Description: Mattson Mini-Modular Quad Buffer
I took Mattson’s DIY Quad Buffer board and added four attenuator pots to turn it into a quad buffered attenuator. I call it a distributor, because each channel has two independently buffered outputs. The board supports cascading the channels by providing a third buffered output for the first three channels that can be connected to the third lug on a switching jack. I designated the four channels A-D, and decided to cascade A into B and C into D. The pot on the first channel impacts both. In other words, the A pot affects the A outputs and the B outputs. Likewise the C pot affects the C and D outputs. The B and D pots only affect their respective outputs. There is a 1% voltage drop on the cascaded channels, due to the use of 100K pots and the 1K output impedance of the buffer. (Note that when wired as intended the Mattson module doesn’t have any voltage drops along the cascade, because the input impedance of the buffers without pots is very high.)
What’s it for? Quite a few modules in my system have control voltage or signal inputs without attenuation. My other buffered attenuators (Oakley Multi-Mix, and Blacet Mixer) are bipolar and don’t have a good zero setting. The Blacet mixers do have a center detent pot and a trimmer to null the center, but a small signal can still penetrate. My own DIY Mixer-Comparator has only one channel. So I really wanted more zero-off buffers.
I used a Front Panel Express Panel design of my own, again using the MOTM jack grid like I did for the CGS Super Psycho LFO and Slope Detectors. This is a compact design that essentially allows fitting more pots onto a panel.
The tricky bit is mounting a Mattson PC board onto a Bridechamber 3-Jack bracket. The bracket isn’t quite wide enough. I had to make an adapter bracket. See my post on the Mattson VC Mixer for all the details.
Wiring up a DIY Mattson module is relatively easy. Mattson DIY boards are assembled and tested. I purchased the corresponding wiring kit with all necessary wiring pre-fitted to connectors. All I had to do was to trim the wires to fit.