Showing posts with label LFM. Show all posts
Showing posts with label LFM. Show all posts

Thursday, March 31, 2016

New Doepfer High End VCOs A-111-2, A-111-3 and A-111-4 Thru-Zero Announced

Doepfer has announced two new High End VCO's at the Superbooth event in Berlin (March 31st - April 2nd, 2016)

The A-111-2 is based on the CEM3340 Rev G chip
There was a close cooperation between Doepfer and OnChip since 2015 regarding to the new re-issue of the CEM3340 and they received the first samples in January during NAMM for development.
The first production batch of the CEM3340 Rev G arrived 2 weeks ago and the production of the A-111-2 has started during the next few days (they are still waiting for the latest front panel and pcb samples). 
Doepfer expects the first modules to be finished around the end of July/August. 
The A-111-3 is also based on the CEM3340 Rev G ,and Doepfer is working on a Thru-Zero VCO based on the CEM3340 Rev G too (module A-111-4).

The Doepfer A-111-2High End Voltage Controlled Oscillator II is the successor of the obsolete High End VCO I A-111-1 and here are the most important features of the planned module:

Triangle core, min. 15 octaves pitch range (typ. 0.5Hz - 20kHz)
perfect 1V/octave tracking over min. 12 octaves (typ. 5Hz - 20kHz)
Exponential frequency controls and inputs:
Tune (~ 1 octave range)
Fine (~ 1 semitone range)
A-111-2 Prototype June 2016
Octave (range switch with 6 positions)
1V/octave CV input
XFM input with attenuator
access to bus CV (via jumper, optional)
Linear frequency controls:
LF (manual linear frequency control: fully CW = standard setting for usual VCO applications, fully CCW: close to 0Hz frequency)
LFM input with attenuator, DC coupled

Pulsewidth controls for rectangle output:
PW (manual pulsewidth control from 0%/output = fixed at "low" state up to 100% / output fixed at "high" state)
PWM input with attenuator
Hard Sync input
Soft Sync input
Waveform outputs:
Sawtooth
Rectangle (with PWM)
Triangle
Sine
Nearly "perfect" waveforms (no glitches)
High end triangle to sine converter with excellent sine waveshape (thanks to Tim Stinchcombe who recommended this circuit)

14 HP Width
Price: about Euro 250.00
Available: spring/early summer 2016

The other new High End VCO  is the A-111-3 High End Precision VCO with a panelwidth of just 4HP.
Essentially it's the same basic circuit as the A-111-2 but with reduced features:

A-111-3 High
End Precision
VCO
Triangle core, min. 15 octaves pitch range (typ. 0.5Hz - 20kHz with appropriate external CV)
Perfect 1V/octave tracking over min. 12 octaves (typ. 5Hz - 20kHz)
Exponential frequency controls and inputs:
Tune (~ 1 or ~ 10 octaves range, selectable via internal jumper, maybe different ranges in the final version)
1V/octave CV input
XM input with attenuator
access to bus CV (via jumper, optional)
Linear frequency controls:
LM input with attenuator, DC coupled


Pulsewidth controls for rectangle output:
PW (manual pulsewidth control from 0%/output = fixed at "low" state up to 100% / output fixed at "high" state)
PW input (without attenuator)
Sync input (selectable hard or soft sync via internal jumper)

Waveform outputs:
Sawtooth
Rectangle (with PWM)
Triangle
Nearly "perfect" waveforms (no glitches)
Only 4HP wide panel

Price: about Euro 150.00
Available: spring/early summer 2016

All features, specifications, prices, date of delivery are still without obligation
Source: http://www.doepfer.de/home_e.htm

Thursday, October 23, 2014

Doepfer A-110-4 Thru Zero Quadrature VCO Announced

Doepfer's latest module-announcement is the A-110-4 Thru Zero Quadrature VCO.
I do have to dig a bit deeper into this module before i completely understand it, but here is the text from the Doepfer website, where they will soon have audio examples and oscilloscope views available...

Doepfer A-110-4
Thru Zero Quadrature VCO
" The term "quadrature" means in this connection that the oscillator outputs sine and cosine waveforms simultaneously. 
The term "Thru-Zero" means that even "negative" frequencies are generated. 
This can be a bit of a misleading term as negative frequencies do not really exist. 
"Negative" means in this connection simply that the sine/cosine waves will stop when the linear control voltage reaches 0V and continue with the opposite direction as the linear control voltage becomes negative and vice versa.

The module has two control sections: linear and a exponential. 
The exponential section consists of the XTune control, the 1V/Oct input and the XFM input with the corresponding attenuator XFM. 
The exponential control voltage is the sum of these three voltages. 
The linear section consists of the LTune control and the LFM input with the corresponding attenuator LFM. 
The linear control voltage is the sum of these two voltages. 
A dual color LED is used to display the polarity of the linear control voltage (green = positive, red = negative). 
The resultion pitch of the sine/cosine outputs is determined by the resulting control voltages of both sections. The linear section is used to control the pitch in a linear manner. 

When the LTune control (LTune means Linear Tune) is fully CW the module works like a normal Quadrature VCO (e.g. like the A-143-9) and the LED lights green. 
The pitch is then controlled by the exponential section with the manual Tune control and the exponential frequency control inputs 1V/Oct and XFM. 1V/Oct is used to control the pitch by a 1V/Oct CV source (e.g. sequencer or Midi/USB-to-CV interface). 
XFM is used to apply an exponential frequency modulation with adjustable depth (e.g. from an LFO or another VCO). 
As the LTune control is turned counterclockwise starting from the fully CW position the frequency is lowered in a linear manner until the sine/cosine waves stop near the center position of LTune (provided that no LFM signal is present). 
As the LTune control is moved from the center towards the CCW position the waves start again but into reverse direction and the LED turns red. 
When the fully CCW position of LTune is reached the module works again like a normal Quadrature VCO. 

But much more exciting is the usage of the LFM input to modify the linear control voltage by an external control voltage (typically another VCO). 
Linear modulation by another oscillator using the thru zero feature generates audio spectra than cannot be obtained from an oscillator without the thru zero function. 
The reason is that a "normal" VCO will simply stop as the linear control voltage becomes zero or negative. 
But a thru zero VCO will start again with "negative" frequencies as the the linear control voltage becomes negative.

The main advantage of the A-110-4 compared to other Thru Zero VCOs is that the design used a sine/cosine core. The sine/cosine waves are not derived from other waveforms (e.g. sawtooth or triangle) by means of waveshaping. 
Rather the sine and cosine waves are the core of the VCO which results in very pure waves with a minimum of distortion and overtones." 

The A-110-4 is planned for early 2015, price ~ Euro 120.00