Direct Out Modifiocation for Allen & Heath ZED Mixer

I recently acquired an Allen & Heath ZED 12-FX mixer to use for home recording and live mixing. This is replacing a Mackie 1202-VLZ Pro that I have used for several years. I was looking to add a more channels and to improve on the EQ capabilities.

For recording, I use a PC/Windows system running Cakewalk SONAR 8.5 with an M-Audio Delta 1010LT sound card. This gives me 8 input channels. I typically have recorded using the direct out capability on the channel Inserts of the Mackie mixer. By inserting a 1/4″ mono plug only half way (to the first click) the Mackie provides a direct out, without interruption of the signal through the channel. Unfortunately, the ZED mixer does not provide this capability.

I have performed this modification only on a ZED 12-FX mixer. However, it should be applicable to all mixers in the ZED series. There will be differences in the removal of the channel cards on some of the other ZED series mixers.

This article describes a modification to the mono channel of the ZED mixer to add a direct output function. This modification is not approved by Allen and Heath. As an unapproved modification, this may void your warranty.

The ZED Mixer INSERT

The diagram to the right shows the connections to the INSERT socket on the ZED mixer. Each of the three connections in the socket have contact closures to provide a signal path when no jack is inserted.

When inserting a 1/4″ jack into the INSERT socket, you can hear 3 distinct “clicks”. At the first click, the tip of the jack is contacting the sleeve of the socket, which is a ground connection.

At the second click, the tip of the jack is contacting the ring of the socket, which is the return connection. At this point, the signal is interrupted, and any input presented to the channel does not flow to the channel. An internal connection in the channel strip will now connect the tip and sleeve of the return connection.

At the third click, the tip of the jack is contacting the tip of the socket, which is the SEND for the INSERT. The ring of the socket is the RETURN.

Note that this modification is for the Mono channels only.  Allen & Heath does not provide INSERT connections for the Stereo channel on the ZED mixer. So, there is no simple way to create direct outs from the Stereo channels.

The Modification

As you can see from the schematic diagram above, when no jack is inserted the Send signal flows through the contact closures of the tip and ring connections. When a jack is inserted to the ring connection, however, the connection is opened and the Send signal no longer flows to the Return.

The modification I applied is to provide a jumper across the pins I have designated as 3 and 4. This provides a path for Send to Return when a jack is inserted to the second click. This also will place the Send signal on the tip of the inserted jack, providing a direct output to the channel. This is shown in the schematic diagram here.

When a jack is inserted all the way, the contact closure on the tip position will open, interrupting the internal signal path, and operating as a standard INSERT.

Tools and Skills Required

While the modifications presented here are moderately simple, they should not be attempted by someone who is not skilled in soldering electronics hardware. It should also be noted that this modification is not approved by Allen and Heath. As an unapproved modification, this may void your warranty.

Proper precautions should be taken to prevent damage to the unit from static electricity. A ground strap should be worn when working on the unit.

The following tools are needed:

• #1 Phillips Head Screwdriver
• T10 Torx Driver
• 7/16″ Nutdriver
• Soldering Iron
• Flat Head Screwdriver

Opening the Mixer

The bottom of the mixer is removed to access the channel cards. I use a thick foam pad in the table to protect the knobs as I place the mixer upside down. Remove the 12 Phillips head screws with the #1 Phillips head screwdriver. The bottom can be removed and set aside.

Remove the Knobs and Front Panel Connectors

For each of the mono channels you are modifying, remove all the control knobs. Use the flat head screwdriver to pry the knobs up gently, then pull them off. Note that if you are modifying channel 6, you will need to remove channels 4 and 5 as well.

Use the T10 Torx driver to remove the 2 screws for the XLR connector. Use the 7/16″ nut driver to remove the nuts on the two 1/4″ connectors and on each of the rotary controls.

You do not need to remove the slider. This will stay in place for this modification.

Remove the Ribbon Cable

A ribbon cable connects to all the channel cards. Remove this from the mono channel cards to allow their removal.

Remove the Channel Cards

The channel cards can now be removed from the unit. They each have wires connected to the slider which is still connected to the front panel. Be careful to not pull on these wires as the channels are removed.

It may be best to remove one at a time, perform the modification, and then return it to the chassis. Unfortunately, due to the mounting of the power supply, channels 4, 5 and 6 may require that the adjacent cards (lower channel numbers) also be removed.

Channel 6 is the hardest to remove. With channels 4 and 5 removed, pull it up slightly, and tilt toward the lower channel numbers.After the knob shafts have cleared through the front panel, rotate the card to bring the solder side upward. The images to the right show this sequence.

Apply the Mod

Now that you have the mixer disassembled and the channel cards removed, this is the easy part. Solder a wire across the two middle pins of the INSERT socket as shown in the photo on the right. Do this for each of the mono channels you wish to.

When the mods are complete, reassemble the mixer by reversing the steps.

Using the Direct Out

The direct out is an unbalanced signal. Use a standard 1/4″ jack and plug it in the INSERT socket only to the second click.

The direct out taps the signal after the input gain stages and after the 100 Hz high pass filter. It is pre-EQ. in my system, I use a recording snake to connect the 6 channels with direct outs to 6 audio inputs of my M-Audio sound card.

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