The Dirty Teen head is an 18W type amplifier with EF86 preamp.
The Dirty Teen 18W amplifier is my take on the famous short-lived 18W 1965 Marshall circuit. With two ECC83 preamp channels, two EL84s in the power amp and one EZ81 as a rectifier, the original amplifier shared most of its genes with the venerable Vox AC15. A lesser-known fact is that it actually shared all of its genes with the 1960 Watkins W20T Dominator. Marshall simply copied the Watkins schematic to a tee as they had done some years before when they cloned a Fender Bassman and called it the JTM45. Hey! If Marshall did it and got away with it, all of us can do it!
A few years ago this circuit was brought back to the spotlight by the nice folks at 18watt.com, who were generous enough to share their knowledge with the world. The original schematic and many ideas and variations of the circuit can be found there. One of the most popular modifications among hobbyists and boutique amp builders is substituting one of the ECC83 channels with a a Vox-style EF86 preamp.
I built one for myself, loved the sound and decided that it would be a nice addition to my line of amplifiers consisting of one model only.
The Dirty Teen has only one channel, and mounts a EF86 as its preamp tube. The EF86 is a single pentode that has more gain than a regular ECC83. The EF86 provides the classic early Vox chime and growl, but it is also very sensitive to vibrations so in return it needs to be well taken care of. That's why the Dirty Teen comes in a head format only. You can see it here pictured with a matching 2x12” cabinet equipped with Celestions.
The high gain of the EF86 is tamed through a Gain toggle switch, for cleaner sounds. Two different EQ circuits follow the first gain stage: a 6-way Colour rotary switch which selects different capacitors for different voicings, and a Bass/Treble EQ circuit, fully switchable to avoid any insertion loss. It is my experience that the fewer components in the signal path, the better an amplifier sounds, so the EQ circuit can be completely switched off without affecting the signal, but only if you need to.
All the Dirty Teen amps come with a set of custom TDS transformers, Sozo signal capacitors, 2W PEC potentiometers, F&T electrolytics and carbon composition resistors.