This is a low power single-ended tridode (SET) hi-fi amp for the workshop. It is essentially a build of the Cascade Tubes "Zebrawood" amp: https://www.cascadetubes.com/the-6cy7-v2-0-zebrawood-amp/. I'm using transformers from MusicalPowerSupplies.com.
PCB design here is 388 x 194mm. It's the standard 1oz copper, 1.6mm thick. Everything is on the PCB. Mounted on a wooden base on 3/4 inch standoffs (including standoffs under the PT). Case is 20mm 80/20 T-slot rail with acrylic side panels. Complete overkill, but I like the industrial look!
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See https://github.com/eshazen/6cy7-amp/blob/main/BuildNotes.md
2021-02-20
Working on a second PCB. MPS has a long lead time on the PT.
Ordered two OT8SE OTs and one of these: AS-1T175 -- (2x 175V @ 280mA, 2x 6.3V @ 3A).
This thing is toroidal, 3.9" dia, 2" h. Plan to mount it vertically on a bracket above the PCB.
2021-01-15
It's done! Sounds great! A couple of concerns:
I forgot the R/C filter for the preamp stage B+. No audible defects due to this, but if someone else wants to consider using this PCB design the R+C should be added.
One of the "NOS" 6CY7s (a Tung-Sol, made in USA) ran very hot (right at 32mA, 5.4W plate diss.) with the 1k cathode resistor. Swapped it for another of indeterminate make and it is fine. Both channels now around 27mA (4.6W).
2021-01-03
- 2/29/20: Iron ordered from MusicalPowerSupplies.com for a ~ 1/15/21 ship date
- 1/2/21: Parts ordered from DigiKey and Antique Electronic Supply
- 1/3/21: PCBs ordered from JLC (white soldermask, black silkscreen, cool, eh?)
Total spent with some spare stuff thrown in ~ US $350.00. Hope to have it running by end of January!
Speakers Need some small bookshelf speakers to go with it. Will test the amp with what I have lying around before making any decisions. The easiest would be to buy another pair of Minimus-7's and apply the 'Zilch' crossover mod.