SERATO CLICKS,
GLITCHES OR DROPS OUT

Serato describe a USB dropout as audio that cannot be fed from the USB buffer to the bus in time, heard as "audio glitches, clicks or dropouts", and the software has a USB dropout indicator that lights when one happens, so you can tell a dropout from a bad cable or a bad file.

That indicator is the whole diagnosis. If it lights, the computer is not delivering audio fast enough and the rest of this page applies. If it never lights and the sound still clicks, look at the file, the cable and the mixer channel first, because the USB path is not the problem.

On a Mac, Serato's list is six settings in order: disable the wireless network, disable Bluetooth, set the screen saver to never, in Energy Saver uncheck "put hard disk to sleep when possible", set computer and display sleep to never, and try another USB port, because in their words "Mac computers generally have one good and one bad USB port, try connecting your audio interface to a different USB port and see if there is an improvement."

Four of the six are things the Mac switches back on by itself. WiFi reconnects at the next known network, Bluetooth comes back after a restart, the screen saver and sleep timers return with a system update. That is why a laptop that was fine at rehearsal glitches at the venue, and why this list is worth running as a pre-gig routine rather than as a repair.

The USB port note is worth taking literally. Try the other port before you try anything else that costs money.

On Windows their first check is the processor. Open Task Manager with Ctrl+Shift+Esc and watch overall CPU use while the glitches happen. If it approaches 100 percent, the instruction is to increase the USB buffer size in Serato, which gives the processor more time per block of audio. If CPU is well below that, the cause is elsewhere and they move to measurement.

A bigger buffer is a trade, not a fix. It buys the processor time and costs you latency, which a DJ feels as a lag between the jog wheel and the sound. If the CPU is not near its limit, do not raise the buffer at all. Go to the next section instead.

One Windows cause is a hidden setting. Serato state that many newer Windows computers, Microsoft Surface and Dell among them, ship with the High Performance power plan hidden, and that "Without enabling these hidden optimizations, your well spec'd Windows PC may struggle with processing real-time audio". Their published way to reveal it is a registry value, CsEnabled under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power, changed from 1 to 0 followed by a restart, and they ask you to back up the registry first.

This is the part every other guide skips. "Set your power plan to High Performance" is standard advice, and on a Surface or a recent Dell the option is not in the list, so a DJ who follows the advice concludes it does not apply to him. It applies. The plan exists and is hidden. Serato's registry change reveals it, and Serato ask you to back the registry up first; do that, on a table, the day before, not in a booth.

Once the plan is visible, select it and leave the laptop on mains power for the set.

The measurement is LatencyMon, the free Home edition from resplendence.com. Serato's procedure: close every program including Serato, connect AC power, launch LatencyMon and select Start Monitor, let it run for several minutes, select Stop Monitor, copy the Stats report and save it, and send it with a support ticket. It names the driver or interrupt that is stalling the audio stream.

Why measuring beats guessing. A dropout on Windows is almost always one badly behaved driver holding the processor for longer than the audio buffer can wait, and there are dozens of drivers on any laptop. LatencyMon names the one. A DJ who disables wifi, bluetooth and antivirus in turn is running the same test by hand, slowly, and may never reach the right one.

One specific case has its own page, because it has a different cause and a different fix: on macOS with DVS hardware, switching WiFi from off to on during playback produces a dropout and then heavy latency, and the only reset is to reconnect the hardware. That known issue is here.

At the decks, the only things on this page fast enough to try are the Mac list and the other USB port. The registry change and the measurement are not booth jobs.

If it keeps glitching, take the laptop out of the set. Any drive you have already exported plays in the decks with no computer involved. Run the full procedure tomorrow, with the laptop on a table and on mains power.