Voltage controlled oscillators are perhaps the most important part behind an analog synthesizer.  Depending on the synthesizer there are a different number of oscillators within each unit.  Here is a rundown of some of the most collectible synthesizers and how many oscillators they have in them.


1 VCO - YAMAHA SY-1. This was Yamaha's very first synthesizer and had only one voltage controlled oscillator.  It was first produced in 1974.

1 VCO - ARP Axxe, this was one of ARP's entry level keyboards hence the fact that it has one voltage controlled oscillator.

1 VCO - ARP Pro-Soloist - although the synthesizer only had one voltage controlled oscillator it was deftly not an entry-level keyboard.  Chosen as the keyboard of choice by Tony Banks in the early 70s one can hear how expressive this instrument truly is.  Perhaps its most unique feature was the fact that it had aftertouch sensitivity for volume.

2 VCO - KORG MiniKorg 700s - this was a notable keyboard as it was Korg's very first ventured to synthesizers. It was a very stable keyboard however it didn't have any pitch bending controls that were often found on the other keyboards from this era, making its functionality very limited.

2 VCO - MOOG Sonic Six - although this unit only had to voltage controlled oscillator's it was actually polyphonic.  It could create two voices.  It was targeted as more of an educational synthesizer but it is still highly collectible today.  It was only produced in 1974.

3 VCO - MOOG Minimoog. This very classic units from Moog had three voltage controlled oscillators.  This gave this monophonic synthesizer the potential to have very fat sounds. It was produced from 1970-81.

3 VCO - ARP 2600. Like its rival the minimoog this classic synth also had three voltage controlled oscillators.

4 VCO - KORG Mono/Poly, This was a fairly sophisticated synthesizer from Korg.  It was made in 1981 and had for voltage controlled oscillators.

16 VCO - OBERHEIM Eight Voice, jumping to the next extreme we have this monster of a polyphonic keyboard. It needed this many oscillators to create its polyphonic sounds as circuit technology was not as advanced when this keyboard was released.  It was produced from 1977 to 1980.

Of course there are many key synthesizers I have left out of this article however I just wanted to give a basic idea about how many oscillators were used in analog synthesizers during the 1970s. One can see that there is a direct relation to the number of oscillators to the thickness and richness of sound.  Of course as the number of voltage controlled oscillators grow one can see how the keyboard has more potential of going out of tune.  Voltage controlled oscillator sound great but of course they are not as stable as digital technology.