INSIDE LONDON POWER AMPLIFIERS:
TUBE CHOICE
STUDIO-10 rear - click to enlarge
STUDIO POWER AMP rear
- click to enlarge
London Power respects the player and gives the player choices. One such choice is the kind of power tube to use in an amp.
Iconic amplifier sounds are often built upon the sonic signature of a given tube: the EL-34 and the "British" sound; the 6L6 and the "American" sound, and so on. Considering that most of the popular octal-based power tubes used in guitar and bass amps have the same pin-out, the provision of easy-to-use bias test points and bias-set pots seems an obvious choice for the designer to make. But few companies offered this feature until a decade after London Power made this a standard feature in all of our amps.
Our early amps had internal tubes, so the meter jacks and bias pots were also internal. Once we had models with external tubes, the meter jacks and bias pots also became externally accessible. This coincidence of accessibility makes sense. London Power retains this coincidence of access on its current models.
Preamp tubes used in London Power amps are those in the 12A_7 family, or that are equivalents, such as: 12AT7, 12AU7, 12AX7, 12AY7, 5751, 7025, 7025A, ECC-81, ECC-82, ECC-83. London Power uses the 12V heater connection for these tubes, so variants that do not allow 12V operation cannot be used in our amps.
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