STUDIO and KC25 Tube Power Amps

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Price: $3,760 CAD
(approximately $3,018 USD)

Please contact London Power if you wish to order any of our Amp & Gear products, or if you have questions. We look forward to hearing from you (and we like to talk about our products).

See our page, Studio Gear Ordering.


London Power offers two feature-packed, all-tube power amplifiers for use in the studio or by musicians: the STUDIO and the KC25.

London Power All-Tube STUDIO Power Amplifier
London Power All-Tube STUDIO Power Amplifier (0-25W, 2U) – click to enlarge
London Power KC25 All-Tube EL-84 Power Amp
KC25 All-Tube EL-84 Power Amp (0-25W, 2U) – click to enlarge

Power Scaled 0-25W output
STUDIO uses any octal-based tube: 6V6, 6L6, 5881, 6550, EL-34, KT-66/77/88
KC25 uses EL-84 output tubes or E84L, EL-844, N709, 6BQ5, 6p15
• uses any 12A_7 tubes: 12AT7, 12AU7, 12AY7, 12AX7, ECC-81-/82/-83
• operate single-ended (SE) or push-pull (PP)
• either tube in cathode or fixed bias
• either tube in triode, ultralinear or pentode mode
• direct-impedance jacks for 4,8,16 ohms
• switched ‘Match’ speaker output
• pedal-friendly
• 2U, 6.1kg, 17″W x 3.3″H x 6.5″ D (plus tubes)
• 100V, 120V, 240V range switch
• rack-mountable with optional kit
• rubber foot storage on rear panel when rack mounted

PDF icon Download the Studio-KC25-Manual-for-web (123 kB PDF)

is the world’s first production guitar amp with Power Scaling. This proprietary technology allows players to use output stage compression and distortion effects within the Human Scale of loudness. Since its introduction in 1995, STUDIO has been in a class of its own – truly unique – with a range of tonal expression far beyond traditional tube amps. It can use all the common octal-based power tubes in singles, in pairs and in mixed pairs.

KC25 is a variation of STUDIO that uses EL-84 output tubes.

STUDIO and KC25 are identical in their capabilities apart from their output tube options, making KC25 the most versatile EL-84 amp ever produced. KC25 is in a class of its own as EL-84 amps go. It boasts a range of tonal expression far beyond traditional “18W” and “AC” amps, and is capable of using power tubes in singles, in pairs and in mixed pairs.

London Power Studio Amp rear
London Power STUDIO Amp rear – click to enlarge

STUDIO & KC25 combine a sophisticated power section with an equally sophisticated front-end. The input stage has true variable gain, and accommodates any signal amplitude with as pristine or warm a result as the player desires. Equalisation is distributed throughout the circuit, offering a much wider range of tone than that found in traditional guitar power amps. The touch responsiveness of the amp is affected by these and other controls, such as Vibe, and by the choice of tubes used.

STUDIO & KC25 can be used as a stand-alone guitar amp with effects pedals in front. You will hear exactly what the pedals do and exactly what the instrument does with them. STUDIO & KC25‘s input stage has far more headroom than that of a standard guitar amp, so over-driving the first stage grid is not possible, and thus grid-blocking distortion is avoided. The very low noise, high-quality components and careful circuit design make STUDIO a “tone microscope”.

Each power tube has its own bias switch for cathode biasing or fixed biasing and can be operated in triode, pentode or ultralinear mode. Both tubes can be set the same way or quite differently – one cathode biased and the other fixed biased, for example. Cathode bias is set here to maximize tonal difference at the expense of output power. Each power tube also has its own Level control, allowing either to be dialed out leaving the single-ended tone of the other tube. Bias pots and meter jacks are on the rear panel, accessible from the outside of the amp.

STUDIO accepts any of the pin-compatible octal-based power tubes singly, in pairs or in mixed pairs. Use any of: 6V6, 6L6, 5881, 6550, EL-34, E34L, KT-66, KT-77, KT-88, or any equivalents.

KC25 uses any EL-84 or equivalent tube in singles, pairs, or mixed pairs. Use 6BQ5, EL-84, E84L, EL-844, N709, 6p15

Yes – you can use a single power tube in STUDIO or KC25!

Power Scaling allows tube compression and distortion effects at any loudness down to a whisper. The standard loudness range is “unusably loud down to unusably quiet,” so the player or sound engineer can decide how quiet “quiet” is. The 25W maximum output is loud enough to damage hearing when used with typical high-efficiency guitar speakers, but Power Scaling lets you have “cranked” tone at safe sound pressure levels.

Specs & details:

STUDIO & KC25 incorporate all of London Power’s standard design and construction features:

• toroidal power and output transformers
• fusing for all power transformer windings
• worldwide mains compatibility – with 100V for Japan
• Galactic Grounding (learn about this in our book, The Ultimate Tone Vol. 3 – or ask us!)
• active hum filtering
• long-life capacitors low noise metal-film resistors
• metal-oxide and wire-wound power resistors
• zero wiring except for the transformer fly-leads
• zero standby power when switched ‘off’

You can rack mount STUDIO & KC25 using the optional 2U6-BRKT, sold as pairs.

Comments our awesome customers have shared with us:

“Fantastic tones”

“STUDIO can out-tweed a tweed amp”

“It’s amazing to be able to play really quietly but have this ripping overdrive for my recording.”

“KC25 does everything you said it would. I’m so pleased!”

Photo Gallery

London Power STUDIO amp from an angle
STUDIO amp from an angle
KC25 amp from above
London Power KC25 amp from above
Inside a London Power STUDIO amp
Inside STUDIO amp
Inside a London Power STUDIO amp
Inside STUDIO amp

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