What are Soft synths?


A software synthesizer, better known as a soft synth, is a generally speaking a computer program, or plugin that generates digital audio, usually for music. Computer software that can create sounds or music is not new. However, advances in processing speed are allowing soft synths to accomplish the same tasks that previously required dedicated hardware. Soft Synths are usually cheaper and more portable than dedicated hardware. In addition, they are easier to interface with other music software such as music sequencers.


Advanced algorithms


Software synthesizers usually have much more advanced algorithms than digital hardware synths. This is because of much greater processing speed (as well as support for Floating Point processing and greater than 24 bit Word size) of the x86-64 CPUs that modern Music production Personal Computers and Macintosh Computers have over the Motorola 56000 DSP processors found in common Hardware Synthesizers like the Waldorf Blofeld, Access Virus, Novation Ultranova, and Clavia Nord Leads.


Hardware advantages


The advantage to dedicated hardware is that it can be more stable. Additionally, it often has a user interface that is physical (knobs and sliders) and therefore easier to manipulate during performances. Many soft synths use mathematical algorithms that directly emulate the electronic components and circuitry of the original hardware synthesizer. This produces an exceptionally authentic sound. It even captures the “flaws” in the original hardware, such as oscillator drift caused by thermal sensitivity of the components.


Synthesis methods


Soft synths can cover a range of synthesis methods. This includes subtractive synthesis (and analog modeling, a subtype), FM synthesis (including the similar phase distortion synthesis), physical modeling synthesis, additive synthesis (including the related resynthesis), and sample-based synthesis. Many popular hardware synthesizers are no longer in production. Nevertheless, they have been emulated in software.


Software emulations


The emulation can even extend to having graphics that model the exact placements of the original hardware controls. Some simulators can even import the original sound patches with accuracy that is nearly indistinguishable from the original synthesizer. Popular synthesizers such as the Minimoog, Yamaha DX7, Korg M1, Prophet-5, Oberheim OB-X, Roland Jupiter 8, ARP 2600 and dozens of other classics exist as software emulations.


Sample usage


Some soft synths are heavily sample-based, and frequently have more capability than hardware units, since computers have fewer restrictions on memory than dedicated hardware synthesizers. A couple of these sample-based synthesizers come with sample libraries many gigabytes in size. Moreover, some are specifically designed to mimic real-world instruments such as pianos. Many sample libraries are available in a common format like .wav, .sf or .sf2, and can be used with almost any sampler-based soft synth.




The major downside of using soft synths can often be more latency (delay between playing the note and hearing the corresponding sound). Decreasing latency requires increasing the demand on the computer’s processor. When the soft synthesizer is running as a plug-in for a host sequencer, both the soft synth and the sequencer are competing for processor time.

Multi-processor computers can handle this better than single-processor computers. As the processor becomes overloaded, sonic artifacts such as “clicks” and “pops” can occur during performance or playback. When the processor becomes completely overloaded, the host sequencer or computer can lock up or crash. Increasing buffer size helps, but also increases latency. However modern professional audio interfaces can frequently operate with extremely low latency, so in recent years this has become much less of a problem than in the early days of computer music.


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