Discuss Quantum Series Interfaces Here
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Just purchased a Quantum 2626, and am wondering about a few things:

  1. The Quantum has Thunderbolt 2 (20 Gbps), and the 2626 has Thunderbolt 3 (40 Gbps). Is the 2626 actually utilizing the doubled bandwidth, or does it have the same performance as the Quantum?
  2. Does the Quantum also have power plan issues? I've already experienced the issue in this thread: No audio 2626 WIN10 after watching/listening to 1st song on youtube, spotify etc

I plan on monitoring & recording live-looping performances with multiple instruments, some of which already have latency (e.g. Line 6 Helix), so I need the interface latency to be as low as possible.

At the time of purchase, I didn't realize that the 2626 doesn't have dedicated headphone channels (watched the Basic Functionality video and assumed it applied to the whole Quantum line since there was no comparable video specifically for the 2626). This is definitely a drawback for me, but I could work with it if necessary.

If the Quantum has the same latency as the 2626, I might return my 2626 to benefit from the improved routing capabilities of the Quantum. But if the 2626 has lower latency, I'll probably keep it and deal with the routing limitations.

Also - in case it's relevant: The settings I've found to work best for live-looping are 192000/128 @ 1.6ms, or 192000/256 @ 2.9ms. Lower sample rates spike the latency too much, and lower buffer sizes result in noise & dropouts. Not sure if the Thunderbolt protocol (2 VS 3) has any effect on those, or if lower latencies are only achievable through lower buffer sizes, in which case the latency difference between the Quantum & 2626 might be irrelevant for my intended usage.
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by frazfraz on Sun Jul 25, 2021 7:30 pm
Hi,

I'll try to explain in a basic way a little bit about bandwidth available for the "connection" technologies used in audio interfaces in general - But I'm not an expert - Then you can do some "swatting" and make a note or two to backup for future reference.

These discussions crop up very often - To the best of my knowledge the following applies.

USB 2 - is around 480 "mega-bits"-per-second - mega stands for million denoted as Mb/s. USB 2 will be good to record 24 inputs simultaneously if the driver and interface & CPU clock speed is good enough.

480 mega-bits per second is roughly half of 1 Gb/s - giga-bits per second (giga=thousands of millions of bits.

USB 3.0 or USB 3.1 GEN 1 or similar = 5 Gb/s - Giga-bits per second - This is 10 times more bandwidth than USB 2 ! - So take the 24 channels on USB 2 X 10 = 240 - This is a huge amount of simultaneous channels that would need the mother of all interfaces and even 4 X Quantum 4848 only comes to 192 - I say only in a joking manner - :D

Thunderbolt 2 = 20 Gb/s (or four times more potent than USB 3.0 - Do the bandwidth capability numbers - 240 X 4 = 960 channels - :D - Even a "serial" recording engineer couldn't do this - Zero chance - :D

OK I think there is no point in looking at thunderbolt 3 @ 40 Gb/s (giga-bits-per-second) which is X2 of what thunderbolt 2 can do.

From a bandwidth point of view the Quantum 2632 (th2) will easily cope with all the inputs and outputs even with four units connected together - Subject to a fast CPU (possibly) with more cycles per second eg - Intel 7700 K @ 4900 Mhz - Delidded for example or a 10 Gen Intel 10850 K and you'll get all the performance you'll ever need.

On a Mac which is nice to use - but slower overall vs PC - You'd need to experiment - Take a note of the numbers and I do apologise if anything is NOT CORRECT - But I'm making an effort to help you understand the numbers.

Thunderbolt 2 is great but thunderbolt 3 is greater - Much is marketing as well.

Thunderbolt 4 is out with enhanced graphics performance for bigger screen resolutions but the 40 Gb/s remains the same as thunderbolt 3 - More marketing - :D
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by oazddwxt on Sun Jul 25, 2021 7:49 pm
Thanks for the detailed response! Ended up returning the 2626 after I ran into some major driver issues with the Quantum as detailed in this thread viewtopic.php?f=359&t=41470

Kind of lost faith in Presonus after watching that thread for a while, receiving an unhelpful canned response from their support team, and observing the insanely convoluted troubleshooting tactics they're recommending.

Ended up getting some MOTU gear and it just works.
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by dwmccurd on Tue Nov 09, 2021 11:45 am
Once you are in the Thunderbolt realm for audio, it does not matter if you have Thunderbolt 2, 3, or 4. They are all so fast relative to even multi-channel 192k audio it is not worth considering one vs. the other.

More problematic is getting any Thunderbolt interface up and running properly on a Windows PC in the first place. Intel and Apple jointly developed the original Thunderbolt standard and these days Intel is taking the lead with regard to "supporting" Thunderbolt on Windows PCs. By "supporting", I mean they throw Thunderbolt chips, firmware (yes there is firmware in some Thunderbolt chips), and drivers over the fence to the motherboard makers, and leave them to provide support and documentation to the end users. Intel itself supports only Thunderbolt systems on its own motherboards, which are few.

Some motherboard makers do a reasonable job of posting updates and documents, but they are also constantly developing new boards and juggling support for older ones on any number of pressing issues. The result is that most motherboard makers are constantly behind the curve on notifying customers of the need for updates.

By my count, Intel has issued at least 3 driver updates in 2021 for the Thunderbolt chip I have in my rig. I have kept up with this by using a subscription service called Driver Fusion, but even its many recommendations for driver updates have to be taken with a grain of salt. I've learned to examine driver author and version numbers carefully before embracing an update. In any event, Intel themselves are seeing Thunderbolt issues all the time and are very actively trying to beat the bugs out with their driver updates.

On a motherboard, Thunderbolt relies on the PCIe bus to transfer data from one place to another another over one of 16 serial "lanes". The PCIe reference clock is supposed to run at 100mHz, plus or minus a small error allowance that ensures each device connected to the bus has enough time to properly decide if an incoming data bit is a 0 or 1. Of course data packet checksums are employed to verify that a batch of data was moved successfully, and to sometimes to even correct the errors on the fly. But there are also times when the errors cannot be corrected. The result of such an event can be the dreaded BSOD (Blue Screen of Death) featuring a message that says "Uncorrectable Error" encountered.

Here's why all this matters to you, the Thunderbolt user: If you bought your motherboard from one of the performance-oriented companies like ASUS, MSI, Gigabyte (among others) you were likely attracted by the possibility of overclocking the CPU to make your rig "better". I fell victim to this myself, accepting my ASUS Bios recommendation that a 25% overclock was perfectly safe on my rig. I ran this for nearly 2 years, living with occasional crashes in my Studio One/Quantum 4848 setup, never knowing why, and always blaming Presonus, Melodyne, Intel, or Microsoft (take your pick on any given day).

What I had never realized is that what had happened to me is the ASUS default 25% overclock package had also increased the clock speed on my PCIe bus by something less than 25% (I had trouble figuring out the exact number). Although this overclock did not affect other things using the PCIe bus (like SATA), it most definitely affected the Thunderbolt interface, allowing an occasional error to get all the way through.

Looking back, there were clues: the occasional audio click or pop in a recording, despite having carefully set buffer size and enabling the Thunderbolt Power Profile in Universal Control; the occasional Melodyne crash that occurred when using it inside of Studio One; and ultimately, the fact that any new instance of Presonus's Ampire plugin would immediately bring my whole system to a grinding halt.

I opened a support ticket with Presonus on the Ampire issue. They dutifully put me through the grill on my whole setup. I even made them an iPhone video of a crash happening, showing how the CPU usage rose all the way to 100% before it all went sideways. I ultimately convinced the frontline support engineer that there was absolutely nothing wrong with my rig and I was scheduled for an in-depth on-line diagnostic review of my system by one of Presonus's more knowledgeable software engineers.

On the eve of what promised to be an interesting online session with Presonus, I happened to take one more look at my overall situation, and decided to eliminate the overclocking just to be thorough. I had brushed this aside a million times because in my view it was just a CPU overclock and the CPU worked great even under intense stress testing using 3rd party apps. I always assumed that overclocking was ultimately a heat issue, and my temperatures were well within norms.

What I did not know was that the packaged ASUS CPU overclocking scheme had also overclocked my PCIe bus. There is nothing in the ASUS documentation or BIOS notes that indicated this was happening. But when I rebooted and reran all my crash tests, there were no crashes. None at all. Suddenly Ampire worked perfectly (even as I piled 10 instances in series onto one channel). Melodyne stopped crashing altogether, even on very long and busy tracks. And I even recorded a full hour of audio at 192khz without a getting single click or pop - something that had been impossible before.

A cautionary tale. No overclocking on audio PCs that utilize Thunderbolt audio interfaces. Better yet, -- no overclocking ever on any PC that is mission-critical. Go ahead and overclock your 'Call of Duty' PC but leave your DAW workstation alone!!
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by Tom Overthere on Mon Mar 06, 2023 12:54 pm
dwmccurd wroteA cautionary tale. No overclocking on audio PCs that utilize Thunderbolt audio interfaces. Better yet, -- no overclocking ever on any PC that is mission-critical. Go ahead and overclock your 'Call of Duty' PC but leave your DAW workstation alone!!


Thanks for this. I just read it two years after the fact, as I plot building a new PC "to avoid Every Conceivable Problem." :mrgreen: I keep things as simple as possible in all aspects of my life. This advice sounds dead-on.

Studio One Pro 4
AMD 6-core processor 3.20 GHz, 16GB ram
Windows 10 pro 64bit
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by georgelea on Sun Jun 25, 2023 12:23 pm
Hey Gang, it's been quite awhile since I've been in the market for a PC DAW, or an accompanying interface, let alone T'bolt. I've done a bit of research, and this is what I'm planning on driving whichever Quantum you guys recommend. At this point, I don't intend on recording much more than solo live vocals, and VSTi. SampleTank seems to soak up WAAY more resources than PresenceXT, which I'm pleasantly surprised with. I may end up recording a live guitar using Ampire, but that's about it. Here's a link to the new Mini PC I have my eyes on. My rough educated opinion is thinking if it can handle T'bold 4, 2 HDMI ports, and a 2.5 Gig LAN, I should be OK. Also, could anyone here advise on what Fader Controllers either of those Quantum's support? I was under the impression that the 192 can support a WiFi tablet. I've had a Fader8 before, and that would be as much as I need. Here's that link.
https://www.ebay.com/itm/374553932062?var=643531280227

i7-12650H CPU, 32Gig RAM/Win 11 Pro. PreSonus 1824C, Native Instr S88 Mk1, ATOM SQ, PreSonus Sphere, Sonar Platinum, SampleTank4, BIAB 2023.
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by georgelea on Sun Jun 25, 2023 12:32 pm
OK. I answered my own question about the Fader controllers.

i7-12650H CPU, 32Gig RAM/Win 11 Pro. PreSonus 1824C, Native Instr S88 Mk1, ATOM SQ, PreSonus Sphere, Sonar Platinum, SampleTank4, BIAB 2023.

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