Sound Production and Music Recording Skills
Lesson 1 - Monday 10/9/2012
Part 1 - Headphone Amp and Monitoring Playback.
We started todays lesson by talking about headphone amps and reasons for their uses. A headphone amp is used to make the sound coming from the control room to the live room louder, boosting the signal so that it can be split between multiple headphones.
Every studio will have small or large differences in equipment, design and space. Being aware of this will enable one to be flexible and quickly adapt to new situations without having moments of panic and not knowing whats going wrong.
Following up from the diagram last week of signal path in order for the headphone amp to be connected the sound needs to be routed from the control room back into the live room via the wall plate.
We were show 2 set up diagrams for (i think) a digital and analogue control room, to show the signal flow from the control room to the wallplate (picture above)
102 Command -
106 Analogue
(spelling error should read analogue)
Practical Exercise
Today our practical exercise was to set up a microphone for recording and monitoring, with knowledge of the signal flow through the patch bay, mixer, into the mac/pc running logic, and the signal flow back into the room. We also started using the patching bay to change the signal flow into different channels.
For referencing purposes I have made a diagram cutting down the equipment to the bare essentials for this task in order to make following whats going on a lot easier.
The "essentials" for this task.
A vocalist would sing into the microphone, the microphone converts the acoustic sound energy into electrical sound energy, which travels down the xlr balanced cable to the snake box. A balanced lead will enable hum and buzzes to be eliminated, we touched on the fact one of the L or R is inverted phase (which we will cover later) is the reason this is possible. The 3 pin xlr cable then goes into the snake boxes first input, which is connected to the wall box which, in turn, is connected to the patch bay.
Snake box - Input 1 is broken/doesn't work and we had problems
with input 2, input 3 was what we found to a reliable input for us to rely on.
In a real studio situation some initial problems usually occur when trying to get a sound in the control room or mac/pc. For example the microphone might not work, cables by being twisted and wrapped up can be damaged as inside it is copper which can be broken. Some inputs might be broke, pins on xlrs can break a myriad of problems can occur in any sound situation and sometimes it can be even get to the point where recording sessions can get cancelled.
Now the patch bay in this studio is set up so that the top row of inputs is connected to bottom row of the inputs at the back, this is true for every plug in the patchbay except for the blue labelled ones.. The top row of inputs(which is yellow in this studio) are numbered 1-24 to match all the inputs on the snake box. The bottom output row (also yellow) are numbered 1 -24 and go to the input channels on the mixing desk into inputs 1 - 24.
Patch bay with a cable redirecting the signal from input 3 to output
4 on the mixing desk. You can also see the blue sections which aren't connected top to bottom.
The mighty mixing desk.
Problems can occur at any point during the signals flow. Considering the patch bay has many many cables if you could have a manager in a studio who at the end of the night might unplug or change the patching in the bay which would lead to major problems with getting the signal flow to the mixing desk!
In this analogue studio the sound is not only patched into the input of the desk, but each channel then outputs to a reel to reel machine and comes back into the same channel to enable the use of this lovely piece of equipment to capture that tape sound and still use our fancy hardware and digital tools.
Close up of channels on mixing desk.
This row of 5 buttons on each channel is very important.
The MIX button at the top enables or disables the ability to monitor the sound through the amp and speakers in the control room. If theres no sound coming out the amp and speakers, in this studio, it's possible the mix button isn't pressed.
The next four numbers are the bus buttons. Pressing one of these will send the signal to the bus on the mixer, now for this mixer it's essential as I mentioned above there is a reel to reel machine in this mix. In order to send the signal to the mac/pc you must press a button down to send to the bus and raise the volume of the bus to get a signal to the software. If the sound isn't coming from the channel into the bus then it's possible you might have the wrong button pressed, it may be panned to the wrong channel or the gain might not be set high enough.
There is a pan control above these buttons, if it's set in the middle the signal will go to both Left and Right and the 1-2 button is pressed the signal will go to channels 1 and 2 on the bus. If it's panned right it will go to bus 2 and if panned left it will go bus 1. From the bus 1 output it will go to the input 1 of the AD/DA interface. Bus 2 output would go to bus 2 of the AD/DA interace and so on. If the 3-4 button was pressed the same principle applies, depending on panning will determine either bus 3 or 4 and the output would go to the corresponding AD/DA interface input. If theres no sound travelling from the bus to the computer it might be that the wrong input is selected on the daw which needs to match the AD/DA output, which if the sound is coming into bus 3 it would be going out into channel 3 on the AD/DA input.
Bus/Sends - This is where the signal comes from the channel and
into the AD/DA interface due to the analogue nature of this
study.
On the computer side of things we have logic loaded up with an empty template. We press the plus button on the top left where the tracks are usually and this creates a new track. In order to record we need the enable record checked and we need to select the channel input to match up with the bus the sound is coming from.
You would set the channel fader volume to 0, the bus level to 0 and adjust the gain on the channel until at the performers loudest performance there was no peaking. Maybe at 12 o'clock maybe a little more.
DA half rack unit turned on
The mix out from the mixer travels to the half rack sized DA input/output and goes to the wall plate in the live room. If this isn't turned on no signal will be sent to the wall plate and neither the headphone amp or the headphones will pick it up.
wall plate with xlr to jack cable
The wallplate connects to the headphone amp with an xlr to jack cable. The headphone amp is essential for live monitoring as many people might need to be listening at the same time to the mix being played. If it was a band for example monitoring can be highly useful. A guitarist might want to be able to hear a clean and distorted tone, a vocalist might need to overdub the vocals after the musics recorded having closed headphones (to prevent sound leakage into the mic) would enable them to sing in time with the song. Instruments might need re recording and this would also enable them to re record in time with the song.
The musicians might want to hear different mixes while playing together, a guitarist might want his guitar louder so he can hear what he's doing, a vocalist might not want to hear his vocals while singing (or he might want to). These are possible without effecting the final mix (we haven't touched on this in depth yet).
Headphone Amp on a Piano
The headphone amp was connected with a IEC power to the wall power socket. The headphones are plugged into the output.
Now if all is set up correctly we should be able to sing in to the microphone, hear a sound throught the speakers in the control room, record in to logic, listen to whats being recorded/played through the headphones in the live room.
Hypothetically let's talk this through. We have the mic plugged into the snake input 1, this is coming through the patch bay to the mixer. We have a drummer playing and can hear him over the monitors. We press the 1-2 button, pan the channel left and we have the signal coming through the bus into the AD/DA interface. We create a new track in Logic naming it drummer, selecting input 1 and record him playing.
Using the same microphone in the same input we get ready to record a singer. We pan the mic to the right and we've changed the bus from 1 to 2. We create a new track in logic selecting input 2 (making sure enable record is always checked when we want to record) and name it vocals. The singer has the headphones on and sings along to the drum track while we record it in to it's own channel.
Or instead of panning the track what we could do is using the mic in the same no 1 input on the snake is to connect a cable from patch bay input 1 from the wallbox to out put 2 to mixer channel 2 on the desk. We could then select 3-4 pan left on channel 2 and the signal would be sent to bus 3 and to the AD/DA interface 3. We would have to create a track with the input number 3 corresponding with the AD/DA interface.