This is the PCB of a preamplifier using popular low noise small signal triode tubes 12AX7 and 12AU7 to guarantee the performance. Supply voltage : +300VDC 20mA , +12.6VDC 1A for the filament. PCB dimension: 148mm x 94mm. PCB thickness 2mm. Thick copper ( 75um) is used, which is three times the normal thickness. Surface finishing : Double-sided solder resist for best reliability and durability ! Schematic is as shown in the listing. We provide a detail schematic with component values to customers by email. We do shipping worldwide at US$5.50 by registered airmail.