I always have dream to have a separate and dedicated passive volume control. There was a time when I was offered to acquire few sets of Grayhill ‘M’ series rotary switch. Although it has 7 Decks which definitely overkill for most application, but seeing the quality of the switch, I decided to grab some.

Although ‘M’ Series from Grayhill is not Military qualified switch, but it meets the requirements of MIL-S-3786 which covers moisture resistance, medium and high shock, vibration, thermal shock (from minus 65 up to over 125 degree Celsius), salt spray, explosion, terminal strength (2 lbs pull minimum), and stop strength (15 pound-inches minimum). Quite convincing, huh? The simple but major different is, the ‘HS’ Military grade will have a sealed shaft and panel. That will make a lot of different in ‘heavy’ environment, but probably not much at home.

Each switch is bundled inside a plastic tube. Nice and convenient way to carry the switch and also easy to be put on the storage bin.

The build quality is like a tank. The rotor contact is silver alloy, plated with gold. Meanwhile all the terminal are brass plated with silver then and with gold also.

Massive 7 Decks will make this switch could support up to 7 channels passive preamp. Well, I will not use this for my home theater project for sure.

The standard Grayhill engraved logo on the back of the switch. You can also see the terminal numbering there.

I’m thinking a stereo ladder stepped attenuator. So at least it will occupy 4 Decks. The rest 3 Decks could be use for other purpose which just flying over my head – but well, I will keep them as secret at this moment πŸ™‚