A-110-2 Basic VCO

The A-110-2 Basic VCO is built on the same technical basis as the “standard” VCO A-110-1 that has been available for a long time. Like the A-110-1, it uses circuitry to keep the temperature-sensitive parts of the oscillator at around 50°C. With 8 TE, it is a bit narrower than the 10 TE wide A-110-1, significantly cheaper and also more economical in some details.

On the other hand, no savings were made on two topics that until now could only be found in the twice as expensive A-111-1 or A-111-2: softsync and linear frequency modulation. In principle, the A-110-1 VCO offers soft sync and linear frequency modulation, but – and that was too great a limitation for many – you had to do some soldering work and then attach two additional sockets somewhere. The result then often looked slightly “tinkered”.

The A-110-2 now brings these previously untapped softsync and linear frequency modulation options to the front panel.

What was left out?

The multi-stage octave selector switch from the A-110-1 has given way to a simple toggle switch -1/0/+1 octave. If, for example, you want to “spread” the distances further when using several A-110-2 VCOs, you have to make do with an additional control voltage (e.g. using the A-176 Manual CV Source or with the additional octave switches on the A-185-2 Precision Adder).

Only one input socket is available for pulse width modulation; the A-110-1 has two input sockets (one without an attenuator).

In contrast to the A-110-1, the A-110-2 does not have a sine output. If necessary, you have to use the triangular signal and add a low-pass filter or use the new A-184-2 sine converter. But then the package becomes wider and more expensive than an A-110-1. Ideally, both (A-110-1 and A-110-2) are combined and the two VCOs are used according to their respective strengths.

User interface

Inputs:

System bus: The VCO can get its pitch control voltage from the system bus, for example via an A-185-1 Bus Access or A-185-2 Precision Adder / Bus Access Module attached there. Unfortunately, the very practical switching socket from the A-110-1, with which the control voltage from the bus could be interrupted and replaced by an externally supplied voltage, was omitted. Voltages at the “1V/Oct.” socket are therefore added to the control voltages on the bus.

As with all VCOs with CV control via the bus, you should deactivate this option if you are not using it: Otherwise, the open lines could work as “antennas” and pick up interference signals.

Outputs:

Controls:

Configuration via the board

The module has (like almost all newer Doepfer creations) a whole series of jumpers to adjust the properties of the module to the individual needs of the owner.

• JP2: CV connection to the A-100 bus
• JP3: range of the Tune control (set = approx. 4 octaves, not set = approx. 1/2 octave)
• JP4: Linear FM input DC/AC coupling (set = DC coupled, unset = AC coupled)

How does that thing vibrate?

Since the A-110-2 is based on the A-110-1, one would expect it to sound no different from the original VCO. And indeed, on the oscilloscope, you see very little difference between the two oscillators. Only the triangle, which otherwise shows a characteristic notch in oscillators with Sawtoth core, is a little different here with a small “tooth” at the negative half-wave. Maybe that’s just a question of fine-tuning, I don’t have another A-110-2 to compare (however, my 7 A-110-1 VCOs all show the “notch” and none the “tooth”).

Sawtooth:

Note: The sawtooth edge is printed on the control panel as a rising edge, but the VCO (like the A-110-1) generates a falling edge.

Triangle:

Square:

Pulse:

Soft- and Hardsync

Unlike the A-110-1, the A-110-2 has both hardsync and softsync inputs (the A-110-1 has only one hardsync input on the panel).

The oscilloscope images show the synchronized triangle from the A-110-2 (slave), which is synchronized by an A-111-1 VCO as master.

Sound examples

Technical specifications

Width	8 HP
Depth	50 mm
Power requirements	150mA (heating up) / 60mA (+12V) / -30mA (-12V)