As a follow-up of the germanium-transistor loaded 1967 Hornby-Skewes Treble Booster now the 1969 version, equipped with one of the earliest FET´s available, appears on the scene under the BSM brand Mk2. This was Ritchie Blackmore´s favourite booster for small and semi-small stages. You can hear this special sound at the 1971 "Beat Club" shows (songs: No No No & Highway Star) or the 1972 BBC Tapes from the famous radio show - this tells more than 1.000 words, doesn´t it ?!?
With less gain compared to it´s forerunner, less distortion but mild and shimmering heighs and a whole lot of airy dynamics, reacting very sensitive to the individual playing style of each player. The long yearned for new edition, now issued under the name Mk2 from BSM, includes the same field-effect transistors as the the original 1969 version.
Almost all British rock guitarists using single coil pickup guitars used a germanium Treble Booster from the late 60's to the mid 70's. By the end of the seventies, the Treble Booster was replaced by a new circuit from Japan, the so called Tube Screamer and other similar overdrive circuits. These were based on the old Treble Boosters and therefore had a very similar frequency response. The treble boosters on the other hand, sadly fell into oblivion despite their unique and inimitable sound. The Mk2 Treble Booster has been designed for single coil or humbucking pickups with a relatively low coil inductance, such as pickups in Fender, Rickenbacker, Gibson. On these pickups, the Mk2 produces (with the volume control of the guitar turned up to the max) a fat, biting and penetrating lead sound, minus any shrill characteristics. By lowering the guitar's volume control, many shades of crunch can be easily dialed in. Another thing to consider is that when a guitar amp's volume is turned up (reaching saturation), the power amp normally begins to mute the highs, which results in a duller sound. At an amp's full tilt, the Mk2 Treble Booster allows a more transparent tone (covering the entire frequency range) to shine through. The presence control on the amp need only be minimally used (if at all). When vintage amps are used (such as the Fender Deluxe, Fender Bassman, Vox AC30, Marshall 100w or Marshall Major) it is amazing what effect the use of a good treble booster has. BSM additionally added a "FOCUS" control to make sure that the Mk2 will be compatible to todays modern pickup-palette. It is also of interest to note that Ritchie Blackmore used modded Marshall Major 200 heads and played on "Beat-club" with the following settings: Presence 0; Bass 5; Middle 5; Treble 6; Volume 6.
The Treble Booster is inserted between guitar and amplifier, not into the FX loop. The magical tone is achieved by the interaction between guitar pickup, treble booster and amplifier. The unit is powered by a 9V battery with a current consumption of approx. 400 uA. The average output level is 7dBm, the maximum output voltage when the strings are struck really hard is 5V max.