Sound Device MixPre-3 II Timecode Issue

Sound Devices MixPre-3 II

In this post I would like to talk about an irritating feature, not to say a flaw, in the Sound Devices MixPre-3 II. You can also listen to the whole post on YouTube.

Let’s take it away.

One of the features of the SoundDevices MixPre-3 is Timecode.

However, as it turns out, there seems to be a major flaw in its implementation, that is only apparent when you change presets or use the File Transfer feature. This essentially makes the timecode unusable as it deviates by seconds within a short period of time, instead of microseconds over a course of 24h.

What do I mean by this?

Timecode on the MixPre-3 is received via the 3.5mm TRS Aux input. So in order to be able to jam from an external source you need to do the following:

  1. Go to Menu, Inputs, Aux In Mode and set it to “Timecode”.
  2. Go to Menu, Timecode, set the TC Mode to “Free Run” and select the “Jam” menu.
  3. Jam the timecode from the external source, by pressing “Jam TC”. Depending on your timecode generator, you need to select either “Aux In 1” or “Aux In 2” as the “Source”.

The timecode in the MixPre-3 should now be jammed from the external source. Note down the value, that is shown in the “Diff” line of the screen.

This all works as expected.

However, as soon as you load another preset or you switch to File Transfer mode, the timecode in the MixPre-3 starts to differ from the external source.

This can easily be verified by either doing on of the following:

Option A: Go to Menu, System, File Transfer, to enter File Transfer Mode; and select Exit to leave it. Do this several times. And then go to Menu, Timecode, Jam and note that the “Diff” value between the external source and the internal timecode generator of the MixPre-3 is now different from the value you noted down earlier.

Option B: Go to Menu, Presets and save the current settings to one of the internal presets by selecting “Save to Int 1, 2, 3 or 4”. Then select the previously saved preset by selecting Menu, Presets, Load Presets and selecting the number of the internal preset you saved earlier. Repeat thus serveral times. Go back to Menu, Timecode, Jam and note that the “Diff” value between the external source and the internal timecode generator of the MixPre-3 is now different from the value that you noted down earlier when you jammed from the external source.

Option C: Go to Menu, Inputs, Aux In Mode and select “Mic” as the source. Then via pressing the “Channel 3 knob” go to Channel 3, Input and select “Off” as the source and then go back to the home screen. Then go back to Channel 3 again and this time select “Mic”. Then go to Menu, Timecode, and select “Aux In 1” or “Aux In 2” as the source, even if the correct source seems to already be selected. After a moment, the screen updates and you should now see that the “Diff” value changed from the value you previously saw when jamming to the external source.

So what does this mean in reality?

First, this means, that you have to re-jam every time you want to transfer a file to your computer via the USB-C cable.

Second, even if you were to re-jam every time you used the File Transfer mode, you could only do this when you would not use Aux input for other purposes at all. This essentially eliminates the use of the TRS input as a microphone input that you would have in a headset such as the Beyerdynamic MMX 300.

Are there workarounds? Of course. But they all come with limitations. That is probably why they are called …

Workaround 1: SoundDevices Support suggested to use a USB stick to transfer files between the MixPre-3 and the computer.

This certainly works, but involves a lot of manual work, as you need to unplug from the MixPre, plug into the computer, transfer files, then unplug from the computer and re-plug into the MixPre again and again.

Workaround 2: Do not use timecode at all.

Really? But this removes the functionality of one of the main features of the device. Instead I could then also directly connect to the computer via a different device altogether.

Workaround 3: Do not use a microphone with a TRS jack. And re-jam every time you transfer a file.

Possible. But a lot of headsets actually happen to have such a jack.

Workaround 4: Use an XLR to TRS adapter if you have to use a microphone with a TRS jack. And re-jam every time you transfer a file.

Also possible. But then you need to carry one more adapter with you. And this changed the form factor of the MixPre-3 considerably.

Workaround 5: Go to Menu, System, USB-C and change the setting to “Power Only”.

When doing this, you cannot use your MixPre-3 when you want to play back sound from your computer. This somehow defeats the workflow to record sound on the MixPre-3 with headphones on, transfer the recording to the computer and edit it and then listen back to it with the same headphones you recorded earlier with.

With most of the workarounds we need to re-jam manually every time we transfer a file. In combination of an “auto jam” mode like on the 8-series recorders this might even be a acceptable workaround.

Sound Devices Support told me, that the out-of-sync behaviour is expected when using File Transfer mode as the device would have to sync to the computer clock. This sounds plausible. But there are two things, that do not seem to fit into the picture.

Regarding the out-of-sync behaviour there has not been any explanation at all.

First, this does not explain the behaviour that the timecode also changes when selecting presets and changing Channel settings.

Second, the Sound Device 8-series does not seem to show the out-of-sync behaviour when using File Transfer mode.

I am a little bit disappointed that depsite the richness of features of the Sound Device MixPre-3 – and the price tag that comes along with it – the device cannot deliver its features at the same time.

Hopefully, Sound Devices addresses this in a future firmware update.

Regarding firmware: the behaviour can be reproduced on a Sound Devices MixPre-3 mark II with firmware version 8.0 with build number 5136. The external timecode generator is a Tentacle Sync E connected via a 3.5mm TRS cable to the mixer. The computer used runs on Windows 11 but has shown this behaviour also with Windows 10.


You cannot use the MixPre-3 reliably with timecode and as a playback device and a TRS microphone at the same time when using the File Transfer mode.

Published by Ronald Rink

I am a senior auditor and consultant at d-fens for business processes and information systems.

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