USB connection, strange pops

M

Martino Judge Shred

Member
I am experimenting crackles and pops when tracking guitars with Logic X and the Axefx3
Axe is connected via usb as input device to the Mac.
Input and output levels are way under clipping, and I set clock to 48hz everywhere (in the daw, in my audio device - a Focusrite Scarlett 18i20, and in the Mac Midi-Audio Manager).
What could it be? It's driving me crazy.

Thanks a lot
 
I also occasionally experimented huge latency (more than a second), when tweaking the Axefx NOT through Axe Edit, if Logic X is opened and the track is armed. Closed the project and opened it again, and the latency was gone
 
Btw, I have another doubt:
My system is the following:
Axefx3 connected via USB to Mac
Focusrite Scarlet 18i20 via USB to Mac also. Kemper connected via Spdif to the Focusrite.
In the DAW, Axefx and the Focusrite work together as Combined Audio Interface, as Input device: this way, I can record the Axefx3 or the Kemper (usb input or spdif input), using only digital connections and avoiding any A/D conversion.
Now, Focusrite clock is 48hz, and its master is Kemper's clock (set to 48); Axefx is obviously 48hz (my projects in Logic are set to 48hz too).
Maybe that creates a conflict and the above mentioned issues?
 
Martino Judge Shred said:
Kemper connected via Spdif to the Focusrite.
Click to expand...

Be sure to set one clock device as Master (Internal clock source) & the other as Slave (External clock source) when connecting devices digitally.

Edit: Re-reading your post I see you did mention master but won't hurt to double check the other is set to slave. Don't be getting this setting mixed up with sample rate settings (All devices need to be at same sample rate, which yours are, in this case 48k).
I'm talking about Clock Source here.

There always must be only one master clock source in a multiple digital device setup.
 
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I think you're misunderstanding what I'm saying.

In your previous post you said "Kemper connected via Spdif to the Focusrite". The clock source master/slave relationship only affects units 'digitally connected' to one another. Going by your words that is the Kemper and Focusrite.
I'd be inclined to select the Focusrite as Master, so set its clock source to Internal, and set Kemper clock source to External (or spdif if that's the only choice) or vice versa if preferred.

The Axe is directly connected to the Mac so it's clock source should be set to 'Internal'. Thus, you only have one Master since the Axe isn't directly connected to the Focusrite or Kemper. The Axe is it's own master with no slave since it isn't sharing any bus; whereas the other two units share a bus so have a master/slave relationship.

Having two units connected digitally with both of them using their internal clock source will cause clicks & pops or even a loud 'white noise' type of hiss.
 
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Ok, thanks a lot.
It was everything set the way you have described.
Focusrite has always been set to spdif and digitally connected to the Kemper, without any issue.
Then pops and crackles should come from something related to the usb connection between Mac and Axfx3 :(
 
Could be. I have searched and someone talks about a general issue with audio devices usb connection with Mac osx Mavericks (and I am stuck to Mavericks: it is stable and has always been issue-free: i onky use for that and don't care for unuseful updates). But it's a problem I have never had with the Focusrite. I am going to search again.
Thanks for your patience and help!
 
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