For anyone observing music recording over the past 20 years, audio technology has evolved at a mind-boggling pace. Giant tape machines, consoles, and racks filled with gear have quickly given way to sleek desktops, laptops and even tablets. Yet while workstation technology has made some older audio equipment obsolete, the lure of certain vintage analog hardware endures.

The Moog four-pole resonant filter is a classic design with a distinctive, characteristic sound. Structurally, the filter is formed by placing four identical one-pole filters in cascade (see Figure 1) and creating a feedback loop around them. As the amount of feedback is increased from zero, the (initially coincident) closed-loop poles of the system diverge, with two poles becoming increasingly resonant.

What is the secret behind the distinctive sound of British rock in the 1960s and ‘70s? Is there really even a distinctive "British" sound? My quest for answers unearthed many theories. Some people believe that it’s all about the gear that was used; others suggest that it was about the powerful combination of cultural forces and new technologies, and even new ways of using old technology.

Q: What is it about the 1176LN and LA-2A compressors that makes them distinctive sounding? How can these distinctive properties be captured in a digital emulation?

A: To answer that, let’s give a brief overview of what compression is, and then focus on the special properties of these two compressors that give them their unique flavors.

Q: How are digital mastering EQs different from digital tracking/mixing EQs?

A: Historically, in terms of application, the mastering EQ is required to achieve high fidelity, offer a wide range of center frequencies for EQ features, provide good agreement between left and right channels, and allow for easy recall of exact settings. The particular curves picked for the EQ should be designed to work well for program material.

Q: How does oversampled peak detection work?

A: Oversampling is sometimes used in order to improve the accuracy of peak level estimates for sampled signals. The idea is that when a signal is sampled, there may be no samples taken at or near the peak values of the signal. When this happens, the maximum sample-values will not be equal (or close) to the peak values of the signal.

The Cooper Time Cube is famous for its spectacular short delay and doubling effects, and its uncanny ability to always sit perfectly in the mix. The Cooper Time Cube plug-in’s delay element has a rather “wiggly” frequency response. The high-frequency and large-scale, low-frequency variations are modeling hardware frequency responses that are largely due to the characteristics of the transducers and the cavities in which they sit.

The UAD 4K is an emulation of the SSL 4000 channel strip, which comprises high and low cut filters, four-band EQ, compression, and expansion/gating. The buss compressor is modeled after the SSL 4000 buss compressor. It features feedback topology, VCA-controlled gain, a wide range of attack and release times, and an “Auto” release mode with program dependence. Compression ratios are also selectable.

Q: Does the Neve 33609 plug-in include a model for saturation in the circuit, or is the signal distorted only due to the action of the compressor?

A: There has been much debate among users on this topic. The 33609 plug-in does model distortion in the audio path separately from distortion caused by gain modulation.