Logic Pro, noise coming when MIDI Out or USB/MIDI attached

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pg-2007 Author

Level 1

8 points

Logic Pro, noise coming when MIDI Out or USB/MIDI attached

When I try and record my Korg R3 in Logic Pro I get background noise from the MIDI-Out. When connecting the R3 via the USB interface to LogicPro I am able to use is as a MIDI controller to play the software instruments. When I then try and record the R3 via Alesis Linelink I get background noise. If I disconnect the Korg/USB the noise goes away.

I thought that this was something to do with the R3 so I connected it to my MacBook Pro/Logic via EMU Xmidi interface that links a USB interface to a MIDI/In/Out. I got the same noise issue when using the EMU until I disconnected the EMU MIDI/Out to the Korg MIDI/In.

I also get the same symptoms when using Garageband. Not sure if this is a USB/MIDI driver issue or config problem

MacBook Pro, Mac OS X (10.5.7), Logic Pro

Posted on Jul 20, 2009 4:03 PM

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Answer 1

Eriksimon

Level 6

15,428 points

Jul 21, 2009 1:41 AM in response to pg-2007

pg-2007 wrote:
When I try and record my Korg R3 in Logic Pro I get background noise from the MIDI-Out.

What sort of noise? Soft clicks?

When connecting the R3 via the USB interface to LogicPro I am able to use is as a MIDI controller to play the software instruments. When I then try and record the R3 via Alesis Linelink I get background noise. If I disconnect the Korg/USB the noise goes away.

I thought that this was something to do with the R3 so I connected it to my MacBook Pro/Logic via EMU Xmidi interface that links a USB interface to a MIDI/In/Out. I got the same noise issue when using the EMU until I disconnected the EMU MIDI/Out to the Korg MIDI/In.

I also get the same symptoms when using Garageband. Not sure if this is a USB/MIDI driver issue or config problem

From what you say here it seems the R3 IS the problem. When you disconnect it the noise goes away. And it produces noise in the same way on a different machine with a different MIDI IF - that would rule out driver issues as far as I'm concerned, unless both drivers exhibit the same mistake... very unlikely. I think you need to ground the R3.
Does the recording (via the LineLink) actually contain the noise? Or is it clean?

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Answer 2

Pancenter

Level 6

14,782 points

Jul 21, 2009 3:42 AM in response to Eriksimon

Eriksimon wrote:

pg-2007 wrote:
When I try and record my Korg R3 in Logic Pro I get background noise from the MIDI-Out.

What sort of noise? Soft clicks?

I was thinking of the grounding hum sometimes generated when laptops are connected to peripheral devices that do not have the same ground potential.

Did I write that? how wordy...

pancenter-

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Answer 3

Eriksimon

Level 6

15,428 points

Jul 21, 2009 4:22 AM in response to Pancenter

How wordy?
Howwordy…
Howwody…
Howdy!

Yeah, you could be right. A more wordy description of the noise would still help though...

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Answer 4

pg-2007 Author

Level 1

8 points

Jul 21, 2009 4:32 AM in response to Eriksimon

Thanks for the responses. The sound is more like a hiss that is defintely noticable and will actually be present on the recorded track on Logic and I can see the sense in it being a grounding issue. If remove the Korg R3 direct to MacBook USB collection from the analysis the following two configurations are what I do not understand:

Config-1
Korg R3 > L/R Output > Alesis Linelink > MacBookPro USB
Korg R3 > MIDI In/Out > EMU MIDI Out/In > MacBook Pro USB

This will produce the hiss when I open an audio track in Logic to either monitor or record and will record the hiss on the track.

Config-2
Korg R3 > L/R Output > Alesis Linelink > MacBookPro USB
Korg R3 > MIDI Out > EMU MIDI In > MacBook Pro USB

In this config the MIDI Out from the EMU has been electrically disconnected from the MIDI In of the Korg. In this config I can drive software instruments and record the R3 with a clean signal, no hiss.

Summary
I will need Config-1 at some point to trasmit SysEx to the R3 as well as driving it from heavily sequenced tracks. Do you this that this is still a grounding issue even though I get no hiss on Config-2. Is there anyway to test for grounding and if present the best way to fix it?

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Answer 5

Pancenter

Level 6

14,782 points

Jul 21, 2009 5:08 AM in response to pg-2007

pg-2007 wrote:
Thanks for the responses. The sound is more like a hiss that is defintely noticable and will actually be present on the recorded track on Logic and I can see the sense in it being a grounding issue.

Well, hiss is not ground hum, nor a digital sync issue.
You can test the ground theory by running the Macbook off the battery for a few minutes, did the noise go away?

Config-2
Korg R3 > L/R Output > Alesis Linelink > MacBookPro USB
Korg R3 > MIDI Out > EMU MIDI In > MacBook Pro USB

In this config the MIDI Out from the EMU has been electrically disconnected from the MIDI In of the Korg. In this config I can drive software instruments and record the R3 with a clean signal, no hiss.

I don't understand it either, doesn't seem the MIDI out from the Emu would make an electrical connection that caused a hiss. The EMU <-> Korg is standard MIDI cables, correct?

Maybe Erik's got an idea on this one.

pancenter-

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Answer 6

Jul 21, 2009 6:59 AM in response to pg-2007

pg-2007 wrote:
Alesis Linelink >

What is this?

The reason I am asking is that I struggled with a hissing problem connecting my Korg Triton to an Alesis io14 to MacbookUSB. I was connecting to wrong 1/4 inputs on the Alesis though. Once corrected, the hissing was gone.

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Answer 7

pg-2007 Author

Level 1

8 points

Jul 21, 2009 9:51 AM in response to juniperis2

The Linelink is a dual quarter inch to USB audion interface:

http://www.alesis.com/linelink

This is an input only interface so there is only one way to connect it.

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Answer 8

pg-2007 Author

Level 1

8 points

Jul 21, 2009 9:52 AM in response to Pancenter

Correct the EMU <-> Korg are standard MIDI cables

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Answer 9

Pancenter

Level 6

14,782 points

Jul 21, 2009 11:13 AM in response to pg-2007

pg-2007 wrote:
Correct the EMU <-> Korg are standard MIDI cables

Did you try running the Macbook on battery only, that's the quickest way to tell if it's ground noise related.

Set it up so it makes the noise then run the system off the battery, should only take a minute to test it.

pancenter-

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Answer 10

pg-2007 Author

Level 1

8 points

Jul 21, 2009 3:27 PM in response to Pancenter

Tried running the MacBook on battery and the noise/hiss was still there but its volume was reduced by half. Decided to take the Korg R3 out of the chain and replaced it with Yamaha DX100.

Config-1
DX100 > L Outpt (Mono) > Alesis Linelink > MacBookPro USB
DX100 > MIDI In/Out > EMU MIDI Out/In > MacBook Pro USB

This produced no hiss whatsoever except for the noisy 16bit DACS on the DX100.

Config-2
Korg R3 > L/R Output > Alesis Linelink > MacBookPro USB
DX100 > MIDI Out > EMU MIDI In > MacBook Pro USB

Again this produced no hiss when recording the Korg R3 and the DX100 was able to drive the software instruments.

Summary
Appreciate any feedback on this one but I am coming to the conclusion that the Korg R3 has a fault in it. This is a recent purchase so I will call the store tomorrow and ask them for their opinion.

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Answer 11

Pancenter

Level 6

14,782 points

Jul 21, 2009 4:09 PM in response to pg-2007

pg-2007 wrote:

DX100 🙂 Those may be 12-bit DACS

Had a DX21 eons ago.

Summary
Appreciate any feedback on this one but I am coming to the conclusion that the Korg R3 has a fault in it. This is a recent purchase so I will call the store tomorrow and ask them for their opinion.

I got nothin'. It might help knowing the Korg MIDI implementaion.

You don't have any continuous data being sent from the MIDI OUT to the R3 by any chance? ie: MIDI Clock or MTC? Might want to check Logic's synchronization (settings/synchronization) menu and make sure there's nothing extra being sent down the pipe. Hmmm... while you're at it check Logic's reset messages (Preferences/MIDI Reset tab) and see if by any chance one of the reset messages is causing a problem. Grasping at straws but you never know.

pancenter-

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Answer 12

pg-2007 Author

Level 1

8 points

Jul 22, 2009 4:52 AM in response to Pancenter

First of all fair point about the DACS, they are 12bit 😉

The following are the Logic Synchronisation settings that are referred to:

Midi clock : off
MTC off MMC : off

General
Synch mode : internal
Auto enable external synch : off
Auto detect format of mtc : on
Validate mtc : always

Not sure if there is anything of note in these. Given electrically disconnecting the Mac-MIDI Out to Korg-MIDI In, stopped the noise, is there anyway to do this in software to see if this has the same effect.

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Answer 13

pg-2007 Author

Level 1

8 points

Aug 13, 2009 5:07 PM in response to Pancenter

I am still trying to get to bottom of the noise problem. The R3 was tested by Korg and they have found no issue with it and they replicated the test with a PC and Edirol equipment. I have subsequently connected the R3 to another Macbook (white plastic chassis version) and the noise was barely audible if at all. Given the noise reduced when my Macbook Pro was powered by the battery I was wondering if there was away to check/fix the ground potential issue that you referred to. Also do you think that there could be an issue with the Macbook Pro hardware?

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Answer 14

pg-2007 Author

Level 1

8 points

Aug 15, 2009 1:36 AM in response to Pancenter

This indeed turned out to be a ground loop issue. Spotted this article in the Apple forums which helped:

http://support.apple.com/kb/HT2743?viewlocale=en_US

I then purchased the following ground loop isolator which removed the noise:

http://www.artproaudio.com/products.asp?id=103&cat=13&type=90

Thanks to everyone for there help on this one.

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Answer 15

Aug 15, 2009 2:37 AM in response to pg-2007

I have the same noise if i connect my MacBook Pro and my Motif via USB.
If i use a USB to Midi(Jack) Converter, it's ok.
So, it has to do with the USB Clock or something...

Greetz

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