The Apollo Preamp Drive Mk. II is a pedal that is based on the Catalinbread RAH, which is an adaptation of the custom Hiwatt amplifier used by Jimmy Page of Led Zeppelin during their “Royal Albert Hall” performance in 1970. The RAH was originally released in 2011 as the “Royal Albert Hall Edition WIIO” and was later discontinued after the release of the RAH.

The main difference between the RAH and the WIIO is the tone stack, which was adapted from Jimmy Page’s amp and differs from the standard Hiwatt amplifiers. The RAH includes a midrange knob for a full three-band tonestack, similar to the original amp. Some other values were tweaked to re-voice it for Led Zeppelin’s tone, but overall the RAH and WIIO are similar.

The RAH circuit uses MOSFETs instead of JFETs, making it stiffer and less compressed compared to other amp-based circuits from Catalinbread. It has been described as “unforgiving” in this regard, but it takes pedals well and benefits from a boosted or overdriven signal at the input.

The Apollo Mk. II is a direct adaptation of the RAH, with the only modification being the addition of a trimmer that allows adjustments to the gain, tone, and feel of the circuit. The WIIO is also available as the Apollo Mk. I.

It is important to note that according to Catalinbread, the WIIO (and thus the RAH and Apollo pedals) should only be run at 9V and should not be used with an 18V adapter or with the Aion FX 18V bypass PCB.

The WIIO and RAH were developed based on recordings of concerts that were held five weeks apart, with Led Zeppelin performing on January 9, 1970, and The Who on February 14.

Summary created by AI from the original source.