Understanding Tape Machines And Emulating Their Sound

The recording process has changed a lot over the years. In the past, engineers used tube mics and analog preamps to record instruments directly to analog tape. The combination of unique tones from those three pieces of gear added a very pleasing texture to the music created.

While it’s still extremely common to see analog preamps and tube mics in a modern studio setting, tape machines are a somewhat rarer bird. While you'll still find them in many studios, the industry-wide shift to working in the box has made bypassing tape a somewhat more feasible practice. Because of this, many engineers feel that modern music is missing something.

Recording to tape gives music a certain character. It rolls off the high-end and adds a small bump in the lows, similar to an equalizer. It rounds off transient peaks, creating a subtle form of compression. Perhaps most importantly, it adds a unique form of saturation, primarily boosting what are known as 3rd order harmonics.

3rd order harmonics mimic the frequency response of a signal two octaves above the source material. For instance, if you recorded a low E on a bass guitar, the root frequency would be 40Hz. 2nd order harmonics, which are typically added by tubes, boost one octave above the source (80Hz). 3rd order harmonics are primarily added by analog tape, and boost two octaves above the source (120Hz). This helps signals “cut through” a mix by adding higher frequencies in a musical way, instead of simply boosting the top band on an EQ. As with all good things, too much can cause negative effects.

In this blog, we are going to talk about the basics of tape machines, how different elements change your final audio output and how we can emulate tape without actually owning a machine. 

Tape Basics
Modern tape emulation units can come shockingly close to recreating the vibe of vintage tape machines. But, in order to understand the differences between these units, you’ve got to know what they’re emulating.

Microphone signals were recorded directly to 16 or 24 track tape machines, which used large (usually 2”) tape reels. These reels would be played back through the console during the mixing stage, and after signal processing would be printed to a smaller (usually 1/2”) 2-track “master” tape. The different tape sizes each have their own unique sonic qualities.

The size of the tape isn’t the only factor that affects the sound, however. The type of tape you use also affects the frequency, compression, and distortion characteristics.

Each tape type has a suggested calibration level, which tells you how loud your average signals should be. Older tape types are usually calibrated at +3dB, while modern tape types are calibrated at +9dB. Early tapes were noisey, and began distorting earlier, while modern tapes have better transient response and less distortion. These are the most common tape types you’ll come across:

- 250 (+3)
- 456 (+6)
- 900 (+9)
- GP9 (+9)

After choosing the tape machine and tape type, it’s time to select the tape speed. Tape speed is measured in inches per second, and has the largest impact on the frequency response of the machine.

Higher speeds add a small boost to the lows, and subtly roll-off the high-end. Lower speeds add a significant boost to the low-end, and aggressively filter the highs. The most common tape speeds for multitrack or 2-track tape machines are 30ips, 15ips, and occasionally 7.5ips.

Tape Machines
Keep in mind, tape machines are actual machines. When they start spinning reels of 2” tape around at 30ips, they generate heat, movement, and noise, which can change the tone of the recording. Variations in the low-end caused by the movement from the tape machine are referred to as "wow," while variations in the high-end are called "flutter."

Finally, tape machines require calibration, and part of that process is setting the bias. Bias controls the sensitivity of different frequencies, and when they begin to distort. A low bias setting will cause more distortion, particularly in the low-end, while a high bias will cause less distortion.

So, how does the modern engineer recreate the unique sound of tape machines? Well, the obvious answer is to buy a tape machine. Brands like Mara Machines have a wide range of options that could fit nicely into your studio space. If you're looking for more cost-effective alternatives, there are many analog and digital options for tape emulation.

Using Tape Emulation
There’s no wrong way to use tape emulation. Some engineers like to recreate the signal flow of yesteryear by putting 2” multitrack tape emulation on each individual channel. This can quickly throttle even the most up-to-date machines, so it’s not uncommon to route multiple tracks into a few busses with tape emulation units on them. Not only does this keep your signal processing low, it also helps recreate the vibe of tracking to a 16 or 24 channel machine.

It’s also common to see 1/2” tape emulation used on the mix bus to help recreate the vibe of mixing to a master tape, which is a much more CPU-efficient way of adding subtle amounts of “tape sound”.

Just remember, part of the charm of recording to tape was the subtle differences between each channel on the machine. Without the compounding effect of multiple channels adding their own unique combination of effects, you won’t get that traditional “tape sound.”

But who cares? The best part about tape emulation units is that you can experiment in ways that analog tape would never allow. Stack 5 different tape machines on a single channel. Use a 2-track machine on every channel. CRUSH THE LIVING HELL OUT OF SOMETHING. Go nuts! There’s no wrong way to use tape emulation!

Options For Tape Emulation
These first few plug-ins are licensed models of actual tape machines used to cut some of the most successful records of all time.

- Slate Virtual Tape Machines: Models of a Studer A827 2” 16-track tape machine from NRG Recording, and a Studer A80 RC ½” 2-track machine from Howie Weinberg Mastering.
- UAD Ampex ATR-102 Master Tape
- UAD Studer A800 Multichannel Tape Recorder
- Waves J37: An emulation of Abbey Road’s historic J37 tape machine.
- Waves Kramer MPX Master Tape: An emulation of the tube tape machine found at Olympic Studios in London

While tape machines are excellent, they have a very specific purpose. You may find more use out of a saturation plug-in that can mimic the effects of tape. While these plug-ins don’t model specific tape machines, they’re great for adding a similar vibe to your tracks.

- Crane Song Phoenix II
- McDSP Analog Channel
- Softube Tape
- XLN Audio RC-20 Retro Color
- SoundToys Decapitator
- UAD Culture Vulture
- UAD Vertigo Sound VSM-3
- Avid Reel Tape Saturation

If you want to introduce some true analog warmth without the hassle of operating and maintaining an actual tape machine, check out some of the following outboard saturation and tape emulation units:

- Rupert Neve Designs Portico 542
- Empirical Labs EL7 FATSO (Full Analog Tape Simulator and Optimizer) 
- Empirical Labs Distressor (Dist 3 mode)
- Overstayer Saturator NT-02A
- Thermionic Culture Vulture

From vintage emulation to modern innovation, the sound of tape can improve almost any track. With these plug-ins and outboard processors, you've got a plethora of options for adding that analog warmth we all know and love. 

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