Poor Man's Tube Mixer

If you just want a few rugged, quiet tube mic pres in a box then the Lunch Box is for you. But it is not a mixer. As soon as you need faders and mixing capabilities you need the Poor Man's Tube Mixer (PMTM). In construction, the PMTM is basically a 3U lunch box minus the rack mounting ears, with an added fader front section. But that is where the similarities end. The PMTM is intended as much as a DIY project as a finished product. As such, keeping materials costs to a minimum is a primary objective. To this end, a number of design simplifications are available:

• Use a single EZTubeMixer twin line amp PCB to provide two mic pres

• Replace stepped gain switches with potentiometers

• Replace expensive input and output transformers with more economical alternatives

• Replace expensive extruded aluminium module enclosures with the much more economic Mark 3 mixer mechanical design

• Use a single bus amp to mix both balanced and unbalanced signals

All the above techniques help to significantly reduce the cost of the PMTM.

The master bus has either a pair of slider faders which can be mechanically linked or a single stereo fader. A monitor output with level control is also provided along with a trim control for the stems. The direct and master outputs are impedance balanced.

Optional extras include output transformers, replacing line inputs with mic inputs and metering.