The Mighty Columbia River has shaped the culture and the landscape of the Northwest for aeons. Mr. Miller thought it only fitting in keeping with the local influence of his amps to name this one The Columbia. Mainly because it’s big and bold! This amp has been through a number of iterations since the first proto-type shown below. It has been stripped down again and will now be offered in a head and separate speaker cabinet standard, with the option of a combo cabinet with 2×12″ speakers.
The all new Columbia head features two channels, one Normal (low gain) in the vein of the original Tweed Bassman, while the Hi Treble channel II goes into “Plexi” territory. Miller has kept the inputs to a minimum, Input I goes into the low gain channel, and Input II is jumpered to both Hi Treble and Normal channels, with both of their volume controls active. The output transformer is now a custom Heyboer transformer featuring cool running M6 laminations and rated for 60 watts, giving this amp some real authority and foundation. This amp will do loud and clean and crunchy depending on settings. Also new is a nice sounding Master Volume control, to enable you to dial in your overall volume without destroying the sustain and gain characteristics of the preamp.
One of the goals was to offer maximum flexibility, while simplifying the amount of controls and inputs. The back panel features an impedance selector for your choice of 4/8 or 16 ohm cabinets, and individual bias test points to enable easy biasing without pulling the chassis. You can check your bias with a standard multi meter set to Millivolts, there is a bias adjustment pot on the top of the chassis. Along with Miller's other new designs, the Columbia now runs in a lower voltage, higher current environment. This allows the tubes to create a more harmonically rich sound and last longer. It comes stock with a GZ34 rectifier for a tighter sound, but you can substitute an 5U4GB for more sag and compression.
As with all Miller builds, the components are built on G11 Glass board with hand pressed turret construction, F&T filter caps, 1% Mil-Spec Metal Film resistors and new Jupiter Vintage Tone & Red Aston coupling caps.
The Columbia comes standard in a smaller style Head and 2×12 semi open back speaker cabinet. Stock speakers will be a pair of Celestion Creamback “M” 65 watt speaker, others available as a special order. The Columbia comes stock in Red tolex and Salt & Pepper style grill cloth, other coverings and grills available.