Testing of USB3 repeater cable and hub

I did some simplified testing of an USB3.0 repeater cable and also USB3.0 hub in various configuration.

The following equipment was used and tested:
WD MyPassport 1TB external USB3 harddrive
Sunsway/STLab 4P USB3 powered hub
eMagic USB3 active repeater cable 5m (not powered)

Some of you might notice right away that the repeater cable is 5m while the maximum length for USB 3.0 is 3m.

The test was simply to copy about 20 large files, approximately 300MB each, from the external harddrive to the computer. Here are the testresults.

USB3 drive connected directly to the computer (reference):
To computer: 65 MB/sec – 75 MB/sec
From computer:  44 MB/sec – 46 MB/sec

Drive connected via USB3 hub.
To computer:  ca 68 MB/sec – 72 MB/sec
From computer:  ca 41 MB/sec – 45 MB/sec

Drive connected to USB3 repeater cable
NO GO!

Drive connected to USB3 hub which in turn is connected via the repeater cable.
To computer:  ca 36 MB/sec – 36 MB/sec
From computer:  ca 28 MB/sec – 32 MB/sec
note: Computer reports that it has downgraded the connection to a USB2 connection

Drive connected to a USB2 hub (Plexgear 7P, powered) and the hub is connected to the computer via a normal USB cable.
To computer:  ca 18 MB/sec – 20 MB/sec
From computer:  ca 14 MB/sec – 20 MB/sec

As reference, maximum theoretical speeds:
LowSpeed USB:            0,19 MB/s (1,5 Mbit/s)
FullSpeed (USB1.1):      1,5  MB/s (12 Mbit/s)
HighSpeed (USB2.0):     60,0  MB/s (480 Mbit/s)
Super Speed (USB3.0):  625,0  MB/s (5 Gbit/s)
and
MIDI:  0,0039 MB/s
24 bit 44,1 kHz stereo:  0,26 MB/s

So that’s how that all played out.
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Noise infecting audio cables, part 3 of 3 (for now)

So here’s the latest story (it’s a pretty long one).

This summer I decided to do some refurnishing in the studio. And with that came the opportunity, well it was pretty much a must, to change how the cables where running.

I dissconnected almost every cable and made sure audiocables, usb-cables and power cables were separated from eachother. In fact even midi-cables were somewhat separated.
None of these types ran alongside eachother anymore.

And even though all the gear was connected to only one grounded outlet I made sure they where all connected to only one single output on the “clean power surge protector”-thingy.

This did help with some of the hum. But let’s see what happened and what was the problem.

I had two problems. First I had a problem with to loud hum, a 50 or 60 Hz signal usually caused by a ground loop. Then I had a problem with a higher sound, a squeal or squeak for no better explanation, that was definitely disturbing some of the equipment.

I isolated the ground to one of the affected synthesizers and the squeaky sound disappeared. This sound was present in some synthesizers when powered off and in some only when the synthesizer was powered on.

And isolating ground is not a good thing (even illegal here).

The changes I did (described previously) did help with lowering the hum and also the squeak but did not solve the latter to a satisfactory degree. I had to search on.

I did connect and disconnect all equipment one by one, a 150+ cables, and it was a pain.

Finally I tracked the squek down! It was one of the powered USB.hubs (I know I know, I did write this before) running a USB-cable into my motif es rack and from there distributing the squeal via ground to all other equipment.
Remember I use optical ADAT connections from my studio into my computer so I wouldn’t have deal with this kind of things. But much is connected by USB today for easier integration with the DAW.

So I wiggled the USB-hub a bit and noticed the sound changed. Strange. When I disconnected it’s own power the squeal went away! So some circuit in there was spreading this pollution into my system. I have another identical hub that doesn’t have this problem.

So now the noise pollution is finally down to acceptable semi-pro levels. You cannot hear it at a normal studio listening level. And since all digitally connected eqipment isn’t affected by it, it is now solved.

So there, now you have a couple of things to check.
A short list:

  • Faulty cables, these are hard to detect and most often the culprit
  • Connectors not inserted correctly or all the way.
  • Power cables not connected correctly or at different outlets
  • Power cables and audio cables running alongside.
  • Through USB-cables or circuits in the USB hubs

Noise infecting audio cables, part 2 (of 3)

When testing the computer for my “Kosmoskatten” (“Cosmic Cat”) project I was hit by another noise infection. The groundloop was overwhelmingly infecting the output of the SB Live card.

The Kosmoskatten-computer along with my studio computer is connected to one electrical outlet (and so is a lot of other stuff in the lounge like routers and TVs etc) and my mixer and gear along with the computer screens to another.

The studio computer and the Kosmoskatten computer is connected via MIDI. And if I remove this midi connection the noise disappears!
But if I put all computers and gear on the same outlet, well then the noise is only about half as strong but when disconnecting MIDI it increases instead. Very weird. It also seems to have something to do with the computer screens because various means to unplug those decreases the noise. But I still cannot see the connection here and the ground loop noise is far too loud.

At least I have my 16 channels of AD/DA connected through fiber so at least I can work safely with those.
Still, the annoying quest continues …

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Noise infecting audio cables, part 1 (of 3)

So I’ve just the last night been looking for the cause of annoying noise in the audio cables. After a few hours it seems that disconnecting one of the USB hubs did the trick.

A lot of my gear can be controlled by the computer via USB connection so I need to find a solution for this.
I need to narrow it down.
This will be continued …

64-bit drivers for the old USB-2-MIDI?

Steinberg once did a simple usb midi interface called USB-2-MIDI. Unfortunately they’re pretty quick on dropping support while trying to cover it up (not one of my favourite companies you probably notice). Well this time it’s understandable though since the inteface is quite old.
But as luck would have it, the rumours tell us that M-Audio’s Midisport 2×2 has a similar construction and they keep their drivers up to date!

So installing the Midisport 64-bit drivers works like a charm!
And even though my chain is pretty long (5m usb cable to a 4-port powered usb hub and then another 3m usb cable to the midi interface and then 3,5m midi cable) there’s no problem with latency.
Go M-Audio!

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