Live Recording Techniques - On A Budget!

A Tutorial by David Breton


Several years ago when Mini Disc (MD) recorders first came out, I thought it would be neat if musicians and singers could have their own Archival CD Recording of a live concert that they had invested so much of their time over several weeks to rehearse for, but never heard from the audience's point of view!


So twenty or so recordings later, I decided to write down the techniques I use, some of which have been learned through hard experience. The techniques described here of course do not rival a recording studio with multi tracking and multiple takes, but focus on how to do a live recording, with no chance of a re-take, how post processing will let you "polish up" the final mix, how to make a professional looking product and how to cover your costs, which includes your recording equipment investments.


Step One - The Live Recording


Of course you want to have a high quality live recording, keep your equipment purchases on a budget, and as portable as possible. An MD recorder can help to address these requirements, the quality is far better than cassette tape, and the portable version of the MD recorder is very small, requiring no AC power.


The most important components in the live recording process are the microphones and the room acoustics! For classical and jazz performances the room should have the right amount of natural reverberation to make for a "live" sound. An acoustically dead room makes for a "dull" live performance and, although you can add some artificial room reverberation into the final mix, it will never match the "real thing".


Selecting the Digital Recorder


The invention of the MD recorder made live recording an affordable hobby. There are many types and brands on the market today, but only the portable models made by Sharp appear to have the right advantages for live recording namely, a proper recording level meter calibrated in dB, no AGC (a live recording killer). Another important consideration is that the MD recorder has the right level of input level compression that prevents the dreaded overload condition. I set my Sharp MD recorder's recording level once by clicking my fingers hard right next to the microphones so the recording level just goes over 0 dB and then leaving it at that setting for the rest of the concert. Even a large orchestra will not clip the recorded signal (if the mics are set back at least 15 feet) and the dynamic range is good enough to pick the quietest vocal soloist!


Where do you buy the MD recorder? I got mine at www.minidisco.com My first Sharp lasted for a while until it got kicked off the top tier of a chorus riser, five feet onto a wood floor. Thankfully, it was connected to plenty of microphone cable and finished recording the concert, but its eject mechanism never worked properly after that traumatic experience. This gave me an opportunity to examine the insides; the thing is a marvel of miniaturization.



Selecting the Recording Microphones


The microphones should be the small condenser recording type. These have a flat response to capture from the lowest bass to the high pitch harmonics of the female singing voice and also preserve the clarity and position of all the reverberances in the live room setting. The small size of the condenser diaphragm allows it to respond quickly to fast sonic attacks.


The other important requirement of a live recording microphone includes the ability to withstand high pressure levels. It is amazing how loud a large orchestra can get, especially with percussion and horns! The one thing that will absolutely spoil your live recording is a mic or recorder overload, since you can not go back and retake it again. The other most important parameter is the condenser microphone's self noise. This coupled with the MD recorder's microphone preamp, always ends up as a slight hiss in your recording, but modern post-production hiss reduction techniques can reduce much of this to a very low level.


Where do you buy these microphones on a budget? My favorite vendor is the www.soundprofessionals.com Web site, which will show the numerous recording microphone options available, ranging from the single point stereo microphone that is fitted inside the same box that encloses your Mini Disc recorder to binaural microphones that fit on top of a microphone stand. You can kit out your microphone requirements for anything between $80 to $250.


I have had some good success with the single point stereo (in rooms that have natural good acoustics) but prefer the Binaural type that sit on top of a microphone, spaced the distance between ones ears.


Locating the Microphones


Since you are making a live recording of an entire group of musicians and/or singers, then the microphone recording location should be far enough away to get the entire mix of sounds without a single instrument or voice drowning out the rest. The concert producer should have made the appropriate arrangements for any sound reinforcement to ensure that the audience hears the right balance, although on occasion this may not happen - typically a soloist is too quiet against the accompaniment. Don't worry too much if the balance is not quite right as there are post processing techniques to address this problem.


Every room, especially large ones, has a sweet spot, where all the sounds reverberate just right. Walking around the room with headphones fully covering the ears and a single point stereo microphone plugged into your portable MD recorder during a rehearsal will help you find the room's sweet spot.


If the ideal recording position is right in the middle of the audience seating area, you have two options. Either sit in the ideal listening position with the MD recorder on your knee (and a single point stereo microphone) or put the microphones high up on a tall pole to clear the audience rustles and coughs. My budget microphone pole is actually the 1/2" diameter poles from two living room stands screwed together to clear 7 feet using one of the original light stands as a base! I then use a 20 foot extension cable bought from the Sound Professional guy (above) to run to my MD recorder. I don't bother putting on my headphones (looks geeky, and hard to do while performing!) but just keep an eye on the MD recorder level meter. Remember also the Sharp MD recorder input level compression is very good at handling peaks.


Step Two - The Post Processing Mix


So you've got home and listened to the live recording. You should be amazed at the recorder's stereo clarity, if it is your first time. However there are some things you can do to "polish up" before burning a CD, this step is called post processing.


Transfer to PC Hardrive


The absolute best way to post process to transfer from the MD player to the PC over a fiber optic cable. Most portable MD recorders cannot do this. In my early days I used the recorder's analog output to my sound card's line input. This would give me a noise floor of about -59 dB, which you can hear as a very quiet hiss under normal listening levels. Later on I invested in a Sharp home MD/CD deck with fiber optic output (because it was on sale for $130) from Minidisco (above). This drops the noise floor to -90 dB, a very respectable number for amateur recording.


The second advantage of using a fiber optic cable is that there is no sound card input gain to adjust. If you are using the analog method, find which setting avoids any overload of the sound card's analog input. Don't bother maximizing the sound level track by track, that can be taken care of in the post-processing mix.


Where can you buy a cost effective sound card with fiber optic inputs? I bought a DiO 2448 for $110 at www.soundprofessionals.com (I should really get a discount for free advertising!) and run it at the same time as my SoundBlaster, which is used for output to my studio amps.


There are many programs available for transferring your MD recording to hard drive. My favorite is N-Track Studio, since it has input VU metering and live monitoring while recording.


Even though the MD recorder has editing facilities, don't use them on your precious live recording MD! One mistake can ruin every thing (if you do, eject the battery so the recorder cannot write the changes back to the disc). An easier way is to use the PC program to create a WAV file which a bit extra at the start and end, you can always trim and fade later in the post mixing step.


The Post Mix


Without a doubt, the absolute best program for post-processing live recording WAV files is Syntrillium's Cool Edit Pro. It is worth every penny of its $399 price. The DEMO version lets you do anything but save for 30 minutes. Failing that Cool Edit 2000 1.1 (with preview) for $69 from the same company is a good alternate.



The post-processing sequence (described in detail later) is as follows, with some steps avoided for certain recordings.



1. Remove "bad" sound artifacts


2. Tone down any overbearing voices or instruments


3. Use dynamic processing for a better balance between instruments and voices


4. Apply any extra room reverb


5 Rebalance left and right to widen or narrow the stereo image


6 Normalize the maximum sound level to about 85% of maximum.


7. Trim the start and end of the track.


8. Save the new file as a separate file from the original



RULE #1 - Your ears can easily get used to overdone effects. Too much filtering can "dull" the sound, too much reverb makes for unnatural echo, too much compression can give the sound a "squeezed" feel. Take frequent breaks and go back to the original MD track to reset your ears to the original recording.


RULE #2 - Filtering effects should first be used to REMOVE unwanted information rather than boost other parts


1) Remove Sound Artifacts


Sound artifacts are basically impairments ending up in the live recording. The Minidisc's ADTRAC compression process adds some very slight high frequency scratching around 8.7 kHz when the music program has a lot of sonic energy (e.g.. a majestic church organ). To eliminate this artifact, you use the sound editor's parametric equalizer to create a narrow -12dB notch (Q = 18). Sweep the filter to find exactly where the artifact is and click the filter in and out in preview mode to make sure you are not compromising the recording. Once the preset has been saved, just use it for every MD track.


Cool Edit Pro has a good Hiss Reduction effect. If possible, select a short portion of a recording with no music and adjust just enough to lower to an acceptable level. Listen carefully to other parts of the track to verify no dullness or warble has been added by Hiss Reduction. Cool Edit Pro remembers the Hiss Reduction setting for subsequent tracks.


2) Tone down any overbearing voices or instruments


Sometimes the level of bass or percussion can be a little overbearing. I normally use the Parametric Equalizer to adjust the levels, because it is easy to click a specific filter in and out. Be careful with how much high frequency you tone down since this can also remove the live feel to a recording.


3) Apply dynamics processing to achieve better balance between instruments and voices


Cool Edit Pro has an excellent Dynamics Processing effect. With some careful compression you can "pull" out a quiet solo voice against much louder accompaniment.


4) Apply any extra room reverb


Normally you don't need to do this step, but in the case of organ recitals you can make the organ appear as though it was in a magnificent cathedral. If the live performance was in a "dull" room, you can add some artificial room reverb, but do it carefully and double check on headphones and studio monitors that it doesn't sound phoney!


5) Rebalance left and right to widen or narrow the stereo image


You can use this step to create a more rounded sound for large choruses. Compare between headphones and studio monitors to ensure you haven't made the image too wide or turned it into mono!


6) Normalize the maximum sound level


There's nothing more annoying when you listen to your finished CD then to find that one track is much louder or softer than the rest. Normalize every track 85% of maximum. Why 85%? It's because some (cheap) CD players can not handle dynamic sonic "bangs" very well.


7) Trim the start and end of the track


Cool Edit Pro allows you to zoom into the start of the WAV file. Highlight the section before the music program starts and delete. Go to the end of the track and highlight 3 to 5 seconds. Use the Envelope effect to taper down to zero by listening to the preview to hear the effect of the decay.


Now save your work as a new WAV file!


Step Three - CD production


Once all your WAV files have been processed, you are ready to make the CD. Remember that this article is focused on how to make an Archival CD Recording of live performances for the benefit of furthering the education of the performers. It is illegal to make CDs for commercial sale without the permission of the copyright holders.


That said, there's no reason not to make your CD recording look professional. There are several vendors of CD labeling products, including AVERY who are carried by the likes of OfficeMax. Make sure you clearly indicate on the CD label and jewel case cover that this is an Archival Recording - not for commercial sale. A charge of about $6 will be sufficient to cover your expenses, offset some of the costs of wear and tear on your equipment and go towards some of the expense in purchasing the recording equipment in the first place.


Conclusion


Well that's about it! I have always been surprised at how many performers appreciated being able to hear themselves as the audience does. It has helped them improve their styles and, for amateurs, gives them another reason to participate in performing live music. I get comments from people who say they still play their Archival CD Recordings years later or when they are a little down. Performing live music makes a nice contrast to the "spoon feeding" of TV and movie theatre commercialism - enough said!


David Breton is a degreed software engineer with experience in audio and video processing. He is a participant in performing live vocal music and a strong supporter of community-based performing arts. He lives in the Newport, Rhode Island area and can be contacted at dbretonusa@yahoo.com.


Copyright David Breton 2001