“Why do I get a delay when I try to record?”

So many people ask me to solve the problem of the monitoring delay time they have when recording their guitars, using a microphone or even when using things like VST fx and midi controllers.

This is all due to latency.

What is latency?

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Everything has some form of latency.
The time it takes for you to press play on your mp3 player to when the music is heard through your headphones can be classed as a form of latency. In a typical home/semi pro home studio, latency is usually derived from the signal chain of your studio components; the time it takes for the signal to flow (and convert) from one device to the next. Think about recording with a microphone – the microphone connects into an audio interface, is then converted from analogue to digital, then sent via a usb/firewire/thunderbolt cable to the computer, is then processed by the computer and recorded into your DAW program and then converted from digital back to analog again to be monitored via speakers or headphones. This round trip and direct processing through the computer is what creates this latency.

In other words, latency = time.

When is low latency important?

Low latency is another way of saying ‘a short amount of time’. And we are talking in terms of miliseconds!

That ‘short amount of time’ becomes very important though, particularly when using midi keyboards and controllers. You expect to be able to hit a key or pad and hear the sound immediately with no audible delay between the time the key or pad is struck, and when the note is heard.
There will also be times when you need to monitor directly through the computer and not via the direct monitoring eg: When recording guitars with amp modelling plugins or vocals with specific effects that need to be heard directly when tracking. This is when you would need to experiment with the lowest audio buffer size your computer and audio interface can handle giving you the “lowest latency” setting.
In a computer based studio, these two situations are essentially the only times in which it is important to have very low latency and buffer sizes. Depending on the computer, a buffer size of 128 or lower should result in very low latency suitable for the above situations. A properly setup audio interface and relatively fast computer can exhibit latency as low as 6ms. The human ear cannot generally distinguish delays lower than 10-12 ms.

When is low latency not important?

Most modern recording interfaces feature zero-latency input monitoring. This makes monitoring live audio sources like microphones, keyboards, basses, guitars etc. easy. When monitoring inputs like these, use the audio interface’s zero-latency monitoring feature as opposed to monitoring through the recording software. Essentially, whatever you have plugged into the interface comes directly out of the monitor outputs or the headphone out with no latency! The signal is separately tapped off to go into your DAW ad it ensures that latency will never be an issue. The DAW software will adjust this latency delay when it is recording without you even hearing it or knowing it has done it as you will be directly monitoring via your audio hardware.

There are many audio interfaces out now that feature a “Direct Monitoring button” on the face of the unit like the Steinberg UR12. Others have direct monitoring switched on/off via a software control panel button. Some interfaces also have a monitor Mix knob that can be used to blend the all ready recorded sounds or tracks playing back from the computer with the new track/s currently being recorded thus letting you control the mix blend of “more from the computer” or “more of the direct newly recorded signal.”

What is Buffer Size?

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Your DAW will present you with the amount of latency (length of time) present for the buffer size currently set. The amount of latency your system has can generally be found in the audio preferences or setup panel listed in Milliseconds.

Adjusting the buffer size and the effect it has on your system can be explained a bit like this.

Imagine a big funnel that is full of sand that has a tiny opening to let the sand drain out. The sand flow is restricted by the size of the funnel opening; if it is small, the sand can only come out very slowly or sometimes it can even get clogged and does not flow out at all. If we make the output of the funnel progressively larger the sand starts to free up and flow more smoothly and at a quicker speed. This is essentially what we are doing when we adjust the buffer size in your DAW software. A small buffer size restricts the funnel outlet; a larger buffer size opens up the outlet. So we try to set a balance between a small opening (buffer size) and a large one. This will usually give the most stable working environment.

Pretty much every DAW program has options, settings or preferences to let the user adjust the buffer size. Buffer size sets the amount of time the computer responds to requests to process audio (or midi).

Large buffer sizes allow the computer to handle more work, but at the cost of a higher latency (longer time). Smaller buffer sizes do give you lower latency (shorter time) but reduce the overall amount of processing the computer can handle.

Buffer sizes can usually be adjusted in increments of 64 (64, 128, 192, 256, 512, 768, 1024 etc.)

  • A buffer setting that is too low can cause audio clicks/cracks or pops in your recording or playback.
  • A buffer setting that is too high will create audible delay and prevent you from playing/recording in time with a track.

Your Latency Guidelines

With this is in mind, here are some basic guidelines when choosing Buffer Settings;

  • When tracking real instruments or microphones, use direct monitoring from your interface when possible, but only if you DON’T need to hear live real-time fx from your DAW.
  • If you DO need to hear live, real-time fx, lower the buffer settings until you find one that doesn’t prevent the computer from processing the fx adequately but DOESN”T cause clicks or pops.
  • Use low-latency settings when using midi keyboards and controllers in order to guarantee NO delay issues.
  • Low Buffer Size for recording/tracking as a general rule.
  • High Buffer Size (ie.1024) or higher for mixing as this will give your computer more time to process all the audio/midi/effect plugins and make everything run a lot smoother.

Till next time.

Scott Chapman is the Chief engineer and Head of Technical Support and Sales at 90º Studio @ Musos Corner.