Factory matched full tube set for your Wooly Coats Spanky MKII 20w amplifier. Preamp tubes include: (2) JJ ECC83S short-plate version for American preamp and EQ 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 Spanky MKII amplifier is that your preamp and EQ tubes must have a wide soundstage with rich harmonics and smooth breakup when pushed. They also need to be low noise. Another key to this set is the (1) JJ GZ34 rectifier tube as it sets the temperament for the entire power supply of the amplifier. In the Spanky MKII, the JJ GZ34’s rugged build quality allows to to work very well with the higher plate voltages onboard this amplifier and exhibits the perfect amount of power supply ‘sag’ when you dig in. 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.