Doepfer A-170 Dual Slew Limiter Video Tutorials by Raul Pena

Yay... a new tutorial series by Raul Pena has started...
The topic this time is the Doepfer A-170 Dual Slew Limiter , enjoy!

Video 1: Doepfer A170 Dual Slew Limiter Basics
" First video in a series on the Doepfer A170 Dual Slew Limiter. Discussing Basic Concepts and features. Audio demonstrations begin in next segment. Sound and Video by Raul Pena. "

Video 2: Doepfer A170 Dual Slew Limiter-Processing and Oscilloscope views Pt 1

" A continuation of the Doepfer A170 Dual Slew Limiter series. In this segment Oscilloscope views of subaudio waveforms are examined when processed through a slew limiter. Audio rate examples begin in the next segment. Sound and Video by Raul Pena."

Video 3: Doepfer A170 Dual Slew Limiter-Processing and Oscilloscope views Pt 2

" A continuation of the Doepfer A170 Dual Slew Limiter series. In this segment Oscilloscope views of subaudio waveforms processed with a slew limiter modulating a VCO are compared to those unprocessed. Sound and Video by Raul Pena."

Video 4: Doepfer A170 Dual Slew Limiter Processing and Oscilloscope Views Pt 3

" A continuation of the Doepfer A170 Dual Slew Limiter series. In this segment we continue to compare oscilloscope views of processed versus unprocessed signals effecting a VCO. Sound and Video by Raul Pena."

Video 5: Doepfer A170 Dual Slew Limiter-Slew Portamento and Filtering Examples

" Continuing the Doepfer A170 Dual Slew Limiter Series. This segment explores a more standard use of the Doepfer A170 Slew Limiter for Portamento. Also included is an example of using the A170 as a Filter. Sound and Video by Raul Pena. " 

Video 6: Doepfer A170 Dual Slew Limiter-Glissando AM example

" A continuation of the Doepfer A170 Slew Limiter Series. In this segment we examine a patch from the manual involving AM.Special thanks to chrisso from the Muff's Module forum.Sound and Video by Raul Pena."

Video 7: Doepfer A170 Dual Slew Limiter -Slew as AR example

" A continuation of the Doepfer A170 Slew Limiter Series. In this segment we examine a patch from the manual involving the A170 as an AR envelope.Sound and Video by Raul Pena."

New videos in this series will be added to this post weekly on Thursdays.

Check out Raul's latest survey at http://www.surveymonkey.com/s/K3Z9PVF

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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 IV - XL Edition

This next quick patch is a small extension of my earlier Best Friends Forever posts.

Although i don't always use this patch, i do like the simplicity of it, getting me more out of my Slew Limiter.

As blogged earlier, I use the A-182-1 Switched Multiple mainly to switch between my keyboard ( via MIDI ) and my A-198 Ribbon Controller.
For this i split up this Multiple in two halves, the upper half controls the Gate, the lower half controls the pitch ( CV )

The black cables that go into the Switched multiple are for ( quantized ) Ribbon Control if channel 2 is selected, the yellow ones are for keyboard control, via channel 1

The only advantage in this patch is that i am now using both halfs of the A-170 Slew Limiter, the lower ( and more extended half ) for the Ribbon Controller, the upper half for the incoming output of the MIDI-CV Interface.

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.