Long USB Solutions

[MBTC]

To the best of my knowledge (and memory, since it's been a long time since I spent any time researching this), "Full Speed" refers to the mode (overall speed of throughput, basically) rather than being tied to a specific USB version; it's more or less a short cut to avoid saying "the mode that maxes out at 12mbps". USB 1.1 compatible devices can run in Full Speed, as can USB 2.0 and 3.0, and if they are running in that mode they are all said to be running at Full Speed.

That said, the upper throughput ceiling of each mode is just that -- it's an "up to" number, meaning that is where throughput would max out under absolutely pristine conditions. The average throughput for any operation on any given device is typically much less than the maximum for that mode. The only thing you see consistently in benchmarking articles is that throughput is significantly faster as the ceiling increases; in other words if you took something like a storage device or media player, and compared the same device at Full Speed to its throughput in High Speed, it might perform on average 4x-7x faster in High Speed (certainly enough to justify the upgrade, but not the 40x improvement that the specification implies on paper). I don't think I've ever seen a USB 2.0 High Speed device achieve anywhere near 480Mbps even though its fair to say the cable spec facilitates such speeds.

In other words the labeling of modes gives us a good relative measure, when all other things are equal, but load predictions are difficult to impossible, I'd say.

There are a number of things that can affect actual throughput, most notably (and easy to envision) is the idea of how fast can the sending device push the data down, and how fast can the receiving device receive it? Best analogy there is let's say you've got a really fast Internet connection like 50mbps and you're streaming a HD movie from some device, and it still pauses and buffers, even though 10mbps should be plenty for movie bandwidth. There can be other things like other devices in the house using bandwidth, server delays and your neighbors competing for bandwidth in some cases that affect the ability to stream the movie smoothly.

Things like the polling rate and technique the software uses to actually transfer data, handle timeouts, etc. add more variance.

In a real-time audio streaming scenario like a synth, I can imagine a number of other things that could get in the way, some of which you mentioned like MIDI bandwidth, which needs to travel both ways across the wire.

Then you have other factors that affect performance, for example how many bytes per transfer? We've been discussing mostly throughput here, without even talking about latency, and in many applications optimizing for throughput versus latency can almost be at odds with each other. For example lots of audio streaming seems to lend itself to more bytes per transfer, however for better latency I would think smaller packet sizes would be preferable.

Then of course you have factors that neither the source nor destination of data have full control over, for example the USB bus and its specific handling of other devices on same bus (this is one reason a dedicated USB card is never a bad idea IMO).

One thing that Access could do is create a software utility that runs on the PC or Mac host that "exercises" the connection, simulating a high-load audio and MIDI scenario, which would allow the user to test their connectivity/latency/throughput to the Virus. Just send a fully-loaded audio and MIDI stream and measure throughput and latency. This might not identify every possible problem, but it should eliminate lots, if not most scenarios, by removing the DAW configuration from the list of possible culprits, it would identify things like bad cables or USB hubs causing problems, problem with the Virus hardware itself, etc.

[namnibor]

I will say that the 10 foot USB cable Focusrite *highly recommended* is specifically: "USB 2.0 Hi-Speed Cable, in which the Hi-Speed STANDARD data rate is up to 480Mbps, as opposed to the USB 1.1, which is 40 times slower in ability to handle data, let alone share much bandwidth with other audio/midi pro gear. Maximum length for audio/midi transmission/receipt on multi-channel set-ups should never exceed 15', with our recommendation of using no longer than 10' or 3m..."----That was copied from my Focusrite Support and thought it still germane to post this. I even still have the Belkin packaging in case need to get another high quality A to B cable and it defines Hi Speed USB 2.0 exactly as Focusrite specified and of course, Timo so rightly did above.

It IS confusing because I actually had no idea there even was a specification divide between two different USB 1's, let alone there even existing two types of USB 1 and cannot ever recall even in military applications let alone real world uses in my life of ever having used USB 1.

Kind of throws a wrench into the whole "Universal Serial Bus" thing, right!!
Not ever owning a Ti, my hypothesis is perhaps many problems people *may have* been having is trying to run too many other USB devices along with the Ti connection because even Sweetwater Sound Support had mentioned that on a USB bandwidth hungry device, even a wireless keyboard and mouse *can* at times cause a wacky connection because even if not using the wireless mouse and keyboard, the USB wireless dongle is ALWAYS seeking a connection, even if by a set times interval, and hence I decided to not push my chances and obtained a wired mouse/keyboard instead.

@MTBC: You mentioned having a dedicated Bus being a great idea and what I know about the dedicated DAW PC tower I had built and again, from Focusrite Support (really like those bloke), they mentioned that even though the Scarlett 18i20 is USB 2.0, since I have a few USB 3.0 ports that know for fact are totally on their own Bus, just as my eSATA port is for external 3rd back-up drive is on, they stated that since USB 3.0 is backward compatible and a recent update to Scarlett Mix Control fully allows this, could easily run my interface on the isolated USB 3.0 Bus if my set-up changed and the need arose to have other USB 2.0 devices, as to not interfere with either midi transmission/receipt, and of course audio.

Like anything with consumerism and marketing, the devil is in the details!
Have learned a lot from some good souls on here!

[MBTC]

Originally Posted by namnibor

@MTBC: You mentioned having a dedicated Bus being a great idea and what I know about the dedicated DAW PC tower I had built and again, from Focusrite Support (really like those bloke), they mentioned that even though the Scarlett 18i20 is USB 2.0, since I have a few USB 3.0 ports that know for fact are totally on their own Bus, just as my eSATA port is for external 3rd back-up drive is on, they stated that since USB 3.0 is backward compatible and a recent update to Scarlett Mix Control fully allows this, could easily run my interface on the isolated USB 3.0 Bus if my set-up changed and the need arose to have other USB 2.0 devices, as to not interfere with either midi transmission/receipt, and of course audio.

Yes, if you run into any issues, I would try the USB3 ports. My music PC has USB3 ports on the motherboard, but I put a dedicated USB3 card in that PC before I decommissioned it from mainstream use and made it a dedicated music machine. Other devices I have (such as car GPS and radar detector) that occasionally need to phone home for updates were taking way longer than they should to update through the built-in ports no matter what cable I used, so I put the dedicated card in to try to solve that problem, and it worked. So, when I got the UltraNova I wasn't going to even risk wasting time plugging it anywhere else.

But yes, USB3 is fully backward compatible and you can plug USB2 devices into it, just as USB2 is backward compatible for USB1.1 devices. I have always heard, however, that there is a "lowest common denominator" effect with regard to USB buses, such that if you plug a USB1.1 device into a USB2.0 bus, it will limit all devices on that bus to the speed of the slowest device, making another good argument for an isolated bus.

Although I'm not 100% sure if that lowest common denominator problem still exists or was solved via newer bus designs. I doubt too many people outside the audio streaming world would ever get a chance to find out, because USB2 has been around so long now that I doubt anyone has any USB 1.1 devices left over, at least not that they use. And, I'm not sure how many people really have USB3 devices, in or out of the music world.

[TweakHead]

plug-and-play

[MBTC]

Originally Posted by TweakHead

plug-and-play

Or in this case, plug-and-pray!

[kittonian]

Just because I'm a dealer for Access (or any of the other products we carry in our line) doesn't mean I stand idly by while there are issues to be discussed. We dropped carrying Apogee years ago because they were quite simply lying through omission to potential customers. We dropped Waves because of poor business practices when it came to upgrades and support on products that people spent their hard earned money on.

The bottom line is that we want each and every one of the products in our line to work as advertised, and beyond that the manufacturers need to stand behind their equipment without fail.

As Total Integration is a major feature of the Ti2 Desktop and Keyboard, and the price point dictates that it will be used by higher end clientele, these are the people that are going to expect to use longer runs in their studios (me being one of them).

I would love for Access to work on this issue and figure out a resolution, rather than responding with "don't go beyond the USB spec, because if you do we have no solution to recommend". Whether or not that occurs remains to be seen, but I do believe that customers (both current and potential) should have all the correct and relevant information before making a purchase, and their dealer should have hands on experience with the products as well as the knowledge to inform.

Access is a great company and they take care of their customers, respond quickly to support requests (at least in our experiences), and build an amazing synth. I personally love what they do and that is why we sell their products here at AudioLot.

[namnibor]

Now,we break for a commercial from Belkin, manufacturer of quality high-end USB solutions for high-end clientele!

[MBTC]

@Kittonian: I agree with everything you've said here; the big question in my mind is that as a past and potential future customer, what can I do to help improve the integration to the point where I can buy the product again with confidence? Creating awareness here in the unofficial forum has not proven a sustainable approach in my case. Not being a current owner of one, I'm not in a position to request customer support from Access for a product I don't have my hands on.

The answer is that without being a current owner of the Virus, there isn't much I can do to improve the situation. I have no choice but to leave it up to you guys, the owners of the product, to lean on Access to address the issues. As a dealer of their products, it seems to me you would be in a position of even greater clout when lobbying for product improvements; at least they should put an emphasis on your feedback since you're both a hands-on user and advocate of their products (that's what I meant before).

Being involved in the creation of technology products myself, I can say that whenever a product continues to sell for a premium price point, there is a perception by all within that organization that "sales are good, it's obviously not broken so there's no reason to fix it". It is only when the wheel starts squeaking loudly enough to affect sales that enough priority is going to be placed on the issue to get anything tangible done about it.

Now for the bad news. In your case, it's possible that having a higher end PT HD system has afforded you better results overall than folks with more modest setups, and I believe your only issue is the restriction on the cable length at this point. Many would envy you, because they just want it to work as advertised with the standard cable length. The reason I say "bad news" is that whether or not you can get the longer cable to ever work may very well be beyond the scope of what Access can fix, even if they put all of their resources into trying. I hope I'm wrong, but the issue of unreliable connectivity with longer USB cables is something I've seen reported with many types of devices, not just synths, and the answer is always the same "stay within spec". This is perhaps because product development teams perceive the goal of pushing their device beyond recommended spec to be throwing money into a hole, something that will work some of the time but mostly just cost them time and money in terms of support.

That said, I will offer a couple of thoughts:

There is a knowledgeable Virus user on another forum that claims there is an inherent 5.6ms latency in the Virus Control plug-in buffer that is present even in live mode; obviously when that is added onto typical DAW latency times, it can be cumbersome. His workaround is to simply use USB for MIDI only and to use the analog outs to his interface. So, I'm wondering if you could get away with a similar setup to achieve the longer cord lengths? It would reduce the load on the USB cable possibly making that connection more reliable, as then its only handling MIDI traffic. Might be worth a try.

As far as why does the 5.6ms latency exist in the first place, that goes back to everything else I've said about leaning on Access to fix it.