Monday, 28 February 2011

A-162 Trigger Delay Modification

An update to this post on how to modify a Doepfer A-162 Dual Trigger Delay for perfect filter pings.

Replacing the A-162's stock 10uF capacitor with a 0.1uF helped, but meant that most of the useful range for pinging filters (0.5 - 2ms) lay within the first 10% of the pot's throw i.e. settings between zero & 1.

An attempt to reduce the resistance of the pot failed to help, so I replaced the 0.1uF with a 0.01uF/ 10nF cap. This did the trick: a setting of 5 now yields a ca. 2ms long pulse.

Here's a clip of three filters being pinged with various pulse widths:

Cwejman MMF-1, RES-4 & Metasonix R54.

As you can hear, the tone and volume are affected by the length of the pulse. This is even more apparent when the filter additionally receives pitch CV. The R54 shows the most dramatic response to changes in pulse length, especially when an attenuated multiple of the trigger is used to apply some pitch bend or 'thwap'. The A-162 is also perfect for pinging low pass gates.

Above is a picture of the solder-side of the board. I've marked two possible connections, depending on the type of capacitor you want to use. The two holes marked in pink are connected by a trace to allow for 'extra leg room'. The cap should be connected between the green and one of the pink holes. Pay attention to the polarity if you're using an electrolytic cap.

Needless to say, this mod will void your warranty and is your own risk. It's not difficult, but if you don't want to do this yourself, Doepfer offer a modification service on most of their modules at very reasonable rates.

Thanks to the Wigglers who helped in this thread.


Anonymous said...

I love these sounds.
Thank you Navs.


Navs said...

As you can tell, I love these sounds too :)

Supermario said...

hey hey

I was just wondering. I did the mod but it only works with the upper one. is this usual?

Navs said...

Hi Supermario, if you only modded the upper one, then yes. The module has two identical trigger delay circuits, so you need to mod both. But this is good because you can use different values for each, according to taste/need. HTH! Navs