Questions & Answers

What is the rated speed of the new Studio 1824c USB-C port?

0 votes
827 views
asked Mar 17, 2019 in Studio Series USB Interfaces by alainzagar (130 points)
The specs only state USB-C connectivity but that could mean anything starting from 480 Mb/s.

It's safe to say it's not rated 480 Mb/s but is it USB3.1 V2 for instance?

Can anyone confirm what the rated speed is?

3 Answers

0 votes
answered Mar 20, 2019 by lightfire (180 points)
Unfortunately they did not change anything form the old interface - really bad move. Cosmetic change and connector change but keeps the out-dated USB 2.0. I was all set to purchase one but found this out. All they had to do was make it USB 3.1.
–1 vote
answered Mar 21, 2019 by griffinneubauer (160 points)
Well, I downloaded the user manual for the Studio 68c, and it says it is fully backwards compatible with USB 2.0 and 3.0.

At first, I assumed that meant it had to be USB 3.1. You can't be BACKWARD compatible with USB 3.0 if you aren't 3.1.

I really hate this kind of marketing ambiguity. This spec matters. I have a bad feeling these new "c" models really are only USB 2.0 because if they were running at USB 3.1 that fact would be shouted by PreSonus from the mountain top.
0 votes
answered Mar 5 by NicholasHowe1078 (140 points)
edited Mar 5 by NicholasHowe1078

According to https://pae-web.presonusmusic.com/downloads/products/pdf/Interface_Comparison_Chart_06-17-221.pdf, the Studio 1824c uses USB 2.0.  While I agree that it's too difficult to find that information, according to my calculations the USB 2.0 bandwidth of 480 Mbps should be more than adequate for the number of inputs and outputs, frequencies, and bit rate that the 1824c supports.

I calculate that 73.728 Mbps is about the maximum bandwidth the 1824c requires.  That would be needed to support 8 inputs and 8 outputs simultaneously at 192 kHz.  Each channel requires 192 kHz * 24 bits, which is 4.608 Mbps, and there are 16 channels.

Enabling more than 16 simultaneous channels requires lowering the bit rate to 96 kHz.  You can then get 28 channels altogether, by adding 2 input and 2 output via S/PDIF, and 4 input and 4 output via ADAT.  But because of the lower sample rate, this should actually require less bandwidth: 64.512 Mbps.

If you go down to 48 khz, you get 4 additional inputs and 4 additional outputs via ADAT, giving you 36 channels, but again the lower sample rate means the bandwidth requirement is even lower: 41.472 Mbps.

Even if you could use 36 24-bit channels simultaneously at 192 kHz, that would only require 165.888 Mbps, so I suspect the sample rate limits of additional channels are imposed by the S/PDIF and ADAT connections, rather than the USB 2.0 connection.

Given all that, I see no reason to lament the fact that the Studio 1824c doesn't sport a USB 3.1 connection.

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