Skip to main content

A-101-2 Vactrol Low Pass Gate

I must say i am very happy with my latest module, the A-101-2 Vactrol Low Pass Gate.
This module is a combination of a 12dB Low-Pass Filter and a Voltage Controlled Amplifier (VCA), with 2 vactrols as controlling elements with very unique characteristics and is very popular amongst the members of the Doepfer A-100 Yahoo Users Group.

The module is based on the Buchla Model 292 Quad Voltage-Controlled Lopass Gate module. '
The term "Low Pass Gate" was first used by Don Buchla for a module that can be switched between Low-Pass and VCA.
Buchla's current (2004) update is the Model 292e Quad Dynamics Manager ,that is functionally identical to the older model, but includes some extra functions like velocity inputs, allowing controllers to control note volumes with performance gestures and preset storage.

Doepfer's LPG module can handle 2 different incoming control voltages that can be used to control the Low-Pass filter, or to open or close the VCA.
Additionally a combined mode LP + VCA is available which makes the sound more dull as the loudness decreases. This is characteristic of all acoustic instruments (the harder you strike, pluck, or bow, the richer the overtone structure), but had been lacking in electronic instrumentation before..

In contrast to the Buchla design the A-101-2 offers attenuators for both CV and audio input, a manual resonance control and two gate inputs to control the function of the module in addition to the manual toggle switch.
The filter is hard to describe, but vactrols are known for their smooth sound behavior. Compared to a 'normal' 12 dB filter like the Low-Pass filter from the A-121, they sound quite the same, but the Vactrol inside the A-101-2 does give it a smoother edge that can perhaps best be compared with a very subtle 'slew' effect. The VCA has that same 'slewy' characteristic, but doesn't sound dramatically different than a regular VCA to my ears.

The combination of the LPG and VCA, is (obviously) my favorite setting and with the resonance up this module really starts to shine. ( Resonance is adjustable all the way up to self-oscillation )
A nice extra are the 2 Gate inputs, that can make you ( rhythmically ) switch between the two functions of the module with an external sequencer or other triggers. I'm not sure if 2 Gate inputs was necessary though.., personally i had rather seen an extra CV input for the Resonance (QCV) for example.
(Perhaps this can be modified?)

Overall this is a very nice-sounding module, that i will use a lot in the near future. I'm not sure if i put it in my top-5 list of favorite modules, but it will at least be in my top 10 for the next few months.

- Check my earlier Vactrol Basics post for more general details about vactrols,
or take a  look at Doepfer's Vactrol Basics page.
More about the A-101-2 LPG  including an audio example at Andreas Krebs blog

Popular posts from this blog

DIY Modular Case Ideas

There are many ways to house your (eurorack) modular synth, i wrote about the pre-manufactured options from Doepfer earlier, find that post HERE, but of course you can also try to build you own case.
There are many ways to make your own A-100/Eurorack case if you start out with just the basic rails and busboard, and you can make it as cheap or expensive as you can.

Check out a few ideas;
Wooden cabinets and side-panels are still very popular amongst (modular) synth enthusiasts.
These simple case standards for the pre-manufactured LC9 cases are very simple, and can be sooo useful
http://synthesizerart.blogspot.com/2011/10/dual-doepfer-lc9-case-stand-v1-design.html Also check out the other great modular pictures on his site.
Matthew Goike (@Goiks) also has some nice wooden cabinets on display and for sale on his website: http://www.goike.com/node/5

...or do what Stretta did (or rather what his brother did), make a high-end wood/brushed aluminium cabinet with integrated LED-lights and some …

Doepfer A-150-8 Octal Manual/Voltage Controlled Programmable Switches Announced

Doepfer has just released some info on their new modules for NAMM 2017 (19-21 jan.) Besides some vintage editions of existing modules, the A-135ABC VC Performance mixer modules, the A-110-6Trapezoid Thru Zero Quadrature VCO and a new A-100LC1 case (economically priced small housing with 48 HP width) there was also one other interesting new module announcement:
Module A-150-8 contains eight manually/voltage controlled switches.  Each of the eight switches has a manual control button (Man.), a control voltage input (CV), a common Out / Input (O/I), and two In / Outputs (I/O1, I/O2).  The switches are bi-directional, i.e. they can work in both directions, so can connect one input to either of two outputs, or either of two inputs to one output. 
Two LEDs show which in / output is active (ie. which is connected to the common out / input).  In addition the LEDs are used for the programming of the module: For each unit the operating mode can be selected:  Toggle or Level controlled. In Toggl…

Happy New Year From PatchPierre

Hi there, it's me again... Happy New Year!

You might have noticed that I havent posted a lot in the last 2 years...
It's been a rough time for me since the sudden loss of two parents within a relatively short time-span and I really needed some time to get myself together... to set things straight, finding myself and selecting priorities... even my regular work suffered from this breakdown.

It took a while to understand it all, and to get a better grip on it, and it's sometimes still not very clear.
I think I have found a way to cope with most of it now... although the slight autism that I have (ADD-like) doesn't make it easy for, especially in crowds with lots of people I don't know...
On my journey I also (re-)discovered the beautiful woman that has always lived inside of me and that i need to accept and cherish... more on that maybe later... I'm not considering changing the name of the blog to PatchPetra.Net 😇 (...yet), but you might spot me somewhere at mod…