Fixing and mixing a musician's home recording
by Bruce Bartlett, Copyright 2011
“We can't afford to record in your studio, so we'll record at home and you can mix it”. Sound familiar?
In a tough economy, an increasing number of musicians don't have the money to spend several days or weeks in a studio at the hourly rate. What's more, a lot of artists need time to develop sonic ideas by trial and error, and can't afford to do that on studio time.
Some performers shun the studio for other reasons. “I get too nervous in the studio… I'll just record myself with a portable recorder and let you overdub the other instruments.”
Many musicians own DAW setups — or flash recorders — and can do their own tracking at home. But some lack the expertise and equipment to make clean recordings in the first place. They might hand you a load of barely usable tracks, and expect you to make them sound good.
While a number of musicians have mastered recording skills and can produce great-sounding tracks, some don't know what they're doing. They need your help. If you want to put your name on their album or demo, you want to work with them so they'll record the cleanest tracks possible. Then you'll spend less time fixing sonic errors and more time being creative.
We'll look at two approaches to improve the end product:
- teach your customers how to record at home effectively
- use plug-ins and editing to improve their recordings.
Offer Advice to Record-at-Home Musicians: Talk with your clients to make sure they can supply you clean tracks. Try to find out their skill level so you don't insult them by telling them stuff they already know.
The advice you give home recordists is the same as you'd give to a novice recording engineer in a pro studio. You can discuss the following points wth the band members, or simply give them this article to read.
First tell your customer that it's difficult or impossible to remove reverb, compression and distortion, so make sure to keep those under control. The same goes for background noise. I'll describe specifically how to keep a handle on those problems.
Listed below are some suggestions for musicians to follow when recording. These tips apply both to 2-track and multitrack recordings.
Get rid of noise sources: Turn off the furnace or air-conditioning when you record. Maybe record in the basement — it tends to be quiet because it's surrounded by earth and cement blocks. Wait for trains and planes to pass. Seal cracks under doors with towels; maybe cover windows temporarily with plywood sheets. Have an electric guitarist rotate or move around to find a spot where hum stops.
Improve room acoustics: Hang some mattress foam, packing blankets, sleeping bags or comforters on the walls or on mic-stand booms. Put a roll of fiberglass insulation in each room corner to act as a bass trap. Or buy some pressed fiberglass panels and put one across each corner. One source is www.atsacoustics.com.
Mike fairly close: If you place a mic or stereo recorder too far from the instruments, it will pick up lots of muddy-sounding room acoustics which can't be removed in the mix. Try to stay no farther than 1 foot from the mics or recorder.
Figure 1. A singer/guitarist is close to the recorder to reduce pickup of room acoustics.
Don't clip the signal: Check the recording levels not only during regular playing, but also during loud accents. Aim for -6 dB maximum level on peak-reading level meters. Some keyboard patches are louder than others — try all of them when setting levels.
Monitor the recording: Put on headphones and listen to what the mics are picking up. Often you can hear background noises much easier with headphones than without. Play back recordings to check balances between instruments and vocals.
Turn off effects: Some recorder-mixers automatically insert compression or other effects when you record. Make sure they are disabled.
Suggestions for Better Multitrack Recordings
Avoid ground loops: Connect recording equipment, keyboards and instrument amps to the same outlet strips. First make sure that the outlet's circuit breaker can handle the current of all that equipment. Use direct boxes between electric instruments and the mixer, and flip the ground-lift switch to the position where you monitor the least hum.
Use good mics: Borrow or rent some if you don't have any. A basic mic collection includes a cardioid dynamic mic for guitar amps and drums (like a Shure SM57), a small-diaphragm cardioid condenser mic for cymbals and acoustic instruments, and a large-diaphragm cardioid condenser for vocals.
Minimize leakage: In other words, try to make each mic pick up only its own instrument. To do that, mike close with cardioid or supercardioid mics — about 8 inches away or less. Record bass and keys direct. Overdub quiet instruments and vocals after recording the loud instruments. You might place the band members in a circle so that adjacent mics aim away from each other.
Use effective mic placement: Ask your recording engineer how to mike various instruments, or refer to articles and books about that topic. (I've received acoustic-guitar tracks made with the mic close to the sound hole, and had to EQ like crazy to get rid of the boomy sound.)
Suggest that the drummer remove the front head of the kick drum, put a pillow or blanket inside, and use a hard beater to get a tight, snappy beat.
Figure 2. One method of miking a kick drum.
Use a pop filter on vocal mics: To prevent breath pops, place a hoop-type pop filter a few inches in front of a vocal mic. You can improvise one: try a coat-hanger wire curved like a shepherd's crook, with a nylon stocking stretched over the loop. You might use a foam windscreen as a last resort.
Solo and export each recorded track starting from time zero: That way, all the tracks should line up when imported into the studio's mixing software. Disable any effects plug-ins when you export the tracks so that the studio can use only their own plug-ins.
Name each track's wave file by the song and instrument: For example, “Road Runner Blues-lead guitar.wav”. Or “Soul Spice-high harmony 2nd chorus.wav”. That avoids confusion in the studio when it comes time to sort out the tracks.
Ways to Minimize Time in the Studio
Some musicians do want to record in the studio because the sound they get is so much better than they can get at home. They need to know how to make the recording process as efficient as possible so they don't run up a huge bill. You might offer these suggestions:
- Record yourself with a simple DAW or recorder-mixer to work out production ideas at home. See what works and what doesn't so you don't need to experiment in the pro studio.
- Bring lyric sheets and charts with each song's arrangement. Work it out at home, then bring in charts as a memory aid in the studio. Make copies of the lyrics and arrangements for the engineer.
- Consider recording fewer songs. A 10-song album costs about half as much to record as a 20-song album. 10 great songs are better than 20 songs with filler.
- Practice until you can play without mistakes. Obviously, that saves studio time that is spent fixing errors.
- Consider punching-in rather than fixing problem spots with editing. Often it's faster to re-record a botched musical phrase than to correct it with copy-paste edits or volume changes.
- If you have changes you want to make in a mix that you auditioned at home, note the time of each change. Finding a time location is a lot quicker than finding a particular lyric in the second bridge!
Fixing It In the Mix
So far you have advised the band on ways to record well at home. Eventually they will hand you a hard drive, flash card or CDs containing their tracks. It's your job to take those raw recordings, clean them up, and add EQ and effects to make a super mix. Let's go over some tricks to achieve that goal. First we'll clean up the individual tracks.
Delete or mute parts of each track where nothing is playing: Those sections contain leakage and noise. Either slip-edit the beginning and end of each clip, or highlight unwanted sections and delete them. Another method is to use volume envelopes or automated mutes to silence the parts you don't need.
Gate drum tracks to reduce leakage or to tighten up the sound: Here's a typical procedure. Play and solo a tom-tom track that has a gate inserted. Gradually increase the gate threshold until the background leakage goes away, but you still hear the tom hits. Set the attack time fast, like 1 msec, and set the hold time for the desired amount of sustain on each note.
Some gate plug-ins have a setting called “lookahead time”. If you set it to 10 msec, for example, the gate opens 10 msec before the transient hit occurs. That lets you use a longer attack time (rise time) without losing the transient's attack.
Click on the file below to hear a tom-tom track before gating. Because the tom head rings in response to the other instruments, there's a low-frequency “cloud" over the sound. (If the file doesn't play continuously, right-click it and save it to play later.) For best sound play the samples over your studio monitor speakers.
Now click on the file below to hear the same track after gating. All you hear is the tom hit — no ringing, no leakage except during the actual strike.
Another way to achieve the same effect is to delete the audio between the tom hits.
Here's a boomy, hollow-sounding kick drum. Listen to the file below.
Here it is again with gating. Nice and tight.
Highpass filter every track: Insert a highpass (low-cut) filter in a track. Set Q to 1.7 and play the track. Start with the filter frequency at 20 Hz, gradually raise it until the sound thins out, then back off a bit. That removes noise and leakage below the lowest fundamental frequency of each instrument and vocal.
Fix clipped notes: Suppose a kick-drum hit is clipped and sounds crackly. Find the full-amplitude spike where the clipping occurred. Zoom way into the waveform until you can see the individual waves (Figure 3).
Figure 3. The waveform of a clipped kick-drum signal.
One solution is to delete the clipped waveforms and add short fades into and out of the “hole" that is left (Figure 4).
Figure 4. The clipped part of the waveform is deleted.
Another solution is to create a clip (region) of those waveforms and lowpass filter the highs in that region. Some DAWs let you redraw the waveform in a smooth curve to remove the clipping.
Here are audio samples of a clipped kick-drum signal before and after editing:
Filter out hum and hiss: Some EQ plug-ins have a hum-filter preset which inserts a comb filter starting at 50 or 60 Hz. Others have de-noise processing. A simple lowpass (high-cut) filter works well to remove hiss in a guitar-amp track. Try a Q of 1.7, and gradually bring down the filter frequency to the point where the sound gets dull, then back off.
Delete breath pops: Find a pop or thump in the vocal track. Zoom far into the waveform there until you can see the longer wavelength of the pop signal. Then highlight and delete it. Add short fades into and out of the deleted section. It's amazing how well this works.
Enhancing Stereo Recordings
Some musicians record themselves with a portable stereo recorder. Here are some tips to improve a recording made on such a device.
Use an analyzer/EQ program such as Harmonic Balancer: This program can work wonders on stereo mixes that have a bad tonal balance. Har-Bal analyzes and displays the spectrum of a mix so you can pull down any over-emphasized frequencies that color the sound (www.har-bal.com).
Click on the samples below to hear a musician's mix before and after processing with Har-Bal. The song is, Copyrighted 2009 by Tony Chapman.
Cut frequencies below 40 Hz: There might be low-frequency rumble from trucks or air conditioning in the stereo mix.
Maybe add reverb: Homes don't have reverb with a long decay time, so you might add just a little reverb with 1.5 - 2.0 seconds RT60. That gives a more “commercial" feel. Try to filter the lows out of the reverb signal so the bass and kick don't get muddy.
Add compression: If a singer really belts the loud notes, tame them with compression.
Widen or narrow the stereo stage: Plug-ins are available that create mid/side (sum/difference) signals from the left-and-right stereo signals. You can vary the amount of difference signal to expand or shrink the stereo image.
There you have a number of tips to enhance your customers' tracks and to optimize those tracks when they record them. Recording at home and mixing in the studio is becoming more common, so it helps to develop skills for this type of record production.