Details:

This board high-voltage power supply uses a voltage-stabilizing circuit, which is adjusted by the Toshiba K2700 FET. The AC lighting method is used to supply the filament, one-point grounding, reasonable layout and routing, and the mutual interference of the tubes is minimized, and there is no noise.

PCB size: 155 x177 x 1.6MM FR4

Works voltage:
0-220V AC >=20mA，
AC3.15V -0- AC3.15V >=3A

This preamp are using 4pcs shuguang 6N8P Tubes.

This board with 30 seconds delay on output. can Avoid howling when power on.

Materials：

BC high-voltage filter capacitors

Chemical high-voltage decoupling capacitors

Famous brand copper foot metal film resistors （BC ,Dale ，Futaba etc）

Gold-plated electronic tube holders

FR SCR and IT ERO coupling capacitors

Note：

Diy kit：all the parts need yourself to solder.（not included 4pcs tubes）

Assembled board：have tested well，（not included 4pcs tubes）

Recommend transformer：https://www.ebay.com/itm/164824849177