-- INTRODUCTION --
I'm going to describe a known, good, working method of creating a multiple sound track overdubbing session from scratch in Audacity 1.3. That is, you record one track and then play it back and add a second track against it. Repeat as needed.
This process uses a single, plain microphone and special USB microphone amplifier. Hardware variations, mixers, etc., are possible and covered in a different talk.
You will hear a useful, controlled theatrical mix of your live performance and the previous tracks. This is the step often missing or damaged without purpose-built hardware or specialty software.
-- HARDWARE --
I'm using an ordinary
Shure SM-58 "rock band" microphone.
Any
XLR microphone
will work. The system is plugged into my Mac, but almost any PC, Mac or Linux machine with fast enough USB and good storage can be used. I'm using my
Mac earbuds
for listening in this example, but nearly any good headphone or earbud is OK.
Headphones are good. Live microphones and live speakers do not get along.
I'm using Audacity 1.3.12, but Audacity 1.3.13 works, too. Audacity 1.2 is more difficult to use and not well supported.
The key is the
Shure X2U
in the middle. The headphones are plugged into the X2U, not the computer.
The Shure X2U has two jobs:
-- It amplifies the microphone signal and digitizes it to USB for the recording.
-- It has an internal headphone mixer. The X2U performs a mix of your track playback and your new, live, undelayed microphone performance.
-- FIRST RECORDING --
We will do a simple recording. No overdubbing or other fancy tricks. The system has to work correctly for simple recording and playback before we go further.
Connect the parts as shown.
http://www.kozco.com/tech/audacity/pix/x2uShureOverdub.jpg
I cheated a bit for the talk. I did my test with an XLR microphone cable between the microphone and the X2U. I also used a mic stand and a Mac instead of a Windows machine. None affect the job, the show, or the talk.
This is not a tutorial on making a simple recording and playing it back, but you need to be able to do that before you do anything else. There are multiple tutorials and wikis on First Recording.
[references]
Set the computer control panels and preferences to recognize the X2U USB device.
Set Audacity Preferences.
Audacity Preferences > Quality > 44100, 32-bit Floating.
Audacity Preferences > Devices > Mono.
Audacity Preferences > Devices > Recording and Playback to the USB sound device.
Audacity Preferences > Recording >
[X] Overdub...
[ ] Hardware Playthrough...
[ ] Software playthrough...
OK > Restart Audacity.
When Audacity starts, expand the sound meters by clicking on the right edge and drag to the right. The rest of the tools and panel graphics will move out of the way.
Click once anywhere inside the red recording meters to put them in Monitor mode. They will measure the microphone sound without sending Audacity into full record and wasting drive space.
Adjust the X2U Mic Gain for comfortable volume. Don't peak much over -6 or -10. You can fix funny levels later, but you cannot fix overloading, smashing, and clipping. You should be able to hear your performance live in the headphones with no delay. Adjust the Volume control as needed for comfortable listening.
Press Record. Audacity will take a second to configure itself and start recording. The blue waves will start to crawl left to right as you perform. Sing a simple song that you can use for rhythm and timing later. Drum. Tap a pencil on the desk. Anything with rhythm.
Press Stop. Play the track you just made. You should hear the track in your headphones. Adjust the Monitor control for good balance between your live voice (still active) and the playback.
This is what you will hear during the overdub sessions. Any combination of existing tracks will play in your headphones in addition to your live voice allowing you to set a good theatrical or musical mix and timing.
-- LATENCY --
Home the cursor and Press record again and you will get a new recording underneath the first one. Sing or perform in time to the first track. Press Stop.
[two track pix]
The show will have the second part of the performance (your live microphone), but it may be seriously out of time or rhythm -- even though you were in perfect time when you recorded it. This is Latency and you can adjust it to zero using Audacity 1.3 Latency tools.
Done properly, both the live recording session and the playback later will be in perfect time.
File > Close > Don't Save
File > New
Generate > Click Track > OK.
Home the cursor > Press Record. Jam the headphones against the microphone and turn both up so the Click Track is playing loudly from the headphones into the microphone and onto the second track.
[pix jamming]
Good fidelity is irrelevant.
Do that for five or ten seconds and press Stop.
Select the new track and Effect > Amplify > OK.
Play and both click tracks will play out of step. Magnify the timeline around one of the pair of clicks (drag-select and Control-E or Command-E.
Drag-Select the distance between the start of the click on the top track and the start of the same click on the bottom track.
[timing error]
That's how much the rhythm misses and that's the latency. Keep magnifying until you can get a good shot at accuracy. Control-3 or Command-3 to back out slightly if you magnify too much by accident.
Bottom of the screen > Middle Time Window > Length
Change the format using the dropdown menu to:
hh:mm:ss: + miliseconds.
You're mostly interested in the milliseconds -- the last numbers on the right. My reading was 241msec.
Audacity Preferences > Recording > Latency > add a negative value of your reading to whatever is already there. If the original number was -150, add negative 241 (in my case) to that to get -391. > OK.
I never went back to touch it up, but you can if you want to.
Restart Audacity and go through generating Click Track, etc., again.
This time the two click tracks should be perfectly on or very close to it. If not, measure the new difference and add that number to the latency value.
Before you get too compulsive about this, an orchestral musician once told me that the chances of any two instruments in the orchestra starting the same note at the same time is zero.
-- PERFORMANCE --
Restart Audacity and you're ready for the first theatrical session.
The first recording can be whatever you're planning to use as a base, guide or rhythm track. It can be anything including Generate > Click Track which can be adjusted for rhythm and composition. I used the music from my rhythm and chord machine playing into the microphone.
Stop > Home the cursor, press record and record track two using your live performance and track playback in your headphone mix as a guide. Repeat until bedtime.
The Mute and Solo controls to the left of each track become valuable in ovedubbing. Solo causes only that track to play and Mute turns just that one track off. The little volume control to the left of each timeline also controls the playback volume -- it affects the headphone mix.
When you get to a stopping point, press Stop and File > Save Project As. As you progress, you should save a new Project periodically with a slightly different filename. Being compulsive, I use date and time.
201110011500.aup
That's today at 3PM. 2011 October First 1500.
I will never duplicate a file by accident. Do Not Use Slash Marks or other punctuation marks in a filename.
201110011520.aup
201110011545.aup
201110011602.aup
New version of the song about every twenty minutes.
Do Not go weeks with the same Project and filename.
Audacity does not save UNDO. If anything happens to that one Project, you're dead and take weeks of work with you. Think of what would happen if the lights went out right now and you were forced to use the last known good version of the performance.
Audacity Projects are brittle and easily damaged.
Export to WAV for archive or Music CD, or MP3 for internet delivery or email. Do Not do production in MP3. You may need to adjust the volumes and levels of the show so the Export doesn't overload.
All of the Audacity editing, filtering, and effects tools are available for each track or any combination of tracks.
Koz
