A-171-2 Voltage Controlled Slew Limiter II Announced

Great news again this morning from the Doepfer Yahoo Usergroup.

The A-171-2 Voltage Controlled Slew Limiter II will be Doepfer's next new module with a lot of additional features beyond a simple slew limiter.

A-171-2 Prototype

It's mostly a licensed copy of Ken Stones VCS which is in turn based on the Serge VCS. (from the POLL earlier, remember?)
Dieter announced that negotiations with Serge and Ken Stone are nearly finished, and that they decided to publish the preliminary info page about the planned module on their website: www.doepfer.de/a1712.htm

The main features:
- Manual control of the Slew-Up time
- CV control of the Slew-Up time with polarizer
- Switch for linear/exponential shape of the rising section of the response curve
- Manual control of the Slew-Down time
- CV control of the Slew-Down time with polarizer
- Switch for linear/exponential shape of the falling section of the response curve
- CV Up and CV Down sockets are normalled
- Signal input (the "to-be-slewed" signal)
- Trigger input
- V/Oct input
- End output
- Cyle on/off (when "on" the End output is internally connected to the Trigger Input)
- Output
- LED display

Doepfer also mentioned that they will add some features so that 3-position switches can be used (e.g. log/lin/exp instead of log/lin only and two different cycle modes), but these decisions depend upon the results with the first prototype which he expects in January 2013.

A-170 Dual Slew Limiter

I mentioned my A-170 Dual Slew Limiter earlier in a few BFF posts, but so far i never took the time to write a separate blogpost about it. Until now that is...

The A-170 Dual Slew Limiter consists of  two separate slew limiters, also known as portamento controllers or integrators.
In electronics, the slew rate represents the maximum rate of change of a signal at any point in a circuit. Just like a Glide circuitry, it flattens or smoothes the incoming signal.

The top section of the module is the 'simplest' of the two Slew Limiters, with one joint control, which sets both rise and fall times (from approx. 0 ...10 sec).

For precision voltage control this one is recommended, but version One (before May 2009 / check your version number on the module's PCB) had a small voltage drop that was caused by the protection resistor at the A-170 output.

( check Doepfer's solutions for that HERE ) 

A-170 modules after May 2009 don't have this voltage loss.

The second Slew Limiter has separate controls for rise and fall times, and you can set the overall range (high/low/medium) for these parameters with a three-position switch. 

Because the diodes in the lower Slew Limiter are voltage-dependant, there is a voltage off-set of around 0.5 V.  This naturally makes it unsuitable for precise 1Volt- per-octave work, but for simple voltage control this is no problem at all.

Not only is the lower Slew Generator suitable for pitch-CV's, you can alternatively use this one as a simple AR (attack/release) envelope generator (works with any gate/trigger or LFO).
Very useful if you don't have enough envelope generators and want some punchy or percussive basslines.

Also worth reading: Wikipedia Current Limiting

Best Friends Forever III

My next unseparable combo is a threesome this time.

This is another essential combination for me, because i use my A-198 Trautonium/Ribbon Controller a lot to control my A-100 system.
The yellow patchcables between these modules always stay connected whenever i start a new patch.

The Voltage Control output ( pitch control ) of the Ribbon Controller goes straight into the A-156 Dual Quantizer.
This module divides the signal into various little steps that provides many different possibilities to scale the notes that are played, allowing the player to play more accurate notes and scales.

Note that I use the lower and more extended half of the Dual Quantizer.
The upper half has less functions and can only divide the signal into steps of 1 /12th Volt = 1 Volt per Octave


Last in the line is the A-170 Dual Slew limiter. With this one i can add a subtile portamento to the signal.

Again, only the lower half of the module is used in this patch, because this half has more possibilities.
The slewrates are adjustable from low to mid or high, and it has separate controls for rise and fall times.

This patch gives me all the control that i need, and i cannot do without any one of these in my live-setup.