Cohort Alpha · July 30 – August 2, 2026

Six builders. Four days. "Six amps fired-up."

The founding cohort of The Foundry spent four days at our KSR shop in Middletown, Ohio. They arrived to a new tool kit, a bare chassis, a pile of parts, and they left with a KSR Ember they built, biased and played themselves.

4
Days
6
Builders
50W
Class AB, all-tube 6L6GC, 12AX7
4
Awards
THE FOUR DAYS

Theory only as deep as the build required.

01
Day 1

The probe came first.

Everyone arrived a guitarist. Before anyone touched the amp, they built a bias probe, a real bench tool they still own, and by mid-afternoon they were reading plate current off a working KSR amp. Ohm’s Law stopped being a lecture and became something they did.

02
Day 2

The chassis and the boards.

Preamp board in the morning, power tube board in the afternoon. Every component was placed and every joint soldered by the person who would play the amp, and by the end of the day both boards were seated in the chassis.

03
Day 3

The wiring.

The longest day: the ground scheme, the signal path, the output section. Lead dress done to KSR shop standard, it's a craft that takes practice to build skill.

04
Day 4

First light. Jam. Awards.

Variac up, voltages checked stage by stage, then the first sound out of each amp. Every builder set their bias with the probe they made on Day 1. Then the guitars came out.

Leading up to the class

Day 1 · Thursday, July 30

Day 2 · Friday, July 31

Day 3 · Saturday, August 1

Day 4 · Sunday, August 2

After the class

“The bias probe is the first thing you build.
It’s the last thing you put down.”
— Kyle Rhodes · KSR Amps
THE AWARDS

Six awards.

  • First to Fire (up)! -- Dave B.
  • Zero Defect! -- Justin K.
  • Cleanest Build! -- Tim W.
  • Most Improvement! -- Gabe M.
  • Best Troubleshooter! -- Brenton W.
  • Bhagavad Gita "I am become death, destroyer of worlds." -- Matt G.
WHAT WE CHANGED

Cohort Alpha made the Ember better.

The first six Embers were also the first real test of the design, and the builders found things. Within a week of class, Michael Klein had turned their notes into changes for Cohort Beta:

  • a daughter board for the effects loop
  • an added coupling capacitor, C14, on the layout and the BOM
  • jumpers at the five relay locations
  • new wire colors for the power and standby switches and for the output transformer
  • the input jack moved to IN_GS

Every Beta builder starts from the amp Alpha helped finish.

Cohort Beta starts October 1.

The same four days, the same shop, the same take-homes. Ten seats, and the last run of 2026.

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