Author Topic: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB  (Read 238 times)

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Offline ChrisX

Hello,

I use my GT-100 in 4cm with tube amps.  Works great.

If I connect the GT-100 to the computer via usb while ALSO having it in 4cm with tube amp, I get a digital background noise.

If I use a notebook computer running from battery, the noise goes away.  This may be some kind of weird ground loop.

First, has anyone else experienced this?

Second, how did you solve it?   My DAW is a desktop computer, I cant record to my Notebook so that option is not good.

I have everything running from same outlet, use hum eliminator to break ground loop, nothing works.  This problem means that I cant use the USB for recording and I can't take advantage of the reamping feature, unless I am just using the built in models and cabs.
« Last Edit: October 07, 2017, 09:21:52 AM by ChrisX »

Offline rolandvg99

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Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #1 on: October 07, 2017, 09:17:32 AM »
My guess is a ground loop caused by the PC power supply.


PS. What might help is an UPS. Preferably an online one.
« Last Edit: October 07, 2017, 09:21:24 AM by rolandvg99 »
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Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #2 on: October 07, 2017, 10:01:40 AM »
Would I have to run from the UPS battery while recording?

Thanks.

Offline szilard

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #3 on: October 07, 2017, 10:35:48 AM »
You can try it and see if it works or fix the ground loop.

Offline szilard


Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #5 on: October 07, 2017, 12:07:28 PM »
The USB cable IS causing the ground loop!!!  An I have no way to isolate ground on a USB cable.

Everything in my studio is powered by Tripp Lite Isolator.  Amps, PC, monitors, GT100.

The GT100 is the bastard step child of the whole system.  Everything is pristene until I connect the GT-100.

The workaround I found for the GT100 (analog outputs) is to put a Hum Eliminator between the GT-100 stereo out, and my computer interface.  Check! That works.

But when I hook the USB cable the similar problem presents and there is no way I can isolate the usb ground.  (The usb noise is more like high pitched whining static or data bursts, the analog out is more like a humming buzzing)

Everything is running from the Trip lite isolator, everything has a common ground. What could this be?

 

« Last Edit: October 07, 2017, 12:10:04 PM by ChrisX »

Offline rolandvg99

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Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #6 on: October 07, 2017, 02:32:09 PM »
Common ground does not guarantee a system free of ground loops. There is also noise from certain PSUs that penetrate the Audio chain. A PC with a budget PSU and/or a high performance GPU can and will cause problems. Badly shielded motherboards might also rise problems.


I have a Mackie DL1608 that whines when wired to an i-device. That stock PSU is not great, but using an UPS the whine is gone. That UPS is running from mains, but the isolating circuits inside works wonders. My UPS is a pure sine, line interactive device and my studio is totaly noise free even with VG-99, GP-10 and SY-300 connected using both USB and (un)balanced analog cables.
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Online admsustainiac

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #7 on: October 07, 2017, 03:12:59 PM »

Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #8 on: October 07, 2017, 05:46:59 PM »
Common ground does not guarantee a system free of ground loops. There is also noise from certain PSUs that penetrate the Audio chain. A PC with a budget PSU and/or a high performance GPU can and will cause problems. Badly shielded motherboards might also rise problems.


I have a Mackie DL1608 that whines when wired to an i-device. That stock PSU is not great, but using an UPS the whine is gone. That UPS is running from mains, but the isolating circuits inside works wonders. My UPS is a pure sine, line interactive device and my studio is totaly noise free even with VG-99, GP-10 and SY-300 connected using both USB and (un)balanced analog cables.

Thanks, I will try this if the act of physically lifting the ground (3rd pin) from my PC does not work.  In fact, I might get one anyway.


Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #9 on: October 07, 2017, 05:47:48 PM »
USB audio output has enormous noise
http://www.vguitarforums.com/smf/index.php?topic=367.0

Thank you.  I'll try lifting ground physically by removing third pin.

Offline gumtown

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #10 on: October 07, 2017, 11:02:48 PM »
Thanks, I will try this if the act of physically lifting the ground (3rd pin) from my PC does not work.  In fact, I might get one anyway.
NOT RECOMMENDED REMOVING THE AC POWER EARTH. !!
unplugging the USB cable will cause power arcing at the USB plug,
 causing damage to the USB ports on the GT-100 and PC,
 and will leave your PC dangerously un-bonded/grounded.

A USB isolator cable is required
https://iftools.com/isolator/isousbcable/index.en.php?gclid=Cj0KCQjw9uHOBRDtARIsALtCa96aXUvFAWaiiqmAoPjEjr06Rn6Bh1r9PUmd2RB6rjVs6ddIBrb-T5EaArGoEALw_wcB

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Offline Brak(E)man

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #11 on: October 08, 2017, 01:06:58 AM »
NOT RECOMMENDED REMOVING THE AC POWER EARTH. !!
unplugging the USB cable will cause power arcing at the USB plug,
 causing damage to the USB ports on the GT-100 and PC,
 and will leave your PC dangerously un-bonded/grounded.

A USB isolator cable is required
https://iftools.com/isolator/isousbcable/index.en.php?gclid=Cj0KCQjw9uHOBRDtARIsALtCa96aXUvFAWaiiqmAoPjEjr06Rn6Bh1r9PUmd2RB6rjVs6ddIBrb-T5EaArGoEALw_wcB

(Image removed from quote.)

I have a similar problem when my MacBook is plugged in and recording GP
( using only GP as monitor through headphones ) so only two plugged in devices.
I've " solved it " by running the laptop on batteries when recording.
Do you think that a USB cable like that above would be the solution ?
(I don't remember having the same problem with VG 99 using the same MacBook and USB cable.
Not with SY300 either but with a different MacBook )
« Last Edit: October 08, 2017, 04:49:37 AM by Brak(E)man »
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Offline GeePeeAxe

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #12 on: October 08, 2017, 03:12:11 AM »
I have also too much noise when any USB connection is used with digital instruments, like VG99 and Roland synths. Because the IsoUsb cable costs 119 euro in Germany, I think about other solutions. A port that works with standard 5-pin midi, usb and wireless would be the right solution. Unfortunately Roland has only usb-midi and not standard midi in newer synths and keyboards in the mid-price-range.

Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #13 on: October 08, 2017, 08:29:41 AM »
NOT RECOMMENDED REMOVING THE AC POWER EARTH. !!
unplugging the USB cable will cause power arcing at the USB plug,
 causing damage to the USB ports on the GT-100 and PC,
 and will leave your PC dangerously un-bonded/grounded.

A USB isolator cable is required
https://iftools.com/isolator/isousbcable/index.en.php?gclid=Cj0KCQjw9uHOBRDtARIsALtCa96aXUvFAWaiiqmAoPjEjr06Rn6Bh1r9PUmd2RB6rjVs6ddIBrb-T5EaArGoEALw_wcB

(Image removed from quote.)

The link someone provided listed cutting the ground as a potential solution.  You should probably remove it from the site.
http://www.vguitarforums.com/smf/index.php?topic=367.0

Amazon has many reasonably priced USB isolators.  I may try this one for $35

https://www.amazon.com/SMAKN-Isolator-Digital-Isolation-Industrial/dp/B00XXPO4UG/ref=sr_1_3?ie=UTF8&qid=1507472922&sr=8-3&keywords=usb+isolator

Offline ChrisX

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #14 on: October 10, 2017, 12:25:33 PM »
Linked device (above) does not work.  It cleans up the noise, but the software cannot identify that teh GT is connected.  However, the device works with mouse.  There might be a device of this type that actually works.

Online admsustainiac

Re: GT-100 - "Digital Noise" when connected via 4cm to Amp AND USB
« Reply #15 on: October 10, 2017, 12:51:13 PM »
Linked device (above) does not work.  It cleans up the noise, but the software cannot identify that teh GT is connected.  However, the device works with mouse.  There might be a device of this type that actually works.

need to

A ) use a USB galvanic  Isolator that supports USB 2.0 @ 480mbps
https://hifimediy.com/high-speed-usb-isolator-480Mbps

or

B) use a laptop PC on battery power.
« Last Edit: October 10, 2017, 01:21:44 PM by admsustainiac »