ProFX16v3 channel faders not doing anything?

[RSSI-Reader]

Hi, not quite sure if this is the right place to ask but if it isn't, could someone point me to the right direction?

I am helping out in a small religious organization, we have a functioning audio visual setup, but we swapped out the old mixer to a new Mackie ProFX16v3 about five months ago. Generally I am not the only one who touches the system, and the people who touches the system have some basic knowledge of AV.

General Setup:
- Main XLR to speakers, 1/4" to audio recorder.
- Channel 1 from stage goose neck (XLR-XLR, requires phantom).
- Channel 10/12 from PC (3.5 to dual 1/4").
- May add more inputs as needed for the day (i.e. wireless microphone, additional line in for guitar or mics for singers).
- Rest of the settings is pretty much out of the box or turned off, except for Phantom, L/R Assign Switches and low cut (these three are on).
- We don't use FX at all.

Previously, we found out that we needed to get the channel faders quite high (i.e. >= +5 above unity gain) to get some volume from channel 1. Also on the Main Meters L is usually louder than R for all inputs.

But recently we realized that the channel faders and the main faders are not doing anything, and the only way I can get any sound out is via engaging the L/R Assign Switches. The only reason why we realized this now is because we left the L/R switched on and we consistently set the channel faders to be roughly the same every week (we do bring the faders down and mute the channels before turning off the mixer as part of our shutdown/startup procedure, and we do not have a power delay control system).

So right now, if
- (1) my channel faders and main mix fader is completely down (< -60dB) , and (2) L/R is not engaged, I have no sound (as expected).
- (1) my channel faders and main mix fader is up (i.e. unity gain) , and (2) L/R is not engaged, I have no sound (the issue).
- (1) my channel faders and main mix fader is at any level , and (2) L/R assign switch is engaged, I have sound and I have no idea how to control the volume.

TDLR / In summary / My question:
Anyone faced a situation where the channel faders and main faders are not doing anything? How did you resolve it?

I will respond to the best of my abilities but, I only have access to the equipment once a week or so.

[Kwackman]

- (1) my channel faders and main mix fader is up (i.e. unity gain) , and (2) L/R is not engaged, I have no sound (the issue).

You mean the L/R button on each channel?
If so, I suspect this is correct.
That button and the two buttons above it (1/2 and 3/4), tell the channel where it's output should go.
If L/R is pressed, then that channel's output (the fader controls how much of it) goes to the Main stereo output fader.
The buttons above 1/2 & 3/4 give the option to go to those groups instead of L/R.

It's been MANY moons since I used a desk like this, so hopefully someone with recent experience will be along to explain why I'm wrong

[sonics]

The buttons above 1/2 & 3/4 give the option to go to those groups instead of L/R.

...or as well as.

The L/R buttons need to be selected to send audio to the L/R outputs, obviously.

[RSSI-Reader]

I see.

So my initial understanding that L/R switches for that channel must be engaged in order for the channel to send to Main is correct.

Then it is really weird that the channel faders and main faders are not doing anything.

[The Korff]

As the others have said, you need the L/R button pressed in on a channel if you want that channel to come out of the main mix.

But the 'faders not doing anything' thing sounds like a PFL issue. Do you have the 'PFL Solo' button pressed in on those channels? Cos you shouldn't...

L/R button pressed in, PFL button out, and all should work as expected.

[RSSI-Reader]

No, PFL is not engaged.

If PFL for any channels was switched on, we would have noticed as the Rude Solo would continuously blink until all currently engaged PFL solo switches are turned off.

[Hugh Robjohns]

That Mackie mixer is very conventional in its signal path and there are no traps I can see in the input to main out path. As is often the case in Mackie desks, though, there are some gotchas in the control room monitoring arrangements.

So, if you haven’t already, I'd strongly advise reading the user manual carefully, and studying the block diagram of the mixer to understand the signal paths.

If you really are listening to the mixer's main XLR outputs, I can see no way of getting sound out of the thing if the channel and main faders are closed. It can't happen...

The stereo mix buss feeds the 'Break' switch (a main output mute), followed by the main fader and XLR outs. So the main fader must always affect the output level via the XLRs unless you've hit the break button, in which case there can be no output.

On the input side, each mic/line channel input routes through the preamp, compressor, insert point and EQ. It then passes through the channel fader, pan control and output routing switches.

Again, you cannot get sound from the channel unless its fader is up and the output routed somewhere.

Pressing the LR routing button sends the channel signal directly to the main stereo mix bus, and thence to the main fader and XLR outputs.

Pressing the sub 1/2 or sub 3/4 buttons sends the channel signal to the sub outputs instead (or in addition)... and the sub outputs can also be sent back to the stereo mix bus, if desired.

So there really is nothing to allow sound from the desk's main XLR outputs that bypasses the channel or main faders.... Therefore, if what you describe is true, the desk is not connected as you say it is!

However... there is a Direct Monitoring route to the control room/headphone outputs that is derived before the channel fader, and is mixed with USB signal via the Blend control. If you were listening to that (rather than the main outputs) you could certainly think the channel and main faders were doing nothing at all... because they aren't involved in that signal path.

Might this be what you're doing?

[Hugh Robjohns]

Just re-reading your original post...

General Setup:
- Main XLR to speakers, 1/4" to audio recorder.

Just be aware that the 1/4-inch outputs are wired directly across the XLR outputs, and if shorted to ground fuel to a broken cable (for example) will kill that main output too.

Previously, we found out that we needed to get the channel faders quite high (i.e. >= +5 above unity gain) to get some volume from channel 1.

Is this with the channel 1 preamp turned fully up? Is the compressor engaged? Are you using the channel EQ?

It is unusual to need to have to push the channel fader above its unity mark if the signal path is gain-staged correctly.

Also on the Main Meters L is usually louder than R for all inputs.

Something is awry there! Using just channel 1 (mute all other inputs), press the Solo button. The left/right meters should be identical. If not the desk is faulty. Next, deselect Solo and check the channel pan control is centred and (only) the LR button engaged (not the sub buttons). Also, make sure the Direct Mon button is not pressed. Again, the LR meters should be identical. Turning the channel pan knob to the left should decrease the right meter, and vice versa.

But recently we realized that the channel faders and the main faders are not doing anything, and the only way I can get any sound out is via engaging the L/R Assign Switches.

The LR assign buttons are required to route the channels to the stereo mix bus, so this is correct. The non-functioning channel/main faders can't happen... unless you're listening to the direct monitoring mode via the control room outputs or headphones. As explained in my previous post.

So right now, if
- (1) my channel faders and main mix fader is completely down (< -60dB) , and (2) L/R is not engaged, I have no sound (as expected).

I'd expect that too.

- (1) my channel faders and main mix fader is up (i.e. unity gain) , and (2) L/R is not engaged, I have no sound (the issue).

Again, correct. The channel LR buttons MUST be engaged to route the channel to the main stereo mix bus and thence the main outputs.

- (1) my channel faders and main mix fader is at any level , and (2) L/R assign switch is engaged, I have sound and I have no idea how to control the volume.

The LR routing is after the channel fader, so it MUST control the signal level.

Have you possibly created a secondary channel path via the computer, perhaps?