FET-GRINDER Dynamics Processing Unit
In 2002, Jakob Erland of Gyraf Audio shared a few projects for DIY, which included documentation and PCB layout for a clone of the classic 1176 compressor. It quickly became a favoured project amongst DIY fanatics, who were happy to self etch boards for their builds.
In 2006 I was working at a professional board manufacturing house, and I started offering small runs of professional boards for DIY'ers. Soon after, a user (Mnats) did a revised edition of the layout, updating pin-out for a few obsolete transistors, and fixing a ground loop in the original file - after that, I left the project alone.
Mnats revised edition kick-started a well known company, which mostly deals in clones of various 1176 revisions, and since they do a great job, I never felt the need to dive into 1176 cloning
I did, however, decide to do something different with the circuit in 2013. My goal was to tackle the linking of units to stereo somewhat differently, just as an experiment, and in 2015, I had a first revision of a unit.
MS Stereo link
To link two units, I applied a Mid-Side matrix to the circuit.
It is well known that existing linking methods are prone to drifts in the centre of the stereo image, and applying the MS technique for linking provides the advantage of allocating any drift to a relative difference between mid and side content. This means there is no sideways shifting of elements across the centre of the mix.
Its also just a fun tool, because it will let you play with stereo width, and fun variations, like processing the sides on a stereo, drum track heavily, without affecting the snare in the middle, or vice versa; dig into experiments with 2 mic set-ups for guitar, or slightly widening or narrowing a full mix.
Which revision is it?
The main difference between the various revisions of the classic 1176 lies in the in- & output sections of the circuit, which has been completely reengineered in this unit. To me, the main sound of an 1176 lies in the compression characteristics, and if you are familiar with it, you will instantly recognise it in this unit.
However, if you are obsessed with the difference between a revision A and F signal path, you will probably find that it sounds like neither.
Output is driven by a pair of Lundahl LL5402.
- 2 channels of FET compression
- Stereo MS link on built in MS matrix
- ALL mode on both channel
- Mix knob on both channels (Pre MS matrix, remains L/R in MS Stereo mode)
- Side chain High pass filter (High passes the detection circuit, not the signal path)
- Lundahl LL5402 Output transformers