# of USB ports and latency

JJ2013
Posts: 10
Joined: Sat Mar 21, 2015 2:09 am

# of USB ports and latency

Postby JJ2013 » Tue Apr 17, 2018 5:57 pm

Hi all,

I posted this in another thread that was quite dated so reposting here for more "visibility."

I am using LP 2 and wanted to ask about latency and its relationship with USB ports.....

My PC has several USB ports (they are all used, WiFi enabled mouse, keyboard, USB/Audio Interface and the 4th one for my external monitor) and I understand that a large # of these may add to latency. Now, I am not sure whether and how many of these USB ports are "daisy-chained" internally in the PC, but I wonder
if any of you have suggestions on how I could best "optimize" use of USB ports while keeping latency to a minimum? I would also think that plugging devices into USB ports that have been daisy-chained to other USB channels will not be ideal from a speed of communications angle. I also bought a USB Hub, but that is basically daisy-chaining USB ports and may not be ideal and will not improve speed of communications.

Note, I don't want to use corded mice or keyboards for a few reasons with one of the most important ones being that I use LP 2 in a "live" application involving short-wave radio (not just receiving but transmitting) and the room I am operate in has Radio Frequency (RF) present. Cords, cables and wires don't mesh well with RF at times as that RF may induce currents on those wires resulting in RF interference creeping into the audio which is obviously not desirable!

I am also contemplating (1 year down the road) acquiring (or building) a gaming "grade" PC which has a quad-core i7 processor, SSD etc., to help cut latency down to minimum (some of the better plug-ins are software emulations of classic hardware processors that cause considerable latency when used by my current hardware). Not that using LP 2 itself would necessitate such a move, but I may have a software defined radio plugged into the PC in future which makes it necessary to have a machine with a lot more number crunching power than my current dual-core i5 equipped lap-top.

Any thoughts or recommendations would be highly appreciated!

Cheers,
Juha
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nikolai
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Re: # of USB ports and latency

Postby nikolai » Thu Apr 19, 2018 8:25 am

Hi
I'm not an expert on USB ports, but in general.
It should not have any effect on latency directly. It is not like if you plug in a mouse or keyboard the latency would change.
However, I have heard that if you do need the full bandwidth of a usb port, it can be a good idea to divide the load.
In device manager in windows you can see the usb ports, and might be able to identify the physical ports that share the same bus.
I have heard about people having issues with iLok on the same port as the sound device.
If you go for a desktop/rack type PC chassie, I would go for PCI cards though.
JJ2013
Posts: 10
Joined: Sat Mar 21, 2015 2:09 am

Re: # of USB ports and latency

Postby JJ2013 » Thu Apr 19, 2018 3:36 pm

Thanks Nikolai,

I am using a lap-top and don't have PCI so perhaps this is something that I need to keep in mind when I get a much better PC and a desk-top at that, not lap-top.

Will check it out but what you wrote certainly makes sense.

Cheers,
Juha
patrass
Posts: 217
Joined: Tue May 04, 2010 1:48 am
Location: france

Re: # of USB ports and latency

Postby patrass » Thu Apr 19, 2018 7:32 pm

usb port have a spécific latency on pc the pci card RME aio can have buffer down to 32 samples the usb RME babyface have a minimum latency of 48 sample but with the same buffer size LP reported more latency for the usb card
for exemple with pci e card with 64 sample buffer LP reported latency is about 1.5ms in and 1.5ms out (total 3ms )
with usb card with the same buffer size the reported latency is about 3ms in and 3ms out (total 6ms )
The Chainmaster
LX6464ES,RME AIO,BABYFACE,HDSP9652 AIC128D win8.1/32*64

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