How to play a track to specific speakers

[Matt Rosine]

Hi all, 

I'm SMing a theatre production, and we have placed three floor speakers underneath the house seats. The idea is that we want to play a horse galloping sound underneath the audience, going from left to right. 

I am fairly novice at Qlab and I don't know how to program this. A volunteer sound guy came in to set the speakers up to the sound board. Here is a photo of the matrix faders for the speakers under the seats: 

Is any body able to explain how I do this in Qlab, or point me towards a good YT video on it?

Thanks so much in advance!

[micpool]

Do you have an audio license?

Are the horses in mono or stereo?

Does the recording of the horses have a point in it where the horses are clearly passing the listener?

Mic

[micpool]

On 26 Sep 2023, at 22:04, Matt wrotYes I have an audio license.
I'm not sure but I think stereo. If it changes the solution I can find out.
The idea is to have the horses start at one end underneath the house seats, and then cross over to the other side - left to right (or right to left).

In the following examples I have 3 speakers L C R on 3 cue outputs



Q1  has a horse galloping from left to right with a clear point between 6 and 8 seconds where the horse passes the listener.

If you played this effect just routed to 2 speakers under the seats left and right (cue outputs 1+3 ) then you would get a very good effect of a horse passing.

As you have a centre speaker under the seats, perhaps placed more behind the audience, this allows you to enhance the effect by building  the level at  the point the horse passes and pulling the image behind the audience at the doppler point.

To do this you would just route the audio cue  to the left and right speakers as normal and also fade up the centre speaker with the left and right channels routed to it over 6 seconds or so and then  fade the centre channel out again. 
In the timeline group Q3:

Q4 is the same horse effect  with the centre speaker fed from both ch of the recording



Q5 Builds in the centre speaker (cue output 2)


Q6 Fades the centre speaker


The other way of doing these effects is with a mono recording with a fairly constant distance and tone and purely using changes in level (amplitude) to achieve the panning

In Timeline group Q7:

We start the audio cue Q8  with cue outputs 1 to 3 out

Then  in Q9 we fade up the Left speaker (cue output 1)

in Q10 we crossfade to the centre speaker (cue output 2)

in Q11 we crossfade to the right speaker  (cue output 3)

and in Q12 we face out the right speaker (cue output 3)



As you can hear in the screen recording (attached to my next post)  amplitude panning a mono cue doesn't have much realism or subtlety and the end result is often crude or comical.

If you listen to the first example which is a true stereo recording you can hear several things that are lacking in the amplitude panned example.

There is a subtle change of pitch when the horse passes the listener (doppler) 

The further away the horse is from the listener, the less high frequency content there is.

In Timeline group Q13 we achieve a doppler in Q17  by quickly fading the playback rate to 0.85 of the original rate



All the levels are the same as in the previous example, but when the audio cue starts there is a LPF (low pass filter) in the audio FX tab set to filter all frequencies above 1500Hz

In Q15 as well as fading up the left speaker we also open the filter to allow all the high frequency content of the audio to be heard



Qs 16 +18 crossfade thru the centre channel as in Qs 10 + 11 in the previous. example (remember Q17 is the rate change doppler)

In Q 19 as well as fading out the right speaker we also close the LPF back down so as the horse recedes so do the upper frequencies.



This sounds much better, though nowhere near as good as a proper stereo or multichannel recording.

Screen recording in the next post......

Mic

[micpool]

On Wednesday, September 27, 2023 at 2:23:56 PM UTC+1 micpool wrote:

On 26 Sep 2023, at 22:04, Matt wrotYes I have an audio license.
I'm not sure but I think stereo. If it changes the solution I can find out.
The idea is to have the horses start at one end underneath the house seats, and then cross over to the other side - left to right (or right to left).

Screen and audio  recording. Watch while referring to the screenshots in previous post

[Matt Rosine]

Hi, thank you SO much for this detailed reply. I appreciate the effort so much, and I'm going to use it to get the effect my need.

My very first issue however is understanding HOW to get qlab playing on only those speakers. Once I've done that, I can use the instruction/example below you kindly provided me. 

I was playing with the soundboard last night to try and figure out how it's set up:

• There are three speakers up in the rails - left, center, right
• There are three speakers under house seats - left, center, right
• Qlab is going into the the first two faders on the board which control the main volume from Qlab - regardless of what speakers it goes to
• On the right side of the board, there are three sliders to control volumes for the rack speaks up top:

• Also on the right side of the board on the matrix bus (if that's the correct name), there are three sliders for the under house seats speakers:

• So I can control the main Qlab volume using the two far left sliders (which I don't do obviously, I control and set in Qlab)
• I can control the volume of the L/C/R speakers up top and down under house separately 

BUT...! What I don't know how to do is tell Qlab just to play to the specific speakers - in this case, the ones under house. I can get a row of sliders to show up in Qlab for the volumes, but I have no idea which is which or how to figure it out. I noticed last night that the sound is playing out of all the speakers - up in rack and down below, which we don't want - regardless of the effect I'm trying to get with this one horse track. So I guess my puzzle is two fold:

• Figure out how to play sound to specifc speakers through Qlab
• Figure out how to get the effect of the horse passing from left to righ (which hopefully I can do with your instructions/examples.

[micpool]

OK,

If you want QLab to be able to route to 6 speakers directly then you need  at least 6 inputs from QLab into channels on your mixer.

If you have a USB interface card on your X32 then you can just plug your mac into that and route audio from QLab to the mixer down this cable, but from your previous posts it seems you might need some help with that from someone that knows the mixer a bit better than you.

What you need to end up with is 6 audio  channels from QLab routed 1 to 1 to the 6 outputs that are going to your 6 amplifiers for the speakers.

Mic

[Matt Rosine]

I do believe the X32 has a USB interface card, as I'm currently connecting to it using a UBC C to USB B cable. 

I need to learn how to "route audio". 

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