MATRIXSYNTH: New module! Dual Retro Vco

Sunday, April 05, 2026

New module! Dual Retro Vco


video upload by Radical Frequencies Modular

"Listen the new Radical Frequencies Dual Retro VCO playing an arpeggio , showing all waveforms and making Pulse with modulation and Hard Sync between the vcos . It goes through the RF Mixer and then to Diode Dream Vcf as it suits this oscillator perfectly! #eurorack #modularsynth #radicalfrequenciesmodular #dualretrovco #drvco #diodedreamvcf #analogsynth"



"Handmade Dual VCO of discrete core capable of internal FM cross modulations - Hard sync and Ring Modulator

• Analog discrete saw core oscillators with Saw, Pulse, Triangle and Ring Modulation wave outputs.The sound is warm and fat, emphasizing odd harmonics for this big retro sound. My purpose here is to approach the sound of classic synths from 70s, that we all loved.
• The SAW wave produces rich bass frequencies, sweet mids and smooth highs but overall, it is still well balanced across the full frequency range. The Triangle wave is almost perfect in shape with no buzzy hum sound. The pulse wave can produce that chorus-like phasing effect, when using an LFO to modulate the PWM input and does so in a very unique way, as it changes the phase of the signal as well.
• Two identical VCOs : VCO ALPHA and VCO BETA, with the ability of hard sync as each VCO syncs internally with the other. Using the attenuator knob for SYNC, you can go from zero to soft sync(11-12 o’clock) to hard sync when the knob is fully CW. For syncing you just need to turn CW, the sync knob of the VCO you want to be the slave. Don’t open both the sync knobs at the same time unless you want to make some weird sounds.
• There are external sync inputs for each VCO as well. External oscillators can be used as masters, just feed the output of the oscillator of your preference, into the sync input or either ALPHA or BETA. Just remember to feed a saw or a square wave, into the SYNC input. This is very important in order to sync the oscillator. A ramp wave it will not sync at all! (The RF DPVCO for example is a ramp out VCO and if you want to use it as master you must invert the signal first.)
• Both ALPHA and BETA track 5 octaves accurately, tempco resistors are attached to the tuning ICs CA3046 on both VCOs.
Separate voltage regulators for each oscillator can achieve the best sounding results without drift or bleed pitch, between VCOs.
• Both VCOs go from a relative fast LFO range with the coarse tuning knob fully CCW, up to high frequency oscillation.
• Octave Switches of 3 positions: 1 octave down - , zero , 1 octave up +, are available and make patching, fast and intuitive.
• There are internal normalisations for exponential as well as linear FM and both have independent EXP FM and LIN FM, attenuators.
• You can select the wave for the internal FM buss via the front panel switches .Options are Triangle and SAW. The internal FM wave, is independent per VCO as well.
• There are also internal normalisations for PWM, where each VCO modulates the pulse width, of the other and both use the triangle waveform.
• There is a PW offset, per VCO - negative phase pulse width at CCW to + positive phase at CW and 50-50 duty cycle square wave, in the middle of the knob.
• Ring Modulation section is a separate feature where X and Y inputs are internally connected with the VCOs as well. It has 2 inputs, X and Ψ and one out, RM. The inputs are internally connected to the internal FM buss switch of triangle - saw selector.
VCO ALPHA is internally connected into Ψ input and VCO BETA, into X input. You can feed the RM inputs any wave you desire from other VCOs as well .
• An external patch cable breaks the normalisation of all internal connections, via input jacks. (EXP FM, LIN FM, PWM, SYNC, X Ψ)

• Important note about tuning : The vcos need at least 30 minutes warm up before using it for good tracking. Also when you have to tune the vcos it’s better the octave switches to be in the middle position and all the fm and sync knobs must be closed (CCW)

• Large range of sounds with countless sweet spots - ultra stable tuning for FM sounds by using the FM and SYNC knobs simultaneously - fat basses, classic leads and drones. Feed the DRVCO into a good filter and you will enjoy it as it was meant to be! The VCF that I suggest is the RF Diode Dream VCF as it is a ladder filter and suits it perfectly! Of course any other filter of your taste can be used with great results."

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