Monday, 31 August 2009

Doepfer A-134-2 VC Crossfader

Here's a quick look at - and a rather longer listen to - Doepfer's voltage controlled crossfader. This is my favorite sort of module: small, versatile and inspiring. The two VCAs accept either audio or CVs and can be configured via jumper to cross-fade either asymmetrically or symmetrically. A simple modification turns the A-134-2 into a 4-in 1-out two-dimensional x-fader.

Before I bought the A-134-2, I tried to patch my own crossfader using a Cwejman VCA-2P. While this worked to an extent, purpose-built modules tend to cut down the time spent cabling and yield quicker results. Within a couple of minutes with the Doepfer, I was up and running.


Doepfer A-134-2 VC Crossfader Demo by navs

1) Audio fade/ symmetrical. Two VCO sequences. LFO as modulator.
2) Audio fade/ asymmetrical. Ducking effect with envelope follower.
3) FM modulator fade/ asymmetrical.
4) FM modulator fade/ asymmetrical.
5) FM modulator fade/ asymmetrical.
6) CV fade/ symmetrical.


Provided you don't overload the VCA by applying too high a CF CV, the audio quality is good. I did notice a slight imbalance in one VCA when used asymmetrically (input one was not at unity at 0V, but rather needed about -0.5V), but I'm sure this can be calibrated. When used symmetrically and with 0V applied, inputs 1 & 2 are balanced at 50/50 rather than at full level. This might bother some users. I personally would prefer the option. Due to the nature of fading, I found the A-134-2 more useful for audio rather than CV sources, where I felt a sequential switch might be more appropriate.

Fading between audio sequences or FM sources are two obvious uses of the A-134-2. In conjunction with an envelope follower, it's also capable of sidechain/ ducking duties (the A-119's sluggish response adding to the severity of the effect!). I don't have a Wiard Boogie, but I could also imagine that, paired with a joystick, a modified A-134-2 would be great for dynamic vector-filtering.

Monday, 24 August 2009

Navs live @ SIN Bar Berlin. Thursday, 21:00.

I'll be playing live this Thursday at Stranded in Neverland, Kreuzberg.

Decidedly old school and modular-free, I hope to have some fun jamming with a P3 sequencer, Korg ES-1 & EX800 and a Novation Bassstation.

Fingers crossed the old tech doesn't crap out on me!

First on the bill is one of my oldest friends, Mat, playing a selection of his songs.

If you're in town, come along.

The address is Schönleinstr. 6 10967 Berlin, U-Bhf Schönleinstrasse on the U8.

Friday, 21 August 2009

More Hazarai! EHX SMMH Modification

Rechner7's modded EHX Stereo Memory Man with more Hazarai!

Following this thread at where ACA describes how he modded his Akai Headrush, I asked Rechner7 how he'd modified his SMMH and he kindly sent me these pictures, sound clips and details.


smmh-mod by rechner7.

trigger/gate A
trigger/gate B
trigger C


input C is always active and high-pass filtered to avoid a unintentional activation of the loop-mode. the high-pass is just a passive 1-pole high-pass with a cuttoff frequency at about 1-3Hz. a selective remoted looping can be done with A or B.
using the REC switch is equivalent to an enduring press of the tap button. this function is handy for long and pitchable delays in the loop-mode.

the function SELECT activates the additional trigger input A or B.
switching HP A/B to ON enables a high-pass filter. if the high-pass is active, A or B cannot release the loop function. bypassing the high-pass (HP A/B OFF) will activate the loop-mode if the gate length exceeds the threshold.

paragraph: Converting Gate to Switched Trigger (S-Trigger)
paragraph: 2. Basic circuits

You can download a zipped folder with more pictures, the text and audio examples here (6MB).

Thanks to Rechner7 for sharing this! If you want to attempt this simple but Hazarai-enhancing mod, beware: apparently the hardest part is freeing the PCB from the enclosure without breaking it. Neither I nor Rechner7 take any responsibility for your SMMH. Just so that's clear, OK? Happy Modding!