project update as of April 2026

It's been a while since I posted in this blog.  Most of my work in recent years has been on the McGrath Mini amp, which has its own blog.

The work I started here has morphed considerably since I last posted.  The first product I plan to build, which will embody the circuit ideas developed here, will be called the McGrath Stereo Amp.  This will be, of course, a stereo tube guitar amp, in combo format, with two (probably) 8-inch or 10-inch speakers (maybe both, as options).  Power will probably consist of 4 x EL84, one push-pull pair per channel, cathode-biased.

The preamp will contain sections developed in the McGrath Mini project, but with generally more features and capabilities.  In particular, there will be dual three-band sweepable-mid EQs, one pre-distortion and one post.  This symmetrical pre and post EQ topology is one of my fundamental design concepts.

There may be a stereo spring reverb, i.e., separate tank for L and R channels (another of my design concepts).  However, this may be an optional component of the power amp section, with the power amp also available with no reverb.

The conversion from mono to stereo will take place via the fx loop.  There will be one mono send (perhaps with two isolated jacks for convenience), and then a stereo pair of return jacks.  Thus, when stereo effects are used such as reverb or delay, the signal will be transformed into stereo.  If no effects are enabled, and if the stereo spring reverb is bypassed or not present, then the amp will simply behave as a twin-speaker mono amp.

The electronics of the amp will be housed in at least two separate 19" rack units, which the cabinet will be designed to contain.  The preamp will be a 2U rack unit, and the power amp and optional spring reverb will be a 1U unit.  There may be one additional 1U space provided, for effects units of the user's choice.

This is the broad overview of where my conception of this project has evolved to, in the intervening years since I last posted here.  I will probably branch this work off into a new blog, specifically titled to reference the McGrath Stereo amp, when I actually begin work on that project in earnest.  For now, I am still mainly engaged with completing the McGrath Mini project.  In fact, I'm about to ship my first unit to a paying customer!