I’ve been experiencing this issue ever since I purchased the Quad Cortex.
When I use the Quad Cortex as my audio interface, I start getting severe and sudden latency after several minutes of playing. Typically, everything works fine for the first 5–10 minutes, and then the latency appears abruptly (1 second of latency). I’ve tried numerous troubleshooting steps, including removing my MacBook’s docking station and connecting the Quad Cortex directly to the USB-C port, enabling Low Latency Mode in Logic, testing on a friend’s M2 MacBook Air, and even using a different Quad Cortex unit. Unfortunately, none of these attempts resolved the issue.
The problem does not occur when I run the Quad Cortex into my Scarlett 2i2 interface and then into my Mac (Quad Cortex Output 3L → Scarlett Input 1 → MacBook). However, using this setup prevents me from connecting the Quad Cortex directly to the computer, which means I can’t use the Quad Cortex software.
@Filip Latency can be caused by a lot of different things. Can you expand specifically on your detailed set-up, from instrument to QC to computer specs, and what you’re using for monitoring? I find the amount of latency you’re experiencing odd, because I travel with an M2 MacBook Air myself and have never had a latency issue using my QC as an interface (or NC for that matter). 1 second is significant and is almost certainly not the QC’s issue in my own experience here, so I recommend reading the QC manual’s ‘Computer Integration’ chapter. Give it a shot, hopefully that resolves your issue. It’s a long one, too, but the Logic Pro manual is your friend as well.
A few helpful tips, though: make sure you’re using a legitimate USB 2.0 cable, type-B for the QC end and type-C for the MacBook end. I personally don’t like USB docks because some work fine, others cause issues… I understand that the Air only has two USB-C inputs, but whenever we add more I/O to a device, we’re adding more capacitance, which all contributes toward more latency, even if albeit minimally.
In Logic, you can fight high latency with a few key adjustments. First I would recommend making sure that under your audio settings, you click on ‘Devices’ and ensure that for multithreading you have ‘Playback & Live Tracks’ selected. This will distribute Logic’s DSP processing across multiple processes to reduce CPU load. Also, the buffer size does indeed play a role in recording latency — this is a topic unto itself, but the default settings in Logic will work just fine for recording (for deep dives on how buffer size should be utilized, I find logicprohelp.com to be a valuable resource).
Also: are you running other resource-heavy programs on top of Logic? Keep in mind that the higher the demand is on your CPU, the longer it will take to process information — you can track Logic’s portion of this in real-time by enabling the Performance Meter (right click the “lcd” track display showing the ‘Beats & Project’ information, then choose ‘Custom’ and make sure that ‘Load Meters’ is ticked on). A high CPU load can sometimes cause a glitchy-ness in monitoring and playback; it’s best not to turn your laptop into something hot enough to cook an egg on just because you were trying to record a sweet riff. Hope this helps
Greetings @keith thanks for the detailed response! I’ll try what you suggested and see how it goes.
To answer your questions: I mainly play through my MacBook’s built-in speakers (M1, 256 GB storage, 8 GB RAM). The latency I’m experiencing isn’t gradual or constant — everything works perfectly for about 5–10 minutes, then it suddenly jumps to roughly ~1 second, which makes it unplayable. Restarting Logic temporarily resolves the issue, but it eventually comes back.
Regarding the USB cable, I’ve been using one from UGREEN. I mostly use Logic just for playing and monitoring; I rarely record. As for resource-heavy applications, I don’t run any — typically I only have Logic open along with a YouTube backing track in Chrome.
When I try to avoid the issue, I use the following setup: Guitar into Input 1 on the Quad Cortex → Quad Cortex Output 3L into Input 1 on a Scarlett 2i2 → Scarlett connected via USB-C cable into the MacBook. The issue occurs when I connect the Quad Cortex directly to my MacBook, using this setup: Guitar into Input 1 on the Quad Cortex → Quad Cortex directly into the MacBook via a USB-B to USB-C cable.
what sample rate are you running in Logic? If you haven’t already, set the Logic project to 48kHz, the same rate the QC is locked to. I’ve heard varying opinions on whether that’s absolutely necessary (some say Logic will adapt to whatever it receives) but it might at least be worth trying if you haven’t already
@Filip In addition to the great suggestion made by @xush, I would also check your I/O buffer size: start at 128 samples. And when you lower the buffer size from that starting point, it will lower the latency as well. And since you are not mixing anything, you can leave the ‘Process Buffer Range’ at its default setting of medium.
If the issue persists, open your MacBook ‘Activity Monitor’ and have it open in the background while you run a session in Logic. Since Logic commands a larger % of the CPU processing power, the “%CPU” in Activity Monitor will spike during start-up but will level off in less than a minute. Go ahead and play, and take note of when the issues in your DAW begin to creep up, and see how that %CPU number changes: if it begins to climb up and spike as the playback issue crops up then the culprit could be an issue with your Mac… but that is beyond my ken. An M1 Mac should perform without issue as you’re well aware, as even standalone Neural plugins work fine on M1 chips.
If you have a concern that it might be your QC, I have a suggestion: I know locally (for me) of a few music stores that have recording sections in them, complete with full set-ups to try out studio gear. Every one of them is based around a Mac. So if you’re able, a simple drop-in to a store near you that has one of these sections could be helpful. You could plug your QC into their set-up, and would easily rule out the issue as a QC one because in earnest, I think it may have something more to do with your computer’s hardware. Because despite my experience with the QC as an interface without issue on my M2, I also have an iMac at home (with an Intel i5, so previous generation to the M1/M2) and again, no issues using the QC as an interface straight in. The gremlins are somewhere, I tell ya…
Changing the sample rate from 44.1 kHz to 48 kHz seems to have resolved the issue — I’ve been testing for about two hours now with no problems so far. I realize this is probably common knowledge, but I’m very much a plug-and-play kind of person. I don’t usually fiddle with settings since my main goal is simply to play .
Thank you for your input and help with this — I’ll be sure to reach out again if anything changes.
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