Factory matched full tube set for your Clean Sink 20w amplifier. Preamp tubes include: (2) JJ ECC83S short-plate version for American and AC preamp circuits, and (2) Sovtek 12AX7LPS long-plate tubes for reverb and phase-inverter circuits. Power tubes include (2) Apex matched JJ 6V6 power tubes. The key to the best performance for the Clean Sink amplifier is that your preamp, mix and EQ tubes must be transparent and 3D with rich harmonics and smooth breakup when pushed. They also need to be low noise. All tubes are selected, installed and tested on the bench by our amp designer prior to shipping your order. Each set is made to order and ships within 3 – 5 business days.