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

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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