can seperate the audio and power lines but it has made no difference at all.
I have a pc, win xp, have tried multiple usb ports. even have bad noise thru desk when the channel that the audio lead from the engine is connected to is muted but again disconnect usb (G2) problem gone. _________________ iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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deknow
Joined: Sep 15, 2004 Posts: 1307 Location: Leominster, MA (USA)
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Posted: Wed Feb 07, 2007 10:34 am Post subject:
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...although others will advise against it, if you ground lift the power on the computer, or ground the computer, the problem will go away. this is due to crappy grounding of computers.
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