How To Use Buffer Size In Logic Pro | Reducing Latency

As a music producer, having a general understanding of how each aspect of a digital audio workstation operates is a must. Strategically adjusting settings based on your computer system, music project, and goals can allow you to streamline your workflow without facing unwanted latencies and system overloads.

The input/output buffer size is one of the primary settings you must change in Logic Pro. It directly affects your monitoring latency and CPU usage. The right I/O buffer size depends on what stage of music production you’re in. Your computer’s CPU and RAM capacities also play a role that can limit how low you can go with the buffer size, especially when dealing with more complex projects in Logic Pro.

In this post, I will break down everything you need to know about buffer size in Logic Pro, what it does, and how to adjust it according to your workflow.

What Is I/O Buffer Size?

When working with audio through digital means, the procedure of turning audio into ones and zeros, processing it, and sending it back to your monitoring headphones or speakers takes time; this is known as latency. Generally, our brains cannot detect any latency below three milliseconds. Anything sound coming with a latency of 3 ms or less is perceived as real-time.

When monitoring audio or performing live, we’d want to have as little latency as possible. However, a lower latency typically means more processing power. A noticeable latency will be off-putting, preventing your brain from associating the heard sound with the action that is taking place. If you’re recording guitars or vocals, too much latency can really throw you off.

When choosing a sample rate in Logic Pro, we set a number for the computer to use as a reference for chopping analog audio into digital samples. For instance, a 44.1-kHz sample rate turns each second of analog audio into 44,100 digitally sampled bits.

When monitoring audio, your setup (computer and audio card) will use analog audio as input, convert it to digital samples based on your sample rate, process it according to your DAW and settings, convert it back to analog data, and send it through your monitoring device. You can increase your computer’s speed in undertaking this process by lowering your input/output buffer size.

Basically, buffer size determines how much time your computer has for processing audio. The less time you give it, the more CPU power it needs to process the task. Ideally, you’d want to lower the buffer size as much as possible. However, that can put too much stress on your computer and result in system overload.

How To Change Buffer Size In Logic

As mentioned above, you’d want to choose the lowest amount of samples possible when capturing audio or working with a MIDI controller. On the other hand, when you’re done recording and want to mix or master your project, it’s best to choose the highest buffer size, even if your computer can handle lower buffer sizes without giving you a system overload error. Higher buffer sizes allow you to listen to your project’s playback with the highest audio quality.

Here’s how you change I/O buffer size in Logic Pro:

•  Click “Logic Pro” from the top-left corner of your screen.
•  Hover your pointer on “settings” and select “Audio…”
•  From the pop-up menu, change the “I/O Buffer Size” variable.

With Logic Pro, the lowest you can go is 32, and the highest is 1028. In my experience, it’s difficult to detect the difference in latencies from 32 to 128 samples, so don’t stress too much if your Mac cannot handle the lowest buffer size possible. In some cases, even going for 256 samples can allow you to record and monitor audio smoothly without any jarring latencies.

If you’re running multiple complex plugins in your session, lower buffer sizes can result in unwanted clipping noises or other artifacts when monitoring audio or during playback. Obviously, one option is to choose a higher buffer size sample. Another workaround is to freeze tracks so that you can free some RAM and processing power.

Other Methods To Reduce Latency In Logic

There are other methods besides adjusting buffer size for reducing latency when monitoring audio in Logic. In another post, I have thoroughly explained everything you need to know about lowering latency in Logic Pro.

First and foremost, make sure you choose the proper sample rate for your project. Although higher sample rates require more processing power, they result in a reduction in input/output latency.

Moreover, Logic has a built-in “Low Latency” Mode that you can use in your projects. Enabling it, Logic will temporarily disable all the plugins that contribute to too much latency when recording audio.

To enable Logic’s “Low Latency” mode:

•  Click “Record” from the top of your screen.
•  Select “Low Latency Monitoring Mode” from the list.

Other Methods To Avoid System Overloads

If you’re still facing system overload alerts despite maxing out the project’s I/O buffer size, you can use other strategies to lower the stress on your computer’s processor. You can click here to read my post about everything you need to know to manage CPU usage in Logic Pro.

One of the things I highly recommend doing is to bounce MIDI tracks in place. Not only does it free up a lot of RAM, but it also creates a mental commitment and stops you from changing MIDI notes over and over.

It’s always a good practice to keep an eye out on your CPU performance meter to prevent system overloads.

•  Control-click the LCD strip and click “Customize Control Bar and Display…”
•  Under the LCD column, check the box next to “Performance Meter (CPU/HD).”

For more tutorials on music production, mixing, mastering, and songwriting, check out my Free 6 Pillars To Learn Logic Pro Faster guidebook.