Saturday, April 26, 2014

Mike Matthews Dirt Road Special - Speaker Upgrade

Several months ago, I posted about a repair on the Mike Matthews Dirt Road Special.  A few days ago, I had the good fortune to run across an exact replacement, electronically and acoustically, for the Celestion 12 Inch original speaker for this amplifier.  For example, the new Fender 12 Inch replacement speaker has almost exactly the same free-air resonance frequency.  The two sound nearly identical under a "tap" test.  By removing the GE (antique) temporary replacement and installing the new Fender, it is now possible to re-install the original power supply transformer to get the original 70 Volt DC power supply level.  The small stone phase shift effect is almost infinitely adjustable with the full 70 Volt supply.  Here is the Mike Matthews Dirt Road Special with new Fender replacement speaker:


Mike Matthews Dirt Road Special with Fender Speaker
Mike Matthews Dirt Road Special with Fender Speaker