Hi,
I need to isolate USB connection between my DJM-900NX2 and PC with USB isolator (because of ground loops and high voltage spikes-based issues).
Problem is that majority of USB isolators on the market are full speed (12 Mbit/s).
Minority of them can operate on high speed (480 Mbit/s) and they are more expensive too.
So, the question is, can I use full speed (12 Mbit/s) version of USB isolator?
DJM900-NXS2 do have USB ports marked as version 2.0 (based on Operation Instructions). At the same time, speed of USB 2.0 is 480 Mbit/s.
Main purpose is to record MIX(REC OUT) output of the mixer in the PC.
Theoretical bitrate should be 24*96000*2 = 4.6 Mbit/s (24bit, 96kHz, two channels a.k.a. stereo).
Am I correct with this simplified calculation or am I missing something?
4.6 Mbit/s is in bandwidth of 12 Mbit/s USB Isolator. Theoretically it may work. But USB 2.0 working at 480 Mbit/s.
Thanks!
Well, considering the DJM-900NXS2 USB audio interface is 10in/12out (22ch), and each channel could handle 24bit / 96kHz, that's a data stream of 50688kb/s, or 6336kB/s, or 6.19MB/s, far below the USB2 theoretical maximum of 40MB/s... so you'd be fine with a USB2-rated isolator. (Never mind the fact it's a USB2 device.) ;)
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Thanks for your previous reply.
There is no such a thing like USB 2.0 isolator (in term of speed).
There are two types of USB isolators, full speed and high speed (both USB 2.0 compatible – it means the standard itself, not speed capabilities, I think).
First one - USB 2.0 full speed isolator is capable to transmit 12 Mbit/s or 1.5 MB/s (not 40 MB/s)
Second one – USB 2.0 high speed isolator is capable to transmit 480 Mbit/s or 60 MB/s.
So, if I would to transmit all 22 channels, I want to buy high speed USB isolator (60 MB/s > 6.336 MB/s > 1.5 MB/s).
But I would to transmit only two channels (4.6 Mbit/s < 12 Mbit/s, 0.575 MB/s < 1.5 MB/s).
I don’t know how USB exactly works. So, my worries are about full speed USB isolator acting as bottleneck between DJM900-NXS2 and PC.
Because I don’t know what happens when the mixer tries to transmit data with higher speed that is full speed USB isolator capable of. Because I don’t know (again :) ) much about the mixer and PC data exchange (occasional high speed metadata, or something like that, that would mixer trying to transmit – because mixer can do this and I don’t know if it do this really).
In other words, when mixer tries to transmit data at higher speed that is USB isolator capable to transmit, will be mixer able to detect that and then slower it’s speed to full speed (1.5 MB/s)?
Thanks!
Can I ask if you've had issues with electrical interference which resulted in the perceived need for an isolator?
I’ve had serious problems with my previously owned DJM900-NXS. USB port stops working, and service guy told me that something went wrong with one of the PCB’s (probably with the main PCB – it’s few months ago, so I don’t remember it exactly).
The thing is that I recently bought DJM900-NXS2 and I would to use USB isolator for sure.
Well, for starters, the USB ports on the DJM-900NXS2 are more robust than the one on the DJM-900nexus, but that doesn't have anything to do with wanting / needing a USB isolator. I asked why you'd need one as you're the first to ever suggest using such a device.