What is Analog Sound?

Sounds themselves are analog signals. We can choose to record these sounds by either analog or digital means. Analog recordings capture the continuous wave of the analog signal—what they hear is what they record. Digital recordings capture binary codes that reflect the sound’s intensity and pitch at precise intervals—in other words digital recordings sample the analog signals of a sound and then reconstruct these samples upon playback. To put this into perspective, think of an election. Polls represent the digital version of how people will vote. The actual vote count on Election Day is the analog version of how people did vote. As we’ve learned, polling (or sampling) is not always 100% accurate.

Analog tape machines use magnetic heads to record and playback on magnetic tape. They have an erase head, a record head and a playback head. As technology improved, tape machines began to add multiple tracks to the recording process. However, it wasn’t until the development of the sync output of the record head that techniques like overdubbing, sound on sound and punch in editing became possible. Since the three magnetic heads are physically separated from each other, the section of tape they are reading are asynchronous from each other. They sync output solved this dilemma by making it possible to hear the previous tracks in sync with the recording head—this allowed musicians and singers to add new tracks that synced up with the previous tracks. Previously, performances—even multi-track ones, were recorded live to tape. The multi-tracks allowed for manipulation of each of the tracks but not much more.

Pioneers in these advanced analog techniques include Les Paul (credited with inventing multi-track recording and sound on sound techniques), The Beatles and the Beach Boys. At the time, four tracks were the maximum available-but creative audio engineers were able to use this to great advantage.

Sound on sound, or overdubbing, allowed for a previously recorded track to be played back while an additional instrument or vocal was added to the track. As recording machines added tracks, it became possible for these additions to be recorded on a separate track, eliminating the possibility of a bad sound on sound take ruining the master recording.

The Beatles and the Beach Boys were masters of bouncing, or dubbing down—a technique where three of the recorded tracks would be mixed down to one track, thus freeing up three tracks to record additional parts of the song. A variation on this technique used two four track recorders, the first would play back the four tracks to one track on the other machine allowing for three additional tracks to be recorded as accompaniment.

Punch in editing allowed for the musician or vocalist to ‘repair’ a bad section of a track. The tape would be played back and the engineer would punch the recording button, on the fly, at the beginning of the section to be recorded and punch out at the end of the section. The musician or singer would hear the old track in their headset up until the punch in point, at which time they would hear themselves live as they recorded the replacement section.

By the late 1960s, eight track tape machines were showing up in recording studios, allowing for additional complexity.

Even as analog recording evolved, it still had limits. The equipment was big and expensive. The number of tracks was limited. In theory, overdubbing and bouncing could allow for as many tracks as needed, in reality there were definite limits as each dub down or bounce degraded the audio signal. Additionally, if you wanted to create duplicates of your final mix for distribution on albums or cassettes they had to be done in real time. In other words, if you wanted to copy a three minute song it would take three minutes.

Perhaps the biggest advantage of the analog recording process was a byproduct of its limits. You really had to have your shit together before you started recording. You had to map out your tracks and plan accordingly. Here’s a plan for a simple four track recording session.

1. Live on tape record the kick drum on track one, the rest of the drum kit on track two and the bass on track three.
2. Bounce these three tracks to track four. Now tracks one, two and three are freed up.
3. Playback track four while recording backup vocals on tracks one and two.
4. Bounce track two background vocal mixed with recording rhythm guitar onto track three. Now track two is freed up.
5. Bounce track one backup vocal mixed with recording lead guitar onto track two. Now track one is freed up.
6. Record lead vocal on track one.
7. Mix down the four track: track one lead vocal, track two lead guitar and backup vocals, track three rhythm guitar and backup vocal, track four bass and drums. Lead vocal, bass and drums (tracks one and four) panned to center; guitars and backup vocals (tracks two and three) panned to the sides—one to the left, one to the right.

And then along came digital audio with unlimited tracks and built in effects. Compression, EQ and echo/reverb and other modern day “plug ins” were developed for analog audio recording. They were stand-alone cumbersome and somewhat limited “black boxes”, or in the case of an echo chamber they were a physical room with acoustics designed to create delay. Today, they are almost always included in any DAW and extremely versatile in their capabilities. This allowed musicians and singers to have the luxury of unlimited overdubbing with precise punch in and punch out points, processed effects at their fingertips, and a wide range of electronically produced sounds and beats. Whether this lifting of analog’s technical limits has led to better music is another story.

Today, the debate of analog vs. digital is essentially new school vs. old school. They both have their places, but digital technology’s merits of smaller and much less expensive gear mean it is here to stay. Digital audio has opened up the doors to recording and distributing music to a much larger group of musicians and audiences, while allowing live DJs to walk into a club with 1000s of songs on a thumb drive instead of 100s of songs in crates of vinyl records. However, it never hurts to have a little historical perspective on things, if for no other reason than to be amazed by how artists like The Beatles or the Beach Boys could do so much with so little.