• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Grommes / Western Electric G5M Tube Mixer Mods

HI, I'm new here and I just aquired a cool device. Its a Grommes / Precision Electronics / Western Electric G5M Tube Mixer. Its a lot like the Altec 1567 Tube mixer but has a lot of important improvements. It has 5 transformer balanced mic inputs, , a line input, tube EQ, and a master gain stage. Basically I want to refresh and modify it. I would like to install DI inputs bypassing the transformer and direct outs for each of the 5 mic channels. It uses both sides of a 12AX7 per channel so I assume there should be sufficient gain for the direct outs. I want to use this as the front end for my DAW. I want the individual outputs for use recording drums and I want to use it as a mixer in its natural state for overdubs, utilising multiple mics into one output. What I'm looking for is any help with this. I could use a schematic if there is one out there. Maybe one of you guys has one of these? How would I go about installing the mods on this? Thanks in advance guys.

Jesse Mesa-Savage


2010-01-26 2:18 pm
Hi guys, I have a schematic for the above mixer along with a few of them.

reply if you are so inclined.

Ken fritz, Richmond, VA
Hey Ken,

Hope you don't mind me contacting you this way. Any chance you could email me a copy of that Grommes G5M schematic? My address is : [email protected]

Also, do you happen to know what type of input transformers it takes / WHERE in the world to get them?

Thanks for any advice you could offer, I appreciate your time.