usb 1 or 2 ??

[nutrinoland]

hey..
i'm a little confused....does the virus ti particularly the snow use USB 1 or USB 2 ?? howcome no firewire as yet??

[Roby31]

USB1 (1.1?)
No firewire because of compatibilty (newer apple laptops come with no firewire) and maybe cost.

[nutrinoland]

why would access not utilize USB 2 on the TI range ?? USB 2 was really common by the time the TI was released??
does it not require higher speeds ?? would it not benefit the TI to have USB 2 ??

[Timo]

Access use USB v2.0 on their TI and Snow.

Generally, USB v2.0 is available in three hardware chipset types (not software):-

Low Speed (1.5 Mbit/s)
Full Speed (12 Mbit/s)
High Speed (480 Mbit/s)

The TI uses the 'Full Speed' USB v2.0 hardware chipset at 12 Mbit/s, which is incidently the fastest that USB v1.1 can achieve. Hence the confusion.

Your question should be why Access chose to use the Full Speed USB v2.0 chipset instead of the High Speed USB v2.0 chipset.

Let's have a look at it. What we do know is that Access chose to use the Full Speed chip. So the TI's USB connection is limited to 12 Mbit (1.5MByte/second) - for everything.

Streaming a mono track at 44,100 Hz 16-bit would require 86 KByte/second.
(16-bits = 2 Bytes [where 1 Byte = 8 bits], therefore 44100 [samples a second] x 2 [Bytes] = 88200 Bytes = 86.13 KBytes).

Access allow six audio channels, so 6 x 86 KB = 517 KB/second (0.5 MByte/second).

Factor in streaming MIDI, Virus Control, VST automation data, Remote control, and error correction, and it'd probably not be far off from using up most of the 1.5 MByte/second bandwidth available.

That said, streaming a mono track at 44,100Hz 24-bits would only require 129 KBytes/second.
(24-bits = 3 Bytes, therefore 44100 x 3 = 132300 Bytes = 129.2 KBytes).

Six channels of 24-bit would need 775 KByte/second. Which is only 258 KByte/sec more than six channels at 16-bit.

I'm unsure as to how much bandwidth MIDI, VC, VST, Remote, and error correction require.

But for what is currently supported, six audio streams at CD quality, with MIDI and the like, USB v2.0 Full Speed is ample.

Personally if I were Access I would have made a user-switchable mode available for using 16- or 24-bit audio streams, with the caveat that only four channels of audio can be used when 24-bit is selected, or six channels when 16-bit is selected, as they both total the same bandwidth. Of course, they may have intentionally refrained from doing this in order to give a TI successor a unique selling point.

[nutrinoland]

Thanks Timo...i understand now....
12Mbit seems to be sufficient for the requirements but just about enough with not much to spare...
yes the 24 bit option would have been great.
With the current hardware that the Ti uses, is it possible for access to make this change,to allow 24 bit options with less channels, within the same bandwidth limitations (12 Mbit)..
is it possible for Access to do this through a software upgrade ?Or would it require different D to A converters ?

it would have been great if we had more sample rate and bit rate options,considering that the virus ti range is one of the most modern synth technologies available today,at a time where most DAW's and digital audio equipment offer higher bit and sample rates.

Anyway...i guess it still is a great synth....thats why its so popular....