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Lynyrd

macrumors newbie
Original poster
Mar 8, 2017
4
0
Hello,

I've noticed strange issue with MBP 13" 2016 w/ touch bar.
So I have 5m length USB cable (aka printer cable) which I'm using to connect the external sound card "Focusrite Scarlett 18i20". This card has it's own power supply not USB powered. Of course on the MBP side I'm using a dongle (USB a to USB c). However I'm noticing weird sounds coming from my DAW (Logic Pro X) when computer is connected to sound card. It works for a couple of seconds and then with strange noise coming from sound card stops working. Computer shows that sound card is still connected but no sound is coming from it. The only way how to restore sound is after restarting sound card but the same issue occurs again after a while. Everything works fine with 3,5m cable. However the same 5m cable I have used with MBP 13" 2013 with an USB-A port and no issues with that and this leads me to think can a dongle be an issue here? I've tried multiple USB-A to USB-C adapters the same issue with all of them.

I know that for USB 2.0 cable length limit is 5m.

So the question: Can this adapter/dongle be an issue for this because total length of connection is more than 5m?

It's ridiculous that little tiny 5cm dongle can mess up with this setup.
 

alFR

macrumors 68030
Aug 10, 2006
2,834
1,070
I know that for USB 2.0 cable length limit is 5m.

So the question: Can this adapter/dongle be an issue for this because total length of connection is more than 5m?

It's ridiculous that little tiny 5cm dongle can mess up with this setup.
You're using a cable that's at the limit of length for USB2 to start with, then introducing an extra connection into the chain (which will degrade the signal) plus some conversion electronics (which will degrade the signal) plus some extra cable length (which will degrade the signal). It's not that surprising it's being a bit flaky, is it?
 
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Lynyrd

macrumors newbie
Original poster
Mar 8, 2017
4
0
I would not be surprised and I thought USB 2.0 cable limit is 4m although you say it is not carrying power

Well that's sad. Looks like I have found the first issue with this USB-C thing for me. :(
 

Lynyrd

macrumors newbie
Original poster
Mar 8, 2017
4
0
What adapter are you using.

https://www.amazon.com/dp/B01B2OYFBM/?tag=thewire06-20&linkCode=xm2&ascsubtag=WC95831
http://www.bestbuy.com/site/insignia-usb-type-c-to-usb-adapter-white/8896017.p?skuId=8896017
https://www.amazon.com/dp/B01AUKU1OO/?tag=thewire06-20&linkCode=xm2&ascsubtag=WC95831

The same issue for all of them.

It's a laptop move it closer and use the shorter cable.

Well of course. In the studio I can move my laptop closer and use ther shorter cable. But sometimes there are situations where I need to use 5m cable for example on the stage. I'm using MBP primary for music production, live performances etc. :)

Well looks like this is a limitation which I have to accept with this computer. :) But still, a little bit strange.

Try a 1 piece cable with the correct ports at each end no longer than 4m

You mean USB Type B to USB Type C cable?

http://www.belkin.com/us/p/P-F2CU035/
 

Samuelsan2001

macrumors 604
Oct 24, 2013
7,729
2,153
https://www.amazon.com/dp/B01B2OYFBM/?tag=thewire06-20&linkCode=xm2&ascsubtag=WC95831
http://www.bestbuy.com/site/insignia-usb-type-c-to-usb-adapter-white/8896017.p?skuId=8896017
https://www.amazon.com/dp/B01AUKU1OO/?tag=thewire06-20&linkCode=xm2&ascsubtag=WC95831

The same issue for all of them.



Well of course. In the studio I can move my laptop closer and use ther shorter cable. But sometimes there are situations where I need to use 5m cable for example on the stage. I'm using MBP primary for music production, live performances etc. :)

Well looks like this is a limitation which I have to accept with this computer. :) But still, a little bit strange.



You mean USB Type B to USB Type C cable?

http://www.belkin.com/us/p/P-F2CU035/

Yeah that's a bit of a nightmare for live performances.

I would try replacement cables over an adapter as suggested above it should be all good.
 

DanDilla

macrumors member
Nov 15, 2016
70
12
Lüneburg, Germany
Just buy a cable and do NOT use dogles or hubs to connect your interface with your macbook.

Also do NOT use a USB cable which is 5m for yor interface, even if the specs provide this.
You will get interferences and noise, with every m it will increase

I would recommend you to use a cable under 2m.
You can get longer cables for your instruments/mics or whatever you use and relocate your setup.
But also keep in mind asymetrical connections also shouldn't be too long...
 
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