noises on G2X out with usb cable connected

dorremifasol · Posted: Tue Oct 11, 2011 4:29 am Post subject:

Now I know why it works. I'm disabling the +5 current pin, which is the one that carries the ground loop noise and it's not needed since the G2 has its own power source. I'm planning to disable every +5 USB pin not needed in my cables (ie. other synthesizers or devices that have their own power source).

Moreover, and I think this is very important: I know that the G2 does not need the +5v USB input pin (it's only used to provide power to some USB devices like mouses, keyboards, controllers, etc), but someway the pin IS connected to the synth board because the effects on the audio signal are very noticeable.

This leads me to think it shouldn't be that way. It may well cause the USB port to break if connected and disconnected very often, or if the computer sends a unusual voltage spike trough the +5v pin. You know there are many posts about broken USB ports in the forum.

What do you think about this?

mosc · Posted: Thu Oct 13, 2011 9:46 am Post subject:

Thanks for great post with all those pictures. Looks like a pretty easy trick to pull off.

Yes I think you're right. If the 5V is not needed in the synthesizer, then it should not be connected to any circuit.

The audio file shows a significant improvement.

Splendid...

modulator_esp · Posted: Sun Nov 18, 2012 2:01 pm Post subject:

I've just done this and it works perfectly for me Smile

Thanks dorremifasol

dorremifasol · Posted: Sun Nov 18, 2012 4:07 pm Post subject:

Glad to read that, Jez! Smile

Next time I open my G2 I'll see if can cut something somewhere to avoid using the cable thingie forever.

modulator_esp · Posted: Sun Nov 18, 2012 5:44 pm Post subject:

Good luck with that Smile

chapelier fou · Posted: Tue Nov 17, 2020 4:55 am Post subject:

First, thanks a lot for this topic.

I have similar problems and tried the "paper in the USB connector" approach.
For some reason, removing the connection to the +5V connector would not produce any result.

However, removing the Ground connection stops the noise. Hurray ? Is it safe ?

dorremifasol · Posted: Tue Nov 17, 2020 6:11 am Post subject:

Hi. Wow, I completely forgot about these pictures and the paper technique!

I wouldn't recommend doing that now. There is a much better and safe alternative, and that is using an USB Isolator. I have had one for years now and my G2 has worked beautifully since then, without any noise in my audio chain.

It was expensive when I bought mine (more than 60€ if I recall correctly) but nowadays they are much cheaper. It worths every cent and I feel more safe now.

This is the one I have:
https://www.olimex.com/Products/USB-Modules/USB-ISO/

Hope it helps!

chapelier fou · Posted: Tue Nov 17, 2020 6:26 am Post subject:

Ok, thanks for the super quick answer, I just bought this Olimex gadget, I'll see if it works.

dorremifasol · Posted: Tue Nov 17, 2020 8:35 am Post subject:

Great! Let us know how it goes.

mosc · Posted: Tue Nov 17, 2020 2:52 pm Post subject:

I agree with Albert, but at the same time removing the ground is probably safe.

I'm not sure how household power is in Europe, but in the USA it can be the source of ground loop nightmares. I learned this from a wise old sound tech many years ago when setting up a huge live preformance system called the Electric Symphony Orchestra. We set up about 40 individual instrument amplifiers on the stage and when we turned it on there was horrible hum.

This old-timer looked at what was set up and said something like, "What idiots, you connect all the grounds together? What do people think these days?" Then he took about 1/2 hour going around with a wire cutter and removed the grounding pin on every single piece of equipment on the stage. When the prower was turned back on there was no hum.

In my studio nothing is grounded and I've never had any hum except for inheritly noisy synths like my 48 year old Moog Modular.

Still, I have never convinced anyone else to even consider massive ground removal. So, use a USB isolator, which removes the ground and power connections anyhow.

Hah, now I'm an old-timer.

chapelier fou · Posted: Wed Nov 18, 2020 2:49 am Post subject:

Nice. So my conclusion is : let this piece of paper until my USB isolator comes in the mail box !
I'll let you know how it works.
Anyway, it's a breathe, as I took the habit to edit the sounds with the headphones to avoid the noise, then disconnect USB for playing/recording.

jamos · Posted: Wed Nov 18, 2020 10:53 am Post subject:

... he fixed the problem by vandalizing the equipment?

Had this old-timer never heard of a ground-lift plug?

chapelier fou · Posted: Fri Nov 20, 2020 4:24 am Post subject:

Received and installed the Olimex USB Isolator. Works like a charm.
Thanks !

mosc · Posted: Sat Nov 21, 2020 6:35 pm Post subject: