Minitaur Noisy Audio Out?

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TC5
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Minitaur Noisy Audio Out?

Post by TC5 » Sat Dec 01, 2012 7:24 pm

I'm getting what I would describe as static noise from the Audio out of my Minitaur. This noise is not exactly hiss but more like electrical static interference noise or something. The Minitaur is connected to an Apogee Duet into Logic 8/MacBook Pro. Audio cable is Mogami. Monitoring thru the Duet headphone out. As a comparison I disconnect the Minitaur and connect a Strat (with noiseless N3 pickups) and it's dead quiet. The controller keyboard is connected to the mac via USB as is the Minitaur. The Minitaur headphone output has no noise.

Any Idea what the problem is? The noise persists even when the Minitaur volume is all the way down.

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till
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Re: Minitaur Noisy Audio Out?

Post by till » Sun Dec 02, 2012 11:59 am

If USB connected and there is no bad sound when using the headphones, you got some USB caused ground loop with interfering digital noise. So if you use the normal Minitaur output, but no USB connected at all, it should be quite again, right?
Try to find a USB ground lifting galvanic isolator. This should stop the ground loop current from passing through the USB shield that is unlike MIDI grounded on both sides. MIDI is ground loop proof by the specs. USB isn't. And USB often transmits some rather digital crosstalk throug its wires. While this is no problem on digital units, it is a problem for analog audio equipment.
I bought myself a little danish USB isolator that work very much like a DI-box on audio cables do.
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TC5
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Re: Minitaur Noisy Audio Out?

Post by TC5 » Sun Dec 02, 2012 12:48 pm

Thank Till. Sounds about right. When moving the computer USB connection of the Minitaur to the same USB hub as for the controller I noticed the noise got lower. Did your USB isolator eliminate the noise completely?

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till
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Re: Minitaur Noisy Audio Out?

Post by till » Mon Dec 03, 2012 12:24 pm

I had no real problems with the Minitaur. I had problems with a DSP driven poly synth hooked to my Mac. But I tested the difference on the Minitaur as well. And the S/N ratio get better that way too.
This problem is very common for USB equipped synths.
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TC5
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Re: Minitaur Noisy Audio Out?

Post by TC5 » Tue Dec 04, 2012 2:02 pm

till wrote:I had no real problems with the Minitaur. I had problems with a DSP driven poly synth hooked to my Mac. But I tested the difference on the Minitaur as well. And the S/N ratio get better that way too.
This problem is very common for USB equipped synths.


I see. Thanks for the info.

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bgirl
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Re: Minitaur Noisy Audio Out?

Post by bgirl » Thu Jan 10, 2013 2:45 pm

I had the same exact problem when minitaur connected with usb. What i did is open the usb cable in the middle, remove the shield on about 1cm and cut the black wire. No more noise from the usb connection.

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till
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Re: Minitaur Noisy Audio Out?

Post by till » Fri Jan 11, 2013 11:21 am

bgirl wrote:I had the same exact problem when minitaur connected with usb. What i did is open the usb cable in the middle, remove the shield on about 1cm and cut the black wire. No more noise from the usb connection.

This is for sure working but slightly off the USB specs. So one can't recommend this to others.
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bgirl
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Re: Minitaur Noisy Audio Out?

Post by bgirl » Fri Jan 11, 2013 1:22 pm

Is it harmfull or something for Minitaur or the computer ? I mean there are many paths for ground already ... And i don't recommend this as a general solution for all cases, but that specific one. Was a nightmare with the usb cable grounded. That's weird, my slim phatty and minitaur do this with usb, all my other synths don't.

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lfo2vco
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Re: Minitaur Noisy Audio Out?

Post by lfo2vco » Sat Mar 09, 2013 7:14 am

I was looking into using a USB Isolator for my MiniTaur too, however with a little Internet research I came up with a much cheaper option.

Using 19mm (3/4") wide Electricians Insulating tape, I cut a 2mm (3/32") wide strip and placed it in the B end of my USB cable. That is the end that goes into the MiniTaur. The insulating strip was placed over pin 4 completely covering it. The excess length stuck down over the outside edge of the plug, enabling easy removal if necessary. Hey presto the ground noise has gone, the MiniTaur still receives MIDI from my DAW and fully responds to the MiniTaur Editor software.

Here is the USB pin information:
Image
1 USB Vcc (Vbus)
2 USB Data
3 USB Data
4 GND

(Credit to Mosc on the electro-music forum for the pin info)

nectarios
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Re: Minitaur Noisy Audio Out?

Post by nectarios » Tue Mar 12, 2013 7:18 am

Thank you so much for the info in the USB issue. Covered pin 4 with tape and the noise is completely gone!
:)
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bichuelo
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Re: Minitaur Noisy Audio Out?

Post by bichuelo » Tue Mar 12, 2013 5:35 pm

Does this fix work with the Phatty series too?
http://audiotecna.info
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Re: Minitaur Noisy Audio Out?

Post by Amos » Fri Mar 15, 2013 8:29 pm

bichuelo wrote:Does this fix work with the Phatty series too?


should work with any device where USB introduces "ground loop" type noise

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lfo2vco
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Re: Minitaur Noisy Audio Out?

Post by lfo2vco » Sat Mar 16, 2013 10:36 am

Hi Alfredo, give it a go and report back the results for other Phatty users. The modification is easily reversed.

peteruertz
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Re: Minitaur Noisy Audio Out?

Post by peteruertz » Fri Mar 29, 2013 6:00 am

bgirl wrote:I had the same exact problem when minitaur connected with usb. What i did is open the usb cable in the middle, remove the shield on about 1cm and cut the black wire. No more noise from the usb connection.


I used your method - Did not work! Hahaha :)
I have still this noise - mistery?

nectarios
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Re: Minitaur Noisy Audio Out?

Post by nectarios » Mon Apr 01, 2013 1:47 pm

bichuelo wrote:Does this fix work with the Phatty series too?

Yes, did it on my Slim Phatty and it worked.
Noise is completely gone, just like it did on my Minitaur.
Eurorack, 5U, x0xb0x, Moog Slim Phatty, MF-102, MF-103, MF-108, CP-251, Beatstep Pro, Nord Lead 1, NI Maschine, MXR-104, ProCo RAT2, Big Muff π Bass, Logic Pro 9.
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